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Concerned about how close Apollo 11's LM, "Eagle", had come to running out of propellant during its lunar descent, mission planners decided that beginning with Apollo 13, the CSM would bring the LM to the low orbit from which the landing attempt would commence. This was a change from Apollo 11 and 12, on which the LM made the burn to bring it to the lower orbit. The change was part of an effort to increase the amount of hover time available to the astronauts as the missions headed into rougher terrain. The plan was to devote the first of the two four-hour lunar surface extravehicular activities (EVAs) to setting up the Apollo Lunar Surface Experiments Package (ALSEP) group of scientific instruments; during the second, Lovell and Haise would investigate Cone crater, near the planned landing site. The two astronauts wore their spacesuits for some 20 walk-throughs of EVA procedures, including sample gathering and use of tools and other equipment. They flew in the "Vomit Comet" in simulated microgravity or lunar gravity, including practice in donning and doffing spacesuits. To prepare for the descent to the Moon's surface, Lovell flew the Lunar Landing Training Vehicle (LLTV) after receiving helicopter training. Despite the crashes of one LLTV and one similar Lunar Landing Research Vehicle (LLRV) prior to Apollo 13, mission commanders considered flying them invaluable experience and so prevailed on reluctant NASA management to retain them.
Experiments and scientific objectives. Apollo 13's designated landing site was near Fra Mauro crater; the Fra Mauro formation was believed to contain much material spattered by the impact that had filled the Imbrium basin early in the Moon's history. Dating it would provide information not only about the Moon, but about the Earth's early history. Such material was likely to be available at Cone crater, a site where an impact was believed to have drilled deep into the lunar regolith. Apollo 11 had left a seismometer on the Moon, but the solar-powered unit did not survive its first two-week-long lunar night. The Apollo 12 astronauts also left one as part of its ALSEP, which was nuclear-powered. Apollo 13 also carried a seismometer (known as the Passive Seismic Experiment, or PSE), similar to Apollo 12's, as part of its ALSEP, to be left on the Moon by the astronauts. That seismometer was to be calibrated by the impact, after jettison, of the ascent stage of Apollo 13's LM, an object of known mass and velocity impacting at a known location.
Other ALSEP experiments on Apollo 13 included a Heat Flow Experiment (HFE), which would involve drilling two holes deep. This was Haise's responsibility; he was also to drill a third hole of that depth for a core sample. A Charged Particle Lunar Environment Experiment (CPLEE) measured the protons and electrons of solar origin reaching the Moon. The package also included a Lunar Atmosphere Detector (LAD) and a Dust Detector, to measure the accumulation of debris. The Heat Flow Experiment and the CPLEE were flown for the first time on Apollo 13; the other experiments had been flown before. To power the ALSEP, the SNAP-27 radioisotope thermoelectric generator (RTG) was flown. Developed by the U.S. Atomic Energy Commission, SNAP-27 was first flown on Apollo 12. The fuel capsule contained about of plutonium oxide. The cask placed around the capsule for transport to the Moon was built with heat shields of graphite and of beryllium, and with structural parts of titanium and of Inconel materials. Thus, it was built to withstand the heat of reentry into the Earth's atmosphere rather than pollute the air with plutonium in the event of an aborted mission.
A United States flag was also taken, to be erected on the Moon's surface. For Apollo 11 and 12, the flag had been placed in a heat-resistant tube on the front landing leg; it was moved for Apollo 13 to the Modularized Equipment Stowage Assembly (MESA) in the LM descent stage. The structure to fly the flag on the airless Moon was improved from Apollo 12's. For the first time, red stripes were placed on the helmet, arms and legs of the commander's A7L spacesuit. This was done as, after Apollo 11, those reviewing the images taken had trouble distinguishing Armstrong from Aldrin, but the change was approved too late for Apollo 12. New drink bags that attached inside the helmets and were to be sipped from as the astronauts walked on the Moon were demonstrated by Haise during Apollo 13's final television broadcast before the accident. Apollo 13's primary mission objectives were to: "Perform selenological inspection, survey, and sampling of materials in a preselected region of the Fra Mauro Formation. Deploy and activate an Apollo Lunar Surface Experiments Package. Develop man's capability to work in the lunar environment. Obtain photographs of candidate exploration sites." The astronauts were also to accomplish other photographic objectives, including of the Gegenschein from lunar orbit, and of the Moon itself on the journey back to Earth. Some of this photography was to be performed by Swigert as Lovell and Haise walked on the Moon. Swigert was also to take photographs of the Lagrangian points of the Earth-Moon system. Apollo 13 had twelve cameras on board, including those for television and moving pictures. The crew was also to downlink bistatic radar observations of the Moon. None of these was attempted because of the accident.
Flight of Apollo 13. Launch and translunar injection. The mission was launched at the planned time, 2:13:00 pm EST (19:13:00 UTC) on April 11. An anomaly occurred when the second-stage, center (inboard) engine shut down about two minutes early. This was caused by severe pogo oscillations. Starting with Apollo 10, the vehicle's guidance system was designed to shut the engine down in response to chamber pressure excursions. Pogo oscillations had occurred on Titan rockets (used during the Gemini program) and on previous Apollo missions, but on Apollo 13 they were amplified by an interaction with turbopump cavitation. A fix to prevent pogo was ready for the mission, but schedule pressure did not permit the hardware's integration into the Apollo 13 vehicle. A post-flight investigation revealed the engine was one cycle away from catastrophic failure. The four outboard engines and the S-IVB third stage burned longer to compensate, and the vehicle achieved very close to the planned circular parking orbit, followed by a translunar injection (TLI) about two hours later, setting the mission on course for the Moon.
After TLI, Swigert performed the separation and transposition maneuvers before docking the CSM "Odyssey" to the LM "Aquarius", and the spacecraft pulled away from the third stage. Ground controllers then sent the third stage on a course to impact the Moon in range of the Apollo 12 seismometer, which it did just over three days into the mission. The crew settled in for the three-day trip to Fra Mauro. At 30:40:50 into the mission, with the TV camera running, the crew performed a burn to place Apollo 13 on a hybrid trajectory. The departure from a free-return trajectory meant that if no further burns were performed, Apollo 13 would miss Earth on its return trajectory, rather than intercept it, as with a free return. A free return trajectory could only reach sites near the lunar equator; a hybrid trajectory, which could be started at any point after TLI, allowed sites with higher latitudes, such as Fra Mauro, to be reached. Communications were enlivened when Swigert realized that in the last-minute rush, he had omitted to file his federal income tax return (due April 15), and amid laughter from mission controllers, asked how he could get an extension. He was found to be entitled to a 60-day extension for being out of the country at the deadline.
Entry into the LM to test its systems had been scheduled for 58:00:00; when the crew awoke on the third day of the mission, they were informed it had been moved up three hours and was later moved up again by another hour. A television broadcast was scheduled for 55:00:00; Lovell, acting as emcee, showed the audience the interiors of "Odyssey" and "Aquarius". The audience was limited since none of the television networks were carrying the broadcast, forcing Marilyn Lovell (Jim Lovell's wife) to go to the VIP room at Mission Control if she wanted to watch her husband and his crewmates. Accident. About six and a half minutes after the TV broadcastapproaching 56:00:00Apollo 13 was about from Earth. Haise was completing the shutdown of the LM after testing its systems while Lovell stowed the TV camera. Jack Lousma, the CAPCOM, sent minor instructions to Swigert, including changing the attitude of the craft to facilitate photography of Comet Bennett. The pressure sensor in one of the SM's oxygen tanks had earlier appeared to be malfunctioning, so Sy Liebergot (the EECOM, in charge of monitoring the CSM's electrical system) requested that the stirring fans in the tanks be activated. Normally this was done once daily; a stir would destratify the contents of the tanks, making the pressure readings more accurate. The Flight Director, Kranz, had Liebergot wait a few minutes for the crew to settle down after the telecast, then Lousma relayed the request to Swigert, who activated the switches controlling the fans, and after a few seconds turned them off again.
Ninety-five seconds after Swigert activated those switches, the astronauts heard a "pretty large bang", accompanied by fluctuations in electrical power and the firing of the attitude control thrusters. Communications and telemetry to Earth were lost for 1.8 seconds, until the system automatically corrected by switching the high-gain S-band antenna, used for translunar communications, from narrow-beam to wide-beam mode. The accident happened at 55:54:53 (03:08 UTC on April 14; 10:08 PM EST, April 13). Swigert reported 26 seconds later, "Okay, Houston, we've had a problem here," echoed at 55:55:42 by Lovell, "Houston, we've had a problem. We've had a Main B Bus undervolt." William Fenner was the guidance officer (GUIDO) who was the first to report a problem in the control room to Kranz. Lovell's initial thought on hearing the noise was that Haise had activated the LM's cabin-repressurization valve, which also produced a bang (Haise enjoyed doing so to startle his crewmates), but Lovell could see that Haise had no idea what had happened. Swigert initially thought that a meteoroid might have struck the LM, but he and Lovell quickly realized there was no leak. The "Main Bus B undervolt" meant that there was insufficient voltage produced by the SM's three fuel cells (fueled by hydrogen and oxygen piped from their respective tanks) to the second of the SM's two electric power distribution systems. Almost everything in the CSM required power. Although the bus momentarily returned to normal status, soon both buses A and B were short on voltage. Haise checked the status of the fuel cells and found that two of them were dead. Mission rules forbade entering lunar orbit unless all fuel cells were operational.
In the minutes after the accident, there were several unusual readings, showing that tank2 was empty and tank1's pressure slowly falling, that the computer on the spacecraft had reset and that the high-gain antenna was not working. Liebergot initially missed the worrying signs from tank2 following the stir, as he was focusing on tank1, believing that its reading would be a good guide to what was present in tank2, as did controllers supporting him in the "back room". When Kranz questioned Liebergot on this, he initially responded that there might be false readings due to an instrumentation problem; he was often teased about that in the years to come. Lovell, looking out the window, reported "a gas of some sort" venting into space, making it clear that there was a serious problem. Since the fuel cells needed oxygen to operate, when Oxygen Tank1 ran dry, the remaining fuel cell would shut down, meaning the CSM's only significant sources of power and oxygen would be the CM's batteries and its oxygen "surge tank". These would be needed for the final hours of the mission, but the remaining fuel cell, already starved for oxygen, was drawing from the surge tank. Kranz ordered the surge tank isolated, saving its oxygen, but this meant that the remaining fuel cell would die within two hours, as the oxygen in tank1 was consumed or leaked away. The volume surrounding the spacecraft was filled with myriad small bits of debris from the accident, complicating any efforts to use the stars for navigation. The mission's goal became simply getting the astronauts back to Earth alive.
Looping around the Moon. The lunar module had charged batteries and full oxygen tanks for use on the lunar surface, so Kranz directed that the astronauts power up the LM and use it as a "lifeboat"a scenario anticipated but considered unlikely. Procedures for using the LM in this way had been developed by LM flight controllers after a training simulation for Apollo 10 in which the LM was needed for survival, but could not be powered up in time. Had Apollo 13's accident occurred on the return voyage, with the LM already jettisoned, the astronauts would have died, as they would have following an explosion in lunar orbit, including one while Lovell and Haise walked on the Moon. A key decision was the choice of return path. A "direct abort" would use the SM's main engine (the Service Propulsion System or SPS) to return before reaching the Moon. However, the accident could have damaged the SPS, and the fuel cells would have to last at least another hour to meet its power requirements, so Kranz instead decided on a longer route: the spacecraft would swing around the Moon before heading back to Earth. Apollo 13 was on the hybrid trajectory which was to take it to Fra Mauro; it now needed to be brought back to a free return. The LM's Descent Propulsion System (DPS), although not as powerful as the SPS, could do this, but new software for Mission Control's computers needed to be written by technicians as it had never been contemplated that the CSM/LM spacecraft would have to be maneuvered from the LM. As the CM was being shut down, Lovell copied down its guidance system's orientation information and performed hand calculations to transfer it to the LM's guidance system, which had been turned off; at his request Mission Control checked his figures. At 61:29:43.49 the DPS burn of 34.23 seconds took Apollo 13 back to a free return trajectory.
The change would get Apollo 13 back to Earth in about four days' timethough with splashdown in the Indian Ocean, where NASA had few recovery forces. Jerry Bostick and other Flight Dynamics Officers (FIDOs) were anxious both to shorten the travel time and to move splashdown to the Pacific Ocean, where the main recovery forces were located. One option would shave 36 hours off the return time, but required jettisoning the SM; this would expose the CM's heat shield to space during the return journey, something for which it had not been designed. The FIDOs also proposed other solutions. After a meeting involving NASA officials and engineers, the senior individual present, Manned Spaceflight Center director Robert R. Gilruth, decided on a burn using the DPS, that would save 12 hours and land Apollo 13 in the Pacific. This "PC+2" burn would take place two hours after pericynthion, the closest approach to the Moon. At pericynthion, Apollo 13 set the record (per the "Guinness Book of World Records"), which still stands, for the furthest distance from Earth by a crewed spacecraft: from Earth at 7:21 pm EST, April 14 (00:21:00 UTC April 15).
While preparing for the burn, the crew was told that the S-IVB had impacted the Moon as planned, leading Lovell to quip, "Well, at least something worked on this flight." Kranz's White team of mission controllers, who had spent most of their time supporting other teams and developing the procedures urgently needed to get the astronauts home, took their consoles for the PC+2 procedure. Normally, the accuracy of such a burn could be assured by checking the alignment Lovell had transferred to the LM's computer against the position of one of the stars astronauts used for navigation, but the light glinting off the many pieces of debris accompanying the spacecraft made that impractical. The astronauts accordingly used the one star available whose position could not be obscuredthe Sun. Houston also informed them that the Moon would be centered in the commander's window of the LM as they made the burn, which was almost perfectless than 0.3 meters (1 foot) per second off. The burn, at 79:27:38.95, lasted four minutes and 23 seconds. The crew then shut down most LM systems to conserve consumables.
