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9,100 | NASA and NOAA have cooperated for decades on the development, delivery and operation of polar and geosynchronous weather satellites. The relationship typically involves NASA developing the space systems, launch solutions, and ground control technology for the satellites and NOAA operating the systems and delivering weather forecasting products to users. Multiple generations of NOAA Polar orbiting platforms have operated to provide detailed imaging of weather from low altitude. Geostationary Operational Environmental Satellites (GOES) provide near-real-time coverage of the western hemisphere to ensure accurate and timely understanding of developing weather phenomenon. | https://en.wikipedia.org/wiki?curid=18426568 |
9,101 | The United States Space Force (USSF) is the space service branch of the United States Armed Forces, while the National Aeronautics and Space Administration (NASA) is an independent agency of the United States government responsible for civil spaceflight. NASA and the Space Force's predecessors in the Air Force have a long-standing cooperative relationship, with the Space Force supporting NASA launches out of Kennedy Space Center, Cape Canaveral Space Force Station, and Vandenberg Space Force Base, to include range support and rescue operations from Task Force 45. NASA and the Space Force also partner on matters such as defending Earth from asteroids. Space Force members can be NASA astronauts, with Colonel Michael S. Hopkins, the commander of SpaceX Crew-1, commissioned into the Space Force from the International Space Station on December 18, 2020. In September 2020, the Space Force and NASA signed a memorandum of understanding formally acknowledging the joint role of both agencies. This new memorandum replaced a similar document signed in 2006 between NASA and Air Force Space Command. | https://en.wikipedia.org/wiki?curid=18426568 |
9,102 | The Landsat program is the longest-running enterprise for acquisition of satellite imagery of Earth. It is a joint NASA / USGS program. On July 23, 1972, the "Earth Resources Technology Satellite" was launched. This was eventually renamed to "Landsat 1" in 1975. The most recent satellite in the series, "Landsat 9", was launched on September 27, 2021. | https://en.wikipedia.org/wiki?curid=18426568 |
9,103 | The instruments on the Landsat satellites have acquired millions of images. The images, archived in the United States and at Landsat receiving stations around the world, are a unique resource for global change research and applications in agriculture, cartography, geology, forestry, regional planning, surveillance and education, and can be viewed through the U.S. Geological Survey (USGS) "EarthExplorer" website. The collaboration between NASA and USGS involves NASA designing and delivering the space system (satellite) solution, launching the satellite into orbit with the USGS operating the system once in orbit. As of October 2022, nine satellites have been built with eight of them successfully operating in orbit. | https://en.wikipedia.org/wiki?curid=18426568 |
9,104 | NASA collaborates with the European Space Agency on a wide range of scientific and exploration requirements. From participation with the Space Shuttle (the Spacelab missions) to major roles on the Artemis program (the Orion Service Module), ESA and NASA have supported the science and exploration missions of each agency. There are NASA payloads on ESA spacecraft and ESA payloads on NASA spacecraft. The agencies have developed joint missions in areas including heliophysics (e.g. Solar Orbiter) and astronomy (Hubble Space Telescope, James Webb Space Telescope). | https://en.wikipedia.org/wiki?curid=18426568 |
9,105 | Under the Artemis Gateway partnership, ESA will contribute habitation and refueling modules, along with enhanced lunar communications, to the Gateway. | https://en.wikipedia.org/wiki?curid=18426568 |
9,106 | NASA and ESA continue to advance cooperation in relation to Earth Science including climate change with agreements to cooperate on various missions including the Sentinel-6 series of spacecraft | https://en.wikipedia.org/wiki?curid=18426568 |
9,107 | NASA and the Japan Aerospace Exploration Agency (JAXA) cooperate on a range of space projects. JAXA is a direct participant in the Artemis program, including the Lunar Gateway effort. JAXA's planned contributions to Gateway include I-Hab's environmental control and life support system, batteries, thermal control, and imagery components, which will be integrated into the module by the European Space Agency (ESA) prior to launch. These capabilities are critical for sustained Gateway operations during crewed and uncrewed time periods. | https://en.wikipedia.org/wiki?curid=18426568 |
9,108 | JAXA and NASA have collaborated on numerous satellite programs, especially in areas of Earth science. NASA has contributed to JAXA satellites and vice versa. Japanese instruments are flying on NASA's Terra and Aqua satellites, and NASA sensors have flown on previous Japanese Earth-observation missions. The NASA-JAXA Global Precipitation Measurement mission was launched in 2014 and includes both NASA- and JAXA-supplied sensors on a NASA satellite launched on a JAXA rocket. The mission provides the frequent, accurate measurements of rainfall over the entire globe for use by scientists and weather forecasters. | https://en.wikipedia.org/wiki?curid=18426568 |
9,109 | NASA and Roscosmos have cooperated on the development and operation of the International Space Station since September 1993. The agencies have used launch systems from both countries to deliver station elements to orbit. Astronauts and Cosmonauts jointly maintain various elements of the station. Both countries provide access to the station via launch systems noting Russia's unique role as the sole provider of delivery of crew and cargo upon retirement of the space shuttle in 2011 and prior to commencement of NASA COTS and crew flights. In July 2022, NASA and Roscosmos signed a deal to share space station flights enabling crew from each country to ride on the systems provided by the other. Current geopolitical conditions in late 2022 make it unlikely that cooperation will be extended to other programs such as Artemis or lunar exploration. | https://en.wikipedia.org/wiki?curid=18426568 |
