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Procedure
Given an array of elements with values or records sorted such that , and target value , the following subroutine uses binary search to find the index of in .
Set to and to .
If , the search terminates as unsuccessful.
Set (the position of the middle element) to the floor of , which is the greatest integer less than or equal to .
If , set to and go to step 2.
If , set to and go to step 2.
Now , the search is done; return .
This iterative procedure keeps track of the search boundaries with the two variables and . The procedure may be expressed in pseudocode as follows, where the variable names and types remain the same as above, floor is the floor function, and unsuccessful refers to a specific value that conveys the failure of the search.
function binary_search(A, n, T) is
L := 0
R := n − 1
while L ≤ R do
m := floor((L + R) / 2)
if A[m] < T then
L := m + 1
else if A[m] > T then
R := m − 1
else:
return m
return unsuccessful
Alternatively, the algorithm may take the ceiling of . This may change the result if the target value appears more than once in the array.
Alternative procedure
In the above procedure, the algorithm checks whether the middle element () is equal to the target () in every iteration. Some implementations leave out this check during each iteration. The algorithm would perform this check only when one element is left (when ). This results in a faster comparison loop, as one comparison is eliminated per iteration, while it requires only one more iteration on average.
Hermann Bottenbruch published the first implementation to leave out this check in 1962.
Set to and to .
While ,
Set (the position of the middle element) to the ceiling of , which is the least integer greater than or equal to .
If , set to .
Else, ; set to .
Now , the search is done. If , return . Otherwise, the search terminates as unsuccessful.
Where ceil is the ceiling function, the pseudocode for this version is: | Binary search | Wikipedia | 437 | 4266 | https://en.wikipedia.org/wiki/Binary%20search | Mathematics | Algorithms | null |
function binary_search_alternative(A, n, T) is
L := 0
R := n − 1
while L != R do
m := ceil((L + R) / 2)
if A[m] > T then
R := m − 1
else:
L := m
if A[L] = T then
return L
return unsuccessful
Duplicate elements
The procedure may return any index whose element is equal to the target value, even if there are duplicate elements in the array. For example, if the array to be searched was and the target was , then it would be correct for the algorithm to either return the 4th (index 3) or 5th (index 4) element. The regular procedure would return the 4th element (index 3) in this case. It does not always return the first duplicate (consider which still returns the 4th element). However, it is sometimes necessary to find the leftmost element or the rightmost element for a target value that is duplicated in the array. In the above example, the 4th element is the leftmost element of the value 4, while the 5th element is the rightmost element of the value 4. The alternative procedure above will always return the index of the rightmost element if such an element exists.
Procedure for finding the leftmost element
To find the leftmost element, the following procedure can be used:
Set to and to .
While ,
Set (the position of the middle element) to the floor of , which is the greatest integer less than or equal to .
If , set to .
Else, ; set to .
Return .
If and , then is the leftmost element that equals . Even if is not in the array, is the rank of in the array, or the number of elements in the array that are less than .
Where floor is the floor function, the pseudocode for this version is:
function binary_search_leftmost(A, n, T):
L := 0
R := n
while L < R:
m := floor((L + R) / 2)
if A[m] < T:
L := m + 1
else:
R := m
return L
Procedure for finding the rightmost element
To find the rightmost element, the following procedure can be used:
Set to and to .
While ,
Set (the position of the middle element) to the floor of , which is the greatest integer less than or equal to .
If , set to .
Else, ; set to .
Return . | Binary search | Wikipedia | 509 | 4266 | https://en.wikipedia.org/wiki/Binary%20search | Mathematics | Algorithms | null |
If and , then is the rightmost element that equals . Even if is not in the array, is the number of elements in the array that are greater than .
Where floor is the floor function, the pseudocode for this version is:
function binary_search_rightmost(A, n, T):
L := 0
R := n
while L < R:
m := floor((L + R) / 2)
if A[m] > T:
R := m
else:
L := m + 1
return R - 1
Approximate matches
The above procedure only performs exact matches, finding the position of a target value. However, it is trivial to extend binary search to perform approximate matches because binary search operates on sorted arrays. For example, binary search can be used to compute, for a given value, its rank (the number of smaller elements), predecessor (next-smallest element), successor (next-largest element), and nearest neighbor. Range queries seeking the number of elements between two values can be performed with two rank queries.
Rank queries can be performed with the procedure for finding the leftmost element. The number of elements less than the target value is returned by the procedure.
Predecessor queries can be performed with rank queries. If the rank of the target value is , its predecessor is .
For successor queries, the procedure for finding the rightmost element can be used. If the result of running the procedure for the target value is , then the successor of the target value is .
The nearest neighbor of the target value is either its predecessor or successor, whichever is closer.
Range queries are also straightforward. Once the ranks of the two values are known, the number of elements greater than or equal to the first value and less than the second is the difference of the two ranks. This count can be adjusted up or down by one according to whether the endpoints of the range should be considered to be part of the range and whether the array contains entries matching those endpoints.
Performance | Binary search | Wikipedia | 412 | 4266 | https://en.wikipedia.org/wiki/Binary%20search | Mathematics | Algorithms | null |
In terms of the number of comparisons, the performance of binary search can be analyzed by viewing the run of the procedure on a binary tree. The root node of the tree is the middle element of the array. The middle element of the lower half is the left child node of the root, and the middle element of the upper half is the right child node of the root. The rest of the tree is built in a similar fashion. Starting from the root node, the left or right subtrees are traversed depending on whether the target value is less or more than the node under consideration.
In the worst case, binary search makes iterations of the comparison loop, where the notation denotes the floor function that yields the greatest integer less than or equal to the argument, and is the binary logarithm. This is because the worst case is reached when the search reaches the deepest level of the tree, and there are always levels in the tree for any binary search.
The worst case may also be reached when the target element is not in the array. If is one less than a power of two, then this is always the case. Otherwise, the search may perform iterations if the search reaches the deepest level of the tree. However, it may make iterations, which is one less than the worst case, if the search ends at the second-deepest level of the tree.
On average, assuming that each element is equally likely to be searched, binary search makes iterations when the target element is in the array. This is approximately equal to iterations. When the target element is not in the array, binary search makes iterations on average, assuming that the range between and outside elements is equally likely to be searched.
In the best case, where the target value is the middle element of the array, its position is returned after one iteration. | Binary search | Wikipedia | 372 | 4266 | https://en.wikipedia.org/wiki/Binary%20search | Mathematics | Algorithms | null |
In terms of iterations, no search algorithm that works only by comparing elements can exhibit better average and worst-case performance than binary search. The comparison tree representing binary search has the fewest levels possible as every level above the lowest level of the tree is filled completely. Otherwise, the search algorithm can eliminate few elements in an iteration, increasing the number of iterations required in the average and worst case. This is the case for other search algorithms based on comparisons, as while they may work faster on some target values, the average performance over all elements is worse than binary search. By dividing the array in half, binary search ensures that the size of both subarrays are as similar as possible.
Space complexity
Binary search requires three pointers to elements, which may be array indices or pointers to memory locations, regardless of the size of the array. Therefore, the space complexity of binary search is in the word RAM model of computation.
Derivation of average case
The average number of iterations performed by binary search depends on the probability of each element being searched. The average case is different for successful searches and unsuccessful searches. It will be assumed that each element is equally likely to be searched for successful searches. For unsuccessful searches, it will be assumed that the intervals between and outside elements are equally likely to be searched. The average case for successful searches is the number of iterations required to search every element exactly once, divided by , the number of elements. The average case for unsuccessful searches is the number of iterations required to search an element within every interval exactly once, divided by the intervals.
Successful searches
In the binary tree representation, a successful search can be represented by a path from the root to the target node, called an internal path. The length of a path is the number of edges (connections between nodes) that the path passes through. The number of iterations performed by a search, given that the corresponding path has length , is counting the initial iteration. The internal path length is the sum of the lengths of all unique internal paths. Since there is only one path from the root to any single node, each internal path represents a search for a specific element. If there are elements, which is a positive integer, and the internal path length is , then the average number of iterations for a successful search , with the one iteration added to count the initial iteration.
Since binary search is the optimal algorithm for searching with comparisons, this problem is reduced to calculating the minimum internal path length of all binary trees with nodes, which is equal to: | Binary search | Wikipedia | 512 | 4266 | https://en.wikipedia.org/wiki/Binary%20search | Mathematics | Algorithms | null |
For example, in a 7-element array, the root requires one iteration, the two elements below the root require two iterations, and the four elements below require three iterations. In this case, the internal path length is:
The average number of iterations would be based on the equation for the average case. The sum for can be simplified to:
Substituting the equation for into the equation for :
For integer , this is equivalent to the equation for the average case on a successful search specified above.
Unsuccessful searches
Unsuccessful searches can be represented by augmenting the tree with external nodes, which forms an extended binary tree. If an internal node, or a node present in the tree, has fewer than two child nodes, then additional child nodes, called external nodes, are added so that each internal node has two children. By doing so, an unsuccessful search can be represented as a path to an external node, whose parent is the single element that remains during the last iteration. An external path is a path from the root to an external node. The external path length is the sum of the lengths of all unique external paths. If there are elements, which is a positive integer, and the external path length is , then the average number of iterations for an unsuccessful search , with the one iteration added to count the initial iteration. The external path length is divided by instead of because there are external paths, representing the intervals between and outside the elements of the array.
This problem can similarly be reduced to determining the minimum external path length of all binary trees with nodes. For all binary trees, the external path length is equal to the internal path length plus . Substituting the equation for :
Substituting the equation for into the equation for , the average case for unsuccessful searches can be determined: | Binary search | Wikipedia | 359 | 4266 | https://en.wikipedia.org/wiki/Binary%20search | Mathematics | Algorithms | null |
Performance of alternative procedure
Each iteration of the binary search procedure defined above makes one or two comparisons, checking if the middle element is equal to the target in each iteration. Assuming that each element is equally likely to be searched, each iteration makes 1.5 comparisons on average. A variation of the algorithm checks whether the middle element is equal to the target at the end of the search. On average, this eliminates half a comparison from each iteration. This slightly cuts the time taken per iteration on most computers. However, it guarantees that the search takes the maximum number of iterations, on average adding one iteration to the search. Because the comparison loop is performed only times in the worst case, the slight increase in efficiency per iteration does not compensate for the extra iteration for all but very large .
Running time and cache use
In analyzing the performance of binary search, another consideration is the time required to compare two elements. For integers and strings, the time required increases linearly as the encoding length (usually the number of bits) of the elements increase. For example, comparing a pair of 64-bit unsigned integers would require comparing up to double the bits as comparing a pair of 32-bit unsigned integers. The worst case is achieved when the integers are equal. This can be significant when the encoding lengths of the elements are large, such as with large integer types or long strings, which makes comparing elements expensive. Furthermore, comparing floating-point values (the most common digital representation of real numbers) is often more expensive than comparing integers or short strings.
On most computer architectures, the processor has a hardware cache separate from RAM. Since they are located within the processor itself, caches are much faster to access but usually store much less data than RAM. Therefore, most processors store memory locations that have been accessed recently, along with memory locations close to it. For example, when an array element is accessed, the element itself may be stored along with the elements that are stored close to it in RAM, making it faster to sequentially access array elements that are close in index to each other (locality of reference). On a sorted array, binary search can jump to distant memory locations if the array is large, unlike algorithms (such as linear search and linear probing in hash tables) which access elements in sequence. This adds slightly to the running time of binary search for large arrays on most systems. | Binary search | Wikipedia | 479 | 4266 | https://en.wikipedia.org/wiki/Binary%20search | Mathematics | Algorithms | null |
Binary search versus other schemes
Sorted arrays with binary search are a very inefficient solution when insertion and deletion operations are interleaved with retrieval, taking time for each such operation. In addition, sorted arrays can complicate memory use especially when elements are often inserted into the array. There are other data structures that support much more efficient insertion and deletion. Binary search can be used to perform exact matching and set membership (determining whether a target value is in a collection of values). There are data structures that support faster exact matching and set membership. However, unlike many other searching schemes, binary search can be used for efficient approximate matching, usually performing such matches in time regardless of the type or structure of the values themselves. In addition, there are some operations, like finding the smallest and largest element, that can be performed efficiently on a sorted array.
Linear search
Linear search is a simple search algorithm that checks every record until it finds the target value. Linear search can be done on a linked list, which allows for faster insertion and deletion than an array. Binary search is faster than linear search for sorted arrays except if the array is short, although the array needs to be sorted beforehand. All sorting algorithms based on comparing elements, such as quicksort and merge sort, require at least comparisons in the worst case. Unlike linear search, binary search can be used for efficient approximate matching. There are operations such as finding the smallest and largest element that can be done efficiently on a sorted array but not on an unsorted array.
Trees
A binary search tree is a binary tree data structure that works based on the principle of binary search. The records of the tree are arranged in sorted order, and each record in the tree can be searched using an algorithm similar to binary search, taking on average logarithmic time. Insertion and deletion also require on average logarithmic time in binary search trees. This can be faster than the linear time insertion and deletion of sorted arrays, and binary trees retain the ability to perform all the operations possible on a sorted array, including range and approximate queries. | Binary search | Wikipedia | 433 | 4266 | https://en.wikipedia.org/wiki/Binary%20search | Mathematics | Algorithms | null |
However, binary search is usually more efficient for searching as binary search trees will most likely be imperfectly balanced, resulting in slightly worse performance than binary search. This even applies to balanced binary search trees, binary search trees that balance their own nodes, because they rarely produce the tree with the fewest possible levels. Except for balanced binary search trees, the tree may be severely imbalanced with few internal nodes with two children, resulting in the average and worst-case search time approaching comparisons. Binary search trees take more space than sorted arrays.
Binary search trees lend themselves to fast searching in external memory stored in hard disks, as binary search trees can be efficiently structured in filesystems. The B-tree generalizes this method of tree organization. B-trees are frequently used to organize long-term storage such as databases and filesystems.
Hashing
For implementing associative arrays, hash tables, a data structure that maps keys to records using a hash function, are generally faster than binary search on a sorted array of records. Most hash table implementations require only amortized constant time on average. However, hashing is not useful for approximate matches, such as computing the next-smallest, next-largest, and nearest key, as the only information given on a failed search is that the target is not present in any record. Binary search is ideal for such matches, performing them in logarithmic time. Binary search also supports approximate matches. Some operations, like finding the smallest and largest element, can be done efficiently on sorted arrays but not on hash tables.
Set membership algorithms
A related problem to search is set membership. Any algorithm that does lookup, like binary search, can also be used for set membership. There are other algorithms that are more specifically suited for set membership. A bit array is the simplest, useful when the range of keys is limited. It compactly stores a collection of bits, with each bit representing a single key within the range of keys. Bit arrays are very fast, requiring only time. The Judy1 type of Judy array handles 64-bit keys efficiently.
For approximate results, Bloom filters, another probabilistic data structure based on hashing, store a set of keys by encoding the keys using a bit array and multiple hash functions. Bloom filters are much more space-efficient than bit arrays in most cases and not much slower: with hash functions, membership queries require only time. However, Bloom filters suffer from false positives. | Binary search | Wikipedia | 501 | 4266 | https://en.wikipedia.org/wiki/Binary%20search | Mathematics | Algorithms | null |
Other data structures
There exist data structures that may improve on binary search in some cases for both searching and other operations available for sorted arrays. For example, searches, approximate matches, and the operations available to sorted arrays can be performed more efficiently than binary search on specialized data structures such as van Emde Boas trees, fusion trees, tries, and bit arrays. These specialized data structures are usually only faster because they take advantage of the properties of keys with a certain attribute (usually keys that are small integers), and thus will be time or space consuming for keys that lack that attribute. As long as the keys can be ordered, these operations can always be done at least efficiently on a sorted array regardless of the keys. Some structures, such as Judy arrays, use a combination of approaches to mitigate this while retaining efficiency and the ability to perform approximate matching.
Variations
Uniform binary search
Uniform binary search stores, instead of the lower and upper bounds, the difference in the index of the middle element from the current iteration to the next iteration. A lookup table containing the differences is computed beforehand. For example, if the array to be searched is , the middle element () would be . In this case, the middle element of the left subarray () is and the middle element of the right subarray () is . Uniform binary search would store the value of as both indices differ from by this same amount. To reduce the search space, the algorithm either adds or subtracts this change from the index of the middle element. Uniform binary search may be faster on systems where it is inefficient to calculate the midpoint, such as on decimal computers.
Exponential search
Exponential search extends binary search to unbounded lists. It starts by finding the first element with an index that is both a power of two and greater than the target value. Afterwards, it sets that index as the upper bound, and switches to binary search. A search takes iterations before binary search is started and at most iterations of the binary search, where is the position of the target value. Exponential search works on bounded lists, but becomes an improvement over binary search only if the target value lies near the beginning of the array.
Interpolation search | Binary search | Wikipedia | 451 | 4266 | https://en.wikipedia.org/wiki/Binary%20search | Mathematics | Algorithms | null |
Instead of calculating the midpoint, interpolation search estimates the position of the target value, taking into account the lowest and highest elements in the array as well as length of the array. It works on the basis that the midpoint is not the best guess in many cases. For example, if the target value is close to the highest element in the array, it is likely to be located near the end of the array.
A common interpolation function is linear interpolation. If is the array, are the lower and upper bounds respectively, and is the target, then the target is estimated to be about of the way between and . When linear interpolation is used, and the distribution of the array elements is uniform or near uniform, interpolation search makes comparisons.
In practice, interpolation search is slower than binary search for small arrays, as interpolation search requires extra computation. Its time complexity grows more slowly than binary search, but this only compensates for the extra computation for large arrays.
Fractional cascading
Fractional cascading is a technique that speeds up binary searches for the same element in multiple sorted arrays. Searching each array separately requires time, where is the number of arrays. Fractional cascading reduces this to by storing specific information in each array about each element and its position in the other arrays.
Fractional cascading was originally developed to efficiently solve various computational geometry problems. Fractional cascading has been applied elsewhere, such as in data mining and Internet Protocol routing. | Binary search | Wikipedia | 309 | 4266 | https://en.wikipedia.org/wiki/Binary%20search | Mathematics | Algorithms | null |
Generalization to graphs
Binary search has been generalized to work on certain types of graphs, where the target value is stored in a vertex instead of an array element. Binary search trees are one such generalization—when a vertex (node) in the tree is queried, the algorithm either learns that the vertex is the target, or otherwise which subtree the target would be located in. However, this can be further generalized as follows: given an undirected, positively weighted graph and a target vertex, the algorithm learns upon querying a vertex that it is equal to the target, or it is given an incident edge that is on the shortest path from the queried vertex to the target. The standard binary search algorithm is simply the case where the graph is a path. Similarly, binary search trees are the case where the edges to the left or right subtrees are given when the queried vertex is unequal to the target. For all undirected, positively weighted graphs, there is an algorithm that finds the target vertex in queries in the worst case.
Noisy binary search
Noisy binary search algorithms solve the case where the algorithm cannot reliably compare elements of the array. For each pair of elements, there is a certain probability that the algorithm makes the wrong comparison. Noisy binary search can find the correct position of the target with a given probability that controls the reliability of the yielded position. Every noisy binary search procedure must make at least comparisons on average, where is the binary entropy function and is the probability that the procedure yields the wrong position. The noisy binary search problem can be considered as a case of the Rényi-Ulam game, a variant of Twenty Questions where the answers may be wrong.
Quantum binary search
Classical computers are bounded to the worst case of exactly iterations when performing binary search. Quantum algorithms for binary search are still bounded to a proportion of queries (representing iterations of the classical procedure), but the constant factor is less than one, providing for a lower time complexity on quantum computers. Any exact quantum binary search procedure—that is, a procedure that always yields the correct result—requires at least queries in the worst case, where is the natural logarithm. There is an exact quantum binary search procedure that runs in queries in the worst case. In comparison, Grover's algorithm is the optimal quantum algorithm for searching an unordered list of elements, and it requires queries. | Binary search | Wikipedia | 491 | 4266 | https://en.wikipedia.org/wiki/Binary%20search | Mathematics | Algorithms | null |
History
The idea of sorting a list of items to allow for faster searching dates back to antiquity. The earliest known example was the Inakibit-Anu tablet from Babylon dating back to . The tablet contained about 500 sexagesimal numbers and their reciprocals sorted in lexicographical order, which made searching for a specific entry easier. In addition, several lists of names that were sorted by their first letter were discovered on the Aegean Islands. Catholicon, a Latin dictionary finished in 1286 CE, was the first work to describe rules for sorting words into alphabetical order, as opposed to just the first few letters.
In 1946, John Mauchly made the first mention of binary search as part of the Moore School Lectures, a seminal and foundational college course in computing. In 1957, William Wesley Peterson published the first method for interpolation search. Every published binary search algorithm worked only for arrays whose length is one less than a power of two until 1960, when Derrick Henry Lehmer published a binary search algorithm that worked on all arrays. In 1962, Hermann Bottenbruch presented an ALGOL 60 implementation of binary search that placed the comparison for equality at the end, increasing the average number of iterations by one, but reducing to one the number of comparisons per iteration. The uniform binary search was developed by A. K. Chandra of Stanford University in 1971. In 1986, Bernard Chazelle and Leonidas J. Guibas introduced fractional cascading as a method to solve numerous search problems in computational geometry.
