http___en.wikipedia.org_wiki_Space_walk_1.xml
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Излизане в открития космос Излизане в открития космос (на английски: Extra-vehicular activity или съкр. (EVA) е действие извършено от космонавт, който се намира в космическото пространство и е извън борда на космически кораб. Терминът по-често се използва за разходка направена извън космически кораб обикалящ около Земята - космическа разходка, но може да се отнася и за разходка направена по повърхността на Луната - лунна разходка. [редактиране] Определение Поради различните конструкции на ранните космически кораби, космическите програми на САЩ и СССР дефинират термина „излизане в открития космос“ по различен начин. Руснаците го определят като състояние на космонавта във вакуум. Американците считат, че излизането е започнало, когато скафандъра бъде включен към собственото си автономно захранване. [редактиране] История На 18 март 1965 г. Алексей Леонов излиза през шлюза на космическия кораб Восход 2 в откритото космическо пространство, привързан със специално здраво въже. Престоят извън кабината на Восход е 21 минути, а извън шлюза в открития космос - 12 минути, при което се отдалечава от кораба на разстояние до 5 м. Това е първото излизане на човек извън борда на космически кораб в откритото космическо пространство. На 3 юни 1965 г. Едуард Уайт осъществява второто (първо са астронавт от САЩ) излизане на човек извън борда на космическия кораб в открития космос. Престоят извън Джемини 4 е 22 минути, през които астронавтът се опитва да маневрира на разстояние от 5 до 10 м. с помощта на специално разработен реактивен пистолет. Поради повреда в механизма за подаване на реактивна тяга опитите са прекратени след няколко минути. Между 1969 и 1972 год. дванадесет американски астронавти осъществяват лунни разходки по време на полетите на космическите кораби Аполо 11, Аполо 12, Аполо 14, Аполо 15, Аполо 16 и Аполо 17. Юджийн Сърнън е човекът с най-продължителни лунни разходки - общото време на лунната повърхност на астронавта е 24 часа и 11 минути. По време на лунната програма са правени космически разходки на окололунна орбита. На 5 август 1971 год. Алфред Уордън става единствения човек осъществил космическа разходка от 38 мин. докато командния модул на Аполо 15 е на невидимата страна на Луната. Първата жена осъществила космическа разходка е Светлана Савицка на 25 юли 1984 год. от борда на космическата станция Салют-7. Излизането в открития космос на Савицка е с продължителност 3 часа и 35 минути. На 7 февруари 1984 год. по време на мисия STS-41B астронавта Брюс Маккендлес осъществява първото автономно придвижване в открития космос с помощта на автономна маневрена единица (на английски: Manned Maneuvering Unit или съкр. Най - продължителната космическа разходка (еднократно излизане) - 8 часа и 56 минути е осъществена на 11 март 2001 год. от астронавтите Сюзан Хелмс и Джеймс Вос по време на мисия STS-102. [редактиране] Опасности Излизанията в открития космос са опасни поради много различни причини. Основната е сблъсък с космически отломки. Скоростта, която се развива в орбита на 300 км над Земята (типично за мисия на совалка), е 7,7 км/с. Това е скорост приблизително десет пъти по-висока от скоростта на куршум. Това означава, че частица приблизително 100 пъти по-малка от куршум ще има същия ефект при тази скорост. Почти всяка космическа мисия създава още орбитиращи отломки, така че този проблем ще става все по-сериозен. Друга опасност идва от факта, че външните условия в космоса се симулират по-трудно преди началото на мисията, въпреки че приблизителни симулации могат да се осъществят в съоръжения като хидро-лабораториите в тренировъчния център „Гагарин“ в Звездния град и лабораторията за неутрална плаваемост на НАСА. Излизания в космоса не са рутинни операции заради техния риск. Поради това те се планират към края на разработката на проекта, когато се открият проблеми, а понякога и по време на самата мисия. Изключителната опасност на излизанията в открития космос неизбежно води до емоционално напрежение за космонавтите. Други възможни проблеми включват отделяне на космонавта от кораба или пробиване на скафандъра, което би довело до дехерметизация и би причинило хипоксия и бърза смърт, ако космонавтът не се внесе бързо в херметизиран космически кораб. Един космонавт е претърпявал пробиване на скафандъра. По време на мисията STS-37 малка пръчка пробила ръкавицата на един от космонавтите (името му не е разкрито, но е бил или Джери Рос или Джером Апт). Пробилият обект се задържал на място и не причинил осезаема дехерметизация и не е бил забелязан до благополучното прибиране на космонавтите в Атлантис. Излизането