9,110 | In September 2014, NASA and Indian Space Research Organisation (ISRO) signed a partnership to collaborate on and launch a joint radar mission, the "NASA-ISO Synthetic Aperature Radar" ("NISAR") mission. The mission is targeted to launch in 2024. NASA will provide the mission's L-band synthetic aperture radar, a high-rate communication subsystem for science data, GPS receivers, a solid-state recorder and payload data subsystem. ISRO provides the spacecraft bus, the S-band radar, the launch vehicle and associated launch services. | https://en.wikipedia.org/wiki?curid=18426568 |
9,111 | The Artemis Accords have been established to define a framework for cooperating in the peaceful exploration and exploitation of the Moon, Mars, asteroids, and comets. The Accords were drafted by NASA and the U.S. State Department and are executed as a series of bilateral agreements between the United States and the participating countries. As of September 2022, 21 countries have signed the accords. They are Australia, Bahrain, Brazil, Canada, Colombia, France, Israel, Italy, Japan, the Republic of Korea, Luxembourg, Mexico, New Zealand, Poland, Romania, the Kingdom of Saudi Arabia, Singapore, Ukraine, the United Arab Emirates, the United Kingdom, and the United States. | https://en.wikipedia.org/wiki?curid=18426568 |
9,112 | The Wolf Amendment was passed by the U.S. Congress into law in 2011 and prevents NASA from engaging in direct, bilateral cooperation with the Chinese government and China-affiliated organizations such as the China National Space Administration without the explicit authorization from Congress and the Federal Bureau of Investigation. The law has been renewed annually since by inclusion in annual appropriations bills. | https://en.wikipedia.org/wiki?curid=18426568 |
9,113 | The exhaust gases produced by rocket propulsion systems, both in Earth's atmosphere and in space, can adversely affect the Earth's environment. Some hypergolic rocket propellants, such as hydrazine, are highly toxic prior to combustion, but decompose into less toxic compounds after burning. Rockets using hydrocarbon fuels, such as kerosene, release carbon dioxide and soot in their exhaust. However, carbon dioxide emissions are insignificant compared to those from other sources; on average, the United States consumed of liquid fuels per day in 2014, while a single Falcon 9 rocket first stage burns around of kerosene fuel per launch. Even if a Falcon 9 were launched every single day, it would only represent 0.006% of liquid fuel consumption (and carbon dioxide emissions) for that day. Additionally, the exhaust from LOx- and LH2- fueled engines, like the SSME, is almost entirely water vapor. NASA addressed environmental concerns with its canceled Constellation program in accordance with the National Environmental Policy Act in 2011. In contrast, ion engines use harmless noble gases like xenon for propulsion. | https://en.wikipedia.org/wiki?curid=18426568 |
9,114 | An example of NASA's environmental efforts is the NASA Sustainability Base. Additionally, the Exploration Sciences Building was awarded the LEED Gold rating in 2010. On May 8, 2003, the Environmental Protection Agency recognized NASA as the first federal agency to directly use landfill gas to produce energy at one of its facilities—the Goddard Space Flight Center, Greenbelt, Maryland. | https://en.wikipedia.org/wiki?curid=18426568 |
9,115 | In 2018, NASA along with other companies including Sensor Coating Systems, Pratt & Whitney, Monitor Coating and UTRC launched the project CAUTION (CoAtings for Ultra High Temperature detectION). This project aims to enhance the temperature range of the Thermal History Coating up to and beyond. The final goal of this project is improving the safety of jet engines as well as increasing efficiency and reducing CO emissions. | https://en.wikipedia.org/wiki?curid=18426568 |
9,116 | NASA also researches and publishes on climate change. Its statements concur with the global scientific consensus that the global climate is warming. Bob Walker, who has advised US President Donald Trump on space issues, has advocated that NASA should focus on space exploration and that its climate study operations should be transferred to other agencies such as NOAA. Former NASA atmospheric scientist J. Marshall Shepherd countered that Earth science study was built into NASA's mission at its creation in the 1958 National Aeronautics and Space Act. NASA won the 2020 Webby People's Voice Award for Green in the category Web. | https://en.wikipedia.org/wiki?curid=18426568 |
9,117 | "Educational Launch of Nanosatellites (ELaNa)". Since 2011, the ELaNa program has provided opportunities for NASA to work with university teams to test emerging technologies and commercial-off-the-shelf solutions by providing launch opportunities for developed CubeSats using NASA procured launch opportunities. By example, two NASA-sponsored CubeSats launched in June 2022 on a Virgin Orbit LauncherOne vehicle as the ELaNa 39 mission. | https://en.wikipedia.org/wiki?curid=18426568 |
9,118 | "Cubes in Space". NASA started an annual competition in 2014 named "Cubes in Space". It is jointly organized by NASA and the global education company "I Doodle Learning", with the objective of teaching school students aged 11–18 to design and build scientific experiments to be launched into space on a NASA rocket or balloon. On June 21, 2017, the world's smallest satellite, KalamSAT, was launched. | https://en.wikipedia.org/wiki?curid=18426568 |
9,119 | US law requires the International System of Units to be used in all US Government programs, "except where impractical". | https://en.wikipedia.org/wiki?curid=18426568 |
9,120 | In 1969, Apollo 11 landed on the Moon using a mix of United States customary units and metric units. In the 1980s, NASA started the transition towards the metric system, but was still using both systems in the 1990s. On September 23, 1999, a mixup between NASA's use of SI units and Lockheed Martin Space's use of US units resulted in the loss of the Mars Climate Orbiter. | https://en.wikipedia.org/wiki?curid=18426568 |
