Anastronaut (from theAncient Greekἄστρον (astron), meaning 'star', andναύτης (nautes), meaning 'sailor') is a person trained, equipped, and deployed by ahuman spaceflight program to serve as a commander or crew member aboard aspacecraft. Although generally reserved for professional space travelers, the term is sometimes applied to anyone who travels into space, including scientists, politicians, journalists, andtourists.[1][2]
"Astronaut" technically applies to all human space travelers regardless of nationality. However, astronauts fielded byRussia or theSoviet Union are typically known instead ascosmonauts (from the Russian "kosmos" (космос), meaning "space", also borrowed from Greekκόσμος).[3] Comparatively recent developments in crewed spaceflight made by China have led to the rise of the termtaikonaut (from theMandarin "tàikōng" (太空), meaning "space"), although its use is somewhat informal and its origin is unclear. In China, thePeople's Liberation Army Astronaut Corpsastronauts and their foreign counterparts are all officially calledhángtiānyuán (航天员, meaning "heaven navigator" or literally "heaven-sailing staff").
Since 1961 and as of 2021, 600 astronauts have flown in space.[4] Until 2002, astronauts were sponsored and trained exclusively by governments, either by the military or by civilian space agencies. With the suborbital flight of the privately fundedSpaceShipOne in 2004, a new category of astronaut was created: thecommercial astronaut.
The criteria for what constituteshuman spaceflight vary, with some focus on the point where the atmosphere becomes so thin thatcentrifugal force, rather thanaerodynamic force, carries a significant portion of the weight of the flight object. TheFédération Aéronautique Internationale (FAI) Sporting Code for astronautics recognizes only flights that exceed theKármán line, at an altitude of 100 kilometers (62 mi).[5] In the United States, professional, military, and commercial astronauts who travel above an altitude of 80 kilometres (50 mi)[6] are awardedastronaut wings.
As of 17 November 2016[update], under the U.S. definition, 558 people qualify as having reached space, above 50 miles (80 km) altitude. Of eightX-15 pilots who exceeded 50 miles (80 km) in altitude, only one,Joseph A. Walker, exceeded 100 kilometers (about 62.1 miles) and he did it two times, becoming the first person in space twice.[7] Space travelers have spent over 41,790man-days (114.5-man-years) in space, including over 100 astronaut-days ofspacewalks.[9][10] As of 2024[update], the man with the longest cumulative time in space isOleg Kononenko, who has spent over 1100 days in space.[11]Peggy A. Whitson holds the record for the most time in space by a woman, at 675 days.[12]
In 1959, when both the United States andSoviet Union were planning, but had yet to launch humans into space,NASA AdministratorT. Keith Glennan and his Deputy Administrator,Hugh Dryden, discussed whether spacecraft crew members should be calledastronauts orcosmonauts. Dryden preferred "cosmonaut", on the grounds that flights would occur in and to the broadercosmos, while the "astro" prefix suggested flight specifically to thestars.[13] Most NASASpace Task Group members preferred "astronaut", which survived by common usage as the preferred American term.[14] When the Soviet Union launched the first man into space,Yuri Gagarin in 1961, they chose a term whichanglicizes to "cosmonaut".[15][16]
A professional space traveler is called anastronaut.[17] The first known use of the term "astronaut" in the modern sense was byNeil R. Jones in his 1930 short story "The Death's Head Meteor". The word itself had been known earlier; for example, inPercy Greg's 1880 bookAcross the Zodiac, "astronaut" referred to a spacecraft. InLes Navigateurs de l'infini (1925) byJ.-H. Rosny aîné, the wordastronautique (astronautics) was used. The word may have been inspired by "aeronaut", an older term for an air traveler first applied in 1784 toballoonists. An early use of "astronaut" in a non-fiction publication isEric Frank Russell's poem "The Astronaut", appearing in the November 1934Bulletin of theBritish Interplanetary Society.[18]
NASA applies the term astronaut to any crew member aboard NASA spacecraft bound for Earth orbit or beyond. NASA also uses the term as a title for those selected to join itsAstronaut Corps.[20] TheEuropean Space Agency similarly uses the term astronaut for members of itsAstronaut Corps.[21]
By convention, an astronaut employed by theRussian Federal Space Agency (or its predecessor, theSoviet space program) is called acosmonaut in English texts.[20] The word is anAnglicization ofkosmonavt (Russian:космонавтRussian pronunciation:[kəsmɐˈnaft]).[22] Other countries of the formerEastern Bloc use variations of the Russian kosmonavt, such as thePolish:kosmonauta (althoughPoles also usedastronauta, and the two words are considered synonyms).[23]