Return to Earth. The LM carried enough oxygen, but that still left the problem of removing carbon dioxide, which was absorbed by canisters of lithium hydroxide pellets. The LM's stock of canisters, meant to accommodate two astronauts for 45 hours on the Moon, was not enough to support three astronauts for the return journey to Earth. The CM had enough canisters, but they were of a different shape and size to the LM's, hence unable to be used in the LM's equipment. Engineers on the ground devised a way to bridge the gap, using plastic covers ripped from procedure manuals, duct tape, and other items available on the spacecraft. NASA engineers referred to the improvised device as "the mailbox". The procedure for building the device was read to the crew by CAPCOM Joseph Kerwin over the course of an hour, and was built by Swigert and Haise; carbon dioxide levels began dropping immediately. Lovell later described this improvisation as "a fine example of cooperation between ground and space".
Inside the darkened spacecraft, the temperature dropped as low as . Lovell considered having the crew don their spacesuits, but decided this would be too hot. Instead, Lovell and Haise wore their lunar EVA boots and Swigert put on an extra coverall. All three astronauts were cold, especially Swigert, who had got his feet wet while filling the water bags and had no lunar overshoes (since he had not been scheduled to walk on the Moon). As they had been told not to discharge their urine to space to avoid disturbing the trajectory, they had to store it in bags. Water condensed on the walls, though any condensation that may have been behind equipment panels caused no problems, partly because of the extensive electrical insulation improvements instituted after the Apollo 1 fire. Despite all this, the crew voiced few complaints. Flight controller John Aaron, along with Mattingly and several engineers and designers, devised a procedure for powering up the command module from full shutdownsomething never intended to be done in flight, much less under Apollo 13's severe power and time constraints. The astronauts implemented the procedure without apparent difficulty: Kranz later credited all three astronauts having been test pilots, accustomed to having to work in critical situations with their lives on the line, for their survival.
Recognizing that the cold conditions combined with insufficient rest would hinder the time-critical startup of the command module prior to reentry, at 133 hours into flight Mission Control gave Lovell the okay to fully power up the LM to raise the cabin temperature, which included restarting the LM's guidance computer. Having the LM's computer running enabled Lovell to perform a navigational sighting and calibrate the LM's Inertial Measurement Unit (IMU). With the lunar module's computer aware of its location and orientation, the command module's computer was later calibrated in a reverse of the normal procedures used to set up the LM, shaving steps from the restart process and increasing the accuracy of the PGNCS-controlled reentry. Reentry and splashdown. Despite the accuracy of the transearth injection, the spacecraft slowly drifted off course, necessitating a correction. As the LM's guidance system had been shut down following the PC+2 burn, the crew was told to use the line between night and day on the Earth to guide them, a technique used on NASA's Earth-orbit missions but never on the way back from the Moon. This DPS burn, at 105:18:42 for 14 seconds, brought the projected entry flight path angle back within safe limits. Nevertheless, yet another burn was needed at 137:40:13, using the LM's reaction control system (RCS) thrusters, for 21.5 seconds. The SM was jettisoned less than half an hour later, allowing the crew to see the damage for the first time, and photograph it. They reported that an entire panel was missing from the SM's exterior, the fuel cells above the oxygen tank shelf were tilted, that the high-gain antenna was damaged, and there was a considerable amount of debris elsewhere. Haise could see possible damage to the SM's engine bell, validating Kranz's decision not to use the SPS. The crew then moved out of the LM back into the CM and reactivated its life support systems.
The last problem to be solved was how to separate the lunar module a safe distance away from the command module just before reentry. The normal procedure, in lunar orbit, was to release the LM and then use the service module's RCS to pull the CSM away, but by this point, the SM had already been released. Grumman, manufacturer of the LM, assigned a team of University of Toronto engineers, led by senior scientist Bernard Etkin, to solve the problem of how much air pressure to use to push the modules apart. The astronauts applied the solution, which was successful. The LM reentered Earth's atmosphere and was destroyed, the remaining pieces falling in the deep ocean. Apollo 13's final midcourse correction had addressed the concerns of the Atomic Energy Commission, which wanted the cask containing the plutonium oxide intended for the SNAP-27 RTG to land in a safe place. The impact point was over the Tonga Trench in the Pacific, one of its deepest points, and the cask sank to the bottom. Later helicopter surveys found no radioactive leakage.
Ionization of the air around the command module during reentry would typically cause a four-minute communications blackout. Apollo 13's shallow reentry path lengthened this to six minutes, longer than had been expected; controllers feared that the CM's heat shield had failed. "Odyssey" regained radio contact and splashed down safely in the South Pacific Ocean, , southeast of American Samoa and from the recovery ship, USS "Iwo Jima". Although fatigued, the crew was in good condition except for Haise, who had developed a serious urinary tract infection because of insufficient water intake. The crew stayed overnight on the ship and flew to Pago Pago, American Samoa, the next day. They flew to Hawaii, where President Richard Nixon awarded them the Presidential Medal of Freedom, the highest civilian honor. They stayed overnight, and then were flown back to Houston. En route to Honolulu, President Nixon stopped at Houston to award the Presidential Medal of Freedom to the Apollo 13 Mission Operations Team. He originally planned to give the award to NASA administrator Thomas O. Paine, but Paine recommended the mission operations team.
Public and media reaction. Worldwide interest in the Apollo program was reawakened by the incident; television coverage was seen by millions. Four Soviet ships headed toward the landing area to assist if needed, and other nations offered assistance should the craft have to splash down elsewhere. President Nixon canceled appointments, phoned the astronauts' families, and drove to NASA's Goddard Space Flight Center in Greenbelt, Maryland, where Apollo's tracking and communications were coordinated. The rescue received more public attention than any spaceflight to that point, other than the first Moon landing on Apollo 11. There were worldwide headlines, and people surrounded television sets to get the latest developments, offered by networks who interrupted their regular programming for bulletins. Pope Paul VI led a congregation of 10,000 people in praying for the astronauts' safe return; ten times that number offered prayers at a religious festival in India. The United States Senate on April 14 passed a resolution urging businesses to pause at 9:00pm local time that evening to allow for employee prayer.
An estimated 40million Americans watched Apollo13's splashdown, carried live on all three networks, with another 30million watching some portion of the 6½ hour telecast. Even more outside the U.S. watched. Jack Gould of "The New York Times" stated that Apollo13, "which came so close to tragic disaster, in all probability united the world in mutual concern more fully than another successful landing on the Moon would have". Investigation and response. Review board. Immediately upon the crew's return, NASA Administrator Paine and Deputy Administrator George Low appointed a review board to investigate the accident. Chaired by NASA Langley Research Center Director Edgar M. Cortright and including Neil Armstrong and six others, the board sent its final report to Paine on June 15. It found that the failure began in the service module's number2 oxygen tank. Damaged Teflon insulation on the wires to the stirring fan inside Oxygen Tank2 allowed the wires to short circuit and ignite this insulation. The resulting fire increased the pressure inside the tank until the tank dome failed, filling the fuel cell bay (SM Sector4) with rapidly expanding gaseous oxygen and combustion products. The pressure rise was sufficient to pop the rivets holding the aluminum exterior panel covering Sector4 and blow it out, exposing the sector to space and snuffing out the fire. The detached panel hit the nearby high-gain antenna, disabling the narrow-beam communication mode and interrupting communication with Earth for 1.8 seconds while the system automatically switched to the backup wide-beam mode. The sectors of the SM were not airtight from each other, and had there been time for the entire SM to become as pressurized as Sector4, the force on the CM's heat shield would have separated the two modules. The report questioned the use of Teflon and other materials shown to be flammable in supercritical oxygen, such as aluminum, within the tank. The board found no evidence pointing to any other theory of the accident.
Mechanical shock forced the oxygen valves closed on the number1 and number3 fuel cells, putting them out of commission. The sudden failure of Oxygen Tank2 compromised Oxygen Tank1, causing its contents to leak out, possibly through a damaged line or valve, over the next 130 minutes, entirely depleting the SM's oxygen supply. With both SM oxygen tanks emptying, and with other damage to the SM, the mission had to be aborted. The board praised the response to the emergency: "The imperfection in Apollo 13 constituted a near disaster, averted only by outstanding performance on the part of the crew and the ground control team which supported them." Oxygen Tank 2 was manufactured by the Beech Aircraft Company of Boulder, Colorado, as subcontractor to North American Rockwell (NAR) of Downey, California, prime contractor for the CSM. It contained two thermostatic switches, originally designed for the command module's 28-volt DC power, but which could fail if subjected to the 65 volts used during ground testing at KSC. Under the original 1962 specifications, the switches would be rated for 28 volts, but revised specifications issued in 1965 called for 65 volts to allow for quicker tank pressurization at KSC. Nonetheless, the switches Beech used were not rated for 65 volts.
At NAR's facility, Oxygen Tank 2 had been originally installed in an oxygen shelf placed in the Apollo 10 service module, SM-106, but which was removed to fix a potential electromagnetic interference problem and another shelf substituted. During removal, the shelf was accidentally dropped at least , because a retaining bolt had not been removed. The probability of damage from this was low, but it is possible that the fill line assembly was loose and made worse by the fall. After some retesting (which did not include filling the tank with liquid oxygen), in November 1968 the shelf was re-installed in SM-109, intended for Apollo 13, which was shipped to KSC in June 1969. The Countdown Demonstration Test took place with SM-109 in its place near the top of the Saturn V and began on March 16, 1970. During the test, the cryogenic tanks were filled, but Oxygen Tank 2 could not be emptied through the normal drain line, and a report was written documenting the problem. After discussion among NASA and the contractors, attempts to empty the tank resumed on March 27. When it would not empty normally, the heaters in the tank were turned on to boil off the oxygen. The thermostatic switches were designed to prevent the heaters from raising the temperature higher than , but they failed under the 65-volt power supply applied. Temperatures on the heater tube within the tank may have reached , most likely damaging the Teflon insulation. The temperature gauge was not designed to read higher than , so the technician monitoring the procedure detected nothing unusual. This heating had been approved by Lovell and Mattingly of the prime crew, as well as by NASA managers and engineers. Replacement of the tank would have delayed the mission by at least a month. The tank was filled with liquid oxygen again before launch; once electric power was connected, it was in a hazardous condition. The board found that Swigert's activation of the Oxygen Tank2 fan at the request of Mission Control caused an electric arc that set the tank on fire.
The board conducted a test of an oxygen tank rigged with hot-wire ignitors that caused a rapid rise in temperature within the tank, after which it failed, producing telemetry similar to that seen with the Apollo 13 Oxygen Tank 2. Tests with panels similar to the one that was seen to be missing on SM Sector4 caused separation of the panel in the test apparatus. Changes in response. For Apollo 14 and subsequent missions, the oxygen tank was redesigned, the thermostats being upgraded to handle the proper voltage. The heaters were retained since they were necessary to maintain oxygen pressure. The stirring fans, with their unsealed motors, were removed, which meant the oxygen quantity gauge was no longer accurate. This required adding a third tank so that no tank would go below half full. The third tank was placed in Bay1 of the SM, on the side opposite the other two, and was given an isolation valve that could isolate it from the fuel cells and from the other two oxygen tanks in an emergency and allow it to feed the CM's environmental system only. The quantity probe was upgraded from aluminum to stainless steel.
All electrical wiring in Bay4 was sheathed in stainless steel. The fuel cell oxygen supply valves were redesigned to isolate the Teflon-coated wiring from the oxygen. The spacecraft and Mission Control monitoring systems were modified to give more immediate and visible warnings of anomalies. An emergency supply of of water was stored in the CM, and an emergency battery, identical to those that powered the LM's descent stage, was placed in the SM. The LM was modified to make transfer of power from the LM to the CM easier. Aftermath. On February 5, 1971, Apollo 14's LM, "Antares", landed on the Moon with astronauts Alan Shepard and Edgar Mitchell aboard, near Fra Mauro, the site Apollo 13 had been intended to explore. Haise served as CAPCOM during the descent to the Moon, and during the second EVA, during which Shepard and Mitchell explored near Cone crater. None of the Apollo 13 astronauts flew in space again. Lovell retired from NASA and the Navy in 1973, entering the private sector. Swigert was to have flown on the 1975 Apollo–Soyuz Test Project (the first joint mission with the Soviet Union) but was removed as part of the fallout from the Apollo 15 postal covers incident. He took a leave of absence from NASA in 1973 and left the agency to enter politics, being elected to the House of Representatives in 1982, but died of cancer before he could be sworn in. Haise was slated to have been the commander of the canceled Apollo 19 mission, and flew the Space Shuttle Approach and Landing Tests before retiring from NASA in 1979.
Several experiments were completed during Apollo 13, even though the mission did not land on the Moon. One involved the launch vehicle's S-IVB (the Saturn V's third stage), which on prior missions had been sent into solar orbit once detached. The seismometer left by Apollo 12 had detected frequent impacts of small objects onto the Moon, but larger impacts would yield more information about the Moon's crust, so it was decided that, beginning with Apollo 13, the S-IVB would be crashed into the Moon. The impact occurred at 77:56:40 into the mission and produced enough energy that the gain on the seismometer, from the impact, had to be reduced. An experiment to measure the amount of atmospheric electrical phenomena during the ascent to orbitadded after Apollo 12 was struck by lightningreturned data indicating a heightened risk during marginal weather. A series of photographs of Earth, taken to test whether cloud height could be determined from synchronous satellites, achieved the desired results. As a joke, Grumman issued an invoice to North American Rockwell, prime contractor for the CSM, for "towing" the CSM most of the way to the Moon and back. Line items included 400001 miles at $1 each (plus $4 for the first mile); $536.05 for battery charging; oxygen; and four nights at $8 per night for an "additional guest in room" (Swigert). After a 20% "commercial discount", and a 2% discount for timely payment, the final total was $312,421.24. North American declined payment, noting that it had ferried three previous Grumman LMs to the Moon without compensation.