9,121 | In August 2007, NASA stated that all future missions and explorations of the Moon would be done entirely using the SI system. This was done to improve cooperation with space agencies of other countries that already use the metric system. As of 2007, NASA is predominantly working with SI units, but some projects still use US units, and some, including the International Space Station, use a mix of both. | https://en.wikipedia.org/wiki?curid=18426568 |
9,122 | Approaching 40 years of service, the NASA TV channel airs content ranging from live coverage of manned missions to video coverage of significant milestones for operating robotic spacecraft (e.g., rover landings on Mars for example) and domestic and international launches. The channel is delivered by NASA and is broadcast by satellite and over the Internet. The system initially started to capture archival footage of important space events for NASA managers and engineers and expanded as public interest grew. The Apollo 8 Christmas Eve broadcast while in orbit around the Moon was received by more than a billion people. NASA's video transmission of the Apollo 11 Moon landing was awarded a primetime Emmy in commemoration of the 40th anniversary of the landing. The channel is a product of the U.S. Government and is widely available across many television and Internet platforms. | https://en.wikipedia.org/wiki?curid=18426568 |
9,123 | NASAcast is the official audio and video podcast of the NASA website. Created in late 2005, the podcast service contains the latest audio and video features from the NASA web site, including NASA TV's "This Week at NASA" and educational materials produced by NASA. Additional NASA podcasts, such as Science@NASA, are also featured and give subscribers an in-depth look at content by subject matter. | https://en.wikipedia.org/wiki?curid=18426568 |
9,124 | NASA EDGE is a video podcast which explores different missions, technologies and projects developed by NASA. The program was released by NASA on March 18, 2007, and, , there have been 200 vodcasts produced. It is a public outreach vodcast sponsored by NASA's Exploration Systems Mission Directorate and based out of the Exploration and Space Operations Directorate at Langley Research Center in Hampton, Virginia. The NASA EDGE team takes an insiders look at current projects and technologies from NASA facilities around the United States, and it is depicted through personal interviews, on-scene broadcasts, computer animations, and personal interviews with top scientists and engineers at NASA. | https://en.wikipedia.org/wiki?curid=18426568 |
9,125 | The show explores the contributions NASA has made to society as well as the progress of current projects in materials and space exploration. NASA EDGE vodcasts can be downloaded from the NASA website and from iTunes. | https://en.wikipedia.org/wiki?curid=18426568 |
9,126 | In its first year of production, the show was downloaded over 450,000 times. the average download rate is more than 420,000 per month, with over one million downloads in December 2009 and January 2010. | https://en.wikipedia.org/wiki?curid=18426568 |
9,127 | NASA and the NASA EDGE have also developed interactive programs designed to complement the vodcast. The Lunar Electric Rover App allows users to drive a simulated Lunar Electric Rover between objectives, and it provides information about and images of the vehicle. The NASA EDGE Widget provides a graphical user interface for accessing NASA EDGE vodcasts, image galleries, and the program's Twitter feed, as well as a live NASA news feed. | https://en.wikipedia.org/wiki?curid=18426568 |
9,128 | Go is a statically typed, compiled programming language designed at Google by Robert Griesemer, Rob Pike, and Ken Thompson. It is syntactically similar to C, but with memory safety, garbage collection, structural typing, and CSP-style concurrency. It is often referred to as Golang because of its former domain name, codice_1, but its proper name is Go. | https://en.wikipedia.org/wiki?curid=25039021 |
9,129 | A third-party source-to-source compiler, GopherJS, compiles Go to JavaScript for front-end web development. | https://en.wikipedia.org/wiki?curid=25039021 |
9,130 | Go was designed at Google in 2007 to improve programming productivity in an era of multicore, networked machines and large codebases. The designers wanted to address criticism of other languages in use at Google, but keep their useful characteristics: | https://en.wikipedia.org/wiki?curid=25039021 |
9,131 | Go was publicly announced in November 2009, and version 1.0 was released in March 2012. Go is widely used in production at Google and in many other organizations and open-source projects. | https://en.wikipedia.org/wiki?curid=25039021 |
9,132 | In November 2016, the Go and Go Mono fonts were released by type designers Charles Bigelow and Kris Holmes specifically for use by the Go project. Go is a humanist sans-serif resembling Lucida Grande, and Go Mono is monospaced. Both fonts adhere to the WGL4 character set and were designed to be legible with a large x-height and distinct letterforms. Both Go and Go Mono adhere to the DIN 1450 standard by having a slashed zero, lowercase codice_2 with a tail, and an uppercase codice_3 with serifs. | https://en.wikipedia.org/wiki?curid=25039021 |
9,133 | In April 2018, the original logo was replaced with a stylized GO slanting right with trailing streamlines. (The Gopher mascot remained the same.) | https://en.wikipedia.org/wiki?curid=25039021 |
9,134 | The lack of support for generic programming in initial versions of Go drew considerable criticism. The designers expressed an openness to generic programming and noted that built-in functions "were" in fact type-generic, but are treated as special cases; Pike called this a weakness that might at some point be changed. The Google team built at least one compiler for an experimental Go dialect with generics, but did not release it. | https://en.wikipedia.org/wiki?curid=25039021 |
9,135 | In August 2018, the Go principal contributors published draft designs for generic programming and error handling and asked users to submit feedback. However, the error handling proposal was eventually abandoned. | https://en.wikipedia.org/wiki?curid=25039021 |