Implementation issues
When Jon Bentley assigned binary search as a problem in a course for professional programmers, he found that ninety percent failed to provide a correct solution after several hours of working on it, mainly because the incorrect implementations failed to run or returned a wrong answer in rare edge cases. A study published in 1988 shows that accurate code for it is only found in five out of twenty textbooks. Furthermore, Bentley's own implementation of binary search, published in his 1986 book Programming Pearls, contained an overflow error that remained undetected for over twenty years. The Java programming language library implementation of binary search had the same overflow bug for more than nine years. | Binary search | Wikipedia | 442 | 4266 | https://en.wikipedia.org/wiki/Binary%20search | Mathematics | Algorithms | null |
In a practical implementation, the variables used to represent the indices will often be of fixed size (integers), and this can result in an arithmetic overflow for very large arrays. If the midpoint of the span is calculated as , then the value of may exceed the range of integers of the data type used to store the midpoint, even if and are within the range. If and are nonnegative, this can be avoided by calculating the midpoint as .
An infinite loop may occur if the exit conditions for the loop are not defined correctly. Once exceeds , the search has failed and must convey the failure of the search. In addition, the loop must be exited when the target element is found, or in the case of an implementation where this check is moved to the end, checks for whether the search was successful or failed at the end must be in place. Bentley found that most of the programmers who incorrectly implemented binary search made an error in defining the exit conditions.
Library support
Many languages' standard libraries include binary search routines: | Binary search | Wikipedia | 208 | 4266 | https://en.wikipedia.org/wiki/Binary%20search | Mathematics | Algorithms | null |
C provides the function bsearch() in its standard library, which is typically implemented via binary search, although the official standard does not require it so.
C++'s standard library provides the functions binary_search(), lower_bound(), upper_bound() and equal_range().
D's standard library Phobos, in std.range module provides a type SortedRange (returned by sort() and assumeSorted() functions) with methods contains(), equaleRange(), lowerBound() and trisect(), that use binary search techniques by default for ranges that offer random access.
COBOL provides the SEARCH ALL verb for performing binary searches on COBOL ordered tables.
Go's sort standard library package contains the functions Search, SearchInts, SearchFloat64s, and SearchStrings, which implement general binary search, as well as specific implementations for searching slices of integers, floating-point numbers, and strings, respectively.
Java offers a set of overloaded binarySearch() static methods in the classes and in the standard java.util package for performing binary searches on Java arrays and on Lists, respectively.
Microsoft's .NET Framework 2.0 offers static generic versions of the binary search algorithm in its collection base classes. An example would be System.Array's method BinarySearch<T>(T[] array, T value).
For Objective-C, the Cocoa framework provides the method in Mac OS X 10.6+. Apple's Core Foundation C framework also contains a CFArrayBSearchValues() function.
Python provides the bisect module that keeps a list in sorted order without having to sort the list after each insertion.
Ruby's Array class includes a bsearch method with built-in approximate matching.
Rust's slice primitive provides binary_search(), binary_search_by(), binary_search_by_key(), and partition_point(). | Binary search | Wikipedia | 418 | 4266 | https://en.wikipedia.org/wiki/Binary%20search | Mathematics | Algorithms | null |
A base pair (bp) is a fundamental unit of double-stranded nucleic acids consisting of two nucleobases bound to each other by hydrogen bonds. They form the building blocks of the DNA double helix and contribute to the folded structure of both DNA and RNA. Dictated by specific hydrogen bonding patterns, "Watson–Crick" (or "Watson–Crick–Franklin") base pairs (guanine–cytosine and adenine–thymine) allow the DNA helix to maintain a regular helical structure that is subtly dependent on its nucleotide sequence. The complementary nature of this based-paired structure provides a redundant copy of the genetic information encoded within each strand of DNA. The regular structure and data redundancy provided by the DNA double helix make DNA well suited to the storage of genetic information, while base-pairing between DNA and incoming nucleotides provides the mechanism through which DNA polymerase replicates DNA and RNA polymerase transcribes DNA into RNA. Many DNA-binding proteins can recognize specific base-pairing patterns that identify particular regulatory regions of genes.
Intramolecular base pairs can occur within single-stranded nucleic acids. This is particularly important in RNA molecules (e.g., transfer RNA), where Watson–Crick base pairs (guanine–cytosine and adenine–uracil) permit the formation of short double-stranded helices, and a wide variety of non–Watson–Crick interactions (e.g., G–U or A–A) allow RNAs to fold into a vast range of specific three-dimensional structures. In addition, base-pairing between transfer RNA (tRNA) and messenger RNA (mRNA) forms the basis for the molecular recognition events that result in the nucleotide sequence of mRNA becoming translated into the amino acid sequence of proteins via the genetic code. | Base pair | Wikipedia | 383 | 4292 | https://en.wikipedia.org/wiki/Base%20pair | Biology and health sciences | Nucleic acids | Biology |
The size of an individual gene or an organism's entire genome is often measured in base pairs because DNA is usually double-stranded. Hence, the number of total base pairs is equal to the number of nucleotides in one of the strands (with the exception of non-coding single-stranded regions of telomeres). The haploid human genome (23 chromosomes) is estimated to be about 3.2 billion base pairs long and to contain 20,000–25,000 distinct protein-coding genes. A kilobase (kb) is a unit of measurement in molecular biology equal to 1000 base pairs of DNA or RNA. The total number of DNA base pairs on Earth is estimated at 5.0 with a weight of 50 billion tonnes. In comparison, the total mass of the biosphere has been estimated to be as much as 4 TtC (trillion tons of carbon).
Hydrogen bonding and stability
Top, a G.C base pair with three hydrogen bonds. Bottom, an A.T base pair with two hydrogen bonds. Non-covalent hydrogen bonds between the bases are shown as dashed lines. The wiggly lines stand for the connection to the pentose sugar and point in the direction of the minor groove.
Hydrogen bonding is the chemical interaction that underlies the base-pairing rules described above. Appropriate geometrical correspondence of hydrogen bond donors and acceptors allows only the "right" pairs to form stably. DNA with high GC-content is more stable than DNA with low GC-content. Crucially, however, stacking interactions are primarily responsible for stabilising the double-helical structure; Watson-Crick base pairing's contribution to global structural stability is minimal, but its role in the specificity underlying complementarity is, by contrast, of maximal importance as this underlies the template-dependent processes of the central dogma (e.g. DNA replication). | Base pair | Wikipedia | 390 | 4292 | https://en.wikipedia.org/wiki/Base%20pair | Biology and health sciences | Nucleic acids | Biology |
The bigger nucleobases, adenine and guanine, are members of a class of double-ringed chemical structures called purines; the smaller nucleobases, cytosine and thymine (and uracil), are members of a class of single-ringed chemical structures called pyrimidines. Purines are complementary only with pyrimidines: pyrimidine–pyrimidine pairings are energetically unfavorable because the molecules are too far apart for hydrogen bonding to be established; purine–purine pairings are energetically unfavorable because the molecules are too close, leading to overlap repulsion. Purine–pyrimidine base-pairing of AT or GC or UA (in RNA) results in proper duplex structure. The only other purine–pyrimidine pairings would be AC and GT and UG (in RNA); these pairings are mismatches because the patterns of hydrogen donors and acceptors do not correspond. The GU pairing, with two hydrogen bonds, does occur fairly often in RNA (see wobble base pair).
Paired DNA and RNA molecules are comparatively stable at room temperature, but the two nucleotide strands will separate above a melting point that is determined by the length of the molecules, the extent of mispairing (if any), and the GC content. Higher GC content results in higher melting temperatures; it is, therefore, unsurprising that the genomes of extremophile organisms such as Thermus thermophilus are particularly GC-rich. On the converse, regions of a genome that need to separate frequently — for example, the promoter regions for often-transcribed genes — are comparatively GC-poor (for example, see TATA box). GC content and melting temperature must also be taken into account when designing primers for PCR reactions.
Examples
The following DNA sequences illustrate pair double-stranded patterns. By convention, the top strand is written from the 5′-end to the 3′-end; thus, the bottom strand is written 3′ to 5′.
A base-paired DNA sequence:
The corresponding RNA sequence, in which uracil is substituted for thymine in the RNA strand:
Base analogs and intercalators | Base pair | Wikipedia | 480 | 4292 | https://en.wikipedia.org/wiki/Base%20pair | Biology and health sciences | Nucleic acids | Biology |
Chemical analogs of nucleotides can take the place of proper nucleotides and establish non-canonical base-pairing, leading to errors (mostly point mutations) in DNA replication and DNA transcription. This is due to their isosteric chemistry. One common mutagenic base analog is 5-bromouracil, which resembles thymine but can base-pair to guanine in its enol form.
Other chemicals, known as DNA intercalators, fit into the gap between adjacent bases on a single strand and induce frameshift mutations by "masquerading" as a base, causing the DNA replication machinery to skip or insert additional nucleotides at the intercalated site. Most intercalators are large polyaromatic compounds and are known or suspected carcinogens. Examples include ethidium bromide and acridine.
Mismatch repair
Mismatched base pairs can be generated by errors of DNA replication and as intermediates during homologous recombination. The process of mismatch repair ordinarily must recognize and correctly repair a small number of base mispairs within a long sequence of normal DNA base pairs. To repair mismatches formed during DNA replication, several distinctive repair processes have evolved to distinguish between the template strand and the newly formed strand so that only the newly inserted incorrect nucleotide is removed (in order to avoid generating a mutation). The proteins employed in mismatch repair during DNA replication, and the clinical significance of defects in this process are described in the article DNA mismatch repair. The process of mispair correction during recombination is described in the article gene conversion.
Length measurements
The following abbreviations are commonly used to describe the length of a D/RNA molecule:
bp = base pair—one bp corresponds to approximately 3.4 Å (340 pm) of length along the strand, and to roughly 618 or 643 daltons for DNA and RNA respectively.
kb (= kbp) = kilo–base-pair = 1,000 bp
Mb (= Mbp) = mega–base-pair = 1,000,000 bp
Gb (= Gbp) = giga–base-pair = 1,000,000,000 bp | Base pair | Wikipedia | 459 | 4292 | https://en.wikipedia.org/wiki/Base%20pair | Biology and health sciences | Nucleic acids | Biology |
For single-stranded DNA/RNA, units of nucleotides are used—abbreviated nt (or knt, Mnt, Gnt)—as they are not paired.
To distinguish between units of computer storage and bases, kbp, Mbp, Gbp, etc. may be used for base pairs.
The centimorgan is also often used to imply distance along a chromosome, but the number of base pairs it corresponds to varies widely. In the human genome, the centimorgan is about 1 million base pairs.
Unnatural base pair (UBP)
An unnatural base pair (UBP) is a designed subunit (or nucleobase) of DNA which is created in a laboratory and does not occur in nature. DNA sequences have been described which use newly created nucleobases to form a third base pair, in addition to the two base pairs found in nature, A-T (adenine – thymine) and G-C (guanine – cytosine). A few research groups have been searching for a third base pair for DNA, including teams led by Steven A. Benner, Philippe Marliere, Floyd E. Romesberg and Ichiro Hirao. Some new base pairs based on alternative hydrogen bonding, hydrophobic interactions and metal coordination have been reported.
In 1989 Steven Benner (then working at the Swiss Federal Institute of Technology in Zurich) and his team led with modified forms of cytosine and guanine into DNA molecules in vitro. The nucleotides, which encoded RNA and proteins, were successfully replicated in vitro. Since then, Benner's team has been trying to engineer cells that can make foreign bases from scratch, obviating the need for a feedstock. | Base pair | Wikipedia | 358 | 4292 | https://en.wikipedia.org/wiki/Base%20pair | Biology and health sciences | Nucleic acids | Biology |
In 2002, Ichiro Hirao's group in Japan developed an unnatural base pair between 2-amino-8-(2-thienyl)purine (s) and pyridine-2-one (y) that functions in transcription and translation, for the site-specific incorporation of non-standard amino acids into proteins. In 2006, they created 7-(2-thienyl)imidazo[4,5-b]pyridine (Ds) and pyrrole-2-carbaldehyde (Pa) as a third base pair for replication and transcription. Afterward, Ds and 4-[3-(6-aminohexanamido)-1-propynyl]-2-nitropyrrole (Px) was discovered as a high fidelity pair in PCR amplification. In 2013, they applied the Ds-Px pair to DNA aptamer generation by in vitro selection (SELEX) and demonstrated the genetic alphabet expansion significantly augment DNA aptamer affinities to target proteins.
In 2012, a group of American scientists led by Floyd Romesberg, a chemical biologist at the Scripps Research Institute in San Diego, California, published that his team designed an unnatural base pair (UBP). The two new artificial nucleotides or Unnatural Base Pair (UBP) were named d5SICS and dNaM. More technically, these artificial nucleotides bearing hydrophobic nucleobases, feature two fused aromatic rings that form a (d5SICS–dNaM) complex or base pair in DNA. His team designed a variety of in vitro or "test tube" templates containing the unnatural base pair and they confirmed that it was efficiently replicated with high fidelity in virtually all sequence contexts using the modern standard in vitro techniques, namely PCR amplification of DNA and PCR-based applications. Their results show that for PCR and PCR-based applications, the d5SICS–dNaM unnatural base pair is functionally equivalent to a natural base pair, and when combined with the other two natural base pairs used by all organisms, A–T and G–C, they provide a fully functional and expanded six-letter "genetic alphabet". | Base pair | Wikipedia | 470 | 4292 | https://en.wikipedia.org/wiki/Base%20pair | Biology and health sciences | Nucleic acids | Biology |
In 2014 the same team from the Scripps Research Institute reported that they synthesized a stretch of circular DNA known as a plasmid containing natural T-A and C-G base pairs along with the best-performing UBP Romesberg's laboratory had designed and inserted it into cells of the common bacterium E. coli that successfully replicated the unnatural base pairs through multiple generations. The transfection did not hamper the growth of the E. coli cells and showed no sign of losing its unnatural base pairs to its natural DNA repair mechanisms. This is the first known example of a living organism passing along an expanded genetic code to subsequent generations. Romesberg said he and his colleagues created 300 variants to refine the design of nucleotides that would be stable enough and would be replicated as easily as the natural ones when the cells divide. This was in part achieved by the addition of a supportive algal gene that expresses a nucleotide triphosphate transporter which efficiently imports the triphosphates of both d5SICSTP and dNaMTP into E. coli bacteria. Then, the natural bacterial replication pathways use them to accurately replicate a plasmid containing d5SICS–dNaM. Other researchers were surprised that the bacteria replicated these human-made DNA subunits.
The successful incorporation of a third base pair is a significant breakthrough toward the goal of greatly expanding the number of amino acids which can be encoded by DNA, from the existing 20 amino acids to a theoretically possible 172, thereby expanding the potential for living organisms to produce novel proteins. The artificial strings of DNA do not encode for anything yet, but scientists speculate they could be designed to manufacture new proteins which could have industrial or pharmaceutical uses. Experts said the synthetic DNA incorporating the unnatural base pair raises the possibility of life forms based on a different DNA code.
Non-canonical base pairing
In addition to the canonical pairing, some conditions can also favour base-pairing with alternative base orientation, and number and geometry of hydrogen bonds. These pairings are accompanied by alterations to the local backbone shape.
The most common of these is the wobble base pairing that occurs between tRNAs and mRNAs at the third base position of many codons during transcription and during the charging of tRNAs by some tRNA synthetases. They have also been observed in the secondary structures of some RNA sequences. | Base pair | Wikipedia | 481 | 4292 | https://en.wikipedia.org/wiki/Base%20pair | Biology and health sciences | Nucleic acids | Biology |
Additionally, Hoogsteen base pairing (typically written as A•U/T and G•C) can exist in some DNA sequences (e.g. CA and TA dinucleotides) in dynamic equilibrium with standard Watson–Crick pairing. They have also been observed in some protein–DNA complexes.
In addition to these alternative base pairings, a wide range of base-base hydrogen bonding is observed in RNA secondary and tertiary structure. These bonds are often necessary for the precise, complex shape of an RNA, as well as its binding to interaction partners. | Base pair | Wikipedia | 116 | 4292 | https://en.wikipedia.org/wiki/Base%20pair | Biology and health sciences | Nucleic acids | Biology |
In computer science, a binary search tree (BST), also called an ordered or sorted binary tree, is a rooted binary tree data structure with the key of each internal node being greater than all the keys in the respective node's left subtree and less than the ones in its right subtree. The time complexity of operations on the binary search tree is linear with respect to the height of the tree.
Binary search trees allow binary search for fast lookup, addition, and removal of data items. Since the nodes in a BST are laid out so that each comparison skips about half of the remaining tree, the lookup performance is proportional to that of binary logarithm. BSTs were devised in the 1960s for the problem of efficient storage of labeled data and are attributed to Conway Berners-Lee and David Wheeler.
The performance of a binary search tree is dependent on the order of insertion of the nodes into the tree since arbitrary insertions may lead to degeneracy; several variations of the binary search tree can be built with guaranteed worst-case performance. The basic operations include: search, traversal, insert and delete. BSTs with guaranteed worst-case complexities perform better than an unsorted array, which would require linear search time.
The complexity analysis of BST shows that, on average, the insert, delete and search takes for nodes. In the worst case, they degrade to that of a singly linked list: . To address the boundless increase of the tree height with arbitrary insertions and deletions, self-balancing variants of BSTs are introduced to bound the worst lookup complexity to that of the binary logarithm. AVL trees were the first self-balancing binary search trees, invented in 1962 by Georgy Adelson-Velsky and Evgenii Landis.
Binary search trees can be used to implement abstract data types such as dynamic sets, lookup tables and priority queues, and used in sorting algorithms such as tree sort.
History
The binary search tree algorithm was discovered independently by several researchers, including P.F. Windley, Andrew Donald Booth, Andrew Colin, Thomas N. Hibbard. The algorithm is attributed to Conway Berners-Lee and David Wheeler, who used it for storing labeled data in magnetic tapes in 1960. One of the earliest and popular binary search tree algorithm is that of Hibbard. | Binary search tree | Wikipedia | 490 | 4320 | https://en.wikipedia.org/wiki/Binary%20search%20tree | Mathematics | Data structures and types | null |
The time complexities of a binary search tree increases boundlessly with the tree height if the nodes are inserted in an arbitrary order, therefore self-balancing binary search trees were introduced to bound the height of the tree to . Various height-balanced binary search trees were introduced to confine the tree height, such as AVL trees, Treaps, and red–black trees.
The AVL tree was invented by Georgy Adelson-Velsky and Evgenii Landis in 1962 for the efficient organization of information. It was the first self-balancing binary search tree to be invented.
Overview
A binary search tree is a rooted binary tree in which nodes are arranged in strict total order in which the nodes with keys greater than any particular node A is stored on the right sub-trees to that node A and the nodes with keys equal to or less than A are stored on the left sub-trees to A, satisfying the binary search property.
Binary search trees are also efficacious in sortings and search algorithms. However, the search complexity of a BST depends upon the order in which the nodes are inserted and deleted; since in worst case, successive operations in the binary search tree may lead to degeneracy and form a singly linked list (or "unbalanced tree") like structure, thus has the same worst-case complexity as a linked list.
Binary search trees are also a fundamental data structure used in construction of abstract data structures such as sets, multisets, and associative arrays.
Operations
Searching
Searching in a binary search tree for a specific key can be programmed recursively or iteratively.
Searching begins by examining the root node. If the tree is , the key being searched for does not exist in the tree. Otherwise, if the key equals that of the root, the search is successful and the node is returned. If the key is less than that of the root, the search proceeds by examining the left subtree. Similarly, if the key is greater than that of the root, the search proceeds by examining the right subtree. This process is repeated until the key is found or the remaining subtree is . If the searched key is not found after a subtree is reached, then the key is not present in the tree.
Recursive search
The following pseudocode implements the BST search procedure through recursion.
The recursive procedure continues until a or the being searched for are encountered. | Binary search tree | Wikipedia | 500 | 4320 | https://en.wikipedia.org/wiki/Binary%20search%20tree | Mathematics | Data structures and types | null |
Iterative search
The recursive version of the search can be "unrolled" into a while loop. On most machines, the iterative version is found to be more efficient.
Since the search may proceed till some leaf node, the running time complexity of BST search is where is the height of the tree. However, the worst case for BST search is where is the total number of nodes in the BST, because an unbalanced BST may degenerate to a linked list. However, if the BST is height-balanced the height is .
Successor and predecessor
For certain operations, given a node , finding the successor or predecessor of is crucial. Assuming all the keys of a BST are distinct, the successor of a node in a BST is the node with the smallest key greater than 's key. On the other hand, the predecessor of a node in a BST is the node with the largest key smaller than 's key. The following pseudocode finds the successor and predecessor of a node in a BST.
Operations such as finding a node in a BST whose key is the maximum or minimum are critical in certain operations, such as determining the successor and predecessor of nodes. Following is the pseudocode for the operations.
Insertion
Operations such as insertion and deletion cause the BST representation to change dynamically. The data structure must be modified in such a way that the properties of BST continue to hold. New nodes are inserted as leaf nodes in the BST. Following is an iterative implementation of the insertion operation.
The procedure maintains a "trailing pointer" as a parent of . After initialization on line 2, the while loop along lines 4-11 causes the pointers to be updated. If is , the BST is empty, thus is inserted as the root node of the binary search tree , if it is not , insertion proceeds by comparing the keys to that of on the lines 15-19 and the node is inserted accordingly.
Deletion | Binary search tree | Wikipedia | 406 | 4320 | https://en.wikipedia.org/wiki/Binary%20search%20tree | Mathematics | Data structures and types | null |
The deletion of a node, say , from the binary search tree has three cases:
If is a leaf node, the parent node of gets replaced by and consequently is removed from the , as shown in (a).
If has only one child, the child node of gets elevated by modifying the parent node of to point to the child node, consequently taking 's position in the tree, as shown in (b) and (c).
If has both left and right children, the successor of , say , displaces by following the two cases:
If is 's right child, as shown in (d), displaces and 's right child remain unchanged.