в открития космос на Алексей Леонов също не минало безпрепятствено. По време на излизането, скафандърът на Леонов се издул до такава степен, че вече не могъл да влезе и да затвори вратата на шлюза на Восход 2. Тъй като дишал чист кислород, той успял да намали налягането на скафандъра си до под 28 kPa и с усилие да се прибере. Към 2012 г., не е имало катастрофални инциденти по време на излизане в космоса и никой космонавт или космонавт не е загивал по време на такова. Имайки предвид значителната опасност, присъща на излизането в космоса, и риска за космонавтите, някои учени работят върху развитието на дистанционно управляеми роботи за външна строителна работа, за да се премахне или намали нуждата от излизания на хора в открития космос. [редактиране] Най - добри постижения към 2012 година [редактиране] Галерия Едуард Уайт осъществява второто излизане на човек в открития космос. Вижда се реактивния пистолет, с който астронавта прави опити за самостоятелни маневри. Едуин Олдрин на лунната повърхност, 21 юли 1969 год., мисия Аполо 11. Брюс Маккендлес осъществява първото автономно придвижване в открития космос на 7 февруари 1984 год., мисия STS-41B. Сергей Волков работи по външния корпус на МКС - 3 август 2011 год. Американския астронавт Стивън Робинсън работи с роботизираната ръка по време на мисия STS-114. [редактиране] Източници "Stand-Up EVA". NASA. http://history.nasa.gov/alsj/a15/a15.seva.html. Retrieved October 21, 2008. - Mark Wade. "Encyclopedia Astronautica Salyut 7 EP-4". - "A pictorial history of welding as seen through the pages of the Welding Journal". American Welding Society. http://www.aws.org/about/time_by5.html. Retrieved November 18, 2011. - William Harwood (2007). "ISS EVA Statistics". CBS News. http://www.cbsnews.com/network/news/space/evastats.html. Retrieved November 8, 2007. [редактиране] Външни препратки - NASA JSC Oral History Project Walking to Olympus: An EVA Chronology PDF document. - NASDA Online Space Notes[мъртъв линк] - Apollo Extravehicular mobility unit. Volume 1: System description - 1971 (PDF document) - Apollo Extravehicular mobility unit. Volume 2: Operational procedures - 1971 (PDF document) - Skylab Extravehicular Activity Development Report - 1974 (PDF document) - Analysis of the Space Shuttle Extravehicular Mobility Unit - 1986 (PDF document) - NASA Space Shuttle EVA tools and equipment reference book - 1993 (PDF document) - Preparing for an American EVA on the ISS - 2006
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Extra-vehicular activity Extra-vehicular activity (EVA) is any activity done by an astronaut or cosmonaut outside a spacecraft beyond the Earth's appreciable atmosphere. The term most commonly applies to a spacewalk made outside a craft orbiting Earth (such as the International Space Station), but also has applied to lunar surface exploration (commonly known as moonwalks) performed by six pairs of American astronauts in the Apollo program from 1969 to 1972. On each of the last three of these missions, astronauts also performed deep-space EVAs on the return to Earth, to retrieve film canisters from the outside of the spacecraft. Astronauts also used EVA in 1973 to repair launch damage to Skylab, the United States' first space station. A "Stand-up" EVA (SEVA) is where the astronaut does not fully leave a spacecraft, but is completely reliant on the spacesuit for environmental support.[1] Its name derives from the astronaut "standing up" in the open hatch, usually to film or assist a spacewalking astronaut. EVAs may be either tethered (the astronaut is connected to the spacecraft; oxygen and electrical power can be supplied through an umbilical cable; no propulsion is needed to return to the spacecraft), or untethered. Untethered spacewalks were only performed on three missions in 1984 using the Manned Maneuvering Unit (MMU), and on a flight test in 1994 of the Simplified Aid for EVA Rescue (SAFER). A SAFER is a safety device worn on tethered U.S. EVAs, since the capability of returning to the spacecraft is essential. Russia, the United States and China have demonstrated the capability to conduct an EVA. Contents Development history[edit] NASA planners invented the term extra-vehicular activity in the early 1960s for the Apollo program to land men on the Moon, because the astronauts would leave the spacecraft to collect lunar material samples and deploy scientific experiments. To support this, and other Apollo objectives, the Gemini program was spun off to develop the capability for astronauts to work outside a two-man Earth orbiting spacecraft. However, the Soviet Union was fiercely competitive in holding the early lead it had gained in manned spaceflight, so the Soviet Communist Party, led by Nikita Khrushchev, ordered the conversion of its single-pilot Vostok capsule into a two- or three-person craft named Voskhod, in order to compete with Gemini and Apollo.