In Chinese, the termYǔ háng yuán (宇航员, "cosmos navigating personnel") is used for astronauts and cosmonauts in general,[29][30] whilehángtiān yuán (航天员, "navigating celestial-heaven personnel") is used for Chinese astronauts. Here,hángtiān (航天, literally "heaven-navigating", orspaceflight) is strictly[31] defined as the navigation ofouter space within the localstar system, i.e.Solar System. The phrasetàikōng rén (太空人, "spaceman") is often used in Hong Kong andTaiwan.[32]
For its2022 Astronaut Group, the European Space Agency envisioned recruiting an astronaut with a physical disability, a category they called "parastronauts", with the intention but not guarantee of spaceflight.[38] The categories of disability considered for the program were individuals with lower limb deficiency (either through amputation or congenital), leg length difference, or a short stature (less than 130 centimetres or 4 feet 3 inches).[39] On 23 November 2022,John McFall was selected to be the first ESA parastronaut;[40] he has rejected the use of the term.[41]
While no nation other than Russia (and previously the Soviet Union), the United States, and China have launched a crewed spacecraft, several other nations have sent people into space in cooperation with one of these countries, e.g. the Soviet-ledInterkosmos program. Inspired partly by these missions, other synonyms for astronaut have entered occasional English usage. For example, the termspationaut (French:spationaute) is sometimes used to describe French space travelers, from theLatin wordspatium for "space"; theMalay termangkasawan (deriving fromangkasa meaning 'space') was used to describe participants in theAngkasawan program (note its similarity with theIndonesian termantariksawan). Plans of theIndian Space Research Organisation to launch its crewedGaganyaan spacecraft have spurred at times public discussion if another term thanastronaut should be used for the crew members, suggestingvyomanaut (from theSanskrit wordvyoman meaning 'sky' or 'space') orgagannaut (from the Sanskrit wordgagan for 'sky').[42][43] InFinland, the NASA astronautTimothy Kopra, aFinnish American, has sometimes been referred to assisunautti, from theFinnish wordsisu.[44] Across Germanic languages, the word for "astronaut" typically translates to "space traveler", as it does with German'sRaumfahrer, Dutch'sruimtevaarder, Swedish'srymdfarare, and Norwegian'sromfarer.
As of 2021 in the United States, astronaut status is conferred on a person depending on the authorizing agency:
one who flies in a vehicle above 50 miles (80 km) for NASA or the military is considered anastronaut (with no qualifier)
one who flies in a vehicle to the International Space Station in a mission coordinated by NASA andRoscosmos is aspaceflight participant
one who flies above 50 miles (80 km) in a non-NASA vehicle as a crewmember and demonstrates activities during flight that are essential to public safety, or contribute to human space flight safety, is considered acommercial astronaut by theFederal Aviation Administration[45]
one who flies to the International Space Station as part of a "privately funded, dedicated commercial spaceflight on a commercial launch vehicle dedicated to the mission ... to conduct approved commercial and marketing activities on the space station (or in a commercial segment attached to the station)" is considered aprivate astronaut by NASA[46] (as of 2020, nobody has yet qualified for this status)
a generally-accepted but unofficial term for a paying non-crew passenger who flies a private non-NASA or military vehicles above 50 miles (80 km) is aspace tourist (as of 2020[needs update], nobody has yet qualified for this status)
On July 20, 2021, the FAA issued an order redefining the eligibility criteria to be an astronaut in response to the private suborbital spaceflights ofJeff Bezos andRichard Branson.[47][48] The new criteria states that one must have "[d]emonstrated activities during flight that were essential to public safety, or contributed tohuman space flight safety" to qualify as an astronaut. This new definition excludes Bezos and Branson.
The first human in space was SovietYuri Gagarin, who was launched on 12 April 1961, aboardVostok 1 and orbited around the Earth for 108 minutes. The first woman in space was SovietValentina Tereshkova, who launched on 16 June 1963, aboardVostok 6 and orbited Earth for almost three days.
Alan Shepard became the first American and second person in space on 5 May 1961, on a 15-minute sub-orbital flight aboardFreedom 7. The first American to orbit the Earth wasJohn Glenn, aboardFriendship 7 on 20 February 1962. The first American woman in space wasSally Ride, duringSpace ShuttleChallenger's missionSTS-7, on 18 June 1983.[49] In 1992,Mae Jemison became the first African American woman to travel in space aboardSTS-47.
CosmonautAlexei Leonov was the first person to conduct anextravehicular activity (EVA), (commonly called a "spacewalk"), on 18 March 1965, on the Soviet Union's Voskhod 2 mission. This was followed two and a half months later by astronautEd White who made the first American EVA on NASA's Gemini 4 mission.[50]
The first crewed mission to orbit the Moon,Apollo 8, included AmericanWilliam Anders who was born in Hong Kong, making him the first Asian-born astronaut in 1968.