If lies within 's right subtree but is not 's right child, as shown in (e), first gets replaced by its own right child, and then it displaces 's position in the tree.
The following pseudocode implements the deletion operation in a binary search tree.
The procedure deals with the 3 special cases mentioned above. Lines 2-3 deal with case 1; lines 4-5 deal with case 2 and lines 6-16 for case 3. The helper function is used within the deletion algorithm for the purpose of replacing the node with in the binary search tree . This procedure handles the deletion (and substitution) of from .
Traversal
A BST can be traversed through three basic algorithms: inorder, preorder, and postorder tree walks.
Inorder tree walk: Nodes from the left subtree get visited first, followed by the root node and right subtree. Such a traversal visits all the nodes in the order of non-decreasing key sequence.
Preorder tree walk: The root node gets visited first, followed by left and right subtrees.
Postorder tree walk: Nodes from the left subtree get visited first, followed by the right subtree, and finally, the root.
Following is a recursive implementation of the tree walks.
Balanced binary search trees | Binary search tree | Wikipedia | 419 | 4320 | https://en.wikipedia.org/wiki/Binary%20search%20tree | Mathematics | Data structures and types | null |
Without rebalancing, insertions or deletions in a binary search tree may lead to degeneration, resulting in a height of the tree (where is number of items in a tree), so that the lookup performance is deteriorated to that of a linear search. Keeping the search tree balanced and height bounded by is a key to the usefulness of the binary search tree. This can be achieved by "self-balancing" mechanisms during the updation operations to the tree designed to maintain the tree height to the binary logarithmic complexity.
Height-balanced trees
A tree is height-balanced if the heights of the left sub-tree and right sub-tree are guaranteed to be related by a constant factor. This property was introduced by the AVL tree and continued by the red–black tree. The heights of all the nodes on the path from the root to the modified leaf node have to be observed and possibly corrected on every insert and delete operation to the tree.
Weight-balanced trees
In a weight-balanced tree, the criterion of a balanced tree is the number of leaves of the subtrees. The weights of the left and right subtrees differ at most by . However, the difference is bound by a ratio of the weights, since a strong balance condition of cannot be maintained with rebalancing work during insert and delete operations. The -weight-balanced trees gives an entire family of balance conditions, where each left and right subtrees have each at least a fraction of of the total weight of the subtree.
Types
There are several self-balanced binary search trees, including T-tree, treap, red-black tree, B-tree, 2–3 tree, and Splay tree.
Examples of applications
Sort
Binary search trees are used in sorting algorithms such as tree sort, where all the elements are inserted at once and the tree is traversed at an in-order fashion. BSTs are also used in quicksort.
Priority queue operations
Binary search trees are used in implementing priority queues, using the node's key as priorities. Adding new elements to the queue follows the regular BST insertion operation but the removal operation depends on the type of priority queue:
If it is an ascending order priority queue, removal of an element with the lowest priority is done through leftward traversal of the BST.
If it is a descending order priority queue, removal of an element with the highest priority is done through rightward traversal of the BST. | Binary search tree | Wikipedia | 507 | 4320 | https://en.wikipedia.org/wiki/Binary%20search%20tree | Mathematics | Data structures and types | null |
A boomerang () is a thrown tool typically constructed with airfoil sections and designed to spin about an axis perpendicular to the direction of its flight. A returning boomerang is designed to return to the thrower, while a non-returning boomerang is designed as a weapon to be thrown straight. Various forms of Boomerang like designs are traditionally used by some Aboriginal Australians for hunting, pre-colonialisation they had a multitude of names.
Historically, boomerangs have been used for hunting, sport, and entertainment and are made in various shapes and sizes to suit different purposes. Although considered an Australian icon, ancient boomerangs have also been discovered in Egypt, the Americas, and Eurasia.
Description
A boomerang is a throwing stick with aerodynamic properties, traditionally made of wood, but also of bone, horn, tusks and even iron. Modern boomerangs used for sport can be made from plywood or plastics such as ABS, polypropylene, phenolic paper, or carbon fibre-reinforced plastics.
Boomerangs come in many shapes and sizes depending on their geographic or tribal origins and intended function, including the traditional Australian type, the cross-stick, the pinwheel, the tumble-stick, the Boomabird, and other less common types. | Boomerang | Wikipedia | 263 | 4359 | https://en.wikipedia.org/wiki/Boomerang | Technology | Projectile weapons | null |
Returning boomerangs fly, and are examples of the earliest heavier-than-air human-made flight. A returning boomerang has two or more aerofoil section wings arranged so that when spinning they create unbalanced aerodynamic forces that curve its path into an ellipse, returning to its point of origin when thrown correctly. Their typical L-shape makes them the most recognisable form of boomerang. Although used primarily for leisure or recreation, returning boomerangs are also used to decoy birds of prey, thrown above the long grass to frighten game birds into flight and into waiting nets. Non-traditional, modern, competition boomerangs come in many shapes, sizes and materials.
Throwing sticks, valari, or kylies, are primarily used as weapons. They lack the aerofoil sections, are generally heavier and designed to travel as straight and forcefully as possible to the target to bring down game. The Tamil valari variant, of ancient origin and mentioned in the Tamil Sangam literature "Purananuru", was one of these. The usual form of the Valari is two limbs set at an angle; one thin and tapering, the other rounded as a handle. Valaris come in many shapes and sizes. They are usually made of iron and cast from moulds. Some may have wooden limbs tipped with iron or sharpened edges.
Etymology
The origin of the term is uncertain. One source asserts that the term entered the language in 1827, adapted from an Aboriginal language of New South Wales, Australia, but mentions a variant, wo-mur-rang, which it dates to 1798. The first recorded encounter with a boomerang by Europeans was at Farm Cove (Port Jackson), in December 1804, when a weapon was witnessed during a tribal skirmish:
David Collins listed "Wo-mur-rāng" as one of eight Aboriginal "Names of clubs" in 1798. but was probably referring to the woomera, which is actually a spear-thrower. An anonymous 1790 manuscript on Aboriginal languages of New South Wales reported "Boo-mer-rit" as "the Scimiter".
In 1822, it was described in detail and recorded as a "bou-mar-rang" in the language of the Turuwal people (a sub-group of the Darug) of the Georges River near Port Jackson. The Turawal used other words for their hunting sticks but used "boomerang" to refer to a returning throw-stick.
History | Boomerang | Wikipedia | 510 | 4359 | https://en.wikipedia.org/wiki/Boomerang | Technology | Projectile weapons | null |
Boomerangs were, historically, used as hunting weapons, percussive musical instruments, battle clubs, fire-starters, decoys for hunting waterfowl, and as recreational play toys. The smallest boomerang may be less than from tip to tip, and the largest over in length. Tribal boomerangs may be inscribed or painted with designs meaningful to their makers. Most boomerangs seen today are of the tourist or competition sort, and are almost invariably of the returning type.
Depictions of boomerangs being thrown at animals, such as kangaroos, appear in some of the oldest rock art in the world, the Indigenous Australian rock art of the Kimberley region, which is potentially up to 50,000 years old. Stencils and paintings of boomerangs also appear in the rock art of West Papua, including on Bird's Head Peninsula and Kaimana, likely dating to the Last Glacial Maximum, when lower sea levels led to cultural continuity between Papua and Arnhem Land in Northern Australia. The oldest surviving Australian Aboriginal boomerang was found in a peat bog in the Wyrie Swamp of South Australia in 1973. It was dated to 10,000 BC and is held by the South Australian Museum in Adelaide.
Although traditionally thought of as Australian, boomerangs have been found also in ancient Europe, Egypt, and North America. There is evidence of the use of non-returning boomerangs by the Native Americans of California and Arizona, and inhabitants of South India for killing birds and rabbits. Some boomerangs were not thrown at all, but were used in hand to hand combat by Indigenous Australians. Ancient Egyptian examples, however, have been recovered, and experiments have shown that they functioned as returning boomerangs. Hunting sticks discovered in Europe seem to have formed part of the Stone Age arsenal of weapons. One boomerang that was discovered in Obłazowa Cave in the Carpathian Mountains in Poland was made of mammoth's tusk and is believed, based on AMS dating of objects found with it, to be about 30,000 years old. In the Netherlands, boomerangs have been found in Vlaardingen and Velsen from the first century BC. King Tutankhamun owned a collection of boomerangs of both the straight flying (hunting) and returning variety. | Boomerang | Wikipedia | 469 | 4359 | https://en.wikipedia.org/wiki/Boomerang | Technology | Projectile weapons | null |
No one knows for sure how the returning boomerang was invented, but some modern boomerang makers speculate that it developed from the flattened throwing stick, still used by Aboriginal Australians and other indigenous peoples around the world, including the Navajo in North America. A hunting boomerang is delicately balanced and much harder to make than a returning one. The curving flight characteristic of returning boomerangs was probably first noticed by early hunters trying to "tune" their throwing sticks to fly straight.
It is thought by some that the shape and elliptical flight path of the returning boomerang makes it useful for hunting birds and small animals, or that noise generated by the movement of the boomerang through the air, or, by a skilled thrower, lightly clipping leaves of a tree whose branches house birds, would help scare the birds towards the thrower. It is further supposed by some that this was used to frighten flocks or groups of birds into nets that were usually strung up between trees or thrown by hidden hunters. In southeastern Australia, it is claimed that boomerangs were made to hover over a flock of ducks; mistaking it for a hawk, the ducks would dive away, toward hunters armed with nets or clubs.
Traditionally, most boomerangs used by Aboriginal groups in Australia were non-returning. These weapons, sometimes called "throwsticks" or "kylies", were used for hunting a variety of prey, from kangaroos to parrots; at a range of about , a non-returning boomerang could inflict mortal injury to a large animal. A throwstick thrown nearly horizontally may fly in a nearly straight path and could fell a kangaroo on impact to the legs or knees, while the long-necked emu could be killed by a blow to the neck. Hooked non-returning boomerangs, known as "beaked kylies", used in northern Central Australia, have been claimed to kill multiple birds when thrown into a dense flock. Throwsticks are used as multi-purpose tools by today's Aboriginal peoples, and besides throwing could be wielded as clubs, used for digging, used to start friction fires, and are sonorous when two are struck together.
Recent evidence also suggests that boomerangs were used as war weapons.
Modern use | Boomerang | Wikipedia | 466 | 4359 | https://en.wikipedia.org/wiki/Boomerang | Technology | Projectile weapons | null |
Today, boomerangs are mostly used for recreation. There are different types of throwing contests: accuracy of return; Aussie round; trick catch; maximum time aloft; fast catch; and endurance (see below). The modern sport boomerang (often referred to as a 'boom' or 'rang') is made of Finnish birch plywood, hardwood, plastic or composite materials and comes in many different shapes and colours. Most sport boomerangs typically weigh less than , with MTA boomerangs (boomerangs used for the maximum-time-aloft event) often under .
Boomerangs have also been suggested as an alternative to clay pigeons in shotgun sports, where the flight of the boomerang better mimics the flight of a bird offering a more challenging target.
The modern boomerang is often computer-aided designed with precision airfoils. The number of "wings" is often more than 2 as more lift is provided by 3 or 4 wings than by 2. Among the latest inventions is a round-shaped boomerang, which has a different look but using the same returning principle as traditional boomerangs. This allows for safer catch for players.
In 1992, German astronaut Ulf Merbold performed an experiment aboard Spacelab that established that boomerangs function in zero gravity as they do on Earth. French Astronaut Jean-François Clervoy aboard Mir repeated this in 1997. In 2008, Japanese astronaut Takao Doi again repeated the experiment on board the International Space Station.
Beginning in the later part of the twentieth century, there has been a bloom in the independent creation of unusually designed art boomerangs. These often have little or no resemblance to the traditional historical ones and on first sight some of these objects may not look like boomerangs at all. The use of modern thin plywoods and synthetic plastics have greatly contributed to their success. Designs are very diverse and can range from animal inspired forms, humorous themes, complex calligraphic and symbolic shapes, to the purely abstract. Painted surfaces are similarly richly diverse. Some boomerangs made primarily as art objects do not have the required aerodynamic properties to return.
Aerodynamics
A returning boomerang is a rotating wing. It consists of two or more arms, or wings, connected at an angle; each wing is shaped as an airfoil section. Although it is not a requirement that a boomerang be in its traditional shape, it is usually flat. | Boomerang | Wikipedia | 496 | 4359 | https://en.wikipedia.org/wiki/Boomerang | Technology | Projectile weapons | null |
Boomerangs can be made for right- or left-handed throwers. The difference between right and left is subtle, the planform is the same but the leading edges of the aerofoil sections are reversed. A right-handed boomerang makes a counter-clockwise, circular flight to the left while a left-handed boomerang flies clockwise to the right. Most sport boomerangs weigh between , have a wingspan, and a range.
A falling boomerang starts spinning, and most then fall in a spiral. When the boomerang is thrown with high spin, a boomerang flies in a curved rather than a straight line. When thrown correctly, a boomerang returns to its starting point. As the wing rotates and the boomerang moves through the air, the airflow over the wings creates lift on both "wings". However, during one-half of each blade's rotation, it sees a higher airspeed, because the rotation tip speed and the forward speed add, and when it is in the other half of the rotation, the tip speed subtracts from the forward speed. Thus if thrown nearly upright, each blade generates more lift at the top than the bottom. While it might be expected that this would cause the boomerang to tilt around the axis of travel, because the boomerang has significant angular momentum, the gyroscopic precession causes the plane of rotation to tilt about an axis that is 90 degrees to the direction of flight, causing it to turn. When thrown in the horizontal plane, as with a Frisbee, instead of in the vertical, the same gyroscopic precession will cause the boomerang to fly violently, straight up into the air and then crash.
Fast Catch boomerangs usually have three or more symmetrical wings (seen from above), whereas a Long Distance boomerang is most often shaped similar to a question mark. Maximum Time Aloft boomerangs mostly have one wing considerably longer than the other. This feature, along with carefully executed bends and twists in the wings help to set up an "auto-rotation" effect to maximise the boomerang's hover time in descending from the highest point in its flight.
Some boomerangs have turbulators — bumps or pits on the top surface that act to increase the lift as boundary layer transition activators (to keep attached turbulent flow instead of laminar separation). | Boomerang | Wikipedia | 501 | 4359 | https://en.wikipedia.org/wiki/Boomerang | Technology | Projectile weapons | null |
Throwing technique
Boomerangs are generally thrown in unobstructed, open spaces at least twice as large as the range of the boomerang. The flight direction to the left or right depends upon the design of the boomerang itself, not the thrower. A right-handed or left-handed boomerang can be thrown with either hand, but throwing a boomerang with the non-matching hand requires a throwing motion that many throwers find awkward. The following technique applies to a right-handed boomerang; the directions are mirrored for a left-handed boomerang. Different boomerang designs have different flight characteristics and are suitable for different conditions. The accuracy of the throw depends on understanding the weight and aerodynamics of that particular boomerang, and the strength, consistency and direction of the wind; from this, the thrower chooses the angle of tilt, the angle against the wind, the elevation of the trajectory, the degree of spin and the strength of the throw. A great deal of trial and error is required to perfect the throw over time.
A properly thrown boomerang will travel out parallel to the ground, sometimes climbing gently, perform a graceful, anti-clockwise, circular or tear-drop shaped arc, flatten out and return in a hovering motion, coming in from the left or spiralling in from behind. Ideally, the hover will allow a practiced catcher to clamp their hands shut horizontally on the boomerang from above and below, sandwiching the centre between their hands.
The grip used depends on size and shape; smaller boomerangs are held between finger and thumb at one end, while larger, heavier or wider boomerangs need one or two fingers wrapped over the top edge in order to induce a spin. The aerofoil-shaped section must face the inside of the thrower, and the flatter side outwards. It is usually inclined outwards, from a nearly vertical position to 20° or 30°; the stronger the wind, the closer to vertical. The elbow of the boomerang can point forwards or backwards, or it can be gripped for throwing; it just needs to start spinning on the required inclination, in the desired direction, with the right force. | Boomerang | Wikipedia | 453 | 4359 | https://en.wikipedia.org/wiki/Boomerang | Technology | Projectile weapons | null |
The boomerang is aimed to the right of the oncoming wind; the exact angle depends on the strength of the wind and the boomerang itself. Left-handed boomerangs are thrown to the left of the wind and will fly a clockwise flight path. The trajectory is either parallel to the ground or slightly upwards. The boomerang can return without the aid of any wind, but even very slight winds must be taken into account however calm they might seem. Little or no wind is preferable for an accurate throw, light winds up to are manageable with skill. If the wind is strong enough to fly a kite, then it may be too strong unless a skilled thrower is using a boomerang designed for stability in stronger winds. Gusty days are a great challenge, and the thrower must be keenly aware of the ebb and flow of the wind strength, finding appropriate lulls in the gusts to launch their boomerang.
Competitions and records
A world record achievement was made on 3 June 2007 by Tim Lendrum in Aussie Round. Lendrum scored 96 out of 100, giving him a national record as well as an equal world record throwing an "AYR" made by expert boomerang maker Adam Carroll.
In international competition, a world cup is held every second year. , teams from Germany and the United States dominated international competition. The individual World Champion title was won in 2000, 2002, 2004, 2012, and 2016 by Swiss thrower Manuel Schütz. In 1992, 1998, 2006, and 2008 Fridolin Frost from Germany won the title.
The team competitions of 2012 and 2014 were won by Boomergang (an international team). World champions were Germany in 2012 and Japan in 2014 for the first time. Boomergang was formed by individuals from several countries, including the Colombian Alejandro Palacio. In 2016 USA became team world champion.
Competition disciplines
Modern boomerang tournaments usually involve some or all of the events listed below In all disciplines the boomerang must travel at least from the thrower. Throwing takes place individually. The thrower stands at the centre of concentric rings marked on an open field.
Events include: | Boomerang | Wikipedia | 442 | 4359 | https://en.wikipedia.org/wiki/Boomerang | Technology | Projectile weapons | null |
Aussie Round: considered by many to be the ultimate test of boomeranging skills. The boomerang should ideally cross the circle and come right back to the centre. Each thrower has five attempts. Points are awarded for distance, accuracy and the catch.
Accuracy: points are awarded according to how close the boomerang lands to the centre of the rings. The thrower must not touch the boomerang after it has been thrown. Each thrower has five attempts. In major competitions there are two accuracy disciplines: Accuracy 100 and Accuracy 50.
Endurance: points are awarded for the number of catches achieved in 5 minutes.
Fast Catch: the time taken to throw and catch the boomerang five times. The winner has the fastest timed catches.
Trick Catch/Doubling: points are awarded for trick catches behind the back, between the feet, and so on. In Doubling, the thrower has to throw two boomerangs at the same time and catch them in sequence in a special way.
Consecutive Catch: points are awarded for the number of catches achieved before the boomerang is dropped. The event is not timed.
MTA 100 (Maximal Time Aloft, ): points are awarded for the length of time spent by the boomerang in the air. The field is normally a circle measuring 100 m. An alternative to this discipline, without the 100 m restriction is called MTA unlimited.
Long Distance: the boomerang is thrown from the middle point of a baseline. The furthest distance travelled by the boomerang away from the baseline is measured. On returning, the boomerang must cross the baseline again but does not have to be caught. A special section is dedicated to LD below.
Juggling: as with Consecutive Catch, only with two boomerangs. At any given time one boomerang must be in the air.
World records
Guinness World Record – Smallest Returning Boomerang
Non-discipline record: Smallest Returning Boomerang: Sadir Kattan of Australia in 1997 with long and wide. This tiny boomerang flew the required , before returning to the accuracy circles on 22 March 1997 at the Australian National Championships.
Guinness World Record – Longest Throw of Any Object by a Human
A boomerang was used to set a Guinness World Record with a throw of by David Schummy on 15 March 2005 at Murarrie Recreation Ground, Australia. This broke the record set by Erin Hemmings who threw an Aerobie on 14 July 2003 at Fort Funston, San Francisco. | Boomerang | Wikipedia | 509 | 4359 | https://en.wikipedia.org/wiki/Boomerang | Technology | Projectile weapons | null |
Long-distance versions
Long-distance boomerang throwers aim to have the boomerang go the furthest possible distance while returning close to the throwing point. In competition the boomerang must intersect an imaginary surface defined as an infinite vertical projection of a line centred on the thrower. Outside of competitions, the definition is not so strict, and throwers may be happy simply not to walk too far to recover the boomerang.
General properties
Long-distance boomerangs are optimised to have minimal drag while still having enough lift to fly and return. For this reason, they have a very narrow throwing window, which discourages many beginners from continuing with this discipline. For the same reason, the quality of manufactured long-distance boomerangs is often difficult to determine.
Today's long-distance boomerangs have almost all an S or ? – question mark shape and have a beveled edge on both sides (the bevel on the bottom side is sometimes called an undercut). This is to minimise drag and lower the lift. Lift must be low because the boomerang is thrown with an almost total layover (flat). Long-distance boomerangs are most frequently made of composite material, mainly fibre glass epoxy composites.
Flight path
The projection of the flight path of long-distance boomerang on the ground resembles a water drop. For older types of long-distance boomerangs (all types of so-called big hooks), the first and last third of the flight path are very low, while the middle third is a fast climb followed by a fast descent. Nowadays, boomerangs are made in a way that their whole flight path is almost planar with a constant climb during the first half of the trajectory and then a rather constant descent during the second half. | Boomerang | Wikipedia | 373 | 4359 | https://en.wikipedia.org/wiki/Boomerang | Technology | Projectile weapons | null |
From theoretical point of view, distance boomerangs are interesting also for the following reason: for achieving a different behaviour during different flight phases, the ratio of the rotation frequency to the forward velocity has a U-shaped function, i.e., its derivative crosses 0. Practically, it means that the boomerang being at the furthest point has a very low forward velocity. The kinetic energy of the forward component is then stored in the potential energy. This is not true for other types of boomerangs, where the loss of kinetic energy is non-reversible (the MTAs also store kinetic energy in potential energy during the first half of the flight, but then the potential energy is lost directly by the drag).