[2] The Soviets were able to launch two Voskhod capsules before U.S. was able to launch its first manned Gemini. The Voskhod's avionics required cooling by cabin air to prevent overheating, therefore an airlock was required for the spacewalking cosmonaut to exit and re-enter the cabin while it remained pressurized. By contrast, the Gemini avionics did not require air cooling, allowing the spacewalking astronaut to exit and re-enter the depressurized cabin through an open hatch. Because of this, the American and Soviet space programs developed different definitions for the duration of an EVA. The Soviet (now Russian) definition begins when the outer airlock hatch is open and the cosmonaut is in vacuum. An American EVA began when the astronaut had at least his head outside the spacecraft.[3] The USA has changed its EVA definition since.[citation needed] As they had with the first satellite and first man in space, the Soviets again stunned the world on March 18, 1965 with the first spacewalk (and the first EVA) performed by Alexey Leonov from the Voskhod 2 spacecraft, for 12 minutes outside the spacecraft. Leonov had no means to control his motion other than pulling on his 50.7-foot (15.5 m) tether. After the flight, he claimed this was easy, but his space suit ballooned from its internal pressure against the vacuum of space, stiffening so much that he could not activate the shutter on his chest-mounted camera.[4] At the end of his space walk, the suit stiffening caused a more serious problem: Leonov had to re-enter the capsule through the inflatable cloth airlock, 3.96 feet (1.21 m) in diameter and 8.25 feet (2.51 m) long. After his spacewalk, he improperly entered the airlock head-first and got stuck sideways. He could not get back in without reducing the pressure in his suit, risking "the bends". This added another 12 minutes to his time in vacuum, and he was overheated by 1.8 °C (3.2 °F) from the exertion. It would be almost four years before the Soviets tried another EVA. They misrepresented to the press how difficult Leonov found it to work in weightlessness and concealed the problems encountered until after the end of the Cold War.[4][5] The first American spacewalk was performed on June 3, 1965, by Edward H. White, II from the second manned Gemini flight, Gemini 4, for 21 minutes, on a 25-foot (7.6 m) tether. White was the first to control his motion in space with a Hand-Held Maneuvering Unit, which worked well but only carried enough propellant for 20 seconds. White found his tether useful for limiting his distance from the spacecraft but difficult to use for moving around, contrary to Leonov's claim.[4] However, a defect in the capsule's hatch latching mechanism caused difficulties opening and closing the hatch, which delayed the start of the EVA and put White and his crewmate at risk of not getting back to Earth alive.[6] No EVAs were planned on the next three Gemini flights. The next EVA was planned to be made by David Scott on Gemini 8, but that mission had to be aborted due to a critical spacecraft malfunction before the EVA could be conducted. Astronauts on the next three Gemini flights (Eugene Cernan, Michael Collins, and Richard Gordon), performed several EVAs, but none was able to successfully work for long periods outside the spacecraft without tiring and overheating. Finally, on November 13, 1966, Edwin "Buzz" Aldrin became the first to successfully work in space without tiring, on the Gemini 12 last flight. Aldrin worked outside the spacecraft for 2 hours and 6 minutes, in addition to two stand-up EVAs in the spacecraft hatch for an additional 3 hours and 24 minutes. Aldrin's interest in scuba diving inspired the use of underwater EVA training to simulate weightlessness, which has been used ever since to allow astronauts to practice techniques of avoiding wasted muscle energy. On January 16, 1969, the Soviet Union achieved the first EVA crew transfer from one spacecraft to another when Aleksei Yeliseyev and Yevgeny Khrunov transferred from Soyuz 5 to Soyuz 4, which were docked together. This was the second Soviet EVA, and it would be almost another nine years before the Soviets performed their third.