With the increase of seats on the Space Shuttle, the U.S. began taking international astronauts. In 1983,Ulf Merbold of West Germany became the first non-US citizen to fly in a US spacecraft. In 1984,Marc Garneau became the first of eightCanadian astronauts to fly in space (through 2010).[59]In 1985,Rodolfo Neri Vela became the first Mexican-born person in space.[60] In 1991,Helen Sharman became the first Briton to fly in space.[61]In 2002,Mark Shuttleworth became the first citizen of an African country to fly in space, as a paying spaceflight participant.[62] In 2003,Ilan Ramon became the first Israeli to fly in space, although he died during are-entry accident.
On 15 October 2003,Yang Liwei became China's first astronaut on theShenzhou 5 spacecraft.
On 30 May 2020,Doug Hurley andBob Behnken became the first astronauts to launch to orbit on a private crewed spacecraft,Crew Dragon.
Age milestones
The youngest person to reach space isOliver Daemen, who was 18 years and 11 months old when he made asuborbital spaceflight onBlue Origin NS-16.[63] Daemen, who was a commercial passenger aboard theNew Shepard, broke the record of SovietcosmonautGherman Titov, who was 25 years old when he flewVostok 2. Titov remains the youngest human to reachorbit; he rounded the planet 17 times. Titov was also the first person to sufferspace sickness and the first person to sleep in space, twice.[64][65] The oldest person to reach space isWilliam Shatner, who was 90 years old when he made a suborbital spaceflight onBlue Origin NS-18.[66] The oldest person to reach orbit isJohn Glenn, one of theMercury 7, who was 77 when he flew onSTS-95.[67]
Duration and distance milestones
The longest time spent in space was by RussianValeri Polyakov, who spent 438 days there.[9]As of 2006, the most spaceflights by an individual astronaut is seven, a record held by bothJerry L. Ross andFranklin Chang-Diaz. The farthest distance from Earth an astronaut has traveled was 401,056 km (249,205 mi), whenJim Lovell,Jack Swigert, andFred Haise went around the Moon during theApollo 13 emergency.[9]
Civilian and non-government milestones
The first civilian in space wasValentina Tereshkova[68] aboardVostok 6 (she also became the first woman in space on that mission).Tereshkova was only honorarily inducted into the USSR's Air Force, which did not accept female pilots at that time. A month later,Joseph Albert Walker became the first American civilian in space when hisX-15 Flight 90 crossed the 100 kilometers (54 nautical miles) line, qualifying him by the international definition of spaceflight.[69][70] Walker had joined the US Army Air Force but was not a member during his flight.The first people in space who had never been a member of any country's armed forces were bothKonstantin Feoktistov andBoris Yegorov aboardVoskhod 1.
The first non-governmental space traveler wasByron K. Lichtenberg, a researcher from theMassachusetts Institute of Technology who flew onSTS-9 in 1983.[71] In December 1990,Toyohiro Akiyama became the first paying space traveler and the first journalist in space forTokyo Broadcasting System, a visit toMir as part of an estimated $12 million (USD) deal with a Japanese TV station, although at the time, the term used to refer to Akiyama was "Research Cosmonaut".[72][73][74] Akiyama suffered severespace sickness during his mission, which affected his productivity.[73]
The first self-fundedspace tourist wasDennis Tito on board the Russian spacecraft Soyuz TM-3 on 28 April 2001.
The first NASA astronauts were selected for training in 1959.[78] Early in the space program, military jet test piloting and engineering training were often cited as prerequisites for selection as an astronaut at NASA, although neither John Glenn nor Scott Carpenter (of theMercury Seven) had any university degree, in engineering or any other discipline at the time of their selection. Selection was initially limited to military pilots.[79][80] The earliest astronauts for both the US and the USSR tended to bejet fighter pilots, and were often test pilots.
Once selected, NASA astronauts go through twenty months of training in a variety of areas, including training forextravehicular activity in a facility such as NASA'sNeutral Buoyancy Laboratory.[1][79] Astronauts-in-training (astronaut candidates) may also experience short periods ofweightlessness (microgravity) in an aircraft called the "Vomit Comet," the nickname given to a pair of modifiedKC-135s (retired in 2000 and 2004, respectively, and replaced in 2005 with aC-9) which performparabolic flights.[78] Astronauts are also required to accumulate a number of flight hours in high-performance jet aircraft. This is mostly done inT-38 jet aircraft out ofEllington Field, due to its proximity to theJohnson Space Center. Ellington Field is also where theShuttle Training Aircraft is maintained and developed, although most flights of the aircraft are conducted fromEdwards Air Force Base.
Astronauts in training must learn how to control and fly the Space Shuttle; further, it is vital that they are familiar with the International Space Station so they know what they must do when they get there.[81]
NASA candidacy requirements
Unless otherwise noted, the following data are incorporated from the Astronaut Requirements article by NASA
The candidate must be a citizen of the United States.