Related terms
In Noongar language, kylie is a flat curved piece of wood similar in appearance to a boomerang that is thrown when hunting for birds and animals. "Kylie" is one of the Aboriginal words for the hunting stick used in warfare and for hunting animals. Instead of following curved flight paths, kylies fly in straight lines from the throwers. They are typically much larger than boomerangs, and can travel very long distances; due to their size and hook shapes, they can cripple or kill an animal or human opponent. The word is perhaps an English corruption of a word meaning "boomerang" taken from one of the Western Desert languages, for example, the Warlpiri word "karli".
Cultural references
Trademarks of Australian companies using the boomerang as a symbol, emblem or logo proliferate, usually removed from Aboriginal context and symbolising "returning" or to distinguish an Australian brand. Early examples included Bain's White Ant Exterminator (1896); Webendorfer Bros. explosives (1898); E. A. Adams Foods (1920); and by the (still current) Boomerang Cigarette Papers Pty. Ltd. | Boomerang | Wikipedia | 391 | 4359 | https://en.wikipedia.org/wiki/Boomerang | Technology | Projectile weapons | null |
"Aboriginalia", including the boomerang, as symbols of Australia dates from the late 1940s and early 1950s and was in widespread use by a largely European arts, crafts and design community. By the 1960s, the Australian tourism industry extended it to the very branding of Australia, particularly to overseas and domestic tourists as souvenirs and gifts and thus Aboriginal culture. At the very time when Aboriginal people and culture were subject to policies that removed them from their traditional lands and sought to assimilate them (physiologically and culturally) into mainstream white Australian culture, causing the Stolen Generations, Aboriginalia found an ironically "nostalgic", entry point into Australian popular culture at important social locations: holiday resorts and in Australian domestic interiors. In the 21st century, souvenir objects depicting Aboriginal peoples, symbolism and motifs including the boomerang, from the 1940s–1970s, regarded as kitsch and sold largely to tourists in the first instance, became highly sought after by both Aboriginal and non-Aboriginal collectors and has captured the imagination of Aboriginal artists and cultural commentators. | Boomerang | Wikipedia | 213 | 4359 | https://en.wikipedia.org/wiki/Boomerang | Technology | Projectile weapons | null |
Biological warfare, also known as germ warfare, is the use of biological toxins or infectious agents such as bacteria, viruses, insects, and fungi with the intent to kill, harm or incapacitate humans, animals or plants as an act of war. Biological weapons (often termed "bio-weapons", "biological threat agents", or "bio-agents") are living organisms or replicating entities (i.e. viruses, which are not universally considered "alive"). Entomological (insect) warfare is a subtype of biological warfare.
Biological warfare is subject to a forceful normative prohibition. Offensive biological warfare in international armed conflicts is a war crime under the 1925 Geneva Protocol and several international humanitarian law treaties. In particular, the 1972 Biological Weapons Convention (BWC) bans the development, production, acquisition, transfer, stockpiling and use of biological weapons. In contrast, defensive biological research for prophylactic, protective or other peaceful purposes is not prohibited by the BWC.
Biological warfare is distinct from warfare involving other types of weapons of mass destruction (WMD), including nuclear warfare, chemical warfare, and radiological warfare. None of these are considered conventional weapons, which are deployed primarily for their explosive, kinetic, or incendiary potential.
Biological weapons may be employed in various ways to gain a strategic or tactical advantage over the enemy, either by threats or by actual deployments. Like some chemical weapons, biological weapons may also be useful as area denial weapons. These agents may be lethal or non-lethal, and may be targeted against a single individual, a group of people, or even an entire population. They may be developed, acquired, stockpiled or deployed by nation states or by non-national groups. In the latter case, or if a nation-state uses it clandestinely, it may also be considered bioterrorism.
Biological warfare and chemical warfare overlap to an extent, as the use of toxins produced by some living organisms is considered under the provisions of both the BWC and the Chemical Weapons Convention. Toxins and psychochemical weapons are often referred to as midspectrum agents. Unlike bioweapons, these midspectrum agents do not reproduce in their host and are typically characterized by shorter incubation periods.
Overview
A biological attack could conceivably result in large numbers of civilian casualties and cause severe disruption to economic and societal infrastructure. | Biological warfare | Wikipedia | 491 | 4361 | https://en.wikipedia.org/wiki/Biological%20warfare | Technology | Weapons of mass destruction | null |
A nation or group that can pose a credible threat of mass casualty has the ability to alter the terms under which other nations or groups interact with it. When indexed to weapon mass and cost of development and storage, biological weapons possess destructive potential and loss of life far in excess of nuclear, chemical or conventional weapons. Accordingly, biological agents are potentially useful as strategic deterrents, in addition to their utility as offensive weapons on the battlefield.
As a tactical weapon for military use, a significant problem with biological warfare is that it would take days to be effective, and therefore might not immediately stop an opposing force. Some biological agents (smallpox, pneumonic plague) have the capability of person-to-person transmission via aerosolized respiratory droplets. This feature can be undesirable, as the agent(s) may be transmitted by this mechanism to unintended populations, including neutral or even friendly forces. Worse still, such a weapon could "escape" the laboratory where it was developed, even if there was no intent to use it – for example by infecting a researcher who then transmits it to the outside world before realizing that they were infected. Several cases are known of researchers becoming infected and dying of Ebola, which they had been working with in the lab (though nobody else was infected in those cases) – while there is no evidence that their work was directed towards biological warfare, it demonstrates the potential for accidental infection even of careful researchers fully aware of the dangers. While containment of biological warfare is less of a concern for certain criminal or terrorist organizations, it remains a significant concern for the military and civilian populations of virtually all nations.
History
Antiquity and Middle Ages | Biological warfare | Wikipedia | 338 | 4361 | https://en.wikipedia.org/wiki/Biological%20warfare | Technology | Weapons of mass destruction | null |
Rudimentary forms of biological warfare have been practiced since antiquity. The earliest documented incident of the intention to use biological weapons is recorded in Hittite texts of 1500–1200 BCE, in which victims of an unknown plague (possibly tularemia) were driven into enemy lands, causing an epidemic. The Assyrians poisoned enemy wells with the fungus ergot, though with unknown results. Scythian archers dipped their arrows and Roman soldiers their swords into excrements and cadavers – victims were commonly infected by tetanus as result. In 1346, the bodies of Mongol warriors of the Golden Horde who had died of plague were thrown over the walls of the besieged Crimean city of Kaffa. Specialists disagree about whether this operation was responsible for the spread of the Black Death into Europe, Near East and North Africa, resulting in the deaths of approximately 25 million Europeans.
Biological agents were extensively used in many parts of Africa from the sixteenth century AD, most of the time in the form of poisoned arrows, or powder spread on the war front as well as poisoning of horses and water supply of the enemy forces. In Borgu, there were specific mixtures to kill, hypnotize, make the enemy bold, and to act as an antidote against the poison of the enemy as well. The creation of biologicals was reserved for a specific and professional class of medicine-men.
18th to 19th century | Biological warfare | Wikipedia | 283 | 4361 | https://en.wikipedia.org/wiki/Biological%20warfare | Technology | Weapons of mass destruction | null |
During the French and Indian War, in June 1763 a group of Native Americans laid siege to British-held Fort Pitt. Following instructions of his superior, Colonel Henry Bouquet, the commander of Fort Pitt, Swiss-born Captain Simeon Ecuyer, ordered his men to take smallpox-infested blankets from the infirmary and give it to a Lenape delegation during the siege. A reported outbreak that began the spring before left as many as one hundred Native Americans dead in Ohio Country from 1763 to 1764. It is not clear whether the smallpox was a result of the Fort Pitt incident or the virus was already present among the Delaware people as outbreaks happened on their own every dozen or so years and the delegates were met again later and seemingly had not contracted smallpox. During the American Revolutionary War, Continental Army officer George Washington mentioned to the Continental Congress that he had heard a rumor from a sailor that his opponent during the Siege of Boston, General William Howe, had deliberately sent civilians out of the city in the hopes of spreading the ongoing smallpox epidemic to American lines; Washington, remaining unconvinced, wrote that he "could hardly give credit to" the claim. Washington had already inoculated his soldiers, diminishing the effect of the epidemic. Some historians have claimed that a detachment of the Corps of Royal Marines stationed in New South Wales, Australia, deliberately used smallpox there in 1789. Dr Seth Carus states: "Ultimately, we have a strong circumstantial case supporting the theory that someone deliberately introduced smallpox in the Aboriginal population."
World War I
By 1900 the germ theory and advances in bacteriology brought a new level of sophistication to the techniques for possible use of bio-agents in war. Biological sabotage in the form of anthrax and glanders was undertaken on behalf of the Imperial German government during World War I (1914–1918), with indifferent results. The Geneva Protocol of 1925 prohibited the first use of chemical and biological weapons against enemy nationals in international armed conflicts. | Biological warfare | Wikipedia | 404 | 4361 | https://en.wikipedia.org/wiki/Biological%20warfare | Technology | Weapons of mass destruction | null |
World War II
With the onset of World War II, the Ministry of Supply in the United Kingdom established a biological warfare program at Porton Down, headed by the microbiologist Paul Fildes. The research was championed by Winston Churchill and soon tularemia, anthrax, brucellosis, and botulism toxins had been effectively weaponized. In particular, Gruinard Island in Scotland, was contaminated with anthrax during a series of extensive tests for the next 56 years. Although the UK never offensively used the biological weapons it developed, its program was the first to successfully weaponize a variety of deadly pathogens and bring them into industrial production. Other nations, notably France and Japan, had begun their own biological weapons programs.
When the United States entered the war, Allied resources were pooled at the request of the British. The U.S. then established a large research program and industrial complex at Fort Detrick, Maryland, in 1942 under the direction of George W. Merck. The biological and chemical weapons developed during that period were tested at the Dugway Proving Grounds in Utah. Soon there were facilities for the mass production of anthrax spores, brucellosis, and botulism toxins, although the war was over before these weapons could be of much operational use.
The most notorious program of the period was run by the secret Imperial Japanese Army Unit 731 during the war, based at Pingfan in Manchuria and commanded by Lieutenant General Shirō Ishii. This biological warfare research unit conducted often fatal human experiments on prisoners, and produced biological weapons for combat use. Although the Japanese effort lacked the technological sophistication of the American or British programs, it far outstripped them in its widespread application and indiscriminate brutality. Biological weapons were used against Chinese soldiers and civilians in several military campaigns. In 1940, the Japanese Army Air Force bombed Ningbo with ceramic bombs full of fleas carrying the bubonic plague. Many of these operations were ineffective due to inefficient delivery systems, although up to 400,000 people may have died. During the Zhejiang-Jiangxi Campaign in 1942, around 1,700 Japanese troops died out of a total 10,000 Japanese soldiers who fell ill with disease when their own biological weapons attack rebounded on their own forces. | Biological warfare | Wikipedia | 473 | 4361 | https://en.wikipedia.org/wiki/Biological%20warfare | Technology | Weapons of mass destruction | null |
During the final months of World War II, Japan planned to use plague as a biological weapon against U.S. civilians in San Diego, California, during Operation Cherry Blossoms at Night. The plan was set to launch on 22 September 1945, but it was not executed because of Japan's surrender on 15 August 1945.
Cold War
In Britain, the 1950s saw the weaponization of plague, brucellosis, tularemia and later equine encephalomyelitis and vaccinia viruses, but the programme was unilaterally cancelled in 1956. The United States Army Biological Warfare Laboratories weaponized anthrax, tularemia, brucellosis, Q-fever and others.
In 1969, US President Richard Nixon decided to unilaterally terminate the offensive biological weapons program of the US, allowing only scientific research for defensive measures. This decision increased the momentum of the negotiations for a ban on biological warfare, which took place from 1969 to 1972 in the United Nation's Conference of the Committee on Disarmament in Geneva. These negotiations resulted in the Biological Weapons Convention, which was opened for signature on 10 April 1972 and entered into force on 26 March 1975 after its ratification by 22 states.
Despite being a party and depositary to the BWC, the Soviet Union continued and expanded its massive offensive biological weapons program, under the leadership of the allegedly civilian institution Biopreparat. The Soviet Union attracted international suspicion after the 1979 Sverdlovsk anthrax leak killed approximately 65 to 100 people.
1948 Arab–Israeli War
According to historians Benny Morris and Benjamin Kedar, Israel conducted a biological warfare operation codenamed Operation Cast Thy Bread during the 1948 Arab–Israeli War. The Haganah initially used typhoid bacteria to contaminate water wells in newly cleared Arab villages to prevent the population including militiamen from returning. Later, the biological warfare campaign expanded to include Jewish settlements that were in imminent danger of being captured by Arab troops and inhabited Arab towns not slated for capture. There was also plans to expand the biological warfare campaign into other Arab states including Egypt, Lebanon and Syria, but they were not carried out.
International law
International restrictions on biological warfare began with the 1925 Geneva Protocol, which prohibits the use but not the possession or development of biological and chemical weapons in international armed conflicts. Upon ratification of the Geneva Protocol, several countries made reservations regarding its applicability and use in retaliation. Due to these reservations, it was in practice a "no-first-use" agreement only. | Biological warfare | Wikipedia | 509 | 4361 | https://en.wikipedia.org/wiki/Biological%20warfare | Technology | Weapons of mass destruction | null |
The 1972 Biological Weapons Convention (BWC) supplements the Geneva Protocol by prohibiting the development, production, acquisition, transfer, stockpiling and use of biological weapons. Having entered into force on 26 March 1975, the BWC was the first multilateral disarmament treaty to ban the production of an entire category of weapons of mass destruction. As of March 2021, 183 states have become party to the treaty. The BWC is considered to have established a strong global norm against biological weapons, which is reflected in the treaty's preamble, stating that the use of biological weapons would be "repugnant to the conscience of mankind". The BWC's effectiveness has been limited due to insufficient institutional support and the absence of any formal verification regime to monitor compliance.
In 1985, the Australia Group was established, a multilateral export control regime of 43 countries aiming to prevent the proliferation of chemical and biological weapons.
In 2004, the United Nations Security Council passed Resolution 1540, which obligates all UN Member States to develop and enforce appropriate legal and regulatory measures against the proliferation of chemical, biological, radiological, and nuclear weapons and their means of delivery, in particular, to prevent the spread of weapons of mass destruction to non-state actors.
Bioterrorism
Biological weapons are difficult to detect, economical and easy to use, making them appealing to terrorists. The cost of a biological weapon is estimated to be about 0.05 percent the cost of a conventional weapon in order to produce similar numbers of mass casualties per kilometer square. Moreover, their production is very easy as common technology can be used to produce biological warfare agents, like that used in production of vaccines, foods, spray devices, beverages and antibiotics. A major factor in biological warfare that attracts terrorists is that they can easily escape before the government agencies or secret agencies have even started their investigation. This is because the potential organism has an incubation period of 3 to 7 days, after which the results begin to appear, thereby giving terrorists a lead. | Biological warfare | Wikipedia | 405 | 4361 | https://en.wikipedia.org/wiki/Biological%20warfare | Technology | Weapons of mass destruction | null |
A technique called Clustered, Regularly Interspaced, Short Palindromic Repeat (CRISPR-Cas9) is now so cheap and widely available that scientists fear that amateurs will start experimenting with them. In this technique, a DNA sequence is cut off and replaced with a new sequence, e.g. one that codes for a particular protein, with the intent of modifying an organism's traits. Concerns have emerged regarding do-it-yourself biology research organizations due to their associated risk that a rogue amateur DIY researcher could attempt to develop dangerous bioweapons using genome editing technology.
In 2002, when CNN went through Al-Qaeda's (AQ's) experiments with crude poisons, they found out that AQ had begun planning ricin and cyanide attacks with the help of a loose association of terrorist cells. The associates had infiltrated many countries like Turkey, Italy, Spain, France and others. In 2015, to combat the threat of bioterrorism, a National Blueprint for Biodefense was issued by the Blue-Ribbon Study Panel on Biodefense. Also, 233 potential exposures of select biological agents outside of the primary barriers of the biocontainment in the US were described by the annual report of the Federal Select Agent Program.
Though a verification system can reduce bioterrorism, an employee, or a lone terrorist having adequate knowledge of a bio-technology company's facilities, can cause potential danger by utilizing, without proper oversight and supervision, that company's resources. Moreover, it has been found that about 95% of accidents that have occurred due to low security have been done by employees or those who had a security clearance.
Entomology | Biological warfare | Wikipedia | 347 | 4361 | https://en.wikipedia.org/wiki/Biological%20warfare | Technology | Weapons of mass destruction | null |
Entomological warfare (EW) is a type of biological warfare that uses insects to attack the enemy. The concept has existed for centuries and research and development have continued into the modern era. EW has been used in battle by Japan and several other nations have developed and been accused of using an entomological warfare program. EW may employ insects in a direct attack or as vectors to deliver a biological agent, such as plague. Essentially, EW exists in three varieties. One type of EW involves infecting insects with a pathogen and then dispersing the insects over target areas. The insects then act as a vector, infecting any person or animal they might bite. Another type of EW is a direct insect attack against crops; the insect may not be infected with any pathogen but instead represents a threat to agriculture. The final method uses uninfected insects, such as bees or wasps, to directly attack the enemy.
Genetics
Theoretically, novel approaches in biotechnology, such as synthetic biology could be used in the future to design novel types of biological warfare agents.
Would demonstrate how to render a vaccine ineffective;
Would confer resistance to therapeutically useful antibiotics or antiviral agents;
Would enhance the virulence of a pathogen or render a nonpathogen virulent;
Would increase the transmissibility of a pathogen;
Would alter the host range of a pathogen;
Would enable the evasion of diagnostic/detection tools;
Would enable the weaponization of a biological agent or toxin.
Most of the biosecurity concerns in synthetic biology are focused on the role of DNA synthesis and the risk of producing genetic material of lethal viruses (e.g. 1918 Spanish flu, polio) in the lab. Recently, the CRISPR/Cas system has emerged as a promising technique for gene editing. It was hailed by The Washington Post as "the most important innovation in the synthetic biology space in nearly 30 years." While other methods take months or years to edit gene sequences, CRISPR speeds that time up to weeks. Due to its ease of use and accessibility, it has raised a number of ethical concerns, especially surrounding its use in the biohacking space.
By target
Anti-personnel | Biological warfare | Wikipedia | 446 | 4361 | https://en.wikipedia.org/wiki/Biological%20warfare | Technology | Weapons of mass destruction | null |
Ideal characteristics of a biological agent to be used as a weapon against humans are high infectivity, high virulence, non-availability of vaccines and availability of an effective and efficient delivery system. Stability of the weaponized agent (the ability of the agent to retain its infectivity and virulence after a prolonged period of storage) may also be desirable, particularly for military applications, and the ease of creating one is often considered. Control of the spread of the agent may be another desired characteristic.
The primary difficulty is not the production of the biological agent, as many biological agents used in weapons can be manufactured relatively quickly, cheaply and easily. Rather, it is the weaponization, storage, and delivery in an effective vehicle to a vulnerable target that pose significant problems.
For example, Bacillus anthracis is considered an effective agent for several reasons. First, it forms hardy spores, perfect for dispersal aerosols. Second, this organism is not considered transmissible from person to person, and thus rarely if ever causes secondary infections. A pulmonary anthrax infection starts with ordinary influenza-like symptoms and progresses to a lethal hemorrhagic mediastinitis within 3–7 days, with a fatality rate that is 90% or higher in untreated patients. Finally, friendly personnel and civilians can be protected with suitable antibiotics.
Agents considered for weaponization, or known to be weaponized, include bacteria such as Bacillus anthracis, Brucella spp., Burkholderia mallei, Burkholderia pseudomallei, Chlamydophila psittaci, Coxiella burnetii, Francisella tularensis, some of the Rickettsiaceae (especially Rickettsia prowazekii and Rickettsia rickettsii), Shigella spp., Vibrio cholerae, and Yersinia pestis. Many viral agents have been studied and/or weaponized, including some of the Bunyaviridae (especially Rift Valley fever virus), Ebolavirus, many of the Flaviviridae (especially Japanese encephalitis virus), Machupo virus, Coronaviruses, Marburg virus, Variola virus, and yellow fever virus. Fungal agents that have been studied include Coccidioides spp. | Biological warfare | Wikipedia | 472 | 4361 | https://en.wikipedia.org/wiki/Biological%20warfare | Technology | Weapons of mass destruction | null |
Toxins that can be used as weapons include ricin, staphylococcal enterotoxin B, botulinum toxin, saxitoxin, and many mycotoxins. These toxins and the organisms that produce them are sometimes referred to as select agents. In the United States, their possession, use, and transfer are regulated by the Centers for Disease Control and Prevention's Select Agent Program.
The former US biological warfare program categorized its weaponized anti-personnel bio-agents as either Lethal Agents (Bacillus anthracis, Francisella tularensis, Botulinum toxin) or Incapacitating Agents (Brucella suis, Coxiella burnetii, Venezuelan equine encephalitis virus, Staphylococcal enterotoxin B).