The CM was disassembled for testing and parts remained in storage for years; some were used for a trainer for the Skylab Rescue Mission. That trainer was subsequently displayed at the Kentucky Science Center. Max Ary of the Cosmosphere made it a project to restore "Odyssey"; it is on display there, in Hutchinson, Kansas. Apollo 13 was called a "successful failure" by Lovell. Mike Massimino, a Space Shuttle astronaut, stated that Apollo 13 "showed teamwork, camaraderie and what NASA was really made of". The response to the accident has been repeatedly called "NASA's finest hour"; it is still viewed that way. Author Colin Burgess wrote, "the life-or-death flight of Apollo 13 dramatically evinced the colossal risks inherent in manned spaceflight. Then, with the crew safely back on Earth, public apathy set in once again." William R. Compton, in his book about the Apollo Program, said of Apollo 13, "Only a heroic effort of real-time improvisation by mission operations teams saved the crew." Rick Houston and Milt Heflin, in their history of Mission Control, stated, "Apollo 13 proved mission control could bring those space voyagers back home again when their lives were on the line." Former NASA chief historian Roger D. Launius wrote, "More than any other incident in the history of spaceflight, recovery from this accident solidified the world's belief in NASA's capabilities". Nevertheless, the accident convinced some officials, such as Manned Spaceflight Center director Gilruth, that if NASA kept sending astronauts on Apollo missions, some would inevitably be killed, and they called for as quick an end as possible to the program. Nixon's advisers recommended canceling the remaining lunar missions, saying that a disaster in space would cost him political capital. Budget cuts made such a decision easier, and during the pause after Apollo 13, two missions were canceled, meaning that the program ended with Apollo 17 in December 1972.
Popular culture, media and 50th anniversary. The 1974 movie "Houston, We've Got a Problem", while set around the Apollo 13 incident, is a fictional drama about the crises faced by ground personnel when the emergency disrupts their work schedules and places further stress on their lives. Lovell publicly complained about the movie, saying it was "fictitious and in poor taste". "Houston... We've Got a Problem" was the title of an episode of the BBC documentary series "A Life At Stake", broadcast in March 1978. This was an accurate, if simplified, reconstruction of the events. In 1994, during the 25th anniversary of Apollo 11, PBS released a 90-minute documentary titled "Apollo 13: To the Edge and Back". Following the flight, the crew planned to write a book, but they all left NASA without starting it. After Lovell retired in 1991, he was approached by journalist Jeffrey Kluger about writing a non-fiction account of the mission. Swigert died in 1982 and Haise was no longer interested in such a project. The resultant book, "Lost Moon: The Perilous Voyage of Apollo 13", was published in 1994.
The next year, in 1995, a film adaptation of the book, "Apollo 13", was released, directed by Ron Howard and starring Tom Hanks as Lovell, Bill Paxton as Haise, Kevin Bacon as Swigert, Gary Sinise as Mattingly, Ed Harris as Kranz, and Kathleen Quinlan as Marilyn Lovell. James Lovell, Kranz, and other principals have stated that this film depicted the events of the mission with reasonable accuracy, given that some dramatic license was taken. For example, the film changes the tense of Lovell's famous follow-up to Swigert's original words from, "Houston, we've had a problem" to "Houston, we have a problem". The film also invented the phrase "Failure is not an option", uttered by Harris as Kranz in the film; the phrase became so closely associated with Kranz that he used it for the title of his 2000 autobiography. The film won two of the nine Academy Awards it was nominated for, Best Film Editing and Best Sound. In the 1998 miniseries "From the Earth to the Moon", co-produced by Hanks and Howard, the mission is dramatized in the episode "We Interrupt This Program". Rather than showing the incident from the crew's perspective as in the "Apollo 13" feature film, it is instead presented from an Earth-bound perspective of television reporters competing for coverage of the event.
In 2020, the BBC World Service began airing "13 Minutes to the Moon", radio programs which draw on NASA audio from the mission, as well as archival and recent interviews with participants. Episodes began airing for Season 2 starting on March 8, 2020, with episode 1, "Time bomb: Apollo 13", explaining the launch and the explosion. Episode 2 details Mission Control's denial and disbelief of the accident, with other episodes covering other aspects of the mission. The seventh and final episode was delayed due to the COVID-19 pandemic. In "Delay to Episode 7", the BBC explained that the presenter of the series, medical doctor Kevin Fong, had been called into service. In advance of the 50th anniversary of the mission in 2020, an Apollo in Real Time site for the mission went online, allowing viewers to follow along as the mission unfolds, view photographs and video, and listen to audio of conversations between Houston and the astronauts as well as between mission controllers. Due to the COVID-19 pandemic, NASA did not hold any in-person events during April 2020 for the flight's 50th anniversary, but premiered a new documentary, "Apollo 13: Home Safe" on April 10, 2020. A number of events were rescheduled for later in 2020. External links. NASA reports Multimedia
Apollo 7 Apollo 7 (October 11–22, 1968) was the first crewed flight in NASA's Apollo program, and saw the resumption of human spaceflight by the agency after the fire that had killed the three Apollo 1 astronauts during a launch rehearsal test on January 27, 1967. The Apollo7 crew was commanded by Walter M. Schirra, with Command Module Pilot Donn F. Eisele and Lunar Module pilot R. Walter Cunningham (so designated even though Apollo7 did not carry a Lunar Module). The three astronauts were originally designated for the second crewed Apollo flight, and then as backups for Apollo1. After the Apollo1 fire, crewed flights were suspended while the cause of the accident was investigated and improvements made to the spacecraft and safety procedures, and uncrewed test flights made. Determined to prevent a repetition of the fire, the crew spent long periods monitoring the construction of their Apollo command and service modules (CSM). Training continued over much of the pause that followed the Apollo1 disaster. Apollo 7 was launched on October 11, 1968, from Cape Kennedy Air Force Station, Florida, and splashed down in the Atlantic Ocean eleven days later. Extensive testing of the CSM took place, and also the first live television broadcast from an American spacecraft. Despite tension between the crew and ground controllers, the mission was a complete technical success, giving NASA the confidence to send Apollo 8 into orbit around the Moon two months later. In part because of these tensions, none of the crew flew in space again, though Schirra had already announced he would retire from NASA after the flight. Apollo7 fulfilled Apollo1's mission of testing the CSM in low Earth orbit, and was a significant step towards NASA's goal of landing astronauts on the Moon.
Background and personnel. Schirra, one of the original "Mercury Seven" astronauts, graduated from the United States Naval Academy in 1945. He flew Mercury-Atlas 8 in 1962, the fifth crewed flight of Project Mercury and the third to reach orbit, and in 1965 was the command pilot for Gemini 6A. He was a 45-year-old captain in the Navy at the time of Apollo7. Eisele graduated from the Naval Academy in 1952 with a B.S. in aeronautics. He elected to be commissioned in the Air Force, and was a 38-year-old major at the time of Apollo7. Cunningham joined the U.S. Navy in 1951, began flight training the following year, and served in a Marine flight squadron from 1953 to 1956, and was a civilian, aged 36, serving in the Marine Corps reserves with a rank of major, at the time of Apollo7. He received degrees in physics from UCLA, a B.A. in 1960 and an M.A. in 1961. Both Eisele and Cunningham were selected as part of the third group of astronauts in 1963. Eisele was originally slotted for a position on Gus Grissom's Apollo 1 crew along with Ed White, but days prior to the official announcement on March 25, 1966, Eisele sustained a shoulder injury that would require surgery. Instead, Roger Chaffee was given the position and Eisele was reassigned to Schirra's crew.
Schirra, Eisele, and Cunningham were first named as an Apollo crew on September 29, 1966. They were to fly a second Earth orbital test of the Apollo Command Module (CM). Although delighted as a rookie to be assigned to a prime crew without having served as a backup, Cunningham was troubled by the fact that a second Earth orbital test flight, dubbed Apollo2, seemed unnecessary if Apollo1 was successful. He learned later that Director of Flight Crew Operations Deke Slayton, another of the Mercury Seven who had been grounded for medical reasons and supervised the astronauts, planned, with Schirra's support, to command the mission if he gained medical clearance. When this was not forthcoming, Schirra remained in command of the crew, and in November 1966, Apollo2 was cancelled and Schirra's crew assigned as backup to Grissom's. Thomas P. Stafford—assigned at that point as the backup commander of the second orbital test—stated that the cancellation followed Schirra and his crew submitting a list of demands to NASA management (Schirra wanted the mission to include a lunar module and a CM capable of docking with it), and that the assignment as backups left Schirra complaining that Slayton and Chief Astronaut Alan Shepard had destroyed his career.
On January 27, 1967, Grissom's crew was conducting a launch-pad test for their planned February 21 mission, when a fire broke out in the cabin, killing all three men. A complete safety review of the Apollo program followed. Soon after the fire, Slayton asked Schirra, Eisele and Cunningham to fly the first mission after the pause. Apollo 7 would use the BlockII spacecraft designed for the lunar missions, as opposed to the Block I CSM used for Apollo 1, which was intended only to be used for the early Earth-orbit missions, as it lacked the capability of docking with a lunar module. The CM and astronauts' spacesuits had been extensively redesigned, to reduce any chance of a repeat of the accident which killed the first crew. Schirra's crew would test the life support, propulsion, guidance and control systems during this "open-ended" mission (meaning it would be extended as it passed each test). The duration was limited to 11 days, reduced from the original 14-day limit for Apollo1. The backup crew consisted of Stafford as commander, John W. Young as command module pilot, and Eugene A. Cernan as lunar module pilot. They became the prime crew of Apollo 10. Ronald E. Evans, John L. 'Jack' Swigert, and Edward G. Givens were assigned to the support crew for the mission. Givens died in a car accident on June 6, 1967, and William R. Pogue was assigned as his replacement. Evans was involved in hardware testing at Kennedy Space Center (KSC). Swigert was the launch capsule communicator (CAPCOM) and worked on the mission's operational aspects. Pogue spent time modifying procedures. The support crew also filled in when the primary and backup crews were unavailable.
CAPCOMs, the person in Mission Control responsible for communicating with the spacecraft (then always an astronaut) were Evans, Pogue, Stafford, Swigert, Young and Cernan. Flight directors were Glynn Lunney, Gene Kranz and Gerry Griffin. Preparation. According to Cunningham, Schirra originally had limited interest in making a third spaceflight, beginning to focus on his post-NASA career. Flying the first mission after the fire changed things: "Wally Schirra was being pictured as the man chosen to rescue the manned space program. And that was a task worthy of Wally's interest." Eisele noted, "coming on the heels of the fire, we knew the fate and future of the entire manned space program—not to mention our own skins—was riding on the success or failure of Apollo7."
The Apollo 7 crew spent five hours in training for every hour they could expect to remain aboard if the mission went its full eleven days. In addition, they attended technical briefings and pilots' meetings, and studied on their own. They undertook launch pad evacuation training, water egress training to exit the vehicle after splashdown, and learned to use firefighting equipment. They trained on the Apollo Guidance Computer at MIT. Each crew member spent 160 hours in CM simulations, in some of which Mission Control in Houston participated live. The "plugs out" test—the test that had killed the Apollo1 crew—was conducted with the prime crew in the spacecraft, but with the hatch open. One reason the Apollo1 crew had died was because it was impossible to open the inward-opening hatch before the fire raced through the cabin; this was changed for Apollo7. Command modules similar to that used on Apollo7 were subjected to tests in the run-up to the mission. A three-astronaut crew (Joseph P. Kerwin, Vance D. Brand and Joe H. Engle) was inside a CM that was placed in a vacuum chamber at the Manned Spaceflight Center in Houston for eight days in June 1968 to test spacecraft systems. Another crew (James Lovell, Stuart Roosa and Charles M. Duke) spent 48 hours at sea aboard a CM lowered into the Gulf of Mexico from a naval vessel in April 1968, to test how systems would respond to seawater. Further tests were conducted the following month in a tank at Houston. Fires were set aboard a boilerplate CM using various atmospheric compositions and pressures. The results led to the decision to use 60 percent oxygen and 40 percent nitrogen within the CM at launch, which would be replaced with a lower pressure of pure oxygen within four hours, as providing adequate fire protection. Other boilerplate spacecraft were subjected to drops to test parachutes, and to simulate the likely damage if a CM came down on land. All results were satisfactory.
During the run-up to the mission, the Soviets sent uncrewed probes Zond 4 and Zond 5 (Zond 5 carried two tortoises) around the Moon, seeming to foreshadow a circumlunar crewed mission. NASA's Lunar Module (LM) was suffering delays, and Apollo Program Spacecraft Manager George Low proposed that if Apollo7 was a success, that Apollo 8 go to lunar orbit without a LM. The acceptance of Low's proposal raised the stakes for Apollo7. According to Stafford, Schirra "clearly felt the full weight of the program riding on a successful mission and as a result became more openly critical and more sarcastic." Throughout the Mercury and Gemini programs, McDonnell Aircraft engineer Guenter Wendt led the spacecraft launch pad teams, with ultimate responsibility for condition of the spacecraft at launch. He earned the astronauts' respect and admiration, including Schirra's. However, the spacecraft contractor had changed from McDonnell (Mercury and Gemini) to North American (Apollo), so Wendt was not the pad leader for Apollo1. So adamant was Schirra in his desire to have Wendt back as pad leader for his Apollo flight, that he got his boss Slayton to persuade North American management to hire Wendt away from McDonnell, and Schirra personally lobbied North American's launch operations manager to change Wendt's shift from midnight to day so he could be pad leader for Apollo7. Wendt remained as pad leader for the entire Apollo program. When he departed the spacecraft area as the pad was evacuated prior to launch, after Cunningham said, "I think Guenter's going", Eisele responded "Yes, I think Guenter went."
