An astronaut or cosmonaut is a person trained by a human spaceflight program to command, pilot, or serve as a crew member of a spacecraft. Although generally reserved for professional space travelers, the terms are at times applied to anyone who travels into space, including scientists, politicians, journalists, and tourists.

Starting in the 1950s up to 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 funded SpaceShipOne in 2004, a new category of astronaut was created: the commercial astronaut.


The criteria for what constitutes human spaceflight vary. The Fédération Aéronautique Internationale (FAI) Sporting Code for astronautics recognises only flights that exceed an altitude of 100 km (62 mi). In the United States, professional, military, and commercial astronauts who travel above an altitude of 50 miles (80 km) are awarded astronaut wings.

As of 8 June 2013, a total of 532 people from 36 countries have reached 100 km (62 mi) or more in altitude, of which 529 reached low Earth orbit or beyond. Of these, 24 people have travelled beyond Low Earth orbit, to either lunar or trans-lunar orbit or to the surface of the moon; three of the 24 did so twice: Jim Lovell, John Young and Eugene Cernan. The three astronauts who haven't reached low Earth orbit are spaceplane pilots Joe Walker, Mike Melvill, and Brian Binnie.

As of 20 June 2011, under the U.S. definition 538 people qualify as having reached space, above 50 miles (80 km) altitude. Of eight X-15 pilots who exceeded 50 miles (80 km) in altitude, only one exceeded 100 km (about 62 miles). Space travellers have spent over 41,790 man-days (114.5 man-years) in space, including over 100 astronaut-days of spacewalks. As of 2016, the man with the longest cumulative time in space is Gennady Padalka, who has spent 879 days in space. Peggy A. Whitson holds the record for the most time in space by a woman, 377 days.


In 1959, when both the United States and Soviet Union were planning, but had yet to launch humans into space, NASA Administrator T. Keith Glennan and his Deputy Administrator, Dr. Hugh Dryden, discussed whether spacecraft crew members should be called astronauts or cosmonauts. Dryden preferred "cosmonaut", on the grounds that flights would occur in the cosmos (near space), while the "astro" prefix suggested flight to the stars. Most NASA Space Task Group members preferred "astronaut", which survived by common usage as the preferred American term. When the Soviet Union launched the first man into space, Yuri Gagarin in 1961, they chose a term which anglicizes to "cosmonaut".


In English-speaking nations, a professional space traveller is called an astronaut. The term derives from the Greek words ástron (ἄστρον), meaning "star", and nautes (ναύτης), meaning "sailor". The first known use of the term "astronaut" in the modern sense was by Neil R. Jones in his short storey "The Death's Head Meteor" in 1930. The word itself had been known earlier. For example, in Percy Greg's 1880 book Across the Zodiac, "astronaut" referred to a spacecraft. In Les Navigateurs de l'Infini (1925) of J.-H. Rosny aîné, the word astronautique (astronautic) was used. The word might have been inspired by "aeronaut", an older term for an air traveller first applied (in 1784) to balloonists. An early use in a non-fiction publication is Eric Frank Russell's poem "The Astronaut" in the November 1934 Bulletin of the British Interplanetary Society.

The first known formal use of the term astronautics in the scientific community was the establishment of the annual International Astronautical Congress in 1950 and the subsequent founding of the International Astronautical Federation the following year.

NASA applies the term astronaut to any crew member aboard NASA spacecraft bound for Earth orbit or beyond. NASA additionally uses the term as a title for those selected to join its Astronaut Corps. The European Space Agency similarly uses the term astronaut for members of its Astronaut Corps.


By convention, an astronaut employed by the Russian Federal Space Agency (or its Soviet predecessor) is called a cosmonaut in English texts. The word is an anglicisation of the Russian word kosmonavt (Russian: космонавт Russian pronunciation: [kəsmɐˈnaft]), one who works in space outside the Earth's atmosphere, a space traveler, which derives from the Greek words kosmos (κόσμος), meaning "universe", and nautes (ναύτης), meaning "sailor". Other countries of the former Eastern Bloc use variations of the Russian word kosmonavt, such as the Polish kosmonauta.

Coinage of the term kosmonavt has been credited to Soviet aeronautics pioneer Mikhail Tikhonravov (1900–1974). The first cosmonaut was Soviet Air Force pilot Yuri Gagarin, additionally the first person in space. Valentina Tereshkova, a Russian factory worker, was the first woman in space, as well as the first civilian among the Soviet cosmonaut or NASA astronaut corps to make a spaceflight. On March 14, 1995, Norman Thagard became the first American to ride to space on board a Russian launch vehicle, and thus became the first "American cosmonaut".