9,136 | In June 2020, a new draft design document was published that would add the necessary syntax to Go for declaring generic functions and types. A code translation tool, "", was provided to allow users to try the new syntax, along with a generics-enabled version of the online Go Playground. | https://en.wikipedia.org/wiki?curid=25039021 |
9,137 | Go 1 guarantees compatibility for the language specification and major parts of the standard library. All versions up to the current Go 1.19 release have maintained this promise. | https://en.wikipedia.org/wiki?curid=25039021 |
9,138 | Go is influenced by C (especially the Plan 9 dialect), but with an emphasis on greater simplicity and safety. It consists of: | https://en.wikipedia.org/wiki?curid=25039021 |
9,139 | Go's syntax includes changes from C aimed at keeping code concise and readable. A combined declaration/initialization operator was introduced that allows the programmer to write codice_9 or codice_10, without specifying the types of variables used. This contrasts with C's codice_11 and codice_12. Semicolons still terminate statements; but are implicit when the end of a line occurs. Methods may return multiple values, and returning a codice_13 pair is the conventional way a method indicates an error to its caller in Go. Go adds literal syntaxes for initializing struct parameters by name and for initializing maps and slices. As an alternative to C's three-statement codice_14 loop, Go's codice_15 expressions allow concise iteration over arrays, slices, strings, maps, and channels. | https://en.wikipedia.org/wiki?curid=25039021 |
9,140 | Go has a number of built-in types, including numeric ones (, , , etc.), booleans, and byte strings (). Strings are immutable; built-in operators and keywords (rather than functions) provide concatenation, comparison, and UTF-8 encoding/decoding. Record types can be defined with the keyword. | https://en.wikipedia.org/wiki?curid=25039021 |
9,141 | For each type and each non-negative integer constant , there is an array type denoted ; arrays of differing lengths are thus of different types. Dynamic arrays are available as "slices", denoted for some type . These have a length and a "capacity" specifying when new memory needs to be allocated to expand the array. Several slices may share their underlying memory. | https://en.wikipedia.org/wiki?curid=25039021 |
9,142 | Pointers are available for all types, and the pointer-to- type is denoted . Address-taking and indirection use the and operators, as in C, or happen implicitly through the method call or attribute access syntax. There is no pointer arithmetic, except via the special type in the standard library. | https://en.wikipedia.org/wiki?curid=25039021 |
9,143 | For a pair of types , , the type is the type of hash tables mapping type- keys to type- values. Hash tables are built into the language, with special syntax and built-in functions. is a "channel" that allows sending values of type "T" between concurrent Go processes. | https://en.wikipedia.org/wiki?curid=25039021 |
9,144 | Aside from its support for interfaces, Go's type system is nominal: the keyword can be used to define a new "named type", which is distinct from other named types that have the same layout (in the case of a , the same members in the same order). Some conversions between types (e.g., between the various integer types) are pre-defined and adding a new type may define additional conversions, but conversions between named types must always be invoked explicitly. For example, the keyword can be used to define a type for IPv4 addresses, based on 32-bit unsigned integers: | https://en.wikipedia.org/wiki?curid=25039021 |
9,145 | With this type definition, interprets the value as an IP address. Simply assigning to a variable of type is a type error. | https://en.wikipedia.org/wiki?curid=25039021 |
9,146 | Constant expressions may be either typed or "untyped"; they are given a type when assigned to a typed variable if the value they represent passes a compile-time check. | https://en.wikipedia.org/wiki?curid=25039021 |
9,147 | Function types are indicated by the keyword; they take zero or more parameters and return zero or more values, all of which are typed. The parameter and return values determine a function type; thus, is the type of functions that take a and a 32-bit signed integer, and return a signed integer (of default width) and a value of the built-in interface type . | https://en.wikipedia.org/wiki?curid=25039021 |
9,148 | Any named type has a method set associated with it. The IP address example above can be extended with a method for checking whether its value is a known standard: | https://en.wikipedia.org/wiki?curid=25039021 |
9,149 | Due to nominal typing, this method definition adds a method to , but not on . While methods have special definition and call syntax, there is no distinct method type. | https://en.wikipedia.org/wiki?curid=25039021 |
9,150 | The second are its "interfaces", which provides runtime polymorphism. Interfaces are a class of types and provide a limited form of structural typing in the otherwise nominal type system of Go. An object which is of an interface type is also of another type, much like C++ objects being simultaneously of a base and derived class. Go interfaces were designed after protocols from the Smalltalk programming language. Multiple sources use the term duck typing when describing Go interfaces. Although the term duck typing is not precisely defined and therefore not wrong, it usually implies that type conformance is not statically checked. Since conformance to a Go interface is checked statically by the Go compiler (except when performing a type assertion), the Go authors prefer the term "structural typing". | https://en.wikipedia.org/wiki?curid=25039021 |
9,151 | The definition of an interface type lists required methods by name and type. Any object of type T for which functions exist matching all the required methods of interface type I is an object of type I as well. The definition of type T need not (and cannot) identify type I. For example, if , are defined as | https://en.wikipedia.org/wiki?curid=25039021 |
9,152 | then both a and a are implicitly a and can be assigned to a -typed variable. In formal language, Go's interface system provides structural rather than nominal typing. Interfaces can embed other interfaces with the effect of creating a combined interface that is satisfied by exactly the types that implement the embedded interface and any methods that the newly defined interface adds. | https://en.wikipedia.org/wiki?curid=25039021 |