Hardware. Spacecraft. The Apollo 7 spacecraft included Command and Service Module 101 (CSM-101), the first BlockII CSM to be flown. The BlockII craft had the capability of docking with a LM, though none was flown on Apollo7. The spacecraft also included the launch escape system and a spacecraft-lunar module adapter (SLA, numbered as SLA-5), though the latter included no LM and instead provided a mating structure between the SM and the S-IVB's Instrument Unit, with a structural stiffener substituted for the LM. The launch escape system was jettisoned after S-IVB ignition, while the SLA was left behind on the spent S-IVB when the CSM separated from it in orbit. Following the Apollo 1 fire, the BlockII CSM was extensively redesigned—more than 1,800 changes were recommended, of which 1,300 were implemented for Apollo7. Prominent among these was the new aluminum and fiberglass outward-opening hatch, which the crew could open in seven seconds from within, and the pad crew in ten seconds from outside. Other changes included replacement of aluminum tubing in the high-pressure oxygen system with stainless steel, replacement of flammable materials with non-flammable (including changing plastic switches for metal ones) and, for crew protection in the event of a fire, an emergency oxygen system to shield them from toxic fumes, as well as firefighting equipment.
After the Gemini 3 craft was dubbed "Molly Brown" by Grissom, NASA forbade naming spacecraft. Despite this prohibition, Schirra wanted to name his ship "Phoenix," but NASA refused him permission. The first CM to be given a call sign other than the mission designation would be that of Apollo 9, which carried a LM that would separate from it and then re-dock, necessitating distinct call signs for the two vehicles. Launch vehicle. Since it flew in low Earth orbit and did not include a LM, Apollo7 was launched with the Saturn IB booster rather than the much larger and more powerful Saturn V. That Saturn IB was designated SA-205, and was the fifth Saturn IB to be flown—the earlier ones did not carry crews into space. It differed from its predecessors in that stronger propellant lines to the augmented spark igniter in the J-2 engines had been installed, so as to prevent a repetition of the early shutdown that had occurred on the uncrewed Apollo 6 flight; postflight analysis had shown that the propellant lines to the J-2 engines, also used in the Saturn V tested on Apollo6, had leaked.
The Saturn IB was a two-stage rocket, with the second stage an S-IVB similar to the third stage of the Saturn V, the rocket used by all later Apollo missions. The Saturn IB was used after the close of the Apollo Program to bring crews in Apollo CSMs to Skylab, and for the Apollo–Soyuz Test Project. Apollo 7 was the only crewed Apollo mission to launch from Cape Kennedy Air Force Station's Launch Complex 34. All subsequent Apollo and Skylab spacecraft flights (including Apollo–Soyuz) were launched from Launch Complex 39 at the nearby Kennedy Space Center. Launch Complex 34 was declared redundant and decommissioned in 1969, making Apollo7 the last human spaceflight mission to launch from the Cape Air Force Station in the 20th century. Mission highlights. The main purposes of the Apollo7 flight were to show that the Block II CM would be habitable and reliable over the length of time required for a lunar mission, to show that the service propulsion system (SPS, the spacecraft's main engine) and the CM's guidance systems could perform a rendezvous in orbit, and later make a precision reentry and splashdown. In addition, there were a number of specific objectives, including evaluating the communications systems and the accuracy of onboard systems such as the propellant tank gauges. Many of the activities aimed at gathering these data were scheduled for early in the mission, so that if the mission was terminated prematurely, they would already have been completed, allowing for fixes to be made prior to the next Apollo flight.
Launch and testing. Apollo 7, the first crewed American space flight in 22 months, launched from Launch Complex 34 at 11:02:45am EDT (15:02:45UTC) on Friday, October 11, 1968. During the countdown, the wind was blowing in from the east. Launching under these weather conditions was in violation of safety rules, since in the event of a launch vehicle malfunction and abort, the CM might be blown back over land instead of making the usual water landing. Apollo7 was equipped with the old Apollo1-style crew couches, which provided less protection than later ones. Schirra later related that he felt the launch should have been scrubbed, but managers waived the rule and he yielded under pressure. Liftoff proceeded flawlessly; the Saturn IB performed well on its first crewed launch and there were no significant anomalies during the boost phase. The astronauts described it as very smooth. The ascent made the 45-year-old Schirra the oldest person to that point to enter space, and, as it proved, the only astronaut to fly Mercury, Gemini and Apollo missions.
Within the first three hours of flight, the astronauts performed two actions which simulated what would be required on a lunar mission. First, they maneuvered the craft with the S-IVB still attached, as would be required for the burn that would take lunar missions to the Moon. Then, after separation from the S-IVB, Schirra turned the CSM around and approached a docking target painted on the S-IVB, simulating the docking maneuver with the lunar module on Moon-bound missions prior to extracting the combined craft. Cunningham reported that the hinged SLA panels on the S-IVB had not fully opened, which CAPCOM Tom Stafford likened to the "angry alligator" from his Gemini 9A flight. Partially open panels would have presented a collision hazard on flights with an LM, so on subsequent missions the SLA panels were jettisoned after the CSM had separated. After station keeping with the S-IVB for 20 minutes, Schirra let it drift away, putting between the CSM and it in preparation for the following day's rendezvous attempt.
The astronauts also enjoyed a hot lunch, the first hot meal prepared on an American spacecraft. Schirra had brought instant coffee along over the opposition of NASA doctors, who argued it added nothing nutritionally. Five hours after launch, he reported having, and enjoying, his first plastic bag full of coffee. The purpose of the rendezvous was to demonstrate the CSM's ability to match orbits with and rescue a LM after an aborted lunar landing attempt, or following liftoff from the lunar surface. This was to occur on the second day; but by the end of the first, Schirra had reported he had a cold, and, despite Slayton coming on the loop to argue in favor, declined Mission Control's request that the crew power up and test the onboard television camera prior to the rendezvous, citing the cold, that the crew had not eaten, and that there was already a very full schedule. The rendezvous was complicated by the fact that the Apollo7 spacecraft lacked a rendezvous radar, something the Moon-bound missions would have. The SPS, the engine that would be needed to send later Apollo CSMs into and out of lunar orbit, had been fired only on a test stand. Although the astronauts were confident it would work, they were concerned it might fire in an unexpected manner, necessitating an early end to the mission. The burns would be computed from the ground but the final work in maneuvering up to the S-IVB would require Eisele to use the telescope and sextant to compute the final burns, with Schirra applying the ship's reaction control system (RCS) thrusters. Eisele was startled by the violent jolt caused by activating the SPS. The thrust caused Schirra to yell, "Yabba dabba doo!" in reference to "The Flintstones" cartoon. Schirra eased the craft close to the S-IVB, which was tumbling out of control, successfully completing the rendezvous.
The first television broadcast took place on October 14. It began with a view of a card reading "From the Lovely Apollo Room high atop everything", recalling tag lines used by band leaders on 1930s radio broadcasts. Cunningham served as camera operator with Eisele as emcee. During the seven-minute broadcast, the crew showed off the spacecraft and gave the audience views of the southern United States. Before the close, Schirra held another sign, "Keep those cards and letters coming in folks", another old-time radio tag line that had been used recently by Dean Martin. This was the first live television broadcast from an American spacecraft (Gordon Cooper had transmitted slow-scan television pictures from "Faith7" in 1963, but the pictures were of poor quality and were never broadcast). According to Jones, "these apparently amiable astronauts delivered to NASA a solid public relations coup." Daily television broadcasts of about 10 minutes each followed, during which the crew held up more signs and educated their audience about spaceflight; after the return to Earth, they were awarded a special Emmy for the telecasts.
Later on October 14, the craft's onboard radar receiver was able to lock onto a ground-based transmitter, again showing a CSM in lunar orbit could keep contact with a LM returning from the Moon's surface. Throughout the remainder of the mission, the crew continued to run tests on the CSM, including of the propulsion, navigation, environmental, electrical and thermal control systems. All checked out well; according to authors Francis French and Colin Burgess, "The redesigned Apollo spacecraft was better than anyone had dared to hope." Eisele found that navigation was not as easy as anticipated; he found it difficult to use Earth's horizon in sighting stars due to the fuzziness of the atmosphere, and water dumps made it difficult to discern which glistening points were stars and which ice particles. By the end of the mission, the SPS engine had been fired eight times without any problems. One difficulty that was encountered was with the sleep schedule, which called for one crew member to remain awake at all times; Eisele was to remain awake while the others slept, and sleep during part of the time the others were awake. This did not work well, as it was hard for crew members to work without making a disturbance. Cunningham later remembered waking up to find Eisele dozing.
Conflict and splashdown. Schirra was angered by NASA managers allowing the launch to proceed despite the winds, saying "The mission pushed us to the wall in terms of risk." Jones said, "This prelaunch dispute was the prelude to a tug of war over command decisions for the rest of the mission." Lack of sleep and Schirra's cold probably contributed to the conflict between the astronauts and Mission Control that surfaced from time to time during the flight. The testing of the television resulted in a disagreement between the crew and Houston. Schirra stated at the time, "You've added two burns to this flight schedule, and you've added a urine water dump; and we have a new vehicle up here, and I can tell you at this point, TV will be delayed without any further discussion until after the rendezvous." Schirra later wrote, "we'd resist anything that interfered with our main mission objectives. On this particular Saturday morning a TV program clearly interfered." Eisele agreed in his memoirs, "We were preoccupied with preparations for that critical exercise and didn't want to divert our attention with what seemed to be trivialities at the time... Evidently the earth people felt differently; there was a real stink about the hotheaded, recalcitrant Apollo7 crew who wouldn't take orders." French and Burgess wrote, "When this point is considered objectively—that in a front-loaded mission the rendezvous, alignment, and engine tests should be done before television shows—it is hard to argue with him [Schirra]." Although Slayton gave in to Schirra, the commander's attitude surprised flight controllers.
On Day 8, after being asked to follow a new procedure passed up from the ground that caused the computer to freeze, Eisele radioed, "We didn't get the results that you were after. We didn't get a damn thing, in fact... you bet your ass... as far as we're concerned, somebody down there screwed up royally when he laid that one on us." Schirra later stated his belief that this was the one main occasion when Eisele upset Mission Control. The next day saw more conflict, with Schirra telling Mission Control after having to make repeated firings of the RCS system to keep the spacecraft stable during a test, "I wish you would find out the idiot's name who thought up this test. I want to find out, and I want to talk to him personally when I get back down." Eisele joined in, "While you are at it, find out who dreamed up 'P22 horizon test'; that is a beauty also."
Apollo 7 splashed down without incident at 11:11:48 UTC on October 22, 1968, SSW of Bermuda and north of the recovery ship USS "Essex". The mission's duration was 10days, 20hours, 9minutes and 3seconds. Assessment and aftermath. After the mission, NASA awarded Schirra, Eisele and Cunningham its Exceptional Service Medal in recognition of their success. On November 2, 1968, President Lyndon B. Johnson held a ceremony at the LBJ Ranch in Johnson City, Texas, to present the astronauts with the medals. He also presented NASA's highest honor, the Distinguished Service Medal, to recently retired NASA administrator James E. Webb, for his "outstanding leadership of America's space program" since the beginning of Apollo. Johnson also invited the crew to the White House, and they went there in December 1968. Despite the difficulties between the crew and Mission Control, the mission successfully met its objectives to verify the Apollo command and service module's flightworthiness, allowing Apollo8's flight to the Moon to proceed just two months later. John T. McQuiston wrote in "The New York Times" after Eisele's death in 1987 that Apollo7's success brought renewed confidence to NASA's space program. According to Jones, "Three weeks after the Apollo7 crew returned, NASA administrator Thomas Paine green-lighted Apollo8 to launch in late December and orbit the Moon. Apollo7 had delivered NASA from its trial by fire—it was the first small step down a path that would lead another crew, nine months later, to the Sea of Tranquility."
General Sam Phillips, the Apollo Program Manager, said at the time, "Apollo7 goes into my book as a perfect mission. We accomplished 101 percent of our objectives." Kraft wrote, "Schirra and his crew did it all—or at least all of it that counted... [T]hey proved to everyone's satisfaction that the SPS engine was one of the most reliable we'd ever sent into space. They operated the Command and Service Modules with true professionalism." Eisele wrote, "We were insolent, high-handed, and Machiavellian at times. Call it paranoia, call it smart—it got the job done. We had a great flight." Kranz stated in 1998, "we all look back now with a longer perspective. Schirra really wasn't on us as bad as it seemed at the time... Bottom line was, even with a grumpy commander, we got the job done as a team."
Schirra, Eisele and Cunningham were the only crew, of all the Apollo, Skylab and Apollo–Soyuz missions, who had not been awarded the Distinguished Service Medal immediately following their missions (though Schirra had received the medal twice before, for his Mercury and Gemini missions). Therefore, NASA administrator Michael D. Griffin decided to belatedly award the medals to the crew in October 2008, "[f]or exemplary performance in meeting all the Apollo7 mission objectives and more on the first crewed Apollo mission, paving the way for the first flight to the Moon on Apollo8 and the first crewed lunar landing on Apollo11." Only Cunningham was still alive at the time as Eisele had died in 1987 and Schirra in 2007. Eisele's widow accepted his medal, and Apollo 8 crew member Bill Anders accepted Schirra's. Other Apollo astronauts, including Neil Armstrong, Buzz Aldrin, and Alan Bean, were present at the award ceremony. Kraft, who had been in conflict with the crew during the mission, sent a conciliatory video message of congratulations, saying: "We gave you a hard time once but you certainly survived that and have done extremely well since... I am frankly, very proud to call you a friend."