Anti-agriculture
Anti-crop/anti-vegetation/anti-fisheries
The United States developed an anti-crop capability during the Cold War that used plant diseases (bioherbicides, or mycoherbicides) for destroying enemy agriculture. Biological weapons also target fisheries as well as water-based vegetation. It was believed that the destruction of enemy agriculture on a strategic scale could thwart Sino-Soviet aggression in a general war. Diseases such as wheat blast and rice blast were weaponized in aerial spray tanks and cluster bombs for delivery to enemy watersheds in agricultural regions to initiate epiphytotic (epidemics among plants). On the other hand, some sources report that these agents were stockpiled but never weaponized. When the United States renounced its offensive biological warfare program in 1969 and 1970, the vast majority of its biological arsenal was composed of these plant diseases. Enterotoxins and Mycotoxins were not affected by Nixon's order.
Though herbicides are chemicals, they are often grouped with biological warfare and chemical warfare because they may work in a similar manner as biotoxins or bioregulators. The Army Biological Laboratory tested each agent and the Army's Technical Escort Unit was responsible for the transport of all chemical, biological, radiological (nuclear) materials. | Biological warfare | Wikipedia | 428 | 4361 | https://en.wikipedia.org/wiki/Biological%20warfare | Technology | Weapons of mass destruction | null |
Biological warfare can also specifically target plants to destroy crops or defoliate vegetation. The United States and Britain discovered plant growth regulators (i.e., herbicides) during the Second World War, which were then used by the UK in the counterinsurgency operations of the Malayan Emergency. Inspired by the use in Malaysia, the US military effort in the Vietnam War included a mass dispersal of a variety of herbicides, famously Agent Orange, with the aim of destroying farmland and defoliating forests used as cover by the Viet Cong. Sri Lanka deployed military defoliants in its prosecution of the Eelam War against Tamil insurgents.
Anti-livestock
During World War I, German saboteurs used anthrax and glanders to sicken cavalry horses in U.S. and France, sheep in Romania, and livestock in Argentina intended for the Entente forces. One of these German saboteurs was Anton Dilger. Also, Germany itself became a victim of similar attacks – horses bound for Germany were infected with Burkholderia by French operatives in Switzerland.
During World War II, the U.S. and Canada secretly investigated the use of rinderpest, a highly lethal disease of cattle, as a bioweapon.
In the 1980s Soviet Ministry of Agriculture had successfully developed variants of foot-and-mouth disease, and rinderpest against cows, African swine fever for pigs, and psittacosis for chickens. These agents were prepared to spray them down from tanks attached to airplanes over hundreds of miles. The secret program was code-named "Ecology".
During the Mau Mau Uprising in 1952, the poisonous latex of the African milk bush was used to kill cattle.
Defensive operations
Medical countermeasures
In 2010 at The Meeting of the States Parties to the Convention on the Prohibition of the Development, Production and Stockpiling of Bacteriological (Biological) and Toxin Weapons and Their Destruction in Geneva
the sanitary epidemiological reconnaissance was suggested as well-tested means for enhancing the monitoring of infections and parasitic agents, for the practical implementation of the International Health Regulations (2005). The aim was to prevent and minimize the consequences of natural outbreaks of dangerous infectious diseases as well as the threat of alleged use of biological weapons against BTWC States Parties. | Biological warfare | Wikipedia | 466 | 4361 | https://en.wikipedia.org/wiki/Biological%20warfare | Technology | Weapons of mass destruction | null |
Many countries require their active-duty military personnel to get vaccinated for certain diseases that may potentially be used as a bioweapon such as anthrax, smallpox, and various other vaccines depending on the Area of Operations of the individual military units and commands.
Public health and disease surveillance
Most classical and modern biological weapons' pathogens can be obtained from a plant or an animal which is naturally infected.
In the largest biological weapons accident known—the anthrax outbreak in Sverdlovsk (now Yekaterinburg) in the Soviet Union in 1979—sheep became ill with anthrax as far as 200 kilometers from the release point of the organism from a military facility in the southeastern portion of the city and still off-limits to visitors today, (see Sverdlovsk Anthrax leak).
Thus, a robust surveillance system involving human clinicians and veterinarians may identify a bioweapons attack early in the course of an epidemic, permitting the prophylaxis of disease in the vast majority of people (and/or animals) exposed but not yet ill.
For example, in the case of anthrax, it is likely that by 24–36 hours after an attack, some small percentage of individuals (those with the compromised immune system or who had received a large dose of the organism due to proximity to the release point) will become ill with classical symptoms and signs (including a virtually unique chest X-ray finding, often recognized by public health officials if they receive timely reports). The incubation period for humans is estimated to be about 11.8 days to 12.1 days. This suggested period is the first model that is independently consistent with data from the largest known human outbreak. These projections refine previous estimates of the distribution of early-onset cases after a release and support a recommended 60-day course of prophylactic antibiotic treatment for individuals exposed to low doses of anthrax. By making these data available to local public health officials in real time, most models of anthrax epidemics indicate that more than 80% of an exposed population can receive antibiotic treatment before becoming symptomatic, and thus avoid the moderately high mortality of the disease.
Common epidemiological warnings
From most specific to least specific: | Biological warfare | Wikipedia | 462 | 4361 | https://en.wikipedia.org/wiki/Biological%20warfare | Technology | Weapons of mass destruction | null |
Single cause of a certain disease caused by an uncommon agent, with lack of an epidemiological explanation.
Unusual, rare, genetically engineered strain of an agent.
High morbidity and mortality rates in regards to patients with the same or similar symptoms.
Unusual presentation of the disease.
Unusual geographic or seasonal distribution.
Stable endemic disease, but with an unexplained increase in relevance.
Rare transmission (aerosols, food, water).
No illness presented in people who were/are not exposed to "common ventilation systems (have separate closed ventilation systems) when illness is seen in persons in close proximity who have a common ventilation system."
Different and unexplained diseases coexisting in the same patient without any other explanation.
Rare illness that affects a large, disparate population (respiratory disease might suggest the pathogen or agent was inhaled).
Illness is unusual for a certain population or age-group in which it takes presence.
Unusual trends of death and/or illness in animal populations, previous to or accompanying illness in humans.
Many affected reaching out for treatment at the same time.
Similar genetic makeup of agents in affected individuals.
Simultaneous collections of similar illness in non-contiguous areas, domestic, or foreign.
An abundance of cases of unexplained diseases and deaths.
Bioweapon identification
The goal of biodefense is to integrate the sustained efforts of the national and homeland security, medical, public health, intelligence, diplomatic, and law enforcement communities. Health care providers and public health officers are among the first lines of defense. In some countries private, local, and provincial (state) capabilities are being augmented by and coordinated with federal assets, to provide layered defenses against biological weapon attacks. During the first Gulf War the United Nations activated a biological and chemical response team, Task Force Scorpio, to respond to any potential use of weapons of mass destruction on civilians.
The traditional approach toward protecting agriculture, food, and water: focusing on the natural or unintentional introduction of a disease is being strengthened by focused efforts to address current and anticipated future biological weapons threats that may be deliberate, multiple, and repetitive. | Biological warfare | Wikipedia | 435 | 4361 | https://en.wikipedia.org/wiki/Biological%20warfare | Technology | Weapons of mass destruction | null |
The growing threat of biowarfare agents and bioterrorism has led to the development of specific field tools that perform on-the-spot analysis and identification of encountered suspect materials. One such technology, being developed by researchers from the Lawrence Livermore National Laboratory (LLNL), employs a "sandwich immunoassay", in which fluorescent dye-labeled antibodies aimed at specific pathogens are attached to silver and gold nanowires.
In the Netherlands, the company TNO has designed Bioaerosol Single Particle Recognition eQuipment (BiosparQ). This system would be implemented into the national response plan for bioweapon attacks in the Netherlands.
Researchers at Ben Gurion University in Israel are developing a different device called the BioPen, essentially a "Lab-in-a-Pen", which can detect known biological agents in under 20 minutes using an adaptation of the ELISA, a similar widely employed immunological technique, that in this case incorporates fiber optics.
List of programs, projects and sites by country
United States
Fort Detrick, Maryland
U.S. Army Biological Warfare Laboratories (1943–69)
Building 470
One-Million-Liter Test Sphere
Operation Sea-Spray
Operation Whitecoat (1954–73)
U.S. entomological warfare program
Operation Big Itch
Operation Big Buzz
Operation Drop Kick
Operation May Day
Project Bacchus
Project Clear Vision
Project SHAD
Project 112
Horn Island Testing Station
Fort Terry
Granite Peak Installation
Vigo Ordnance Plant
United Kingdom
Porton Down
Gruinard Island
Nancekuke
Operation Vegetarian (1942–1944)
Open-air field tests:
Operation Harness off Antigua, 1948–1950.
Operation Cauldron off Stornoway, 1952.
Operation Hesperus off Stornoway, 1953.
Operation Ozone off Nassau, 1954.
Operation Negation off Nassau, 1954–5.
Soviet Union and Russia | Biological warfare | Wikipedia | 372 | 4361 | https://en.wikipedia.org/wiki/Biological%20warfare | Technology | Weapons of mass destruction | null |
Biopreparat (18 labs and production centers)
Stepnogorsk Scientific and Technical Institute for Microbiology, Stepnogorsk, northern Kazakhstan
Institute of Ultra Pure Biochemical Preparations, Leningrad, a weaponized plague center
Vector State Research Center of Virology and Biotechnology (VECTOR), a weaponized smallpox center
Institute of Applied Biochemistry, Omutninsk
Kirov bioweapons production facility, Kirov, Kirov Oblast
Zagorsk smallpox production facility, Zagorsk
Berdsk bioweapons production facility, Berdsk
Bioweapons research facility, Obolensk
Sverdlovsk bioweapons production facility (Military Compound 19), Sverdlovsk, a weaponized anthrax center
Institute of Virus Preparations
Poison laboratory of the Soviet secret services
Vozrozhdeniya
Project Bonfire
Project Factor
Japan
Unit 731
Zhongma Fortress
Kaimingjie germ weapon attack
Khabarovsk War Crime Trials
Epidemic Prevention and Water Purification Department
Iraq
Al Hakum
Salman Pak facility
Al Manal facility
South Africa
Project Coast
Delta G Scientific Company
Roodeplaat Research Laboratories
Protechnik
Rhodesia
Canada
Grosse Isle, Quebec, site (1939–45) of research into anthrax and other agents
DRDC Suffield, Suffield, Alberta
List of associated people
Bioweaponeers:
Includes scientists and administrators
Shyh-Ching Lo
Kanatjan Alibekov, known as Ken Alibek
Ira Baldwin
Wouter Basson
Kurt Blome
Eugen von Haagen
Anton Dilger
Paul Fildes
Arthur Galston (unwittingly)
Kurt Gutzeit
Riley D. Housewright
Shiro Ishii
Elvin A. Kabat
George W. Merck
Frank Olson
Vladimir Pasechnik
William C. Patrick III
Sergei Popov
Theodor Rosebury
Rihab Rashid Taha
Prince Tsuneyoshi Takeda
Huda Salih Mahdi Ammash
Nassir al-Hindawi
Erich Traub
Auguste Trillat
Baron Otto von Rosen
Yujiro Wakamatsu
Yazid Sufaat
Writers and activists:
Jack Trudel
Daniel Barenblatt
Leonard A. Cole
Stephen Endicott
Arthur Galston
Jeanne Guillemin
Edward Hagerman
Sheldon H. Harris
Nicholas D. Kristof
Joshua Lederberg
Matthew Meselson
Toby Ord
Richard Preston
Ed Regis
Mark Wheelis
David Willman
Aaron Henderson
In popular culture | Biological warfare | Wikipedia | 490 | 4361 | https://en.wikipedia.org/wiki/Biological%20warfare | Technology | Weapons of mass destruction | null |
Bioterrorism is terrorism involving the intentional release or dissemination of biological agents. These agents include bacteria, viruses, insects, fungi, and/or their toxins, and may be in a naturally occurring or a human-modified form, in much the same way as in biological warfare. Further, modern agribusiness is vulnerable to anti-agricultural attacks by terrorists, and such attacks can seriously damage economy as well as consumer confidence. The latter destructive activity is called agrobioterrorism and is a subtype of agro-terrorism.
Definition
Bioterrorism agents are typically found in nature, but could be mutated or altered to increase their ability to cause disease, make them resistant to current medicines, or to increase their ability to be spread into the environment. Biological agents can be spread through the air, water, or in food. Biological agents are attractive to terrorists because they are extremely difficult to detect and do not cause illness for several hours to several days. Some bioterrorism agents, like the smallpox virus, can be spread from person to person and some, like anthrax, cannot.
Bioterrorism may be favored because biological agents are relatively easy and inexpensive to obtain, can be easily disseminated, and can cause widespread fear and panic beyond the actual physical damage. Military leaders, however, have learned that, as a military asset, bioterrorism has some important limitations; it is difficult to use a bioweapon in a way that only affects the enemy and not friendly forces. A biological weapon is useful to terrorists mainly as a method of creating mass panic and disruption to a state or a country. However, technologists such as Bill Joy have warned of the potential power which genetic engineering might place in the hands of future bio-terrorists.
The use of agents that do not cause harm to humans, but disrupt the economy, have also been discussed. One such pathogen is the foot-and-mouth disease (FMD) virus, which is capable of causing widespread economic damage and public concern (as witnessed in the 2001 and 2007 FMD outbreaks in the UK), while having almost no capacity to infect humans.
History
By the time World War I began, attempts to use anthrax were directed at animal populations. This generally proved to be ineffective. | Bioterrorism | Wikipedia | 467 | 4393 | https://en.wikipedia.org/wiki/Bioterrorism | Technology | Biotechnology | null |
Shortly after the start of World War I, Germany launched a biological sabotage campaign in the United States, Russia, Romania, and France. At that time, Anton Dilger lived in Germany, but in 1915 he was sent to the United States carrying cultures of glanders, a virulent disease of horses and mules. Dilger set up a laboratory in his home in Chevy Chase, Maryland. He used stevedores working the docks in Baltimore to infect horses with glanders while they were waiting to be shipped to Britain. Dilger was under suspicion as being a German agent, but was never arrested. Dilger eventually fled to Madrid, Spain, where he died during the Influenza Pandemic of 1918. In 1916, the Russians arrested a German agent with similar intentions. Germany and its allies infected French cavalry horses and many of Russia's mules and horses on the Eastern Front. These actions hindered artillery and troop movements, as well as supply convoys.
In 1972, police in Chicago arrested two college students, Allen Schwander and Stephen Pera, who had planned to poison the city's water supply with typhoid and other bacteria. Schwander had founded a terrorist group, "R.I.S.E.", while Pera collected and grew cultures from the hospital where he worked. The two men fled to Cuba after being released on bail. Schwander died of natural causes in 1974, while Pera returned to the U.S. in 1975 and was put on probation.
In 1979, anthrax spores killed around 66 people after the spores were unintentionally released from a military lab near Sverdlovsk, Russia. This occurrence of inhalational anthrax had provided a majority of the knowledge scientists understand about clinical anthrax. Soviet officials and physicians claimed the epidemic was produced by the consumption of infected game meat, but further investigation proves the source of infection were the inhaled spores. There is continued discussion about the intentionality of the epidemic and some speculate it was calculated by the Soviet government. | Bioterrorism | Wikipedia | 420 | 4393 | https://en.wikipedia.org/wiki/Bioterrorism | Technology | Biotechnology | null |
In 1980, the World Health Organization (WHO) announced the eradication of smallpox, a highly contagious and incurable disease. Although the disease has been eliminated in the wild, frozen stocks of smallpox virus are still maintained by the governments of the United States and Russia. Disastrous consequences are feared if rogue politicians or terrorists were to get hold of the smallpox strains. Since vaccination programs are now terminated, the world population is more susceptible to smallpox than ever before.
In Oregon in 1984, followers of the Bhagwan Shree Rajneesh attempted to control a local election by incapacitating the local population. They infected salad bars in 11 restaurants, produce in grocery stores, doorknobs, and other public domains with Salmonella typhimurium bacteria in the city of The Dalles, Oregon. The attack infected 751 people with severe food poisoning. There were no fatalities. This incident was the first known bioterrorist attack in the United States in the 20th century. It was also the single largest bioterrorism attack on U.S. soil.
In June 1993, the religious group Aum Shinrikyo released anthrax in Tokyo. Eyewitnesses reported a foul odor. The attack was a failure, because it did not infect a single person. The reason for this is due to the fact that the group used the vaccine strain of the bacterium. The spores which were recovered from the site of the attack showed that they were identical to an anthrax vaccine strain that was given to animals at the time. These vaccine strains are missing the genes that cause a symptomatic response.
In September and October 2001, several cases of anthrax broke out in the United States, apparently deliberately caused. Letters laced with infectious anthrax were concurrently delivered to news media offices and the U.S. Congress. The letters killed five people. | Bioterrorism | Wikipedia | 382 | 4393 | https://en.wikipedia.org/wiki/Bioterrorism | Technology | Biotechnology | null |
Scenarios
There are multiple considerable scenarios, how terrorists might employ biological agents. In 2000, tests conducted by various US agencies showed that indoor attacks in densely populated spaces are much more serious than outdoor attacks. Such enclosed spaces are large buildings, trains, indoor arenas, theaters, malls, tunnels and similar. Contra-measures against such scenarios are building architecture and ventilation systems engineering. In 1993, sewage was spilled out into a river, subsequently drawn into the water system and affected 400,000 people in Milwaukee, Wisconsin. The disease-causing organism was cryptosporidium parvum. This man-made disaster can be a template for a terrorist scenario. Nevertheless, terrorist scenarios are considered more likely near the points of delivery than at the water sources before the water treatment. Release of biological agents is more likely for a single building or a neighborhood. Counter-measures against this scenario include the further limitation of access to the water supply systems, tunnels, and infrastructure. Agricultural crop-duster flights might be misused as delivery devices for biological agents as well. Counter-measures against this scenario are background checks of employees of crop-dusting companies and surveillance procedures.
In the most common hoax scenario, no biological agents are employed. For instance, an envelope with powder in it that says, “You've just been exposed to anthrax.” Such hoaxes have been shown to have a large psychological impact on the population.
Anti-agriculture attacks are considered to require relatively little expertise and technology. Biological agents that attack livestock, fish, vegetation, and crops are mostly not contagious to humans and are therefore easier for attackers to handle. Even a few cases of infection can disrupt a country's agricultural production and exports for months, as evidenced by FMD outbreaks.
Types of agents
Under current United States law, bio-agents which have been declared by the U.S. Department of Health and Human Services or the U.S. Department of Agriculture to have the "potential to pose a severe threat to public health and safety" are officially defined as "select agents." The CDC categorizes these agents (A, B or C) and administers the Select Agent Program, which regulates the laboratories which may possess, use, or transfer select agents within the United States. As with US attempts to categorize harmful recreational drugs, designer viruses are not yet categorized and avian H5N1 has been shown to achieve high mortality and human-communication in a laboratory setting. | Bioterrorism | Wikipedia | 499 | 4393 | https://en.wikipedia.org/wiki/Bioterrorism | Technology | Biotechnology | null |
Category A
These high-priority agents pose a risk to national security, can be easily transmitted and disseminated, result in high mortality, have potential major public health impact, may cause public panic, or require special action for public health preparedness. | Bioterrorism | Wikipedia | 50 | 4393 | https://en.wikipedia.org/wiki/Bioterrorism | Technology | Biotechnology | null |
SARS and COVID-19, though not as lethal as other diseases, was concerning to scientists and policymakers for its social and economic disruption potential. After the global containment of the pandemic, the United States President George W. Bush stated "...A global influenza pandemic that infects millions and lasts from one to three years could be far worse."
Tularemia or "rabbit fever": Tularemia has a very low fatality rate if treated, but can severely incapacitate. The disease is caused by the Francisella tularensis bacterium, and can be contracted through contact with fur, inhalation, ingestion of contaminated water or insect bites. Francisella tularensis is very infectious. A small number of organisms (10–50 or so) can cause disease. If F. tularensis were used as a weapon, the bacteria would likely be made airborne for exposure by inhalation. People who inhale an infectious aerosol would generally experience severe respiratory illness, including life-threatening pneumonia and systemic infection, if they are not treated. The bacteria that cause tularemia occur widely in nature and could be isolated and grown in quantity in a laboratory, although manufacturing an effective aerosol weapon would require considerable sophistication. | Bioterrorism | Wikipedia | 262 | 4393 | https://en.wikipedia.org/wiki/Bioterrorism | Technology | Biotechnology | null |
Anthrax: Anthrax is a non-contagious disease caused by the spore-forming bacterium Bacillus anthracis. The ability of Anthrax to produce within small spores, or bacilli bacterium, makes it readily permeable to porous skin and can cause abrupt symptoms within 24 hours of exposure. The dispersal of this pathogen among densely populated areas is said to carry less than one percent mortality rate, for cutaneous exposure, to a ninety percent or higher mortality for untreated inhalational infections. An anthrax vaccine does exist but requires many injections for stable use. When discovered early, anthrax can be cured by administering antibiotics (such as ciprofloxacin). Its first modern incidence in biological warfare were when Scandinavian "freedom fighters" supplied by the German General Staff used anthrax with unknown results against the Imperial Russian Army in Finland in 1916. In 1993, the Aum Shinrikyo used anthrax in an unsuccessful attempt in Tokyo with zero fatalities. Anthrax was used in a series of attacks by a microbiologist at the US Army Medical Research Institute of Infection Disease on the offices of several United States senators in late 2001. The anthrax was in a powder form and it was delivered by the mail. This bioterrorist attack inevitably prompted seven cases of cutaneous anthrax and eleven cases of inhalation anthrax, with five leading to deaths. Additionally, an estimated 10 to 26 cases had prevented fatality through treatment supplied to over 30,000 individuals. Anthrax is one of the few biological agents that federal employees have been vaccinated for. In the US an anthrax vaccine, Anthrax Vaccine Adsorbed (AVA) exists and requires five injections for stable use. Other anthrax vaccines also exist. The strain used in the 2001 anthrax attacks was identical to the strain used by the USAMRIID. | Bioterrorism | Wikipedia | 400 | 4393 | https://en.wikipedia.org/wiki/Bioterrorism | Technology | Biotechnology | null |
Smallpox: Smallpox is a highly contagious virus. It is transmitted easily through the atmosphere and has a high mortality rate (20–40%). Smallpox was eradicated in the world in the 1970s, thanks to a worldwide vaccination program. However, some virus samples are still available in Russian and American laboratories. Some believe that after the collapse of the Soviet Union, cultures of smallpox have become available in other countries. Although people born pre-1970 will have been vaccinated for smallpox under the WHO program, the effectiveness of vaccination is limited since the vaccine provides high level of immunity for only 3 to 5 years. Revaccination's protection lasts longer. As a biological weapon smallpox is dangerous because of the highly contagious nature of both the infected and their pox. Also, the infrequency with which vaccines are administered among the general population since the eradication of the disease would leave most people unprotected in the event of an outbreak. Smallpox occurs only in humans, and has no external hosts or vectors.