[4] The first EVA on the lunar surface was performed by Americans Neil Armstrong and Buzz Aldrin on July 21, 1969 (UTC), after the Apollo 11 Moon landing. This first Moon walk lasted 2 hours, 36 minutes. A total of fifteen Moon walks were performed by members of six Apollo crews, including Charles "Pete" Conrad, Alan Bean, Alan Shepard, Edgar Mitchell, David Scott, James Irwin, John Young, Charles Duke, Eugene "Gene" Cernan, and Dr. Harrison "Jack" Schmitt. Cernan was the last Apollo astronaut to step off the surface of the Moon.[4] The first EVA in deep space was made on August 5, 1971, by American Al Worden, to retrieve a film and data recording canister from the Apollo 15 Service Module on the return trip from the Moon. Worden was assisted by James Irwin, doing a standup EVA in the Command Module hatch. This was repeated by Ken Mattingly and Charles Duke on Apollo 16 and by Ronald Evans and Harrison Schmitt on Apollo 17.[4] The first EVA repairs of a spacecraft were made by Charles "Pete" Conrad, Joseph Kerwin, and Paul J. Weitz on May 26, June 7, and June 19, 1973, on the Skylab 2 mission. They rescued the functionality of the launch-damaged Skylab space station by freeing a stuck solar panel, deploying a solar heating shield, and freeing a stuck circuit breaker relay. The Skylab 2 crew made three EVAs, and a total of ten EVAs were made by the three Skylab crews.[4] They found that activities in weightlessness required about 2 1/2 times the duration as on Earth because many astronauts suffered spacesickness early in their flights.[7] After Skylab, no more EVAs were made by the United States until the advent of the Space Shuttle program in the early 1980s. In this period, the Soviets resumed EVAs, making four from the Salyut 6 and Salyut 7 space stations between December 20, 1977, and July 30, 1982.[4] When the United States resumed EVAs on April 7, 1983, astronauts started using an Extravehicular Mobility Unit (EMU) for self-contained life support independent of the spacecraft. Also, for the first time, American astronauts used an airlock to enter and exit the spacecraft like the Soviets. Accordingly, the American definition of EVA start time was redefined to when the astronaut switches the EMU to battery power.[citation needed] Milestones[edit] Capability milestones[edit] - The first untethered spacewalk was made by American Bruce McCandless II on February 7, 1984, during Challenger mission STS-41-B, using the Manned Maneuvering Unit. He was subsequently joined by Robert L. Stewart during the 5 hour 55 minute spacewalk. A self-contained spacewalk was first attempted by Eugene Cernan in 1966 on Gemini 9A, but Cernan could not reach the maneuvering unit without tiring. - The first metalwork in open space, consisting of welding, brazing and metal spraying, was conducted by Soviet cosmonauts Svetlana Savitskaya and Vladimir Dzhanibekov on July 25, 1984. A specially designed URI[expand acronym] multipurpose tool was used to perform these activities during a 3 hour, 30 minute EVA outside the Salyut 7 space station.[8][9][10] - The first three-person EVA was performed on May 13, 1992, as the third EVA of STS-49, the maiden flight of Endeavour.[11] Pierre Thuot, Richard Hieb, and Thomas Akers conducted the EVA to hand-capture and repair a non-functional Intelsat VI-F3 satellite. As of 2013[update] it was the only three-person EVA.[12] - The first EVA to perform an in-flight repair of the Space Shuttle was by American Steve Robinson on August 3, 2005, during "Return to Flight" mission STS-114. Robinson was sent to remove two protruding gap fillers from Discovery's heat shield, after engineers determined there was a small chance they could affect the shuttle upon re-entry. Robinson successfully removed the loose material while Discovery was docked to the International Space Station. - The longest EVA as of 2007, was 8 hours and 56 minutes, performed by Susan J. Helms and James S. Voss on March 11, 2001.[13] Personal cumulative duration records[edit] - Russian Anatoly Solovyev holds both the record for most EVAs and for the greatest cumulative duration spent in EVA (16 EVAs; 82 hr and 22 min). - Michael Lopez-Alegria holds the American record (10 EVAs; 67 hr and 40 min). - Christer Fuglesang holds the European (non-Russian) record (5 EVAs; 31 hr and 55 min).