Mission insignia. The insignia for the flight shows a command and service module with its SPS engine firing, the trail from that fire encircling a globe and extending past the edges of the patch symbolizing the Earth-orbital nature of the mission. The Roman numeralVII appears in the South Pacific Ocean and the crew's names appear on a wide black arc at the bottom. The patch was designed by Allen Stevens of Rockwell International. Spacecraft location. In January 1969, the Apollo7 command module was displayed on the NASA float in the inauguration parade of President Richard M. Nixon. The Apollo7 astronauts rode in an open car. After being transferred to the Smithsonian Institution in 1970, the spacecraft was loaned to the National Museum of Science and Technology, in Ottawa, Ontario. It was returned to the United States in 2004. Currently, the Apollo7 CM is on loan to the Frontiers of Flight Museum at Love Field in Dallas, Texas. Depiction in media. On November 6, 1968, comedian Bob Hope broadcast one of his variety television specials from NASA's Manned Spacecraft Center in Houston to honor the Apollo7 crew. Barbara Eden, star of the popular comedy series "I Dream of Jeannie", which featured fictional astronauts among its regular characters, appeared with Schirra, Eisele and Cunningham.
Schirra parlayed the head cold he contracted during Apollo7 into a television advertising contract as a spokesman for Actifed, an over-the-counter version of the medicine he took in space. The Apollo 7 mission is dramatized in the 1998 miniseries "From the Earth to the Moon" episode "We Have Cleared the Tower", with Mark Harmon as Schirra, John Mese as Eisele, Fredric Lehne as Cunningham and Nick Searcy as Slayton.
Apollo 9 Apollo 9 (March 3–13, 1969) was the third human spaceflight in NASA's Apollo program, which successfully tested systems and procedures critical to landing on the Moon. The three-man crew consisted of Commander James McDivitt, Command Module Pilot David Scott, and Lunar Module Pilot Rusty Schweickart. Flown in low Earth orbit, it was the second crewed Apollo mission that the United States launched via a Saturn V rocket, and was the first flight of the full Apollo spacecraft: the command and service module (CSM) with the Lunar Module (LM). The mission was flown to qualify the LM for lunar orbit operations in preparation for the first Moon landing by demonstrating its descent and ascent propulsion systems, showing that its crew could fly it independently, then rendezvous and dock with the CSM again, as would be required for the first crewed lunar landing. Other objectives of the flight included firing the LM descent engine to propel the spacecraft stack as a backup mode (as was required on the Apollo 13 mission), and use of the portable life support system backpack outside the LM cabin.
After launching on March 3, 1969, the crew performed the first crewed flight of a lunar module, the first docking and extraction of the same, one two-person spacewalk (EVA), and the second docking of two crewed spacecraft—two months after the Soviets performed a spacewalk crew transfer between and . The mission concluded on March 13 and was a complete success. It proved the LM worthy of crewed spaceflight, setting the stage for the dress rehearsal for the lunar landing, Apollo 10, before the ultimate goal, landing on the Moon. Mission background. In April 1966, McDivitt, Scott, and Schweickart were selected by Director of Flight Crew Operations Deke Slayton as the second Apollo crew. Their initial job was as backup to the first Apollo crew to be chosen, Gus Grissom, Ed White, and Roger Chaffee, for the first crewed Earth orbital test flight of the block I command and service module, designated AS-204. Delays in the block I CSM development pushed AS-204 into 1967. The revised plan had the McDivitt crew scheduled for the second crewed CSM, which was to rendezvous in Earth orbit with an uncrewed LM, launched separately. The third crewed mission, to be commanded by Frank Borman, was to be the first launch of a SaturnV with a crew.
On January 27, 1967, Grissom's crew was conducting a launch-pad test for their planned February 21 mission, which they named Apollo 1, when a fire broke out in the cabin, killing all three men. A complete safety review of the Apollo program followed. During this time Apollo 5 took place, an uncrewed launch to test the first lunar module (LM-1). Under the new schedule, the first Apollo crewed mission to go into space would be Apollo 7, planned for October 1968. This mission, which was to test the block II command module, did not include a lunar module. In 1967, NASA had adopted a series of lettered missions leading up to the crewed lunar landing, the "G mission", completion of one being a prerequisite to the next. Apollo7 would be the "Cmission", but the "Dmission" required testing of the crewed lunar module, which was running behind schedule and endangering John F. Kennedy's goal of Americans walking on the Moon and returning safely to Earth by the end of the 1960s. McDivitt's crew had been announced by NASA in November 1967 as prime crew for the Dmission, lengthy testing of the command and lunar modules in Earth orbit.
Seeking to keep Kennedy's goal on schedule, in August 1968, Apollo Program Manager George M. Low proposed that if Apollo7 in October went well, Apollo8 would go to lunar orbit without a LM. Until then, Apollo8 was the Dmission with Apollo9 the "E mission", testing in medium Earth orbit. After NASA approved sending Apollo8 to the Moon, while making Apollo9 the Dmission, Slayton offered McDivitt the opportunity to stay with Apollo8 and thus go to lunar orbit. McDivitt turned it down on behalf of his crew, preferring to stay with the Dmission, now Apollo9. Apollo7 went well, and the crews were switched. The crew swap also affected who would be the first astronauts to land on the Moon, for when the crews for Apollo8 and9 were swapped, so were the backup crews. Since the rule of thumb was for backup crews to fly as prime crew three missions later, this put Neil Armstrong's crew (Borman's backup) in position to make the first landing attempt on Apollo 11 instead of Pete Conrad's crew, who made the second landing on Apollo 12.
Framework. Crew and key Mission Control personnel. McDivitt was in the Air Force; selected as a member of the second group of astronauts in 1962, he was command pilot of Gemini 4 (1965). Scott, also Air Force, was selected in the third astronaut group in 1963 and flew alongside Neil Armstrong in Gemini 8, on which the first spacecraft docking was performed. Schweickart, a civilian who had served in the Air Force and Massachusetts Air National Guard, was selected as a Group3 astronaut but was not assigned to a Gemini mission and had no spaceflight experience. The backup crew consisted of Pete Conrad as commander, Command Module Pilot Richard F. Gordon Jr., and Lunar Module Pilot Alan L. Bean. This crew flew as prime on Apollo 12 in November 1969. The support crew for Apollo9 consisted of Stuart A. Roosa, Jack R. Lousma, Edgar D. Mitchell and Alfred M. Worden. Lousma was not an original member of the Apollo9 support crew, but was assigned after Fred W. Haise Jr. was moved to the position of backup lunar module pilot on Apollo 8—several astronauts were shifted in the wake of Michael Collins being removed from the Apollo8 prime crew because of treatment for bone spurs.
The flight directors were Gene Kranz, first shift, Gerry Griffin, second shift, and Pete Frank, third shift. Capsule communicators were Conrad, Gordon, Bean, Worden, Roosa and Ronald Evans. Mission insignia. The circular patch shows a drawing of a Saturn V rocket with the letters USA on it. To its right, an Apollo CSM is shown next to a LM, with the CSM's nose pointed at the "front door" of the LM rather than at its top docking port. The CSM is trailing rocket fire in a circle. The crew's names are along the top edge of the circle, with APOLLO IX at the bottom. The "D" in McDivitt's name is filled with red to mark that this was the "Dmission" in the alphabetic sequence of Apollo missions. The patch was designed by Allen Stevens of Rockwell International. Planning and training. Apollo 9's main purpose was to qualify the LM for crewed lunar flight, demonstrating that it could perform the maneuvers in space that would be needed for a lunar landing, including docking with the CSM. Colin Burgess and Francis French, in their book about the Apollo Program, deemed McDivitt's crew among the best trained ever—they had worked together since January 1966, at first as backups for Apollo 1, and they always had the assignment of being the first to fly the LM. Flight Director Gene Kranz deemed the Apollo9 crew the best prepared for their mission, and felt Scott was an extremely knowledgeable CMP. Crew members underwent 1,800 hours of mission-specific training, about seven hours for every hour they would spend in flight. Their training started on the day before the Apollo1 fire, in the very first Block II spacecraft in which they were originally intended to fly. They took part in the vehicle checkouts for the CSM at North American Rockwell's facility in Downey, California, and for the LM at Grumman's plant in Bethpage, New York. They also participated in testing of the modules at the launch site.
Among the types of the training which the crew underwent were simulations of zero-G, both underwater and in the Vomit Comet. During these exercises, they practiced for the planned extravehicular activities (EVAs). They traveled to Cambridge, Massachusetts, for training on the Apollo Guidance Computer (AGC) at MIT. The crew studied the sky at the Morehead Planetarium and at the Griffith Planetarium, especially focusing on the 37 stars used by the AGC. They each spent more than 300 hours in the CM and LM simulators at Kennedy Space Center (KSC) and at Houston, some involving live participation by Mission Control. Additional time was spent in simulators in other locations. The first mission to use the CSM, the LM and a SaturnV, Apollo9 allowed the launch preparations team at KSC its first opportunity to simulate the launch of a lunar landing mission. The LM arrived from Grumman in June 1968 and was subjected to extensive testing including in the altitude chamber, simulating space conditions. As this occurred, other technicians assembled the SaturnV inside the Vehicle Assembly Building (VAB). The CM and SM arrived in October, but even the experienced KSC team from North American had trouble joining them together. When the lander was done with the altitude chamber, the CSM took its place, letting the LM be available for installation of equipment such as rendezvous radar and antennas. There were no lengthy delays, and on January 3, 1969, the launch vehicle was taken out of the VAB and moved to Launch Complex 39A by crawler. Flight readiness reviews for the CM, the LM, and the SaturnV were held and passed in the following weeks.
Hardware. Launch vehicle. The Saturn V (AS-504) used on Apollo9 was the fourth to be flown, the second to carry astronauts to space, and the first to bear a lunar module. Although similar in configuration to the SaturnV used on Apollo 8, several changes were made. The inner core of the F-1 engine chamber in the first (S-IC) stage was removed, thus saving weight and allowing for a slight increase in specific impulse. Weight was also saved by replacing the skins of the liquid oxygen tanks with lighter ones, and by providing lighter versions of other components. Efficiency was increased in the S-II second stage with uprated J-2 engines, and through a closed-loop propellant utilization system rather than Apollo 8's open-loop system. Of the weight reduction in the second stage, about half came from a 16 percent reduction in the thickness of the tank side walls. Spacecraft, equipment and call signs. Apollo9 used CSM-104, the third Block II CSM to be flown with astronauts aboard. Apollo 8, lacking a lunar module, did not have docking equipment; Apollo9 flew the probe-and-drogue assembly used for docking along with other equipment added near the forward hatch of the CM; this allowed for rigid docking of the two craft, and for internal transfer between CM and LM. Had the switch in missions between Apollo8 and9 not occurred, the Earth-orbit mission would have flown CSM-103, which flew on Apollo 8.
The Earth-orbit mission was originally supposed to use LM-2 as its lunar module, but the crew found numerous flaws in it, many associated with it being the first flight-ready lunar module off Grumman's production line. The delay occasioned by the switch in missions allowed LM-3 to be available, a machine the crew found far superior. Neither LM-2 nor LM-3 could have been sent to the Moon as both were too heavy; Grumman's weight reduction program for the LMs only became fully effective with LM-5, designated for Apollo 11. Small cracks in LM-3's aluminum alloy structure due to stresses such as the insertion of a rivet proved an ongoing issue; Grumman's engineers continued working to fix them until the LM had to be mounted on the SaturnV in December 1968, where it was housed inside the Spacecraft-Lunar Module Adapter, numbered as SLA-11A. LM-2 never flew in space and is in the National Air and Space Museum. The Apollo astronauts were provided with early versions of the Sony Walkman, portable cassette recorders intended to allow them to make observations during the mission. The Apollo9 crew was the first to be allowed to bring music mixtapes, one each, that could be played in that device. McDivitt and Scott preferred easy listening and country music; Schweickart's cassette tape of classical music went missing until the ninth day of the ten-day mission, when it was presented to him by Scott.
After the Gemini 3 craft was dubbed "Molly Brown" by Grissom, NASA forbade naming spacecraft. The fact that during the Apollo9 mission, the CSM and LM would separate and need different call signs caused the Apollo9 astronauts to push for a change. In simulations, they began to refer to the CSM as "Gumdrop", a name inspired by the CM's appearance while in the blue protective wrapping in which it was transported from the manufacturer, and the LM as "Spider", inspired by the LM's appearance with landing legs deployed. Personnel in NASA public relations thought the names were too informal, but the call signs ultimately gained official sanction. NASA required more formal call signs for future missions, starting with Apollo 11. Life Support System backpack. The Extravehicular Mobility Unit (EMU) backpack flew for the first time on Apollo9, used by Schweickart during his EVA. This included the Portable Life Support System (PLSS), providing oxygen to the astronaut and water for the Liquid Cooling Garment (LCG), which helped prevent overheating during extravehicular activity. Also present was the Oxygen Purge System (OPS), the "bedroll" atop the backpack, which could provide oxygen for up to roughly an hour if the PLSS failed. A more advanced version of the EMU was used for the lunar landing on Apollo 11.
During his stand-up EVA, Scott did not wear a PLSS, but was connected to the CM's life support systems through an umbilical, utilizing a Pressure Control Valve (PCV). This device had been created in 1967 to allow for stand-up EVAs from the hatches of the LM or CM, or for brief ventures outside. It was later used by Scott for his lunar surface stand-up EVA on Apollo 15, and for the deep-space EVAs by the command module pilots of the final three Apollo flights. Mission highlights. First through fifth days (March 3–7). Originally scheduled to launch on February 28, 1969, the liftoff of Apollo9 was postponed because all three astronauts had colds, and NASA did not want to risk that the mission might be affected. Around-the-clock labor shifts were required to keep the spacecraft in readiness; the delay cost $500,000. The rocket launched from KSC at 11:00:00 EST (16:00:00 GMT) on March 3. This was well within the launch window, which would have remained open for another three and a quarter hours. Present in the firing control room was Vice President Spiro Agnew on behalf of the new Nixon administration.