Botulinum toxin: The neurotoxin Botulinum is the deadliest toxin known to man, and is produced by the bacterium Clostridium botulinum. Botulism causes death by respiratory failure and paralysis. Furthermore, the toxin is readily available worldwide due to its cosmetic applications in injections.
Bubonic plague: Plague is a disease caused by the Yersinia pestis bacterium. Rodents are the normal host of plague, and the disease is transmitted to humans by flea bites and occasionally by aerosol in the form of pneumonic plague. The disease has a history of use in biological warfare dating back many centuries, and is considered a threat due to its ease of culture and ability to remain in circulation among local rodents for a long period of time. The weaponized threat comes mainly in the form of pneumonic plague (infection by inhalation) It was the disease that caused the Black Death in Medieval Europe. | Bioterrorism | Wikipedia | 408 | 4393 | https://en.wikipedia.org/wiki/Bioterrorism | Technology | Biotechnology | null |
Viral hemorrhagic fevers: This includes hemorrhagic fevers caused by members of the family Filoviridae (Marburg virus and Ebola virus), and by the family Arenaviridae (for example Lassa virus and Machupo virus). Ebola virus disease, in particular, has caused high fatality rates ranging from 25 to 90% with a 50% average. No cure currently exists, although vaccines are in development. The Soviet Union investigated the use of filoviruses for biological warfare, and the Aum Shinrikyo group unsuccessfully attempted to obtain cultures of Ebola virus. Death from Ebola virus disease is commonly due to multiple organ failure and hypovolemic shock. Marburg virus was first discovered in Marburg, Germany. No treatments currently exist aside from supportive care. The arenaviruses have a somewhat reduced case-fatality rate compared to disease caused by filoviruses, but are more widely distributed, chiefly in central Africa and South America. | Bioterrorism | Wikipedia | 207 | 4393 | https://en.wikipedia.org/wiki/Bioterrorism | Technology | Biotechnology | null |
Category B
Category B agents are moderately easy to disseminate and have low mortality rates.
Brucellosis (Brucella species)
Epsilon toxin of Clostridium perfringens
Food safety threats (for example, Salmonella species, E coli O157:H7, Shigella, Staphylococcus aureus)
Glanders (Burkholderia mallei)
Melioidosis (Burkholderia pseudomallei)
Psittacosis (Chlamydia psittaci)
Q fever (Coxiella burnetii)
Ricin toxin from Ricinus communis (castor beans)
Abrin toxin from Abrus precatorius (Rosary peas)
Staphylococcal enterotoxin B
Typhus (Rickettsia prowazekii)
Viral encephalitis (alphaviruses, for example,: Venezuelan equine encephalitis, eastern equine encephalitis, western equine encephalitis)
Water supply threats (for example, Vibrio cholerae, Cryptosporidium parvum)
Category C
Category C agents are emerging pathogens that might be engineered for mass dissemination because of their availability, ease of production and dissemination, high mortality rate, or ability to cause a major health impact.
Nipah virus
Hantavirus
Planning and monitoring
Planning may involve the development of biological identification systems. Until recently in the United States, most biological defense strategies have been geared to protecting soldiers on the battlefield rather than ordinary people in cities. Financial cutbacks have limited the tracking of disease outbreaks. Some outbreaks, such as food poisoning due to E. coli or Salmonella, could be of either natural or deliberate origin.
Global defense strategies have also been put into place including the introduction of the Biological and Toxin Weapons Convention in 1975. A majority of countries across the globe participated in the conventions (144) but a handful chose not to take part in the defense. Many of the countries who opted out of the convention are located in the Middle East and former Soviet Union countries. | Bioterrorism | Wikipedia | 425 | 4393 | https://en.wikipedia.org/wiki/Bioterrorism | Technology | Biotechnology | null |
Preparedness
Export controls on biological agents are not applied uniformly, providing terrorists a route for acquisition. Laboratories are working on advanced detection systems to provide early warning, identify contaminated areas and populations at risk, and to facilitate prompt treatment. Methods for predicting the use of biological agents in urban areas as well as assessing the area for the hazards associated with a biological attack are being established in major cities. In addition, forensic technologies are working on identifying biological agents, their geographical origins and/or their initial source. Efforts include decontamination technologies to restore facilities without causing additional environmental concerns.
Early detection and rapid response to bioterrorism depend on close cooperation between public health authorities and law enforcement; however, such cooperation is lacking. National detection assets and vaccine stockpiles are not useful if local and state officials do not have access to them. | Bioterrorism | Wikipedia | 167 | 4393 | https://en.wikipedia.org/wiki/Bioterrorism | Technology | Biotechnology | null |
Aspects of protection against bioterrorism in the United States include:
Detection and resilience strategies in combating bioterrorism. This occurs primarily through the efforts of the Office of Health Affairs (OHA), a part of the Department of Homeland Security (DHS), whose role is to prepare for an emergency situation that impacts the health of the American populace. Detection has two primary technological factors. First there is OHA's BioWatch program in which collection devices are disseminated to thirty high risk areas throughout the country to detect the presence of aerosolized biological agents before symptoms present in patients. This is significant primarily because it allows a more proactive response to a disease outbreak rather than the more passive treatment of the past.
Implementation of the Generation-3 automated detection system. This advancement is significant simply because it enables action to be taken in four to six hours due to its automatic response system, whereas the previous system required aerosol detectors to be manually transported to laboratories. Resilience is a multifaceted issue as well, as addressed by OHA. One way in which this is ensured is through exercises that establish preparedness; programs like the Anthrax Response Exercise Series exist to ensure that, regardless of the incident, all emergency personnel will be aware of the role they must fill. Moreover, by providing information and education to public leaders, emergency medical services and all employees of the DHS, OHS suggests it can significantly decrease the impact of bioterrorism.
Enhancing the technological capabilities of first responders is accomplished through numerous strategies. The first of these strategies was developed by the Science and Technology Directorate (S&T) of DHS to ensure that the danger of suspicious powders could be effectively assessed, (as many dangerous biological agents such as anthrax exist as a white powder). By testing the accuracy and specificity of commercially available systems used by first responders, the hope is that all biologically harmful powders can be rendered ineffective. | Bioterrorism | Wikipedia | 401 | 4393 | https://en.wikipedia.org/wiki/Bioterrorism | Technology | Biotechnology | null |
Enhanced equipment for first responders. One recent advancement is the commercialization of a new form of Tyvex™ armor which protects first responders and patients from chemical and biological contaminants. There has also been a new generation of Self-Contained Breathing Apparatuses (SCBA) which has been recently made more robust against bioterrorism agents. All of these technologies combine to form what seems like a relatively strong deterrent to bioterrorism. However, New York City as an entity has numerous organizations and strategies that effectively serve to deter and respond to bioterrorism as it comes. From here the logical progression is into the realm of New York City's specific strategies to prevent bioterrorism. | Bioterrorism | Wikipedia | 146 | 4393 | https://en.wikipedia.org/wiki/Bioterrorism | Technology | Biotechnology | null |
Excelsior Challenge. In the second week of September 2016, the state of New York held a large emergency response training exercise called the Excelsior Challenge, with over 100 emergency responders participating. According to WKTV, "This is the fourth year of the Excelsior Challenge, a training exercise designed for police and first responders to become familiar with techniques and practices should a real incident occur." The event was held over three days and hosted by the State Preparedness Training Center in Oriskany, New York. Participants included bomb squads, canine handlers, tactical team officers and emergency medical services. In an interview with Homeland Preparedness News, Bob Stallman, assistant director at the New York State Preparedness Training Center, said, "We're constantly seeing what's happening around the world and we tailor our training courses and events for those types of real-world events." For the first time, the 2016 training program implemented New York's new electronic system. The system, called NY Responds, electronically connects every county in New York to aid in disaster response and recovery. As a result, "counties have access to a new technology known as Mutualink, which improves interoperability by integrating telephone, radio, video, and file-sharing into one application to allow local emergency staff to share real-time information with the state and other counties." The State Preparedness Training Center in Oriskany was designed by the State Division of Homeland Security, and Emergency Services (DHSES) in 2006. It cost $42 million to construct on over 1100 acres and is available for training 360 days a year. Students from SUNY Albany's College of Emergency Preparedness, Homeland Security and Cybersecurity, were able to participate in this year's exercise and learn how "DHSES supports law enforcement specialty teams." | Bioterrorism | Wikipedia | 373 | 4393 | https://en.wikipedia.org/wiki/Bioterrorism | Technology | Biotechnology | null |
Project BioShield. The accrual of vaccines and treatments for potential biological threats, also known as medical countermeasures has been an important aspect in preparing for a potential bioterrorist attack; this took the form of a program beginning in 2004, referred to as Project BioShield. The significance of this program should not be overlooked as “there is currently enough smallpox vaccine to inoculate every United States citizen and a variety of therapeutic drugs to treat the infected.” The Department of Defense also has a variety of laboratories currently working to increase the quantity and efficacy of countermeasures that comprise the national stockpile. Efforts have also been taken to ensure that these medical countermeasures can be disseminated effectively in the event of a bioterrorist attack. The National Association of Chain Drug Stores championed this cause by encouraging the participation of the private sector in improving the distribution of such countermeasures if required. | Bioterrorism | Wikipedia | 190 | 4393 | https://en.wikipedia.org/wiki/Bioterrorism | Technology | Biotechnology | null |
On a CNN news broadcast in 2011, the CNN chief medical correspondent, Dr. Sanjay Gupta, weighed in on the American government's recent approach to bioterrorist threats. He explains how, even though the United States would be better fending off bioterrorist attacks now than they would be a decade ago, the amount of money available to fight bioterrorism over the last three years has begun to decrease. Looking at a detailed report that examined the funding decrease for bioterrorism in fifty-one American cities, Dr. Gupta stated that the cities "wouldn't be able to distribute vaccines as well" and "wouldn't be able to track viruses." He also said that film portrayals of global pandemics, such as Contagion, were actually quite possible and may occur in the United States under the right conditions.
A news broadcast by MSNBC in 2010 also stressed the low levels of bioterrorism preparedness in the United States. The broadcast stated that a bipartisan report gave the Obama administration a failing grade for its efforts to respond to a bioterrorist attack. The news broadcast invited the former New York City police commissioner, Howard Safir, to explain how the government would fare in combating such an attack. He said how "biological and chemical weapons are probable and relatively easy to disperse." Furthermore, Safir thought that efficiency in bioterrorism preparedness is not necessarily a question of money, but is instead dependent on putting resources in the right places. The broadcast suggested that the nation was not ready for something more serious.
In a September 2016 interview conducted by Homeland Preparedness News, Daniel Gerstein, a senior policy researcher for the RAND Corporation, stresses the importance in preparing for potential bioterrorist attacks on the nation. He implored the U.S. government to take the proper and necessary actions to implement a strategic plan of action to save as many lives as possible and to safeguard against potential chaos and confusion. He believes that because there have been no significant instances of bioterrorism since the anthrax attacks in 2001, the government has allowed itself to become complacent making the country that much more vulnerable to unsuspecting attacks, thereby further endangering the lives of U.S. citizens. | Bioterrorism | Wikipedia | 469 | 4393 | https://en.wikipedia.org/wiki/Bioterrorism | Technology | Biotechnology | null |
Gerstein formerly served in the Science and Technology Directorate of the Department of Homeland Security from 2011 to 2014. He claims there has not been a serious plan of action since 2004 during George W. Bush's presidency, in which he issued a Homeland Security directive delegating responsibilities among various federal agencies. He also stated that the blatant mishandling of the Ebola virus outbreak in 2014 attested to the government's lack of preparation. This past May, legislation that would create a national defense strategy was introduced in the Senate, coinciding with the timing of ISIS-affiliated terrorist groups get closer to weaponizing biological agents. In May 2016, Kenyan officials apprehended two members of an Islamic extremist group in motion to set off a biological bomb containing anthrax. Mohammed Abdi Ali, the believed leader of the group, who was a medical intern, was arrested along with his wife, a medical student. The two were caught just before carrying out their plan. The Blue Ribbon Study Panel on Biodefense, which comprises a group of experts on national security and government officials, in which Gerstein had previously testified to, submitted its National Blueprint for Biodefense to Congress in October 2015 listing their recommendations for devising an effective plan. | Bioterrorism | Wikipedia | 259 | 4393 | https://en.wikipedia.org/wiki/Bioterrorism | Technology | Biotechnology | null |
Bill Gates said in a February 18, 2017 Business Insider op-ed (published near the time of his Munich Security Conference speech) that it is possible for an airborne pathogen to kill at least 30 million people over the course of a year. In a New York Times report, the Gates Foundation predicted that a modern outbreak similar to the Spanish Influenza pandemic (which killed between 50 million and 100 million people) could end up killing more than 360 million people worldwide, even considering widespread availability of vaccines and other healthcare tools. The report cited increased globalization, rapid international air travel, and urbanization as increased reasons for concern. In a March 9, 2017, interview with CNBC, former U.S. Senator Joe Lieberman, who was co-chair of the bipartisan Blue Ribbon Study Panel on Biodefense, said a worldwide pandemic could end the lives of more people than a nuclear war. Lieberman also expressed worry that a terrorist group like ISIS could develop a synthetic influenza strain and introduce it to the world to kill civilians. In July 2017, Robert C. Hutchinson, former agent at the Department of Homeland Security, called for a "whole-of-government" response to the next global health threat, which he described as including strict security procedures at our borders and proper execution of government preparedness plans. | Bioterrorism | Wikipedia | 266 | 4393 | https://en.wikipedia.org/wiki/Bioterrorism | Technology | Biotechnology | null |
Also, novel approaches in biotechnology, such as synthetic biology, could be used in the future to design new types of biological warfare agents. Special attention has to be laid on future experiments (of concern) that:
Would demonstrate how to render a vaccine ineffective;
Would confer resistance to therapeutically useful antibiotics or antiviral agents;
Would enhance the virulence of a pathogen or render a nonpathogen virulent;
Would increase transmissibility of a pathogen;
Would alter the host range of a pathogen;
Would enable the evasion of diagnostic/detection tools;
Would enable the weaponization of a biological agent or toxin
Most of the biosecurity concerns in synthetic biology, however, are focused on the role of DNA synthesis and the risk of producing genetic material of lethal viruses (e.g. 1918 Spanish flu, polio) in the lab. The CRISPR/Cas system has emerged as a promising technique for gene editing. It was hailed by The Washington Post as "the most important innovation in the synthetic biology space in nearly 30 years." While other methods take months or years to edit gene sequences, CRISPR speeds that time up to weeks. However, due to its ease of use and accessibility, it has raised a number of ethical concerns, especially surrounding its use in the biohacking space.
Biosurveillance
In 1999, the University of Pittsburgh's Center for Biomedical Informatics deployed the first automated bioterrorism detection system, called RODS (Real-Time Outbreak Disease Surveillance). RODS is designed to collect data from many data sources and use them to perform signal detection, that is, to detect a possible bioterrorism event at the earliest possible moment. RODS, and other systems like it, collect data from sources including clinic data, laboratory data, and data from over-the-counter drug sales. In 2000, Michael Wagner, the codirector of the RODS laboratory, and Ron Aryel, a subcontractor, conceived the idea of obtaining live data feeds from "non-traditional" (non-health-care) data sources. The RODS laboratory's first efforts eventually led to the establishment of the National Retail Data Monitor, a system which collects data from 20,000 retail locations nationwide. | Bioterrorism | Wikipedia | 455 | 4393 | https://en.wikipedia.org/wiki/Bioterrorism | Technology | Biotechnology | null |
On February 5, 2002, George W. Bush visited the RODS laboratory and used it as a model for a $300 million spending proposal to equip all 50 states with biosurveillance systems. In a speech delivered at the nearby Masonic temple, Bush compared the RODS system to a modern "DEW" line (referring to the Cold War ballistic missile early warning system).
The principles and practices of biosurveillance, a new interdisciplinary science, were defined and described in the Handbook of Biosurveillance, edited by Michael Wagner, Andrew Moore and Ron Aryel, and published in 2006. Biosurveillance is the science of real-time disease outbreak detection. Its principles apply to both natural and man-made epidemics (bioterrorism).
Data which potentially could assist in early detection of a bioterrorism event include many categories of information. Health-related data such as that from hospital computer systems, clinical laboratories, electronic health record systems, medical examiner record-keeping systems, 911 call center computers, and veterinary medical record systems could be of help; researchers are also considering the utility of data generated by ranching and feedlot operations, food processors, drinking water systems, school attendance recording, and physiologic monitors, among others.
In Europe, disease surveillance is beginning to be organized on the continent-wide scale needed to track a biological emergency. The system not only monitors infected persons, but attempts to discern the origin of the outbreak.
Researchers have experimented with devices to detect the existence of a threat:
Tiny electronic chips that would contain living nerve cells to warn of the presence of bacterial toxins (identification of broad range toxins)
Fiber-optic tubes lined with antibodies coupled to light-emitting molecules (identification of specific pathogens, such as anthrax, botulinum, ricin)
Some research shows that ultraviolet avalanche photodiodes offer the high gain, reliability and robustness needed to detect anthrax and other bioterrorism agents in the air. The fabrication methods and device characteristics were described at the 50th Electronic Materials Conference in Santa Barbara on June 25, 2008. Details of the photodiodes were also published in the February 14, 2008, issue of the journal Electronics Letters and the November 2007 issue of the journal IEEE Photonics Technology Letters.
The United States Department of Defense conducts global biosurveillance through several programs, including the Global Emerging Infections Surveillance and Response System. | Bioterrorism | Wikipedia | 498 | 4393 | https://en.wikipedia.org/wiki/Bioterrorism | Technology | Biotechnology | null |
Another powerful tool developed within New York City for use in countering bioterrorism is the development of the New York City Syndromic Surveillance System. This system is essentially a way of tracking disease progression throughout New York City, and was developed by the New York City Department of Health and Mental Hygiene (NYC DOHMH) in the wake of the 9/11 attacks. The system works by tracking the symptoms of those taken into the emergency department—based on the location of the hospital to which they are taken and their home address—and assessing any patterns in symptoms. These established trends can then be observed by medical epidemiologists to determine if there are any disease outbreaks in any particular locales; maps of disease prevalence can then be created rather easily. This is an obviously beneficial tool in fighting bioterrorism as it provides a means through which such attacks could be discovered in their nascence; assuming bioterrorist attacks result in similar symptoms across the board, this strategy allows New York City to respond immediately to any bioterrorist threats that they may face with some level of alacrity.
Response to bioterrorism incident or threat
Government agencies which would be called on to respond to a bioterrorism incident would include law enforcement, hazardous materials and decontamination units, and emergency medical units, if available.
The US military has specialized units, which can respond to a bioterrorism event; among them are the United States Marine Corps' Chemical Biological Incident Response Force and the U.S. Army's 20th Support Command (CBRNE), which can detect, identify, and neutralize threats, and decontaminate victims exposed to bioterror agents. US response would include the Centers for Disease Control.
Historically, governments and authorities have relied on quarantines to protect their populations. International bodies such as the World Health Organization already devote some of their resources to monitoring epidemics and have served clearing-house roles in historical epidemics. | Bioterrorism | Wikipedia | 401 | 4393 | https://en.wikipedia.org/wiki/Bioterrorism | Technology | Biotechnology | null |
Media attention toward the seriousness of biological attacks increased in 2013 to 2014. In July 2013, Forbes published an article with the title "Bioterrorism: A Dirty Little Threat With Huge Potential Consequences." In November 2013, Fox News reported on a new strain of botulism, saying that the Centers for Disease and Control lists botulism as one of two agents that have "the highest risks of mortality and morbidity", noting that there is no antidote for botulism. USA Today reported that the U.S. military in November was trying to develop a vaccine for troops from the bacteria that cause the disease Q fever, an agent the military once used as a biological weapon. In February 2014, the former special assistant and senior director for biodefense policy to President George W. Bush called the bioterrorism risk imminent and uncertain and Congressman Bill Pascrell called for increasing federal measures against bioterrorism as a "matter of life or death." The New York Times wrote a story saying the United States would spend $40 million to help certain low and middle-income countries deal with the threats of bioterrorism and infectious diseases.
Bioterrorism can additionally harm the psychological aspect of victims and the general public. Victims exposed to biological weapons have shown an increased presence of clinical anxiety compared to the normal population.