[13] National, ethnic and gender firsts[edit] - The first woman to perform an EVA was Soviet Svetlana Savitskaya on July 25, 1984 while aboard the Salyut 7 space station. Her EVA lasted 3 hours and 35 minutes. - The first American woman to perform an EVA was Kathryn D. Sullivan on October 11, 1984 during Space Shuttle Challenger mission STS-41-G. - The first EVA by a non-Soviet, non-American was made on December 9, 1988 by Jean-Loup Chrétien of France during a three-week stay on the Mir space station. - The first EVA by a Briton was on February 9, 1995 by Michael Foale (who carries dual British-American citizenship). - The first EVA by a black African-American was on February 9, 1995 by Bernard A. Harris, Jr.. - The first EVA by a Japanese astronaut was made on November 25, 1997 by Takao Doi during STS-87. - The first EVA by an Australian-born person was on March 13, 2001 by Andy Thomas (although he is a naturalized US citizen). - The first EVA by a Canadian was made on April 22, 2001 by Chris Hadfield. During his spacewalk, Hadfield installed the Canadarm2 onto the International Space Station. - The first EVA by a Scandinavian astronaut was made on December 12, 2006 by Christer Fuglesang. - The first EVA by a Chinese astronaut was made on September 27, 2008 by Zhai Zhigang during Shenzhou 7 mission. The spacewalk, using a Feitian space suit, made China the third country to independently carry out an EVA. - The first EVA by an Italian astronaut was made on July 9, 2013 by Luca Parmitano along with NASA Astronaut Chris Cassidy during Expedition 36 on the International Space Station. Commemoration[edit] The first spacewalk, that of the Soviet cosmonaut Alexey Leonov was commemorated in several Eastern Bloc stamps (see the stamps section in the Alexey Leonov article). Since the Soviet Union did not distribute diagrams or images of the Voskhod spacecraft at the time, the spaceship depiction in the stamps was purely fictional. The US Post Office issued the Accomplishments in Space stamp in 1967. Along with astronaut Ed White, the issue depicts the Gemini IV spacecraft in orbit. Designations[edit] NASA "spacewalkers" during the space shuttle program were designated as EV-1, EV-2, EV-3 and EV-4 (assigned to mission specialists for each mission, if applicable).[14][15] Camp-out procedure[edit] For EVAs from the International Space Station, NASA now routinely employs a camp out procedure to reduce the risk of decompression sickness.[16] This was first tested by the Expedition 12 crew. During a camp out, astronauts sleep overnight in the airlock prior to an EVA, lowering the air pressure to 10.2 psi (70 kPa), compared to the normal station pressure of 14.7 psi (101 kPa).[16] Spending a night at the lower air pressure helps flush nitrogen from the body, thereby preventing "the bends".[17][18] See also[edit] References[edit] "Stand-Up EVA". NASA. Retrieved October 21, 2008. - ^ Siddiqi, Asif A. (2003a). Sputnik and the Soviet Space Challenge. Gainesville: University Press of Florida. - ^ Walking to Olympus, page ix - ^ a b c d e f g h Portree, David S. F.; Robert C. Treviño (October 1997). "Walking to Olympus: An EVA Chronology" (PDF). Monographs in Aerospace History Series #7. NASA History Office. - ^ Rincon, Paul; Lachmann, Michael (October 13, 2014). "The First Spacewalk How the first human to take steps in outer space nearly didn't return to Earth". BBC News. BBC News. Archived from the original on 2014-10-14. - ^ Oral History Transcript / James A. McDivitt / Interviewed by Doug Ward / Elk Lake, Michigan - 29 June 1999 - ^ Skylab Reuse Study, p. 3-53. Martin Marietta and Bendix for NASA, September 1978. - ^ Mark Wade. "Encyclopedia Astronautica Salyut 7 EP-4". Astronautix.com. Retrieved November 18, 2011. - ^ "A pictorial history of welding as seen through the pages of the Welding Journal". American Welding Society. Retrieved November 18, 2011. - ^ "Space welding anniversary". RuSpace.com. Retrieved November 18, 2011. NASA. Retrieved December 7, 2007. - ^ Facts about spacesuits and spacewalks (NASA.gov) - ^ a b William Harwood (2007). "ISS EVA Statistics". CBS News. Retrieved November 8, 2007. - ^ "Extravehicular Activity Radiation Monitoring (EVARM)". NASA. Check date values in: |date=(help) - ^ "Extravehicular Activity Radiation Monitoring (EVARM)". Marschall Space Flight Center. Check date values in: |date=(help) - ^ a b NASA (2006). "Preflight Interview: Joe Tanner". NASA. Retrieved February 8, 2008. - ^ NASA. "International Space Station Status Report #06-7". NASA. - ^ NASA. "Pass the S'mores Please! Station Crew 'Camps Out'". NASA. External links[edit] - NASA JSC Oral History Project Walking to Olympus: An EVA Chronology PDF document. - Astronaut space walk picture - NASDA Online Space Notes[dead link] - Apollo Extravehicular mobility unit. Volume 1: System description - 1971 (PDF document) - Apollo Extravehicular mobility unit. Volume 2: Operational procedures - 1971 (PDF document) - Skylab Extravehicular Activity Development Report - 1974 (PDF document) - Analysis of the Space Shuttle Extravehicular Mobility Unit - 1986 (PDF document) - NASA Space Shuttle EVA tools and equipment reference book - 1993 (PDF document) - Preparing for an American EVA on the ISS - 2006