McDivitt reported a smooth ride during the launch, although there was some vibration and the astronauts were surprised to be pushed forward when the Saturn V's first stage stopped firing, before its second stage took over, when they were pushed back into their couches. Each of the first two stages slightly underperformed; a deficiency made up, more or less, by the S-IVB third stage. Once the third stage cut out at 00:11:04.7 into the mission, Apollo9 had entered a parking orbit of . The crew began their first major orbital task with the separation of the CSM from the S-IVB at 02:41:16 into the mission, seeking to turn around and then dock with the LM, which was on the end of the S-IVB, after which the combined spacecraft would separate from the rocket. If it was not possible to make such a docking, the lunar landing could not take place. It was Scott's responsibility to fly the CSM, which he did to a successful docking, as the probe-and-drogue docking assembly worked properly. After McDivitt and Schweickart inspected the tunnel connecting the CM and LM, the assembled spacecraft separated from the S-IVB. The next task was to demonstrate that two docked spacecraft could be maneuvered by one engine. The five-second burn took place at 05:59.01.1 into the mission, accomplished with the SM's Service Propulsion System (SPS), after which Scott excitedly reported the LM was still in place. Thereafter, the S-IVB was fired again, and the stage was sent into solar orbit.
From 09:00:00 to 19:30:00, a sleep period was scheduled. The astronauts slept well, but complained of being woken by non-English transmissions. Scott theorized that they were possibly in Chinese. The highlight of the second day in orbit (March 4) was three SPS burns. The initial burn, at 22:12:04.1, lasted 110 seconds, and including swiveling or "gimbaling" the engine to test whether the autopilot could dampen the induced oscillations, which it did within five seconds. Two more SPS burns followed, lightening the SM's fuel load. The spacecraft and engine passed every test, sometimes proving more robust than expected. The performance of the CSM in remaining stable while the engine was being gimbaled would in 1972 help cause McDivitt, by then manager of the Apollo Spacecraft Program, to approve the continuation of Apollo 16 when its CSM was experiencing an unstable gimbal after separation from its LM in lunar orbit.
In the LM, Schweickart vomited again, causing McDivitt to request a private channel to the doctors in Houston. The first episode had not been reported to the ground because of its brief nature, and when the media learned what had happened to Schweickart, there were "repercussions and a spate of unfriendly stories". They finished the LM checkout, including the successful firing of the descent engine, and returned to Scott in "Gumdrop". The burn lasted 367 seconds and simulated the throttle pattern to be used during the landing on the Moon. After they returned, a fifth firing of the SPS was made, designed to circularize Apollo9's orbit in preparation for the rendezvous. This took place at 54:26:12.3, raising the craft's orbit to . The fourth day's program (March 6) was for Schweickart to exit the hatch on the LM and make his way along the outside of the spacecraft to the CM's hatch, where Scott would stand by to assist, demonstrating that this could be done in the event of an emergency. Schweickart was to wear the life support backpack, or PLSS, to be worn on the lunar surface EVAs. This was the only EVA scheduled before the lunar landing, and thus the only opportunity to test the PLSS in space. McDivitt initially canceled the EVA due to Schweickart's condition, but with the lunar module pilot feeling better, decided to allow him to exit the LM, and once he was there, to move around the LM's exterior using handholds. Scott stood in the CM's hatch; both men photographed each other and retrieved experiments from the exterior of their vehicles. Schweickart found moving around easier than it had been in simulations; both he and Scott were confident that Schweickart could have completed the exterior transfer if called upon to do so, but considered it unnecessary. During the EVA, Schweickart used the call sign "Red Rover", a nod to the color of his hair.
On March 7, the fifth day, came "the key event of the entire mission: the separation and rendezvous of the lunar module and the command module". The lunar module lacked the capability to return the astronauts to Earth; this was the first time space travelers had flown in a vehicle that could not take them home. McDivitt and Schweickart entered the LM early, having obtained permission to do so without wearing their helmets and gloves, making it easier to set up the LM. When Scott in "Gumdrop" pushed the button to release the LM, it initially hung on the latches at the end of the docking probe, but he hit the button again and "Spider" was released. After spending about 45 minutes near "Gumdrop", "Spider" went into a slightly higher orbit, meaning that over time, the two craft would separate, with "Gumdrop" ahead. Over the next hours, McDivitt fired the LM's descent engine at several throttle settings; by the end of the day the LM was thoroughly test-flown. At a distance of , "Spider" fired to lower its orbit and thus begin to catch up with "Gumdrop", a process that would take over two hours, and the descent stage was jettisoned.
The approach and rendezvous were conducted as near as possible to what was planned for the lunar missions. To demonstrate that rendezvous could be performed by either craft, "Spider" was the active party during the maneuver. McDivitt brought "Spider" close to "Gumdrop", then maneuvered the LM to show each side to Scott, allowing him to inspect for any damage. Then, McDivitt docked the craft. Due to glare from the Sun, he had trouble doing this and Scott guided him in. During the later missions, the job of docking the two spacecraft in lunar orbit would fall to the command module pilot. After McDivitt and Schweickart returned to "Gumdrop", "Spider" was jettisoned, its engine fired to fuel depletion remotely by Mission Control as part of further testing of the engine, simulating an ascent stage's climb from the lunar surface. This raised "Spider" to an orbit with apogee of over . The only major lunar module system not fully tested was the landing radar, as this could not be done in Earth orbit. Sixth through eleventh days (March 8–13).
Apollo 9 was to remain in space for about ten days to check how the CSM would perform over the period of time required for a lunar mission. Most major events had been scheduled for the first days so that they would be accomplished if the flight needed to be ended early. The remaining days in orbit were to be conducted at a more leisurely pace. With the main goals of the mission accomplished, the hatch window was used for special photography of Earth, using four identical Hasselblad cameras, coupled together and using film sensitive to different parts of the electromagnetic spectrum. Such photography allowed different features of the Earth's surface to appear, for example, tracking of water pollution as it exits mouths of rivers into the sea, and the highlighting of agricultural areas using infrared. The camera system was a prototype, and would pave the way for the Earth Resources Technology Satellite, predecessor to the Landsat series. The photography was successful, as the ample time in orbit meant the crew could wait to allow cloud cover to pass, and would inform Skylab's mission planning.
Scott used a sextant to track landmarks on the Earth, and turned the instrument to the skies to observe the planet Jupiter, practicing navigation techniques that were to be used on later missions. The crew was able to track the Pegasus 3 satellite (launched in 1965) as well as the ascent stage of "Spider". The sixth burn of the SPS engine took place on the sixth day, though it was postponed one orbit as the reaction control system (RCS) thruster burn needed to settle the reactants in their tanks was not properly programmed. The SPS burn lowered the perigee of Apollo9's orbit, allowing for improved RCS thruster deorbit capability as a backup to the SPS. Considerable testing of the CSM took place, but this was principally Scott's responsibility, allowing McDivitt and Schweickart leisure to observe the Earth; they alerted Scott if anything particularly noteworthy was upcoming, letting him leave his work for a moment to look at Earth too. The seventh burn of the SPS system took place on the eighth day, March 10; its purpose was again to aid RCS deorbit capability, as well as extending "Gumdrop" orbital lifetime.
The seventh burn of the SPS system took place on the eighth day, March 10; its purpose was again to aid RCS deorbit capability, as well as extending "Gumdrop" orbital lifetime. It shifted the apogee of the orbit to the Southern Hemisphere, allowing for a longer free-fall time to entry when Apollo9 returned to Earth. The burn was extended to allow for testing of the propellent gaging system, which had been behaving anomalously during earlier SPS burns. Once it was accomplished, Apollo9's RCS thrusters could have returned it to Earth and still allowed it to land in the primary recovery zone had the SPS engine failed. The eighth and final SPS burn, to return the vehicle to Earth, was accomplished on March 13, less than an hour after the ten-day mark of the mission, after which the service module was jettisoned. The landing was delayed one orbit because of unfavorable weather in the primary landing zone some ESE of Bermuda. Instead, Apollo9 splashed down east of the Bahamas, about from the recovery carrier, the USS "Guadalcanal", after a mission lasting 10 days, 1hour, 54 seconds. Instead, Apollo9 splashed down east of the Bahamas, about from the recovery carrier, the USS "Guadalcanal", after a mission lasting 10 days, 1hour, 54 seconds. Apollo9 was the last spacecraft to splash down in the Atlantic Ocean for a half century, until the Crew Dragon Demo-1 mission in 2019, and last crewed splashdown in the Atlantic until Inspiration4 in 2021.
Hardware disposition. The Apollo9 Command Module "Gumdrop" (1969-018A) is on display at the San Diego Air & Space Museum. "Gumdrop" was formerly displayed at the Michigan Space and Science Center, Jackson, Michigan, until April 2004, when the center closed. The service module, jettisoned shortly after the deorbit burn, reentered the atmosphere and disintegrated. The ascent stage of LM-3 "Spider" (1969-018C) reentered on October 23, 1981. The descent stage of LM-3 "Spider" (1969-018D) reentered on March 22, 1969, landing in the Indian Ocean near North Africa. The S-IVB (1969-018B) was sent into solar orbit, with initial aphelion of , perihelion of and orbital period of 245 days. It remains in solar orbit . Appraisal and aftermath. As NASA Associate Administrator George Mueller put it, "Apollo9 was as successful a flight as any of us could ever wish for, as well as being as successful as any of us have ever seen." Gene Kranz called Apollo9 "sheer exhilaration". Apollo Program Director Samuel C. Phillips stated, "in every way, it has exceeded even our most optimistic expectations." Apollo11 astronaut Buzz Aldrin stood in Mission Control as "Spider" and "Gumdrop" docked after their separate flights, and with the docking, according to Andrew Chaikin, "Apollo9 had fulfilled all its major objectives. At that moment, Aldrin knew Apollo10 would also succeed, and that he and Armstrong would attempt to land on the Moon. On March 24, NASA made it official."
Although he might have been offered command of an Apollo lunar landing mission, McDivitt chose to leave the Astronaut Corps after Apollo9, becoming manager of the Apollo Spacecraft Program later in 1969. Scott was soon given another spaceflight assignment as backup commander of Apollo 12, and then was made mission commander of Apollo 15, landing on the Moon in 1971. Schweickart volunteered for medical investigation of his spacesickness, but was unable to shake its stigma, and was never again assigned to a prime crew. He took a leave of absence from NASA in 1977 that eventually became permanent. Eugene Cernan, commander of Apollo 17, stated that when it came to understanding spacesickness, Schweickart "paid the price for them all". Following the success of Apollo 9, NASA did not conduct the "E mission" (further testing in medium Earth orbit), and even considered skipping the "F mission", the dress rehearsal for the lunar landing, going straight to the landing attempt. As the spacecraft designated for the first landing attempt were still being assembled, this was not done. NASA officials also felt that given the past difficulties with the LM, there was a need for a further test flight before the actual landing attempt, and that orbiting the Moon would give them the opportunity to study mass concentrations there, which had affected Apollo8's orbit. According to French and Burgess in their study of the Apollo program, "Apollo9's success had ensured that the next Apollo mission would go back to the moon."
Arthritis Arthritis is a general medical term used to describe a disorder that affects joints. Symptoms generally include joint pain and stiffness. Other symptoms may include redness, warmth, swelling, and decreased range of motion of the affected joints. In certain types of arthritis, other organs such as the skin are also affected. Onset can be gradual or sudden. There are several types of arthritis. The most common forms are osteoarthritis (most commonly seen in weightbearing joints) and rheumatoid arthritis. Osteoarthritis usually occurs as an individual ages and often affects the hips, knees, shoulders, and fingers. Rheumatoid arthritis is an autoimmune disorder that often affects the hands and feet. Other types of arthritis include gout, lupus, and septic arthritis. These are inflammatory based types of rheumatic disease. Early treatment for arthritis commonly includes resting the affected joint and conservative measures such as heating or icing. Weight loss and exercise may also be useful to reduce the force across a weightbearing joint. Medication intervention for symptoms depends on the form of arthritis. These may include anti-inflammatory medications such as ibuprofen and paracetamol (acetaminophen). With severe cases of arthritis, joint replacement surgery may be necessary.
Osteoarthritis is the most common form of arthritis affecting more than 3.8% of people, while rheumatoid arthritis is the second most common affecting about 0.24% of people. In Australia about 15% of people are affected by arthritis, while in the United States more than 20% have a type of arthritis. Overall arthritis becomes more common with age. Arthritis is a common reason people are unable to carry out their work and can result in decreased ability to complete activities of daily living. The term arthritis is derived from "arthr-" (meaning 'joint') and "-itis" (meaning 'inflammation'). Classification. There are several diseases where joint pain is the most prominent symptom. Generally when a person has "arthritis" it means that they have one of the following diseases: Joint pain can also be a symptom of other diseases. In this case, the person may not have arthritis and instead have one of the following diseases: An "undifferentiated arthritis" is an arthritis that does not fit into well-known clinical disease categories, possibly being an early stage of a definite rheumatic disease.
Signs and symptoms. Pain in varying severity is a common symptom in most types of arthritis. Other symptoms include swelling, joint stiffness, redness, and aching around the joint(s). Arthritic disorders like lupus and rheumatoid arthritis can affect other organs in the body, leading to a variety of symptoms including: Causes. Several factors contribute to the development of arthritis, differing on the type of arthritis. Osteoarthritis occurs from damage to joint cartilage from prior injury or long-term wear-and-tear, resulting in bone-to-bone contact and grinding. The resulting arthritis can occur over years, or be worsened by further injury or infection. If joint cartilage is severely damaged, inflammation and swelling may add to the extent and pain of osteoarthritis. In rheumatoid arthritis, the immune system itself, which normally serves to protect against infection and diseases, attacks the lining of the joint capsule, causing inflammation and swelling. Gout is a form of arthritis caused by excessive uric acid production, resulting in urate crystals depositing in joints, particularly in extremities, such as toes. Urate levels in the blood may increase from consuming purine-rich foods or from body factors affecting urate clearance from the blood, a topic remaining under study.