The candidate must have at least two years of related professional experience obtained after degree completion or at least 1,000 hourspilot-in-command time onjet aircraft.
The candidate must be able to pass the NASA long-duration flight astronaut physical.
The candidate must also have skills in leadership, teamwork and communications.
The master's degree requirement can also be met by:
Two years of work toward a doctoral program in a related science, technology, engineering or math field.
Applicants must have a bachelor's degree with teaching experience, including work at the kindergarten through twelfth grade level. An advanced degree, such as a master's degree or a doctoral degree, is not required, but is strongly desired.[82]
A 2006 Space Shuttle experiment found thatSalmonella typhimurium, a bacterium that can causefood poisoning, became more virulent when cultivated in space.[101] More recently, in 2017, bacteria were found to be more resistant toantibiotics and to thrive in the near-weightlessness of space.[102]Microorganisms have been observed to survive thevacuum of outer space.[103][104]
Over the last decade, flight surgeons and scientists at NASA have seen a pattern of vision problems in astronauts on long-duration space missions. The syndrome, known asvisual impairment intracranial pressure (VIIP), has been reported in nearly two-thirds of space explorers after long periods spent aboard the International Space Station (ISS).[110]
On 2 November 2017, scientists reported that significant changes in the position and structure of the brain have been found in astronauts who have takentrips in space, based onMRI studies. Astronauts who took longer space trips were associated with greater brain changes.[111][112]
Being in space can be physiologically deconditioning on the body. It can affect theotolith organs and adaptive capabilities of thecentral nervous system.Zero gravity andcosmic rays can cause many implications for astronauts.[113]
In October 2018,NASA-funded researchers found that lengthy journeys intoouter space, including travel to theplanet Mars, may substantially damage thegastrointestinal tissues of astronauts. The studies support earlier work that found such journeys could significantly damage the brains of astronauts, andage them prematurely.[114]
A study by Russian scientists published in April 2019 stated that astronauts facing spaceradiation could face temporary hindrance of theirmemory centers. While this does not affect their intellectual capabilities, it temporarily hinders formation of new cells in brain's memory centers. The study conducted by Moscow Institute of Physics and Technology (MIPT) concluded this after they observed that mice exposed to neutron and gamma radiation did not impact the rodents' intellectual capabilities.[117]
A 2020study conducted on the brains of eight male Russian cosmonauts after they returned from long stays aboard theInternational Space Station showed that long-durationspaceflight causes manyphysiological adaptions, including macro- andmicrostructural changes. While scientists still know little about the effects ofspaceflight on brain structure, this study showed that space travel can lead to newmotor skills (dexterity), but also slightly weakervision, both of which could possibly be long lasting. It was the first study to provide clear evidence ofsensorimotor neuroplasticity, which is the brain's ability to change through growth and reorganization.[118][119]
Astronauts making and eating hamburgers on board the ISS, 2002[120]
An astronaut on the International Space Station requires about 830 g (29 oz) mass of food per meal each day (inclusive of about 120 g or 4.2 oz packaging mass per meal).
Space Shuttle astronauts worked with nutritionists to select menus that appealed to their individual tastes. Five months before flight, menus were selected and analyzed for nutritional content by the shuttle dietician. Foods are tested to see how they will react in a reduced gravity environment. Caloric requirements are determined using a basal energy expenditure (BEE) formula. On Earth, the average American uses about 35 US gallons (130 L) of water every day. On board the ISS astronauts limit water use to only about three US gallons (11 L) per day.[121]
At NASA, those who complete astronaut candidate training receive a silverlapel pin. Once they have flown in space, they receive a gold pin. U.S. astronauts who also have active-duty military status receive a special qualification badge, known as theAstronaut Badge, after participation on a spaceflight. TheUnited States Air Force also presents an Astronaut Badge to its pilots who exceed 50 miles (80 km) in altitude.
As of 2020[update], eighteen astronauts (fourteen men and four women) have died during four space flights. By nationality, thirteen were American, four were Russian (Soviet Union), and one was Israeli.
As of 2020[update], eleven people (all men) have died training for spaceflight: eight Americans and three Russians. Six of these were in crashes of training jet aircraft, one drowned during water recovery training, and four were due to fires in pure oxygen environments.
AstronautDavid Scott left a memorial consisting of a statuette titledFallen Astronaut on the surface of the Moon during his 1971Apollo 15 mission, along with a list of the names of eight of the astronauts and six cosmonauts known at the time to have died in service.[122]
TheSpace Mirror Memorial, which stands on the grounds of theKennedy Space Center Visitor Complex, is maintained by the Astronauts Memorial Foundation and commemorates the lives of the men and women who have died during spaceflight and during training in the space programs of the United States. In addition to twenty NASA career astronauts, the memorial includes the names of anX-15 test pilot, aU.S. Air Force officer who died while training for a then-classified military space program, and a civilianspaceflight participant.
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