Bill Gates has warned that bioterrorism could kill more people than nuclear war.
In February 2018, a CNN employee discovered on an airplane a "sensitive, top-secret document in the seatback pouch explaining how the Department of Homeland Security would respond to a bioterrorism attack at the Super Bowl."
2017 U.S. budget proposal affecting bioterrorism programs
President Donald Trump promoted his first budget around keeping America safe. However, one aspect of defense would receive less money: "protecting the nation from deadly pathogens, man-made or natural," according to The New York Times. Agencies tasked with biosecurity get a decrease in funding under the Administration's budget proposal. | Bioterrorism | Wikipedia | 416 | 4393 | https://en.wikipedia.org/wiki/Bioterrorism | Technology | Biotechnology | null |
For example:
The Office of Public Health Preparedness and Response would be cut by $136 million, or 9.7 percent. The office tracks outbreaks of disease.
The National Center for Emerging and Zoonotic Infectious Diseases would be cut by $65 million, or 11 percent. The center is a branch of the Centers for Disease Control and Prevention that fights threats like anthrax and the Ebola virus, and additionally towards research on HIV/AIDS vaccines.
Within the National Institutes of Health, the National Institute of Allergy and Infectious Diseases (NIAID) would lose 18 percent of its budget. NIAID oversees responses to Zika, Ebola and HIV/AIDS vaccine research.
"The next weapon of mass destruction may not be a bomb," Lawrence O. Gostin, the director of the World Health Organization's Collaborating Center on Public Health Law and Human Rights, told The New York Times. "It may be a tiny pathogen that you can't see, smell or taste, and by the time we discover it, it'll be too late."
Lack of international standards on public health experiments
Tom Inglesy, the CEO and director of the Center for Health Security at the Johns Hopkins Bloomberg School of Public Health and an internationally recognized expert on public health preparedness, pandemic and emerging infectious disease said in 2017 that the lack of an internationally standardized approval process that could be used to guide countries in conducting public health experiments for resurrecting a disease that has already been eradicated increases the risk that the disease could be used in bioterrorism. This was in reference to the lab synthesis of horsepox in 2017 by researchers at the University of Alberta. The researchers recreated horsepox, an extinct cousin of the smallpox virus, in order to research new ways to treat cancer.
In popular culture
Incidents | Bioterrorism | Wikipedia | 371 | 4393 | https://en.wikipedia.org/wiki/Bioterrorism | Technology | Biotechnology | null |
The Northrop B-2 Spirit, also known as the Stealth Bomber, is an American heavy strategic bomber, featuring low-observable stealth technology designed to penetrate dense anti-aircraft defenses. A subsonic flying wing with a crew of two, the plane was designed by Northrop (later Northrop Grumman) as the prime contractor, with Boeing, Hughes, and Vought as principal subcontractors, and was produced from 1987 to 2000. The bomber can drop conventional and thermonuclear weapons, such as up to eighty Mk 82 JDAM GPS-guided bombs, or sixteen B83 nuclear bombs. The B-2 is the only acknowledged in-service aircraft that can carry large air-to-surface standoff weapons in a stealth configuration.
Development began under the Advanced Technology Bomber (ATB) project during the Carter administration, which cancelled the Mach 2-capable B-1A bomber in part because the ATB showed such promise. But development difficulties delayed progress and drove up costs. Ultimately, the program produced 21 B-2s at an average cost of $2.13 billion (~$ billion in ), including development, engineering, testing, production, and procurement. Building each aircraft cost an average of US$737 million, while total procurement costs (including production, spare parts, equipment, retrofitting, and software support) averaged $929 million (~$ in ) per plane. The project's considerable capital and operating costs made it controversial in the U.S. Congress even before the winding down of the Cold War dramatically reduced the desire for a stealth aircraft designed to strike deep in Soviet territory. Consequently, in the late 1980s and 1990s lawmakers shrank the planned purchase of 132 bombers to 21.
The B-2 can perform attack missions at altitudes of up to ; it has an unrefueled range of more than and can fly more than with one midair refueling. It entered service in 1997 as the second aircraft designed with advanced stealth technology, after the Lockheed F-117 Nighthawk attack aircraft. Primarily designed as a nuclear bomber, the B-2 was first used in combat to drop conventional, non-nuclear ordnance in the Kosovo War in 1999. It was later used in Iraq, Afghanistan, Libya and Yemen. | Northrop B-2 Spirit | Wikipedia | 463 | 4396 | https://en.wikipedia.org/wiki/Northrop%20B-2%20Spirit | Technology | Specific aircraft | null |
The United States Air Force has nineteen B-2s in service as of 2024; one was destroyed in a 2008 crash and another one damaged in a crash in 2022 was retired from service likely on account of the cost and duration of a potential repair. The Air Force plans to operate the B-2s until 2032, when the Northrop Grumman B-21 Raider is to replace them.
Development
Origins
By the mid-1970s, military aircraft designers had learned of a new method to avoid missiles and interceptors, known today as "stealth". The concept was to build an aircraft with an airframe that deflected or absorbed radar signals so that little was reflected back to the radar unit. An aircraft having radar stealth characteristics would be able to fly nearly undetected and could be attacked only by weapons and systems not relying on radar. Although other detection measures existed, such as human observation, infrared scanners, and acoustic locators, their relatively short detection range or poorly developed technology allowed most aircraft to fly undetected, or at least untracked, especially at night.
In 1974, DARPA requested information from U.S. aviation firms about the largest radar cross-section of an aircraft that would remain effectively invisible to radars. Initially, Northrop and McDonnell Douglas were selected for further development. Lockheed had experience in this field with the development of the Lockheed A-12 and SR-71, which included several stealthy features, notably its canted vertical stabilizers, the use of composite materials in key locations, and the overall surface finish in radar-absorbing paint. A key improvement was the introduction of computer models used to predict the radar reflections from flat surfaces where collected data drove the design of a "faceted" aircraft. Development of the first such designs started in 1975 with the Have Blue, a model Lockheed built to test the concept. | Northrop B-2 Spirit | Wikipedia | 379 | 4396 | https://en.wikipedia.org/wiki/Northrop%20B-2%20Spirit | Technology | Specific aircraft | null |
Plans were well advanced by the summer of 1975, when DARPA started the Experimental Survivability Testbed project. Northrop and Lockheed were awarded contracts in the first round of testing. Lockheed received the sole award for the second test round in April 1976 leading to the Have Blue program and eventually the F-117 stealth attack aircraft. Northrop also had a classified technology demonstration aircraft, the Tacit Blue in development in 1979 at Area 51. It developed stealth technology, LO (low observables), fly-by-wire, curved surfaces, composite materials, electronic intelligence, and Battlefield Surveillance Aircraft Experimental. The stealth technology developed from the program was later incorporated into other operational aircraft designs, including the B-2 stealth bomber.
ATB program
By 1976, these programs had progressed to a position in which a long-range strategic stealth bomber appeared viable. President Jimmy Carter became aware of these developments during 1977, and it appears to have been one of the major reasons the B-1 was canceled. Further studies were ordered in early 1978, by which point the Have Blue platform had flown and proven the concepts. During the 1980 presidential election campaign in 1979, Ronald Reagan repeatedly stated that Carter was weak on defense and used the B-1 as a prime example. In response, on 22 August 1980 the Carter administration publicly disclosed that the United States Department of Defense was working to develop stealth aircraft, including a bomber.
The Advanced Technology Bomber (ATB) program began in 1979. Full development of the black project followed, funded under the code name "Aurora". After the evaluations of the companies' proposals, the ATB competition was narrowed to the Northrop/Boeing and Lockheed/Rockwell teams with each receiving a study contract for further work. Both teams used flying wing designs. The Northrop proposal was code named "Senior Ice", and the Lockheed proposal code named "Senior Peg". Northrop had prior experience developing the YB-35 and YB-49 flying wing aircraft. The Northrop design was larger and had curved surfaces while the Lockheed design was faceted and included a small tail. In 1979, designer Hal Markarian produced a sketch of the aircraft that bore considerable similarities to the final design. The USAF originally planned to procure 165 ATB bombers. | Northrop B-2 Spirit | Wikipedia | 458 | 4396 | https://en.wikipedia.org/wiki/Northrop%20B-2%20Spirit | Technology | Specific aircraft | null |
The Northrop team's ATB design was selected over the Lockheed/Rockwell design on 20 October 1981. The Northrop design received the designation B-2 and the name "Spirit". The bomber's design was changed in the mid-1980s when the mission profile was changed from high-altitude to low-altitude, terrain-following. The redesign delayed the B-2's first flight by two years and added about US$1 billion to the program's cost. An estimated US$23 billion was secretly spent for research and development on the B-2 by 1989. MIT engineers and scientists helped assess the mission effectiveness of the aircraft under a five-year classified contract during the 1980s. ATB technology was also fed into the Advanced Tactical Fighter program, which would result in the Lockheed YF-22 and Northrop YF-23, and later the Lockheed Martin F-22. Northrop was the B-2's prime contractor; major subcontractors included Boeing, Hughes Aircraft (now Raytheon), GE, and Vought Aircraft.
Secrecy and espionage
During its design and development, the Northrop B-2 program was a black project; all program personnel needed a secret clearance. Still, it was less closely held than the Lockheed F-117 program; more people in the federal government knew about the B-2, and more information about the project was available. Both during development and in service, considerable effort has been devoted to maintaining the security of the B-2's design and technologies. Staff working on the B-2 in most, if not all, capacities need a level of special-access clearance and undergo extensive background checks carried out by a special branch of the USAF.
A former Ford automobile assembly plant in Pico Rivera, California, was acquired and heavily rebuilt; the plant's employees were sworn to secrecy. To avoid suspicion, components were typically purchased through front companies, military officials would visit out of uniform, and staff members were routinely subjected to polygraph examinations. Nearly all information on the program was kept from the Government Accountability Office (GAO) and members of Congress until the mid-1980s. | Northrop B-2 Spirit | Wikipedia | 435 | 4396 | https://en.wikipedia.org/wiki/Northrop%20B-2%20Spirit | Technology | Specific aircraft | null |
The B-2 was first publicly displayed on 22 November 1988 at United States Air Force Plant 42 in Palmdale, California, where it was assembled. This viewing was heavily restricted, and guests were not allowed to see the rear of the B-2. However, Aviation Week editors found that there were no airspace restrictions above the presentation area and took aerial photographs of the aircraft's secret rear section with suppressed engine exhausts. The B-2's (s/n / AV-1) first public flight was on 17 July 1989 from Palmdale to Edwards Air Force Base.
In 1984, Northrop employee Thomas Patrick Cavanagh was arrested for attempting to sell classified information from the Pico Rivera factory to the Soviet Union. Cavanagh was sentenced to life in prison in 1985 but released on parole in 2001. In October 2005, Noshir Gowadia, a design engineer who worked on the B-2's propulsion system, was arrested for selling classified information to China. Gowadia was convicted and sentenced to 32 years in prison.
Program costs and procurement
A procurement of 132 aircraft was planned in the mid-1980s but was later reduced to 75. By the early 1990s the Soviet Union dissolved, effectively eliminating the Spirit's primary Cold War mission. Under budgetary pressures and Congressional opposition, in his 1992 State of the Union address, President George H. W. Bush announced B-2 production would be limited to 20 aircraft. In 1996, however, the Clinton administration, though originally committed to ending production of the bombers at 20 aircraft, authorized the conversion of a 21st bomber, a prototype test model, to Block 30 fully operational status at a cost of nearly $500 million (~$ in ). In 1995, Northrop made a proposal to the USAF to build 20 additional aircraft with a flyaway cost of $566 million each. | Northrop B-2 Spirit | Wikipedia | 374 | 4396 | https://en.wikipedia.org/wiki/Northrop%20B-2%20Spirit | Technology | Specific aircraft | null |
The program was the subject of public controversy for its cost to American taxpayers. In 1996, the GAO disclosed that the USAF's B-2 bombers "will be, by far, the costliest bombers to operate on a per aircraft basis", costing over three times as much as the B-1B (US$9.6 million annually) and over four times as much as the B-52H (US$6.8 million annually). In September 1997, each hour of B-2 flight necessitated 119 hours of maintenance. Comparable maintenance needs for the B-52 and the B-1B are 53 and 60 hours, respectively, for each hour of flight. A key reason for this cost is the provision of air-conditioned hangars large enough for the bomber's wingspan, which are needed to maintain the aircraft's stealth properties, particularly its "low-observable" stealth skins. Maintenance costs are about $3.4 million per month for each aircraft. An August 1995 GAO report disclosed that the B-2 had trouble operating in heavy rain, as rain could damage the aircraft's stealth coating, causing procurement delays until an adequate protective coating could be found. In addition, the B-2's terrain-following/terrain-avoidance radar had difficulty distinguishing rain from other obstacles, rendering the subsystem inoperable during rain. However a subsequent report in October 1996 noted that the USAF had made some progress in resolving the issues with the radar via software fixes and hoped to have these fixes undergoing tests by the spring of 1997.
The total "military construction" cost related to the program was projected to be US$553.6 million in 1997 dollars. The cost to procure each B-2 was US$737 million in 1997 dollars (equivalent to US$ billion in 2021), based only on a fleet cost of US$15.48 billion. The procurement cost per aircraft, as detailed in GAO reports, which include spare parts and software support, was $929 million per aircraft in 1997 dollars.
The total program cost projected through 2004 was US$44.75 billion in 1997 dollars (equivalent to US$ billion in 2021). This includes development, procurement, facilities, construction, and spare parts. The total program cost averaged US$2.13 billion per aircraft. The B-2 may cost up to $135,000 per flight hour to operate in 2010, which is about twice that of the B-52 and B-1. | Northrop B-2 Spirit | Wikipedia | 506 | 4396 | https://en.wikipedia.org/wiki/Northrop%20B-2%20Spirit | Technology | Specific aircraft | null |
Opposition
In its consideration of the fiscal year 1990 defense budget, the House Armed Services Committee trimmed $800 million from the B-2 research and development budget, while at the same time staving off a motion to end the project. Opposition in committee and in Congress was mostly broad and bipartisan, with Congressmen Ron Dellums (D-CA), John Kasich (R-OH), and John G. Rowland (R-CT) authorizing the motion to end the project—as well as others in the Senate, including Jim Exon (D-NE) and John McCain (R-AZ) also opposing the project. Dellums and Kasich, in particular, worked together from 1989 through the early 1990s to limit production to 21 aircraft and were ultimately successful.
The escalating cost of the B-2 program and evidence of flaws in the aircraft's ability to elude detection by radar were among factors that drove opposition to continue the program. At the peak production period specified in 1989, the schedule called for spending US$7 billion to $8 billion per year in 1989 dollars, something Committee Chair Les Aspin (D-WI) said "won't fly financially". In 1990, the Department of Defense accused Northrop of using faulty components in the flight control system; it was also found that redesign work was required to reduce the risk of damage to engine fan blades by bird ingestion.
In time, several prominent members of Congress began to oppose the program's expansion, including Senator John Kerry (D-MA), who cast votes against the B-2 in 1989, 1991, and 1992. By 1992, Bush had called for the cancellation of the B-2 and promised to cut military spending by 30% in the wake of the collapse of the Soviet Union. In October 1995, former Chief of Staff of the United States Air Force, General Mike Ryan, and former chairman of the Joint Chiefs of Staff, General John Shalikashvili, strongly recommended against Congressional action to fund the purchase of any additional B-2s, arguing that to do so would require unacceptable cuts in existing conventional and nuclear-capable aircraft, and that the military had greater priorities in spending a limited budget. | Northrop B-2 Spirit | Wikipedia | 452 | 4396 | https://en.wikipedia.org/wiki/Northrop%20B-2%20Spirit | Technology | Specific aircraft | null |
Some B-2 advocates argued that procuring twenty additional aircraft would save money because B-2s would be able to deeply penetrate anti-aircraft defenses and use low-cost, short-range attack weapons rather than expensive standoff weapons. However, in 1995, the Congressional Budget Office (CBO) and its Director of National Security Analysis found that additional B-2s would reduce the cost of expended munitions by less than US$2 billion in 1995 dollars during the first two weeks of a conflict, in which the USAF predicted bombers would make their greatest contribution; this was a small fraction of the US$26.8 billion (in 1995 dollars) life cycle cost that the CBO projected for an additional 20 B-2s.
In 1997, as Ranking Member of the House Armed Services Committee and National Security Committee, Congressman Ron Dellums (D-CA), a long-time opponent of the bomber, cited five independent studies and offered an amendment to that year's defense authorization bill to cap production of the bombers to the existing 21 aircraft; the amendment was narrowly defeated. Nonetheless, Congress did not approve funding for additional B-2s.
Further developments
Several upgrade packages have been applied to the B-2. In July 2008, the B-2's onboard computing architecture was extensively redesigned; it now incorporates a new integrated processing unit that communicates with systems throughout the aircraft via a newly installed fiber optic network; a new version of the operational flight program software was also developed, with legacy code converted from the JOVIAL programming language to standard C. Updates were also made to the weapon control systems to enable strikes upon moving targets, such as ground vehicles.
On 29 December 2008, USAF officials awarded a US$468 million contract to Northrop Grumman to modernize the B-2 fleet's radars. Changing the radar's frequency was required as the United States Department of Commerce had sold that radio spectrum to another operator. In July 2009, it was reported that the B-2 had successfully passed a major USAF audit. In 2010, it was made public that the Air Force Research Laboratory had developed a new material to be used on the part of the wing trailing edge subject to engine exhaust, replacing existing material that quickly degraded. | Northrop B-2 Spirit | Wikipedia | 457 | 4396 | https://en.wikipedia.org/wiki/Northrop%20B-2%20Spirit | Technology | Specific aircraft | null |
In July 2010, political analyst Rebecca Grant speculated that when the B-2 becomes unable to reliably penetrate enemy defenses, the Lockheed Martin F-35 Lightning II may take on its strike/interdiction mission, carrying B61 nuclear bombs as a tactical bomber. However, in March 2012, The Pentagon announced that a $2 billion, 10-year-long modernization of the B-2 fleet was to begin. The main area of improvement would be replacement of outdated avionics and equipment. Continued modernization efforts likely have continued in secret, as alluded to by a B-2 commander from Whiteman Air Force Base in April 2021, possibly indicating offensive weapons capability against threatening air defenses and aircraft. He stated:
It was reported in 2011 that The Pentagon was evaluating an unmanned stealth bomber, characterized as a "mini-B-2", as a potential replacement in the near future. In 2012, USAF Chief of Staff General Norton Schwartz stated the B-2's 1980s-era stealth technologies would make it less survivable in future contested airspaces, so the USAF is to proceed with the Next-Generation Bomber despite overall budget cuts. In 2012 projections, it was estimated that the Next-Generation Bomber would have an overall cost of $55 billion.
In 2013, the USAF contracted for the Defensive Management System Modernization (DMS-M) program to replace the antenna system and other electronics to increase the B-2's frequency awareness. The Common Very Low Frequency Receiver upgrade allows the B-2s to use the same very low frequency transmissions as the Ohio-class submarines so as to continue in the nuclear mission until the Mobile User Objective System is fielded. In 2014, the USAF outlined a series of upgrades including nuclear warfighting, a new integrated processing unit, the ability to carry cruise missiles, and threat warning improvements. Due to ongoing software challenges, DMS-M was canceled by 2020, and the existing work was repurposed for cockpit upgrades.
In 1998, a Congressional panel advised the USAF to refocus resources away from continued B-2 production and instead begin development of a new bomber, either a new build or a variant of the B-2. In its 1999 bomber roadmap the USAF eschewed the panel's recommendations, believing its current bomber fleet could be maintained until the 2030s. The service believed that development could begin in 2013, in time to replace aging B-2s, B-1s and B-52s around 2037. | Northrop B-2 Spirit | Wikipedia | 505 | 4396 | https://en.wikipedia.org/wiki/Northrop%20B-2%20Spirit | Technology | Specific aircraft | null |
Although the USAF previously planned to operate the B-2 until 2058, the FY 2019 budget moved up its retirement to "no later than 2032". It also moved the retirement of the B-1 to 2036 while extending the B-52's service life into the 2050s, because the B-52 has lower maintenance costs, versatile conventional payload, and the ability to carry nuclear cruise missiles (which the B-1 is treaty-prohibited from doing). The decision to retire the B-2 early was made because the small fleet of 20 is considered too expensive per plane to retain, with its position as a stealth bomber being taken over with the introduction of the B-21 Raider starting in the mid-2020s.
Design
Overview
The B-2 Spirit was developed to take over the USAF's vital penetration missions, allowing it to travel deep into enemy territory to deploy ordnance, which could include nuclear weapons. The B-2 is a flying wing aircraft, meaning that it has no fuselage or tail. It has significant advantages over previous bombers due to its blend of low-observable technologies with high aerodynamic efficiency and a large payload. Low observability provides greater freedom of action at high altitudes, thus increasing both range and field of view for onboard sensors. The USAF reports its range as approximately . At cruising altitude, the B-2 refuels every six hours, taking on up to of fuel at a time.
The development and construction of the B-2 required pioneering use of computer-aided design and manufacturing technologies due to its complex flight characteristics and design requirements to maintain very low visibility to multiple means of detection. The B-2 bears a resemblance to earlier Northrop aircraft; the YB-35 and YB-49 were both flying wing bombers that had been canceled in development in the early 1950s, allegedly for political reasons. The resemblance goes as far as B-2 and YB-49 having the same wingspan. The YB-49 also had a small radar cross-section. | Northrop B-2 Spirit | Wikipedia | 410 | 4396 | https://en.wikipedia.org/wiki/Northrop%20B-2%20Spirit | Technology | Specific aircraft | null |
Approximately 80 pilots fly the B-2. Each aircraft has a crew of two, a pilot in the left seat and mission commander in the right, and has provisions for a third crew member if needed. For comparison, the B-1B has a crew of four and the B-52 has a crew of five. The B-2 is highly automated, and one crew member can sleep in a camp bed, use a toilet, or prepare a hot meal while the other monitors the aircraft, unlike most two-seat aircraft. Extensive sleep cycle and fatigue research was conducted to improve crew performance on long sorties. Advanced training is conducted at the USAF Weapons School.