Arthritis types may also include ankylosing spondylitis, juvenile idiopathic arthritis, psoriatic arthritis, and reactive arthritis, among others. Risk factors. There are common risk factors that increase a person's chance of developing arthritis later in adulthood. Some of these are modifiable while others are not. Some common risk factors that can increase the chances of developing osteoarthritis include obesity, prior injury to the joint, type of joint, and muscle strength. The risk factors with the strongest association for developing inflammatory arthritis (such as rheumatoid arthritis and lupus arthritis) are the female sex, a family history, age, obesity, joint damage from a previous injury, and exposure to tobacco smoke. Smoking has been linked to an increased susceptibility of developing arthritis, particularly rheumatoid arthritis. Diagnosis. Diagnosis is made by clinical examination from an appropriate health professional, and may be supported by tests such as radiologic imaging and blood tests, depending on the type of suspected arthritis. Pain patterns may vary depending on the type of arthritis and the location. Rheumatoid arthritis is generally worse in the morning and associated with stiffness lasting over 30 minutes. On the other hand, with osteoarthritis, the pain tends to initially be related to activity and then becomes more constant over time.
Important features to look out for include the following: Physical examination may include observing the affected joints, evaluating gait, and examining the skin for findings that could be related to rheumatological disease or pulmonary inflammation. Physical examination may confirm the diagnosis or may indicate systemic disease. Chest radiographs are often used to follow progression or help assess severity. Screening blood tests for suspected arthritis include: rheumatoid factor, antinuclear factor (ANF), extractable nuclear antigen, and specific antibodies. Rheumatoid arthritis patients often have elevated erythrocyte sedimentation rate (ESR, also known as sed rate) or C-reactive protein (CRP) levels, which indicates the presence of an inflammatory process in the body. Anti-cyclic citrullinated peptide (anti-CCP) antibodies and rheumatoid factor (RF) are two more common blood tests when assessing for rheumatoid arthritis. Imaging tests like X-rays are commonly utilized to diagnose and monitor arthritis. Other imaging tests for rheumatoid arthritis that may be considered include computed tomography (CT) scanning, positron emission tomography (PET) scanning, bone scanning, and dual-energy X-ray absorptiometry (DEXA).
Osteoarthritis. Osteoarthritis (OA) is the most common form of arthritis. It affects humans and other animals, notably dogs, but also occurs in cats and horses. It can affect both the larger (ie. knee, hip, shoulder, etc.) and the smaller joints (ie. fingers, toes, foot, etc.) of the body. The disease is caused by daily wear and tear of the joint. This process can progress more rapidly as a result of injury to the joint. Osteoarthritis is caused by the break down of the smooth surface between two bones, known as cartilage, which can eventually lead to the two opposing bones coming in direct contact and eroding one another. OA symptoms typically begin with minor pain during physical activity, but can eventually progress to be present at rest. The pain can be debilitating and prevent one from doing activities that they would normally do as part of their daily routine. OA typically affects the weight-bearing joints, such as the back, knee and hip due to the mechanical nature of this disease process. Unlike rheumatoid arthritis, osteoarthritis is most commonly a disease of the elderly. The strongest predictor of osteoarthritis is increased age, likely due to the declining ability of chondrocytes to maintain the structural integrity of cartilage. More than 30 percent of women have some degree of osteoarthritis by age 65. One of the primary tools for diagnosing OA are X-rays of the joint. Findings on X-ray that are consistent with OA include those with joint space narrowing (due to cartilage breakdown), bone spurs, sclerosis, and bone cysts.
Rheumatoid arthritis. Rheumatoid arthritis (RA) is a disorder in which the body's own immune system starts to attack body tissues specifically the cartilage at the end of bones known as articular cartilage. The attack is not only directed at the joint but to many other parts of the body. RA often affects joints in the fingers, wrists, knees and elbows, is symmetrical (appears on both sides of the body), and can lead to severe progressive deformity in a matter of years if not adequately treated. RA usually onsets earlier in life than OA and commonly effects people aged 20 and above. In children, the disorder can present with a skin rash, fever, pain, disability, and limitations in daily activities. With earlier diagnosis and appropriate aggressive treatment, many individuals can obtain control of their symptoms leading to a better quality of life compared to those without treatment. One of the main triggers of bone erosion in the joints in rheumatoid arthritis is inflammation of the synovium (lining of the joint capsule), caused in part by the production of pro-inflammatory cytokines and receptor activator of nuclear factor kappa B ligand (RANKL), a cell surface protein present in Th17 cells and osteoblasts. Osteoclast activity can be directly induced by osteoblasts through the RANK/RANKL mechanism.
Lupus. Lupus is an autoimmune collagen vascular disorder that can be present with severe arthritis. In fact, about 90% of patients with Lupus have musculoskeletal involvement. Symptoms in these patients can often mimic those of rheumatoid arthritis with similar stiffness and pain patterns. Joints in the fingers, wrist, and knee tend to be the most affected. Other features commonly seen in patients with Lupus include a skin rash (pictured on the right), extreme photosensitivity, hair loss, kidney problems, and shortness of breath secondary to scarring that occurs in the lungs. Gout. In the early stages of gout, usually only one joint is affected; however over time, many joints can become affected. Gout most commonly occurs in joints located in the big toe, knee, and/or fingers. During a gout flare, the affected joints often become swollen with associated warmth and redness. The resulting pain can be significant and potentially debilitating. When one of these flares occurs, management involves the use of anti-inflammatories, such as NSAIDs, colchicine, or glucocorticoids. In between gout flares, it is recommended that patients take medications that decrease the production of uric acid (i.e. allopurinol, febuxostat) or increase the elimination of uric acid from the body (i.e. probenecid).
Gout has been associated with excessive intake of alcohol and food, such as red meat. Thus, it is also recommended that patients with gout adhere to a diet rich in fiber, vegetables, and whole grains, while limiting the intake of alcohol and fatty foods. There is also an uncommon form of gout that is known as pseudogout, which is caused by the formation of calcium pyrophosphate crystals in the joint. Unlike gout, no targeted treatments are currently available. At this time, management is aimed at decreasing inflammation in order to reduce the intensity and frequency of flares. Other. Infectious arthritis is another severe form of arthritis that is sometimes referred to as septic arthritis. It typically occurs when a patient is ill or has an infection. Common symptoms include the sudden onset of chills, fever, and joint pain. The condition is caused by bacteria that spread through the blood stream from elsewhere in the body. This bacteria can travel to specific joints and start to erode cartilage. Infectious arthritis must be rapidly diagnosed and treated promptly in order to prevent irreversible joint damage. Only about 1% of cases of infectious arthritis are a result of viruses. Within recent years, the virus SARS-CoV-2, which causes Covid-19, has been added to this list. SARS-CoV-2 tends to cause reactive arthritis rather than local septic arthritis.
Psoriasis can develop into psoriatic arthritis. With psoriatic arthritis, most individuals first develop skin symptoms (such as scaly patches and itchiness) and then begin to experience joint related symptoms. They typically experience continuous joint pain, stiffness and swelling like other forms of arthritis. This disease can go into remission, but there is currently no known cure for the disorder. Treatment current revolves around decreasing autoimmune attacks with immune suppressive medications. A small percentage of patients with psoriatic arthritis can develop a severely painful and destructive form of arthritis which destroys the small joints in the hands and sometimes lead to permanent disability and loss of hand function. Treatment. There is no known cure for arthritis and rheumatic diseases. Treatment options vary depending on the type of arthritis and include physical therapy, exercise and diet, orthopedic bracing, and oral and topical medications. Joint replacement surgery may be required to repair damage, restore function, or relieve pain.
Physical therapy. In general, studies have shown that physical exercise of the affected joint can noticeably improve long-term pain relief. Furthermore, exercise of the arthritic joint is encouraged to maintain the health of the particular joint and the overall body of the person. Individuals with arthritis can benefit from both physical and occupational therapy. In arthritis the joints become stiff and the range of movement can be limited. Physical therapy has been shown to significantly improve function, decrease pain, and delay the need for surgical intervention in advanced cases. Exercise prescribed by a physical therapist has been shown to be more effective than medications in treating osteoarthritis of the knee. Exercise often focuses on improving muscle strength, endurance and flexibility. In some cases, exercises may be designed to train balance. Occupational therapy can provide assistance with activities. Assistive technology is a tool used to aid a person's disability by reducing their physical barriers by improving the use of their damaged body part, typically after an amputation. Assistive technology devices can be customized to the patient or bought commercially.
Medications. There are several types of medications that are used for the treatment of arthritis. Treatment typically begins with medications that have the fewest side effects with further medications being added if insufficiently effective. Depending on the type of arthritis, the medications that are given may be different. For example, the first-line treatment for osteoarthritis is acetaminophen (paracetamol) while for inflammatory arthritis it involves non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen. Opioids and NSAIDs may be less well tolerated. However, topical NSAIDs may have better safety profiles than oral NSAIDs. For more severe cases of osteoarthritis, intra-articular corticosteroid injections may also be considered. The drugs to treat rheumatoid arthritis (RA) range from corticosteroids to monoclonal antibodies given intravenously. Due to the autoimmune nature of RA, treatments may include not only pain medications and anti-inflammatory drugs, but also another category of drugs called disease-modifying antirheumatic drugs (DMARDs). csDMARDs, TNF biologics and tsDMARDs are specific kinds of DMARDs that are recommended for treatment. Treatment with DMARDs is designed to slow down the progression of RA by initiating an adaptive immune response, in part by CD4+ T helper (Th) cells, specifically Th17 cells. Th17 cells are present in higher quantities at the site of bone destruction in joints and produce inflammatory cytokines associated with inflammation, such as interleukin-17 (IL-17).
Surgery. A number of surgical interventions have been incorporated in the treatment of arthritis since the 1950s. The primary surgical treatment option of arthritis is joint replacement surgery known as arthroplasty. Common joints that are replaced due to arthritis include the shoulder, hip, and knee. Arthroscopic surgery for osteoarthritis of the knee provides no additional benefit to patients when compared to optimized physical and medical therapy. Joint replacement surgery can last anywhere from 15-30 years depending on the patient. Following joint replacement surgery, patients can expect to get back to several physical activities including those such as swimming, tennis, and golf. Adaptive aids. People with hand arthritis can have trouble with simple activities of daily living tasks (ADLs), such as turning a key in a lock or opening jars, as these activities can be cumbersome and painful. There are adaptive aids or assistive devices (ADs) available to help with these tasks, but they are generally more costly than conventional products with the same function. It is now possible to 3-D print adaptive aids, which have been released as open source hardware to reduce patient costs. Adaptive aids can significantly help arthritis patients and the vast majority of those with arthritis need and use them.
Alternative medicine. Further research is required to determine if transcutaneous electrical nerve stimulation (TENS) for knee osteoarthritis is effective for controlling pain. Low level laser therapy may be considered for relief of pain and stiffness associated with arthritis. Evidence of benefit is tentative. Pulsed electromagnetic field therapy (PEMFT) has tentative evidence supporting improved functioning but no evidence of improved pain in osteoarthritis. The FDA has not approved PEMFT for the treatment of arthritis. In Canada, PEMF devices are legally licensed by Health Canada for the treatment of pain associated with arthritic conditions. Epidemiology. Arthritis is predominantly a disease of the elderly, but children can also be affected by the disease. Arthritis is more common in women than men at all ages and affects all races, ethnic groups and cultures. In the United States, a CDC survey based on data from 2013 to 2015 showed 54.4 million (22.7%) adults had self-reported doctor-diagnosed arthritis, and 23.7 million (43.5% of those with arthritis) had arthritis-attributable activity limitation (AAAL). With an aging population, this number is expected to increase. Adults with co-morbid conditions, such as heart disease, diabetes, and obesity, were seen to have a higher than average prevalence of doctor-diagnosed arthritis (49.3%, 47.1%, and 30.6% respectively).
Disability due to musculoskeletal disorders increased by 45% from 1990 to 2010. Of these, osteoarthritis is the fastest increasing major health condition. Among the many reports on the increased prevalence of musculoskeletal conditions, data from Africa are lacking and underestimated. A systematic review assessed the prevalence of arthritis in Africa and included twenty population-based and seven hospital-based studies. The majority of studies, twelve, were from South Africa. Nine studies were well-conducted, eleven studies were of moderate quality, and seven studies were conducted poorly. The results of the systematic review were as follows: History. Evidence of osteoarthritis and potentially inflammatory arthritis has been discovered in dinosaurs. The first known traces of human arthritis date back as far as 4500 BC. In early reports, arthritis was frequently referred to as the most common ailment of prehistoric peoples. It was noted in skeletal remains of Native Americans found in Tennessee and parts of what is now Olathe, Kansas. Evidence of arthritis has been found throughout history, from Ötzi, a mummy () found along the border of modern Italy and Austria, to the Egyptian mummies .
In 1715, William Musgrave published the second edition of his most important medical work, "De arthritide symptomatica", which concerned arthritis and its effects. Augustin Jacob Landré-Beauvais, a 28-year-old resident physician at Salpêtrière Asylum in France was the first person to describe the symptoms of rheumatoid arthritis. Though Landré-Beauvais' classification of rheumatoid arthritis as a relative of gout was inaccurate, his dissertation encouraged others to further study the disease. John Charnley completed the first hip replacement (total hip arthroplasty) in England to treat arthritis in the 1960s. Society and culture. Arthritis is the most common cause of disability in the United States. More than 20 million individuals with arthritis in the United States have severe limitations in function on a daily basis. Absenteeism and frequent visits to the physician are common in individuals who have arthritis. Arthritis can make it difficult for individuals to be physically active and some become home bound. It is estimated that the total cost of arthritis cases is close to $100 billion of which almost 50% is from lost earnings. Terminology. The term is derived from "arthr-" (from ) and "-itis" (from , , ), the latter suffix having come to be associated with inflammation. The word "arthritides" is the plural form of arthritis, and denotes the collective group of arthritis-like conditions.