9,153 | The Go standard library uses interfaces to provide genericity in several places, including the input/output system that is based on the concepts of and . | https://en.wikipedia.org/wiki?curid=25039021 |
9,154 | Besides calling methods via interfaces, Go allows converting interface values to other types with a run-time type check. The language constructs to do so are the "type assertion", which checks against a single potential type: | https://en.wikipedia.org/wiki?curid=25039021 |
9,155 | The "empty interface" codice_16 is an important base case because it can refer to an item of "any" concrete type. It is similar to the class in Java or C# and is satisfied by any type, including built-in types like . Code using the empty interface cannot simply call methods (or built-in operators) on the referred-to object, but it can store the codice_16 value, try to convert it to a more useful type via a type assertion or type switch, or inspect it with Go's codice_18 package. Because codice_16 can refer to any value, it is a limited way to escape the restrictions of static typing, like codice_20 in C but with additional run-time type checks. | https://en.wikipedia.org/wiki?curid=25039021 |
9,156 | The codice_16 type can be used to model structured data of any arbitrary schema in Go, such as JSON or YAML data, by representing it as a codice_22 (map of string to empty interface). This recursively describes data in the form of a dictionary with string keys and values of any type. | https://en.wikipedia.org/wiki?curid=25039021 |
9,157 | Interface values are implemented using pointer to data and a second pointer to run-time type information. Like some other types implemented using pointers in Go, interface values are codice_23 if uninitialized. | https://en.wikipedia.org/wiki?curid=25039021 |
9,158 | In Go's package system, each package has a path (e.g., codice_24 or codice_25) and a name (e.g., codice_26 or codice_27). References to other packages' definitions must "always" be prefixed with the other package's name, and only the "capitalized" names from other packages are accessible: codice_28 is public but codice_29 is not. The codice_7 command can retrieve packages stored in a remote repository and developers are encouraged to develop packages inside a base path corresponding to a source repository (such as example.com/user_name/package_name) to reduce the likelihood of name collision with future additions to the standard library or other external libraries. | https://en.wikipedia.org/wiki?curid=25039021 |
9,159 | The Go language has built-in facilities, as well as library support, for writing concurrent programs. Concurrency refers not only to CPU parallelism, but also to asynchrony: letting slow operations like a database or network read run while the program does other work, as is common in event-based servers. | https://en.wikipedia.org/wiki?curid=25039021 |
9,160 | The primary concurrency construct is the "goroutine", a type of light-weight process. A function call prefixed with the codice_31 keyword starts a function in a new goroutine. The language specification does not specify how goroutines should be implemented, but current implementations multiplex a Go process's goroutines onto a smaller set of operating-system threads, similar to the scheduling performed in Erlang. | https://en.wikipedia.org/wiki?curid=25039021 |
9,161 | While a standard library package featuring most of the classical concurrency control structures (mutex locks, etc.) is available, idiomatic concurrent programs instead prefer "channels", which send messages between goroutines. Optional buffers store messages in FIFO order and allow sending goroutines to proceed before their messages are received. | https://en.wikipedia.org/wiki?curid=25039021 |
9,162 | Channels are typed, so that a channel of type can only be used to transfer messages of type . Special syntax is used to operate on them; is an expression that causes the executing goroutine to block until a value comes in over the channel , while sends the value (possibly blocking until another goroutine receives the value). The built-in -like statement can be used to implement non-blocking communication on multiple channels; see below for an example. Go has a memory model describing how goroutines must use channels or other operations to safely share data. | https://en.wikipedia.org/wiki?curid=25039021 |
9,163 | The existence of channels sets Go apart from actor model-style concurrent languages like Erlang, where messages are addressed directly to actors (corresponding to goroutines). The actor style can be simulated in Go by maintaining a one-to-one correspondence between goroutines and channels, but the language allows multiple goroutines to share a channel or a single goroutine to send and receive on multiple channels. | https://en.wikipedia.org/wiki?curid=25039021 |
9,164 | From these tools one can build concurrent constructs like worker pools, pipelines (in which, say, a file is decompressed and parsed as it downloads), background calls with timeout, "fan-out" parallel calls to a set of services, and others. Channels have also found uses further from the usual notion of interprocess communication, like serving as a concurrency-safe list of recycled buffers, implementing coroutines (which helped inspire the name "goroutine"), and implementing iterators. | https://en.wikipedia.org/wiki?curid=25039021 |
9,165 | Concurrency-related structural conventions of Go (channels and alternative channel inputs) are derived from Tony Hoare's communicating sequential processes model. Unlike previous concurrent programming languages such as Occam or Limbo (a language on which Go co-designer Rob Pike worked), Go does not provide any built-in notion of safe or verifiable concurrency. While the communicating-processes model is favored in Go, it is not the only one: all goroutines in a program share a single address space. This means that mutable objects and pointers can be shared between goroutines; see , below. | https://en.wikipedia.org/wiki?curid=25039021 |