Armaments and equipment
In the envisaged Cold War scenario, the B-2 was to perform deep-penetrating nuclear strike missions, making use of its stealthy capabilities to avoid detection and interception throughout the missions. There are two internal bomb bays in which munitions are stored either on a rotary launcher or two bomb-racks; the carriage of the weapons loadouts internally results in less radar visibility than external mounting of munitions. The B-2 is capable of carrying of ordnance. Nuclear ordnance includes the B61 and B83 nuclear bombs; the AGM-129 ACM cruise missile was also intended for use on the B-2 platform.
In light of the dissolution of the Soviet Union, it was decided to equip the B-2 for conventional precision attacks as well as for the strategic role of nuclear-strike. The B-2 features a sophisticated GPS-Aided Targeting System (GATS) that uses the aircraft's APQ-181 synthetic aperture radar to map out targets prior to the deployment of GPS-aided bombs (GAMs), later superseded by the Joint Direct Attack Munition (JDAM). In the B-2's original configuration, up to 16 GAMs or JDAMs could be deployed; An upgrade program in 2004 raised the maximum carrier capacity to 80 JDAMs. | Northrop B-2 Spirit | Wikipedia | 399 | 4396 | https://en.wikipedia.org/wiki/Northrop%20B-2%20Spirit | Technology | Specific aircraft | null |
The B-2 has various conventional weapons in its arsenal, including Mark 82 and Mark 84 bombs, CBU-87 Combined Effects Munitions, GATOR mines, and the CBU-97 Sensor Fuzed Weapon. In July 2009, Northrop Grumman reported the B-2 was compatible with the equipment necessary to deploy the Massive Ordnance Penetrator (MOP), which is intended to attack reinforced bunkers; up to two MOPs could be equipped in the B-2's bomb bays with one per bay, the B-2 is the only platform compatible with the MOP as of 2012. As of 2011, the AGM-158 JASSM cruise missile is an upcoming standoff munition to be deployed on the B-2 and other platforms. This is to be followed by the Long Range Standoff Weapon, which may give the B-2 standoff nuclear capability for the first time.
Avionics and systems
To make the B-2 more effective than previous bombers, many advanced and modern avionics systems were integrated into its design; these have been modified and improved following a switch to conventional warfare missions. One system is the low probability of intercept AN/APQ-181 multi-mode radar, a fully digital navigation system that is integrated with terrain-following radar and Global Positioning System (GPS) guidance, NAS-26 astro-inertial navigation system (first such system tested on the Northrop SM-62 Snark cruise missile) and a Defensive Management System (DMS) to inform the flight crew of possible threats. The onboard DMS is capable of automatically assessing the detection capabilities of identified threats and indicated targets. The DMS will be upgraded by 2021 to detect radar emissions from air defenses to allow changes to the auto-router's mission planning information while in-flight so it can receive new data quickly to plan a route that minimizes exposure to dangers. | Northrop B-2 Spirit | Wikipedia | 389 | 4396 | https://en.wikipedia.org/wiki/Northrop%20B-2%20Spirit | Technology | Specific aircraft | null |
For safety and fault-detection purposes, an on-board test system is linked with the majority of avionics on the B-2 to continuously monitor the performance and status of thousands of components and consumables; it also provides post-mission servicing instructions for ground crews. In 2008, many of the 136 standalone distributed computers on board the B-2, including the primary flight management computer, were being replaced by a single integrated system. The avionics are controlled by 13 EMP-resistant MIL-STD-1750A computers, which are interconnected through 26 MIL-STD-1553B-busses; other system elements are connected via optical fiber.
In addition to periodic software upgrades and the introduction of new radar-absorbent materials across the fleet, the B-2 has had several major upgrades to its avionics and combat systems. For battlefield communications, both Link-16 and a high frequency satellite link have been installed, compatibility with various new munitions has been undertaken, and the AN/APQ-181 radar's operational frequency was shifted to avoid interference with other operators' equipment. The arrays of the upgraded radar features were entirely replaced to make the AN/APQ-181 into an active electronically scanned array (AESA) radar. Due to the B-2's composite structure, it is required to stay away from thunderstorms, to avoid static discharge and lightning strikes.
Flight controls
To address the inherent flight instability of a flying wing aircraft, the B-2 uses a complex quadruplex computer-controlled fly-by-wire flight control system that can automatically manipulate flight surfaces and settings without direct pilot inputs to maintain aircraft stability. The flight computer receives information on external conditions such as the aircraft's current air speed and angle of attack via pitot-static sensing plates, as opposed to traditional pitot tubes which would impair the aircraft's stealth capabilities. The flight actuation system incorporates both hydraulic and electrical servoactuated components, and it was designed with a high level of redundancy and fault-diagnostic capabilities. | Northrop B-2 Spirit | Wikipedia | 422 | 4396 | https://en.wikipedia.org/wiki/Northrop%20B-2%20Spirit | Technology | Specific aircraft | null |
Northrop had investigated several means of applying directional control that would infringe on the aircraft's radar profile as little as possible, eventually settling on a combination of split brake-rudders and differential thrust. Engine thrust became a key element of the B-2's aerodynamic design process early on; thrust not only affects drag and lift but pitching and rolling motions as well. Four pairs of control surfaces are located along the wing's trailing edge; while most surfaces are used throughout the aircraft's flight envelope, the inner elevons are normally only in use at slow speeds, such as landing. To avoid potential contact damage during takeoff and to provide a nose-down pitching attitude, all of the elevons remain drooped during takeoff until a high enough airspeed has been attained.
Stealth
The B-2's low-observable, or "stealth", characteristics enable the undetected penetration of sophisticated anti-aircraft defenses and to attack even heavily defended targets. This stealth comes from a combination of reduced acoustic, infrared, visual and radar signatures (multi-spectral camouflage) to evade the various detection systems that could be used to detect and be used to direct attacks against an aircraft. The B-2's stealth enables the reduction of supporting aircraft that are required to provide air cover, Suppression of Enemy Air Defenses and electronic countermeasures, making the bomber a "force multiplier". , there have been no instances of a missile being launched at a B-2.
To reduce optical visibility during daylight flights, the B-2 is painted in an anti-reflective paint. The undersides are dark because it flies at high altitudes (), and at that altitude a dark grey painting blends well into the sky. It is speculated to have an upward-facing light sensor which alerts the pilot to increase or reduce altitude to match the changing illuminance of the sky. The original design had tanks for a contrail-inhibiting chemical, but this was replaced in production aircraft by a contrail sensor that alerts the crew when they should change altitude. The B-2 is vulnerable to visual interception at ranges of or less. The B-2 is stored in a $5 million specialized air-conditioned hangar to maintain its stealth coating. Every seven years, this coating is carefully washed away with crystallized wheat starch so that the B-2's surfaces can be inspected for any dents or scratches. | Northrop B-2 Spirit | Wikipedia | 496 | 4396 | https://en.wikipedia.org/wiki/Northrop%20B-2%20Spirit | Technology | Specific aircraft | null |
Radar
The B-2's clean, low-drag flying wing configuration not only provides exceptional range but is also beneficial to reducing its radar profile. Reportedly, the B-2 has a radar cross-section (RCS) of about . The bomber does not always fly stealthily; when nearing air defenses pilots "stealth up" the B-2, a maneuver whose details are secret. The aircraft is stealthy, except briefly when the bomb bay opens. The flying wing design most closely resembles a so-called infinite flat plate (as vertical control surfaces dramatically increase RCS), the perfect stealth shape, as it would lack angles to reflect back radar waves (initially, the shape of the Northrop ATB concept was flatter; it gradually increased in volume according to specific military requirements). Without vertical surfaces to reflect radar laterally, side aspect radar cross section is also reduced. Radars operating at a lower frequency band (S or L band) are able to detect and track certain stealth aircraft that have multiple control surfaces, like canards or vertical stabilizers, where the frequency wavelength can exceed a certain threshold and cause a resonant effect.
RCS reduction as a result of shape had already been observed on the Royal Air Force's Avro Vulcan strategic bomber, and the USAF's F-117 Nighthawk. The F-117 used flat surfaces (faceting technique) for controlling radar returns as during its development (see Lockheed Have Blue) in the early 1970s, technology only allowed for the simulation of radar reflections on simple, flat surfaces; computing advances in the 1980s made it possible to simulate radar returns on more complex curved surfaces. The B-2 is composed of many curved and rounded surfaces across its exposed airframe to deflect radar beams. This technique, known as continuous curvature, was made possible by advances in computational fluid dynamics, and first tested on the Northrop Tacit Blue.
Infrared
Some analysts claim infra-red search and track systems (IRSTs) can be deployed against stealth aircraft, because any aircraft surface heats up due to air friction and with a two channel IRST is a (4.3 μm absorption maxima) detection possible, through difference comparing between the low and high channel. | Northrop B-2 Spirit | Wikipedia | 451 | 4396 | https://en.wikipedia.org/wiki/Northrop%20B-2%20Spirit | Technology | Specific aircraft | null |
Burying engines deep inside the fuselage also minimizes the thermal visibility or infrared signature of the exhaust. At the engine intake, cold air from the boundary layer below the main inlet enters the fuselage (boundary layer suction, first tested on the Northrop X-21) and is mixed with hot exhaust air just before the nozzles (similar to the Ryan AQM-91 Firefly). According to the Stefan–Boltzmann law, this results in less energy (thermal radiation in the infrared spectrum) being released and thus a reduced heat signature. The resulting cooler air is conducted over a surface composed of heat resistant carbon-fiber-reinforced polymer and titanium alloy elements, which disperse the air laterally, to accelerate its cooling. The B-2 lacks afterburners as the hot exhaust would increase the infrared signature; breaking the sound barrier would produce an obvious sonic boom as well as aerodynamic heating of the aircraft skin which would also increase the infrared signature.
Materials
According to the Huygens–Fresnel principle, even a very flat plate would still reflect radar waves, though much less than when a signal is bouncing at a right angle. Additional reduction in its radar signature was achieved by the use of various radar-absorbent materials (RAM) to absorb and neutralize radar beams. The majority of the B-2 is made out of a carbon-graphite composite material that is stronger than steel, lighter than aluminum, and absorbs a significant amount of radar energy.
The B-2 is assembled with unusually tight engineering tolerances to avoid leaks as they could increase its radar signature. Innovations such as alternate high frequency material (AHFM) and automated material application methods were also incorporated to improve the aircraft's radar-absorbent properties and reduce maintenance requirements. In early 2004, Northrop Grumman began applying a newly developed AHFM to operational B-2s. To protect the operational integrity of its sophisticated radar absorbent material and coatings, each B-2 is kept inside a climate-controlled hangar (Extra Large Deployable Aircraft Hangar System) large enough to accommodate its wingspan. | Northrop B-2 Spirit | Wikipedia | 423 | 4396 | https://en.wikipedia.org/wiki/Northrop%20B-2%20Spirit | Technology | Specific aircraft | null |
Shelter system
B-2s are supported by portable, environmentally-controlled hangars called B-2 Shelter Systems (B2SS). The hangars are built by American Spaceframe Fabricators Inc. and cost approximately US$5 million apiece. The need for specialized hangars arose in 1998 when it was found that B-2s passing through Andersen Air Force Base did not have the climate-controlled environment maintenance operations required. In 2003, the B2SS program was managed by the Combat Support System Program Office at Eglin Air Force Base. B2SS hangars are known to have been deployed to Naval Support Facility Diego Garcia and RAF Fairford.
Operational history
1990s
The first operational aircraft, christened Spirit of Missouri, was delivered to Whiteman Air Force Base, Missouri, where the fleet is based, on 17 December 1993. The B-2 reached initial operational capability (IOC) on 1 January 1997. Depot maintenance for the B-2 is accomplished by USAF contractor support and managed at Oklahoma City Air Logistics Center at Tinker Air Force Base. Originally designed to deliver nuclear weapons, modern usage has shifted towards a flexible role with conventional and nuclear capability.
The B-2's combat debut was in 1999, during the Kosovo War. It was responsible for destroying 33% of selected Serbian bombing targets in the first eight weeks of U.S. involvement in the war. During this war, six B-2s flew non-stop to Yugoslavia from their home base in Missouri and back, totaling 30 hours. Although the bombers accounted 50 sorties out of a total of 34,000 NATO sorties, they dropped 11 percent of all bombs. The B-2 was the first aircraft to deploy GPS satellite-guided JDAM "smart bombs" in combat use in Kosovo. The use of JDAMs and precision-guided munitions effectively replaced the controversial tactic of carpet-bombing, which had been harshly criticized due to it causing indiscriminate civilian casualties in prior conflicts, such as the 1991 Gulf War. On 7 May 1999, a B-2 dropped five JDAMs on the Chinese Embassy, killing several staff. By then, the B-2 had dropped 500 bombs in Yugoslavia. | Northrop B-2 Spirit | Wikipedia | 443 | 4396 | https://en.wikipedia.org/wiki/Northrop%20B-2%20Spirit | Technology | Specific aircraft | null |
2000s
The B-2 saw service in Afghanistan, striking ground targets in support of Operation Enduring Freedom. With aerial refueling support, the B-2 flew one of its longest missions to date from Whiteman Air Force Base in Missouri to Afghanistan and back. B-2s would be stationed in the Middle East as a part of a US military buildup in the region from 2003.
The B-2's combat use preceded a USAF declaration of "full operational capability" in December 2003. The Pentagon's Operational Test and Evaluation 2003 Annual Report noted that the B-2's serviceability for Fiscal Year 2003 was still inadequate, mainly due to the maintainability of the B-2's low observable coatings. The evaluation also noted that the Defensive Avionics suite had shortcomings with "pop-up threats".
During the Iraq War, B-2s operated from Diego Garcia and an undisclosed "forward operating location". Other sorties in Iraq have launched from Whiteman AFB. the longest combat mission has been 44.3 hours. "Forward operating locations" have been previously designated as Andersen Air Force Base in Guam and RAF Fairford in the United Kingdom, where new climate controlled hangars have been constructed. B-2s have conducted 27 sorties from Whiteman AFB and 22 sorties from a forward operating location, releasing more than of munitions, including 583 JDAM "smart bombs" in 2003.
2010s
In response to organizational issues and high-profile mistakes made within the USAF, all of the B-2s, along with the nuclear-capable B-52s and the USAF's intercontinental ballistic missiles (ICBMs), were transferred to the newly formed Air Force Global Strike Command on 1 February 2010.
In March 2011, B-2s were the first U.S. aircraft into action in Operation Odyssey Dawn, the UN mandated enforcement of the Libyan no-fly zone. Three B-2s dropped 40 bombs on a Libyan airfield in support of the UN no-fly zone. The B-2s flew directly from the U.S. mainland across the Atlantic Ocean to Libya; a B-2 was refueled by allied tanker aircraft four times during each round trip mission. | Northrop B-2 Spirit | Wikipedia | 453 | 4396 | https://en.wikipedia.org/wiki/Northrop%20B-2%20Spirit | Technology | Specific aircraft | null |
In August 2011, The New Yorker reported that prior to the May 2011 U.S. Special Operations raid into Abbottabad, Pakistan that resulted in the death of Osama bin Laden, U.S. officials had considered an airstrike by one or more B-2s as an alternative; the use of a bunker busting bomb was rejected due to potential damage to nearby civilian buildings. There were also concerns an airstrike would make it difficult to positively identify Bin Laden's remains, making it hard to confirm his death.
On 28 March 2013, two B-2s flew a round trip of from Whiteman Air Force base in Missouri to South Korea, dropping dummy ordnance on the Jik Do target range. The mission, part of the annual South Korean–U.S. military exercises, was the first time that B-2s overflew the Korean Peninsula. Tensions between the Koreas were high; North Korea protested against the B-2's participation and made threats of retaliatory nuclear strikes against South Korea and the United States.
On 18 January 2017, two B-2s attacked an ISIS training camp southwest of Sirte, Libya, killing around 85 militants. The B-2s together dropped 108 precision-guided Joint Direct Attack Munition (JDAM) bombs. These strikes were followed by an MQ-9 Reaper unmanned aerial vehicle firing Hellfire missiles. Each B-2 flew a 33-hour, round-trip mission from Whiteman Air Force Base, Missouri with four or five (accounts differ) refuelings during the trip.
2020s
On 16 October 2024, B-2As carried out strikes on weapons storage facilities in Yemen, including underground facilities owned by the Houthis. Five hardened underground weapons storage locations were struck as part of the campaign against the Houthis for attacking international shipping during the Red Sea crisis. It was believed the strikes also served as a warning to Iran, demonstrating the stealth bomber's ability to destroy targets buried underground. RAAF Base Tindal in the Northern Territory, Australia was used as a staging ground for the strikes.
Operators | Northrop B-2 Spirit | Wikipedia | 428 | 4396 | https://en.wikipedia.org/wiki/Northrop%20B-2%20Spirit | Technology | Specific aircraft | null |
United States Air Force (19 aircraft in active inventory)
Air Force Global Strike Command
509th Bomb Wing – Whiteman Air Force Base, Missouri (18 B-2s)
13th Bomb Squadron 2005–present
325th Bomb Squadron 1998–2005
393rd Bomb Squadron 1993–present
394th Combat Training Squadron 1996–2018
Air Combat Command
53rd Wing – Eglin Air Force Base, Florida
72nd Test and Evaluation Squadron (Whiteman AFB, Missouri) 1998–present
57th Wing – Nellis AFB, Nevada
325th Weapons Squadron – Whiteman AFB, Missouri 2005–present
715th Weapons Squadron 2003–2005
Air National Guard
131st Bomb Wing (Associate) – Whiteman AFB, Missouri 2009–present
110th Bomb Squadron
Air Force Materiel Command
412th Test Wing – Edwards Air Force Base, California (has one B-2)
419th Flight Test Squadron 1997–present
420th Flight Test Squadron 1992–1997
Air Force Systems Command
6510th Test Wing – Edwards AFB, California 1989–1992
6520th Flight Test Squadron
Accidents and incidents
On 23 February 2008, B-2 "AV-12" Spirit of Kansas crashed on the runway shortly after takeoff from Andersen Air Force Base in Guam. Spirit of Kansas had been operated by the 393rd Bomb Squadron, 509th Bomb Wing, Whiteman Air Force Base, Missouri, and had logged 5,176 flight hours. The two-person crew ejected safely from the aircraft. The aircraft was destroyed, a hull loss valued at US$1.4 billion. After the accident, the USAF took the B-2 fleet off operational status for 53 days, returning on 15 April 2008. The cause of the crash was later determined to be moisture in the aircraft's Port Transducer Units during air data calibration, which distorted the information being sent to the bomber's air data system. As a result, the flight control computers calculated an inaccurate airspeed, and a negative angle of attack, causing the aircraft to pitch upward 30 degrees during takeoff. This was the first crash and loss of a B-2. | Northrop B-2 Spirit | Wikipedia | 420 | 4396 | https://en.wikipedia.org/wiki/Northrop%20B-2%20Spirit | Technology | Specific aircraft | null |
In February 2010, a serious incident involving a B-2 occurred at Andersen Air Force Base in Guam. The aircraft involved was AV-11 Spirit of Washington. The aircraft was severely damaged by fire while on the ground and underwent 18 months of repairs to enable it to fly back to the mainland U.S. for more comprehensive repairs. Spirit of Washington was repaired and returned to service in December 2013. At the time of the accident, the USAF had no training to deal with tailpipe fires on the B-2s.
On the night of 13–14 September 2021, B-2 Spirit of Georgia made an emergency landing at Whiteman AFB. The aircraft landed and went off the runway into the grass and came to rest on its left side. The cause was later determined to be faulty landing gear springs and "microcracking" in hydraulic connections on the aircraft. The lock link springs in the left landing gear had likely not been replaced in at least a decade, and produced about 11% less tension than specified. The "microcracking" reduced hydraulic support to the landing gear. These problems allowed the landing gear to fold upon landing. The accident resulted in a minimum of $10.1 million in repair damages, but the final repair cost was still being determined in March 2022.
On 10 December 2022, an in-flight malfunction aboard a B-2 forced an emergency landing at Whiteman AFB. No personnel, including the flight crew, sustained injuries during the incident; there was a post-crash fire that was quickly put out. Subsequently, all B-2s were grounded. On 18 May 2023, Air Force officials lifted the grounding without disclosing any details about what caused the incident, or what steps had been taken return the aircraft to operation. In May 2024, the Air Force announced the B-2 would be divested, as it had been deemed to be "uneconomical to repair." Although no cost estimate was provided, the decision was likely influenced by the coming introduction of the B-21 bomber; after the B-2 crash in 2010, it took almost four years and over $100 million to return the aircraft to service because not losing one of the few penetrating bombers in the inventory was considered necessary to justify the effort. However, the impending arrival of the B-21 and coming retirement of the B-2 sometime after 2029 likely made USAF leaders decide it wouldn't be worth the expense to repair it, only for it to soon be retired. | Northrop B-2 Spirit | Wikipedia | 511 | 4396 | https://en.wikipedia.org/wiki/Northrop%20B-2%20Spirit | Technology | Specific aircraft | null |
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