Acetylene Acetylene (systematic name: ethyne) is the chemical compound with the formula and structure . It is a hydrocarbon and the simplest alkyne. This colorless gas is widely used as a fuel and a chemical building block. It is unstable in its pure form and thus is usually handled as a solution. Pure acetylene is odorless, but commercial grades usually have a marked odor due to impurities such as divinyl sulfide and phosphine. As an alkyne, acetylene is unsaturated because its two carbon atoms are bonded together in a triple bond. The carbon–carbon triple bond places all four atoms in the same straight line, with CCH bond angles of 180°. Discovery. Acetylene was discovered in 1836 by Edmund Davy, who identified it as a "new carburet of hydrogen". It was an accidental discovery while attempting to isolate potassium metal. By heating potassium carbonate with carbon at very high temperatures, he produced a residue of what is now known as potassium carbide, (K2C2), which reacted with water to release the new gas. It was rediscovered in 1860 by French chemist Marcellin Berthelot, who coined the name "acétylène". Berthelot's empirical formula for acetylene (C4H2), as well as the alternative name "quadricarbure d'hydrogène" (hydrogen quadricarbide), were incorrect because many chemists at that time used the wrong atomic mass for carbon (6 instead of 12). Berthelot was able to prepare this gas by passing vapours of organic compounds (methanol, ethanol, etc.) through a red hot tube and collecting the effluent. He also found that acetylene was formed by sparking electricity through mixed cyanogen and hydrogen gases. Berthelot later obtained acetylene directly by passing hydrogen between the poles of a carbon arc.
Preparation. Partial combustion of hydrocarbons. Since the 1950s, acetylene has mainly been manufactured by the partial combustion of methane in the US, much of the EU, and many other countries: It is a recovered side product in production of ethylene by cracking of hydrocarbons. Approximately 400,000 tonnes were produced by this method in 1983. Its presence in ethylene is usually undesirable because of its explosive character and its ability to poison Ziegler–Natta catalysts. It is selectively hydrogenated into ethylene, usually using Pd–Ag catalysts. Dehydrogenation of alkanes. The heaviest alkanes in petroleum and natural gas are cracked into lighter molecules which are dehydrogenated at high temperature: This last reaction is implemented in the process of anaerobic decomposition of methane by microwave plasma. Carbochemical method. The first acetylene produced was by Edmund Davy in 1836, via potassium carbide. Acetylene was historically produced by hydrolysis (reaction with water) of calcium carbide: This reaction was discovered by Friedrich Wöhler in 1862, but a suitable commercial scale production method which allowed acetylene to be put into wider scale use was not found until 1892 by the Canadian inventor Thomas Willson while searching for a viable commercial production method for aluminum.
As late as the early 21st century, China, Japan, and Eastern Europe produced acetylene primarily by this method. The use of this technology has since declined worldwide with the notable exception of China, with its emphasis on coal-based chemical industry, as of 2013. Otherwise oil has increasingly supplanted coal as the chief source of reduced carbon. Calcium carbide production requires high temperatures, ~2000 °C, necessitating the use of an electric arc furnace. In the US, this process was an important part of the late-19th century revolution in chemistry enabled by the massive hydroelectric power project at Niagara Falls. Bonding. In terms of valence bond theory, in each carbon atom the 2s orbital hybridizes with one 2p orbital thus forming an sp hybrid. The other two 2p orbitals remain unhybridized. The two ends of the two sp hybrid orbital overlap to form a strong σ valence bond between the carbons, while on each of the other two ends hydrogen atoms attach also by σ bonds. The two unchanged 2p orbitals form a pair of weaker π bonds.
Since acetylene is a linear symmetrical molecule, it possesses the D∞h point group. Physical properties. Changes of state. At atmospheric pressure, acetylene cannot exist as a liquid and does not have a melting point. The triple point on the phase diagram corresponds to the melting point (−80.8 °C) at the minimal pressure at which liquid acetylene can exist (1.27 atm). At temperatures below the triple point, solid acetylene can change directly to the vapour (gas) by sublimation. The sublimation point at atmospheric pressure is −84.0 °C. Other. At room temperature, the solubility of acetylene in acetone is 27.9 g per kg. For the same amount of dimethylformamide (DMF), the solubility is 51 g. At 20.26 bar, the solubility increases to 689.0 and 628.0 g for acetone and DMF, respectively. These solvents are used in pressurized gas cylinders. Applications. Welding.
Chemicals. Acetylene is useful for many processes, but few are conducted on a commercial scale. One of the major chemical applications is ethynylation of formaldehyde. Acetylene adds to aldehydes and ketones to form α-ethynyl alcohols: The reaction gives butynediol, with propargyl alcohol as the by-product. Copper acetylide is used as the catalyst. In addition to ethynylation, acetylene reacts with carbon monoxide, acetylene reacts to give acrylic acid, or acrylic esters. Metal catalysts are required. These derivatives form products such as acrylic fibers, glasses, paints, resins, and polymers. Except in China, use of acetylene as a chemical feedstock has declined by 70% from 1965 to 2007 owing to cost and environmental considerations. In China, acetylene is a major precursor to vinyl chloride. Historical uses. Prior to the widespread use of petrochemicals, coal-derived acetylene was a building block for several industrial chemicals. Thus acetylene can be hydrated to give acetaldehyde, which in turn can be oxidized to acetic acid. Processes leading to acrylates were also commercialized. Almost all of these processes became obsolete with the availability of petroleum-derived ethylene and propylene.
Niche applications. In 1881, the Russian chemist Mikhail Kucherov described the hydration of acetylene to acetaldehyde using catalysts such as mercury(II) bromide. Before the advent of the Wacker process, this reaction was conducted on an industrial scale. The polymerization of acetylene with Ziegler–Natta catalysts produces polyacetylene films. Polyacetylene, a chain of CH centres with alternating single and double bonds, was one of the first discovered organic semiconductors. Its reaction with iodine produces a highly electrically conducting material. Although such materials are not useful, these discoveries led to the developments of organic semiconductors, as recognized by the Nobel Prize in Chemistry in 2000 to Alan J. Heeger, Alan G MacDiarmid, and Hideki Shirakawa. In the 1920s, pure acetylene was experimentally used as an inhalation anesthetic. Acetylene is sometimes used for carburization (that is, hardening) of steel when the object is too large to fit into a furnace. Acetylene is used to volatilize carbon in radiocarbon dating. The carbonaceous material in an archeological sample is treated with lithium metal in a small specialized research furnace to form lithium carbide (also known as lithium acetylide). The carbide can then be reacted with water, as usual, to form acetylene gas to feed into a mass spectrometer to measure the isotopic ratio of carbon-14 to carbon-12.
Acetylene combustion produces a strong, bright light and the ubiquity of carbide lamps drove much acetylene commercialization in the early 20th century. Common applications included coastal lighthouses, street lights, and automobile and mining headlamps. In most of these applications, direct combustion is a fire hazard, and so acetylene has been replaced, first by incandescent lighting and many years later by low-power/high-lumen LEDs. Nevertheless, acetylene lamps remain in limited use in remote or otherwise inaccessible areas and in countries with a weak or unreliable central electric grid. Natural occurrence. The energy richness of the C≡C triple bond and the rather high solubility of acetylene in water make it a suitable substrate for bacteria, provided an adequate source is available. A number of bacteria living on acetylene have been identified. The enzyme acetylene hydratase catalyzes the hydration of acetylene to give acetaldehyde: Acetylene is a moderately common chemical in the universe, often associated with the atmospheres of gas giants. One curious discovery of acetylene is on Enceladus, a moon of Saturn. Natural acetylene is believed to form from catalytic decomposition of long-chain hydrocarbons at temperatures of and above. Since such temperatures are highly unlikely on such a small distant body, this discovery is potentially suggestive of catalytic reactions within that moon, making it a promising site to search for prebiotic chemistry.
Reactions. Vinylation reactions. In vinylation reactions, H−X compounds add across the triple bond. Alcohols and phenols add to acetylene to give vinyl ethers. Thiols give vinyl thioethers. Similarly, vinylpyrrolidone and vinylcarbazole are produced industrially by vinylation of 2-pyrrolidone and carbazole. The hydration of acetylene is a vinylation reaction, but the resulting vinyl alcohol isomerizes to acetaldehyde. The reaction is catalyzed by mercury salts. This reaction once was the dominant technology for acetaldehyde production, but it has been displaced by the Wacker process, which affords acetaldehyde by oxidation of ethylene, a cheaper feedstock. A similar situation applies to the conversion of acetylene to the valuable vinyl chloride by hydrochlorination vs the oxychlorination of ethylene. Vinyl acetate is used instead of acetylene for some vinylations, which are more accurately described as transvinylations. Higher esters of vinyl acetate have been used in the synthesis of vinyl formate. Organometallic chemistry.
Acetylene and its derivatives (2-butyne, diphenylacetylene, etc.) form complexes with transition metals. Its bonding to the metal is somewhat similar to that of ethylene complexes. These complexes are intermediates in many catalytic reactions such as alkyne trimerisation to benzene, tetramerization to cyclooctatetraene, and carbonylation to hydroquinone: Metal acetylides, species of the formula , are also common. Copper(I) acetylide and silver acetylide can be formed in aqueous solutions with ease due to a favorable solubility equilibrium. Acid-base reactions. Acetylene has a p"K"a of 25, acetylene can be deprotonated by a superbase to form an acetylide: Various organometallic and inorganic reagents are effective. Hydrogenation. Acetylene can be semihydrogenated to ethylene, providing a feedstock for a variety of polyethylene plastics. Halogens add to the triple bond. Safety and handling.
Information on safe storage of acetylene in upright cylinders is provided by the OSHA, Compressed Gas Association, United States Mine Safety and Health Administration (MSHA), EIGA, and other agencies. Copper catalyses the decomposition of acetylene, and as a result acetylene should not be transported in copper pipes. Cylinders should be stored in an area segregated from oxidizers to avoid exacerbated reaction in case of fire/leakage. Acetylene cylinders should not be stored in confined spaces, enclosed vehicles, garages, and buildings, to avoid unintended leakage leading to explosive atmosphere. In the US, National Electric Code (NEC) requires consideration for hazardous areas including those where acetylene may be released during accidents or leaks. Consideration may include electrical classification and use of listed Group A electrical components in US. Further information on determining the areas requiring special consideration is in NFPA 497. In Europe, ATEX also requires consideration for hazardous areas where flammable gases may be released during accidents or leaks.
Arabic numerals The ten Arabic numerals (0, 1, 2, 3, 4, 5, 6, 7, 8, and 9) are the most commonly used symbols for writing numbers. The term often also implies a positional notation number with a decimal base, in particular when contrasted with Roman numerals. However the symbols are also used to write numbers in other bases, such as octal, as well as non-numerical information such as trademarks or license plate identifiers. They are also called Western Arabic numerals, Western digits, European digits, Ghubār numerals, or Hindu–Arabic numerals due to positional notation (but not these digits) originating in India. The "Oxford English Dictionary" uses lowercase "Arabic numerals" while using the fully capitalized term "Arabic Numerals" for Eastern Arabic numerals. In contemporary society, the terms "digits", "numbers", and "numerals" often implies only these symbols, although it can only be inferred from context. Europeans first learned of Arabic numerals , though their spread was a gradual process. After Italian scholar Fibonacci of Pisa encountered the numerals in the Algerian city of Béjaïa, his 13th-century work "" became crucial in making them known in Europe. However, their use was largely confined to Northern Italy until the invention of the printing press in the 15th century. European trade, books, and colonialism subsequently helped popularize the adoption of Arabic numerals around the world. The numerals are used worldwide—significantly beyond the contemporary spread of the Latin alphabet—and have become common in the writing systems where other numeral systems existed previously, such as Chinese and Japanese numerals.
History. Origin. Positional decimal notation including a zero symbol was developed in India, using symbols visually distinct from those that would eventually enter into international use. As the concept spread, the sets of symbols used in different regions diverged over time. The immediate ancestors of the digits now commonly called "Arabic numerals" were introduced to Europe in the 10th century by Arabic speakers of Spain and North Africa, with digits at the time in wide use from Libya to Morocco. In the east from Egypt to Iraq and the Arabian Peninsula, the Arabs were using the Eastern Arabic numerals or "Mashriki" numerals: ٠, ١, ٢, ٣, ٤, ٥, ٦, ٧, ٨, ٩. Al-Nasawi wrote in the early 11th century that mathematicians had not agreed on the form of the numerals, but most of them had agreed to train themselves with the forms now known as Eastern Arabic numerals. The oldest specimens of the written numerals available are from Egypt and date to 873–874 AD. They show three forms of the numeral "2" and two forms of the numeral "3", and these variations indicate the divergence between what later became known as the Eastern Arabic numerals and the Western Arabic numerals. The Western Arabic numerals came to be used in the Maghreb and Al-Andalus from the 10th century onward. Some amount of consistency in the Western Arabic numeral forms endured from the 10th century, found in a Latin manuscript of Isidore of Seville's "" from 976 and the Gerbertian abacus, into the 12th and 13th centuries, in early manuscripts of translations from the city of Toledo.
Calculations were originally performed using a dust board (, Latin: ), which involved writing symbols with a stylus and erasing them. The use of the dust board appears to have introduced a divergence in terminology as well: whereas the Hindu reckoning was called in the east, it was called 'calculation with dust' in the west. The numerals themselves were referred to in the west as 'dust figures' or 'dust letters'. Al-Uqlidisi later invented a system of calculations with ink and paper 'without board and erasing' (). A popular myth claims that the symbols were designed to indicate their numeric value through the number of angles they contained, but there is no contemporary evidence of this, and the myth is difficult to reconcile with any digits past 4. Adoption and spread. The first mentions of the numerals from 1 to 9 in the West are found in the 976 "", an illuminated collection of various historical documents covering a period from antiquity to the 10th century in Hispania. Other texts show that numbers from 1 to 9 were occasionally supplemented by a placeholder known as , represented as a circle or wheel, reminiscent of the eventual symbol for zero. The Arabic term for zero is (), transliterated into Latin as , which became the English word "cipher".

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