9,166 | Although Go's concurrency features are not aimed primarily at parallel processing, they can be used to program shared-memory multi-processor machines. Various studies have been done into the effectiveness of this approach. One of these studies compared the size (in lines of code) and speed of programs written by a seasoned programmer not familiar with the language and corrections to these programs by a Go expert (from Google's development team), doing the same for Chapel, Cilk and Intel TBB. The study found that the non-expert tended to write divide-and-conquer algorithms with one statement per recursion, while the expert wrote distribute-work-synchronize programs using one goroutine per processor. The expert's programs were usually faster, but also longer. | https://en.wikipedia.org/wiki?curid=25039021 |
9,167 | Go's approach to concurrency can be summarized as "don't communicate by sharing memory; share memory by communicating". There are no restrictions on how go-routines access shared data, making race conditions possible. Specifically, unless a program explicitly synchronizes via channels or other means, writes from one go-routine might be partly, entirely, or not at all visible to another, often with no guarantees about ordering of writes. Furthermore, Go's "internal data structures" like interface values, slice headers, hash tables, and string headers are not immune to race conditions, so type and memory safety can be violated in multithreaded programs that modify shared instances of those types without synchronization. Instead of language support, safe concurrent programming thus relies on conventions; for example, Chisnall recommends an idiom called "aliases xor mutable", meaning that passing a mutable value (or pointer) over a channel signals a transfer of ownership over the value to its receiver. | https://en.wikipedia.org/wiki?curid=25039021 |
9,168 | The linker in the gc toolchain creates statically linked binaries by default; therefore all Go binaries include the Go runtime. | https://en.wikipedia.org/wiki?curid=25039021 |
9,169 | Go deliberately omits certain features common in other languages, including (implementation) inheritance, assertions, pointer arithmetic, implicit type conversions, untagged unions, and tagged unions. The designers added only those facilities that all three agreed on. | https://en.wikipedia.org/wiki?curid=25039021 |
9,170 | Of the omitted language features, the designers explicitly argue against assertions and pointer arithmetic, while defending the choice to omit type inheritance as giving a more useful language, encouraging instead the use of interfaces to achieve dynamic dispatch and composition to reuse code. Composition and delegation are in fact largely automated by embedding; according to researchers Schmager "et al.", this feature "has many of the drawbacks of inheritance: it affects the public interface of objects, it is not fine-grained (i.e, no method-level control over embedding), methods of embedded objects cannot be hidden, and it is static", making it "not obvious" whether programmers will overuse it to the extent that programmers in other languages are reputed to overuse inheritance. | https://en.wikipedia.org/wiki?curid=25039021 |
9,171 | Exception handling was initially omitted in Go due to lack of a "design that gives value proportionate to the complexity". An exception-like / mechanism that avoids the usual codice_32 control structure was proposed and released in the March 30, 2010 snapshot. The Go authors advise using it for unrecoverable errors such as those that should halt an entire program or server request, or as a shortcut to propagate errors up the stack within a package. Across package boundaries, Go includes a canonical error type, and multi-value returns using this type are the standard idiom. | https://en.wikipedia.org/wiki?curid=25039021 |
9,172 | It also includes profiling and debugging support, runtime instrumentation (for example, to track garbage collection pauses), and a race condition tester. | https://en.wikipedia.org/wiki?curid=25039021 |
9,173 | An ecosystem of third-party tools adds to the standard distribution, such as codice_52, which enables code autocompletion in many text editors, codice_53, which automatically adds/removes package imports as needed, and codice_54, which detects code that might unintentionally ignore errors. | https://en.wikipedia.org/wiki?curid=25039021 |
9,174 | The following simple program demonstrates Go's concurrency features to implement an asynchronous program. It launches two lightweight threads ("goroutines"): one waits for the user to type some text, while the other implements a timeout. The statement waits for either of these goroutines to send a message to the main routine, and acts on the first message to arrive (example adapted from David Chisnall's book). | https://en.wikipedia.org/wiki?curid=25039021 |
9,175 | Test code (note that assert keyword is missing in Go; tests live in <filename>_test.go at the same package): | https://en.wikipedia.org/wiki?curid=25039021 |
9,176 | Other notable companies and sites using Go (generally together with other languages, not exclusively) include: | https://en.wikipedia.org/wiki?curid=25039021 |
9,177 | The interface system, and the deliberate omission of inheritance, were praised by Michele Simionato, who likened these characteristics to those of Standard ML, calling it "a shame that no popular language has followed [this] particular route". | https://en.wikipedia.org/wiki?curid=25039021 |
9,178 | Go was named Programming Language of the Year by the TIOBE Programming Community Index in its first year, 2009, for having a larger 12-month increase in popularity (in only 2 months, after its introduction in November) than any other language that year, and reached 13th place by January 2010, surpassing established languages like Pascal. By June 2015, its ranking had dropped to below 50th in the index, placing it lower than COBOL and Fortran. But as of January 2017, its ranking had surged to 13th, indicating significant growth in popularity and adoption. Go was awarded TIOBE programming language of the year 2016. | https://en.wikipedia.org/wiki?curid=25039021 |
9,179 | A 2011 evaluation of the language and its implementation in comparison to C++ (GCC), Java and Scala by a Google engineer found: | https://en.wikipedia.org/wiki?curid=25039021 |
9,180 | The evaluation got a rebuttal from the Go development team. Ian Lance Taylor, who had improved the Go code for Hundt's paper, had not been aware of the intention to publish his code, and says that his version was "never intended to be an example of idiomatic or efficient Go"; Russ Cox then optimized the Go code, as well as the C++ code, and got the Go code to run slightly faster than C++ and more than an order of magnitude faster than the code in the paper. | https://en.wikipedia.org/wiki?curid=25039021 |
9,181 | On November 10, 2009, the day of the general release of the language, Francis McCabe, developer of the Go! programming language (note the exclamation point), requested a name change of Google's language to prevent confusion with his language, which he had spent 10 years developing. McCabe raised concerns that "the 'big guy' will end up steam-rollering over" him, and this concern resonated with the more than 120 developers who commented on Google's official issues thread saying they should change the name, with some even saying the issue contradicts Google's motto of: Don't be evil. | https://en.wikipedia.org/wiki?curid=25039021 |
9,182 | On October 12, 2010, the issue was closed by Google developer Russ Cox (@rsc) with the custom status "Unfortunate" accompanied by the following comment: "There are many computing products and services named Go. In the 11 months since our release, there has been minimal confusion of the two languages." | https://en.wikipedia.org/wiki?curid=25039021 |
9,183 | The Boeing 777, commonly referred to as the Triple Seven, is an American long-range wide-body airliner developed and manufactured by Boeing Commercial Airplanes. It is the world's largest twinjet. | https://en.wikipedia.org/wiki?curid=89260 |
9,184 | The 777 was designed to bridge the gap between Boeing's other wide body airplanes, the twin-engined 767 and quad-engined 747, and to replace older DC-10s and L-1011 trijets. | https://en.wikipedia.org/wiki?curid=89260 |
9,185 | Developed in consultation with eight major airlines, with a first meeting in January 1990, the program was launched in October, with an order from United Airlines. The prototype was rolled out in April 1994, and first flew in June. The 777 entered service with the launch customer, United Airlines, in June 1995. Longer range variants were launched in 2000, and were first delivered in 2004. | https://en.wikipedia.org/wiki?curid=89260 |
9,186 | It can accommodate a ten–abreast seating layout and has a typical 3-class capacity of 301 to 368 passengers, with a range of . | https://en.wikipedia.org/wiki?curid=89260 |
9,187 | It is recognizable for its large-diameter turbofan engines, six wheels on each main landing gear, fully circular fuselage cross-section, and a blade-shaped tail cone. It is the first Boeing aircraft with fly-by-wire controls. | https://en.wikipedia.org/wiki?curid=89260 |
9,188 | It initially competed with the Airbus A340 and the McDonnell Douglas MD-11, both now out of production, and competes with the Airbus A350 and A330-900. | https://en.wikipedia.org/wiki?curid=89260 |
9,189 | The original 777 with a maximum takeoff weight (MTOW) of was produced in two fuselage lengths: the initial -200 was followed by the extended-range 777-200ER in 1997; and the longer 777-300 in 1998. Those 777 Classics were powered by General Electric GE90, Pratt & Whitney PW4000, or Rolls-Royce Trent 800 engines. The longer-range 777-300ER, with a MTOW of , entered service in 2004, the ultra long-range 777-200LR in 2006, and the 777F freighter in 2009. These long haul variants use GE90 engines and have extended raked wingtips. In November 2013, Boeing announced the 777X development with the -8 and -9 variants, both featuring composite wings with folding wingtips and General Electric GE9X engines. | https://en.wikipedia.org/wiki?curid=89260 |
9,190 | The 777 has been ordered and delivered more than any other wide-body airliner; , more than 60 customers had placed orders for 2,136 aircraft of all variants, with 1,695 delivered. The most common and successful variant is the 777-300ER with 838 aircraft ordered and 832 delivered. By March 2018, the 777 had become the most produced Boeing wide-body jet, overtaking the Boeing 747. , Emirates was the largest operator, with 163 aircraft. | https://en.wikipedia.org/wiki?curid=89260 |
9,191 | , the 777 had been involved in 31 aviation accidents and incidents, including 8 hull losses (5 during flight and 3 on the ground) with 541 fatalities, and 3 hijackings. | https://en.wikipedia.org/wiki?curid=89260 |
9,192 | In the early 1970s, the Boeing 747, McDonnell Douglas DC-10, and the Lockheed L-1011 TriStar became the first generation of wide-body passenger airliners to enter service. In 1978, Boeing unveiled three new models: the twin-engine Boeing 757 to replace its 727, the twin-engine 767 to challenge the Airbus A300, and a trijet 777 concept to compete with the DC-10 and L-1011. The mid-size 757 and 767 launched to market success, due in part to 1980s' extended-range twin-engine operational performance standards (ETOPS) regulations governing transoceanic twinjet operations. These regulations allowed twin-engine airliners to make ocean crossings at up to three hours' distance from emergency diversionary airports. Under ETOPS rules, airlines began operating the 767 on long-distance overseas routes that did not require the capacity of larger airliners. The trijet 777 was later dropped, following marketing studies that favored the 757 and 767 variants. Boeing was left with a size and range gap in its product line between the 767-300ER and the 747-400. | https://en.wikipedia.org/wiki?curid=89260 |
9,193 | By the late 1980s, DC-10 and L-1011 models were approaching retirement age, prompting manufacturers to develop replacement designs. McDonnell Douglas was working on the MD-11, a stretched and upgraded successor of the DC-10, while Airbus was developing its A330 and A340 series. In 1986, Boeing unveiled proposals for an enlarged 767, tentatively named 767-X, to target the replacement market for first-generation wide-bodies such as the DC-10, and to complement existing 767 and 747 models in the company lineup. The initial proposal featured a longer fuselage and larger wings than the existing 767, along with winglets. Later plans expanded the fuselage cross-section but retained the existing 767 flight deck, nose, and other elements. | https://en.wikipedia.org/wiki?curid=89260 |
9,194 | Airline customers were uninterested in the 767-X proposals, and instead wanted an even wider fuselage cross-section, fully flexible interior configurations, short- to intercontinental-range capability, and an operating cost lower than that of any 767 stretch. Airline planners' requirements for larger aircraft had become increasingly specific, adding to the heightened competition among aircraft manufacturers. By 1988, Boeing realized that the only answer was a new clean-sheet design, which became the 777 twin-jet. The company opted for the twin-engine configuration given past design successes, projected engine developments, and reduced-cost benefits. On December 8, 1989, Boeing began issuing offers to airlines for the 777. | https://en.wikipedia.org/wiki?curid=89260 |
9,195 | Alan Mulally served as the Boeing 777 program's director of engineering, and then was promoted in September 1992 to lead it as vice-president and general manager. The design phase for the new twinjet was different from Boeing's previous commercial jetliners. For the first time, eight major airlines – All Nippon Airways, American Airlines, British Airways, Cathay Pacific, Delta Air Lines, Japan Airlines, Qantas, and United Airlines – had a role in the development. This was a departure from industry practice, where manufacturers typically designed aircraft with minimal customer input. The eight airlines that contributed to the design process became known within Boeing as the "Working Together" group. At the first group meeting in January 1990, a 23-page questionnaire was distributed to the airlines, asking what each wanted in the design. By March 1990, Boeing and the airlines had decided upon a basic design configuration: a cabin cross-section close to the 747's, capacity up to 325 passengers, flexible interiors, a glass cockpit, fly-by-wire controls, and 10 percent better seat-mile costs than the A330 and MD-11. Boeing selected its Everett factory in Washington, home of 747 production, as the 777's final assembly site. | https://en.wikipedia.org/wiki?curid=89260 |
9,196 | On October 14, 1990, United Airlines became the 777's launch customer when it placed an order for 34 Pratt & Whitney-powered aircraft valued at US$11 billion with options on an additional 34. The development phase coincided with United's replacement program for its aging DC-10s. United required that the new aircraft be capable of flying three different routes: Chicago to Hawaii, Chicago to Europe, and non-stop from Denver, a hot and high airport, to Hawaii. ETOPS certification was also a priority for United, given the overwater portion of United's Hawaii routes. In January 1993, a team of United developers joined other airline teams and Boeing designers at the Everett factory. The 240 design teams, with up to 40 members each, addressed almost 1,500 design issues with individual aircraft components. The fuselage diameter was increased to suit Cathay Pacific, the baseline model grew longer for All Nippon Airways, and British Airways' input led to added built-in testing and interior flexibility, along with higher operating weight options. | https://en.wikipedia.org/wiki?curid=89260 |
9,197 | The 777 was the first commercial aircraft designed entirely by computer. Each design drawing was created on a three-dimensional CAD software system known as CATIA, sourced from Dassault Systemes and IBM. This lets engineers assemble a virtual aircraft, in simulation, to check for interference and verify that the thousands of parts fit properly—thus reducing costly rework. Boeing developed its high-performance visualization system, FlyThru, later called IVT (Integrated Visualization Tool) to support large-scale collaborative engineering design reviews, production illustrations, and other uses of the CAD data outside of engineering. Boeing was initially not convinced of CATIA's abilities and built a physical mock-up of the nose section to verify its results. The test was so successful that additional mock-ups were canceled. The 777 "was completed with such precision that it was the first Boeing jet that didn't need its kinks worked out on an expensive physical mock-up plane", which contrasted sharply with the development of Boeing's next new airliner, the 787. | https://en.wikipedia.org/wiki?curid=89260 |
9,198 | The production process included substantial international content, an unprecedented level of global subcontracting for a Boeing jetliner, later exceeded by the 787. International contributors included Mitsubishi Heavy Industries and Kawasaki Heavy Industries (fuselage panels), Fuji Heavy Industries, Ltd. (center wing section), Hawker de Havilland (elevators), and Aerospace Technologies of Australia (rudder). An agreement between Boeing and the Japan Aircraft Development Corporation, representing Japanese aerospace contractors, made the latter risk-sharing partners for 20 percent of the entire development program. The initial 777-200 model was launched with propulsion options from three manufacturers, General Electric, Pratt & Whitney, and Rolls-Royce, giving the airlines their choice of engines from competing firms. Each manufacturer agreed to develop an engine in the and higher thrust class (a measure of jet engine output) for the world's largest twinjet. | https://en.wikipedia.org/wiki?curid=89260 |
9,199 | To accommodate production of its new airliner, Boeing doubled the size of the Everett factory at the cost of nearly US$1.5 billion to provide space for two new assembly lines. New production methods were developed, including a turn machine that could rotate fuselage subassemblies 180 degrees, giving workers access to upper body sections. Major assembly of the first aircraft began on January 4, 1993. By the start of production, the program had amassed 118 firm orders, with options for 95 more from 10 airlines. Total investment in the program was estimated at over US$4 billion from Boeing, with an additional US$2 billion from suppliers. | https://en.wikipedia.org/wiki?curid=89260 |
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