Official English-language texts issued by the government of China use astronaut while texts in Russian use космонавт (cosmonaut). In official Chinese-language texts, "yǔ háng yuán" (宇航员, "space navigating personnel") is used for astronauts and cosmonauts, and "háng tiān yuán" (航天员, "space navigating personnel") is used for Chinese astronauts. The phrase "tài kōng rén" (太空人, "spaceman") is often used in Hong Kong and Taiwan.

The term taikonaut is used by a few English-language news media organisations for professional space travellers from China. The word has featured in the Longman and Oxford English dictionaries, the latter of which describes it as "a hybrid of the Chinese term taikong (space) and the Greek naut (sailor)"; the term became more common in 2003 when China sent its first astronaut Yang Liwei into space aboard the Shenzhou 5 spacecraft. This is the term used by Xinhua News Agency in the English version of the Chinese People's Daily after the advent of the Chinese space program. The origin of the term is unclear; as early as May 1998, Chiew Lee Yih (趙裡昱) from Malaysia, used it in newsgroups.

Other terms

With the rise of space tourism, NASA and the Russian Federal Space Agency agreed to use the term "spaceflight participant" to distinguish those space travellers from professional astronauts on missions coordinated by those two agencies.

While no nation additional than the Russian Federation (and previously the former Soviet Union), the United States, and China have launched a manned spacecraft, several additional nations have sent people into space in cooperation with one of these countries. Inspired partly by these missions, additional synonyms for astronaut have entered occasional English usage. For example, the term spationaut (French spelling: spationaute) is at times used to describe French space travelers, from the Latin word spatium for "space", the Malay term angkasawan was used to describe participants in the Angkasawan program, and the Indian Space Research Organisation hope to launch a spacecraft in 2018 that would carry vyomanauts, coined from the Sanskrit word for space.

Space travel milestones

Yuri Gagarin, first human in space (1961)
Valentina Tereshkova, first woman in space (1963)
Neil Armstrong, first human to walk on the Moon (1969)
Dr. Sally Ride, the first American female astronaut (1980s)
Yang Liwei, first person sent into space by China (2003)

The first human in space was Soviet Yuri Gagarin, who was launched on April 12, 1961 aboard Vostok 1 and orbited around the Earth for 108 minutes. The first woman in space was Soviet Valentina Tereshkova, who launched on June 16, 1963 aboard Vostok 6 and orbited Earth for almost three days.

Alan Shepard became the first American and second person in space on May 5, 1961 on a 15-minute sub-orbital flight. The first American woman in space was Sally Ride, throughout Space Shuttle Challenger's mission STS-7, on June 18, 1983. In 1992 Mae Jemison became the first African American woman to travel in space aboard STS-47.

Cosmonaut Alexei Leonov was the first person to conduct an extravehicular activity (EVA), (commonly called a "spacewalk"), on March 18, 1965, on the Soviet Union's Voskhod 2 mission. This was followed two and a half months later by astronaut Ed White who made the first American EVA on NASA's Gemini 4 mission.

The first manned mission to orbit the Moon, Apollo 8, included American William Anders who was born in Hong Kong, making him the first Asian-born astronaut in 1968.

The Soviet Union, through its Intercosmos program, allowed people from additional "socialist" (i.e. Warsaw Pact and additional Soviet-allied) countries to fly on its missions, with the notable exception of France participating in Soyuz TM-7. An example is Czechoslovak Vladimír Remek, the first cosmonaut from a country additional than the Soviet Union or the United States, who flew to space in 1978 on a Soyuz-U rocket.

On July 23, 1980, Pham Tuan of Vietnam became the first Asian in space when he flew aboard Soyuz 37. Also in 1980, Cuban Arnaldo Tamayo Méndez became the first person of Hispanic and black African descent to fly in space, and in 1983, Guion Bluford became the first African American to fly into space. In April 1985, Taylor Wang became the first ethnic Chinese person in space. The first person born in Africa to fly in space was Patrick Baudry (France), in 1985. In 1985, Saudi Arabian Prince Sultan Bin Salman Bin AbdulAziz Al-Saud became the first Arab Muslim astronaut in space. In 1988, Abdul Ahad Mohmand became the first Afghan to reach space, spending nine days aboard the Mir space station.

With the larger number of seats available 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 8 Canadian astronauts to fly in space (through 2010). In 1985, Rodolfo Neri Vela became the first Mexican-born person in space. In 1991, Helen Sharman became the first Briton to fly in space. In 2002, Mark Shuttleworth became the first citizen of an African country to fly in space, as a paying spaceflight participant. In 2003, Ilan Ramon became the first Israeli to fly in space, although he died throughout a re-entry accident.

On October 15, 2003, Yang Liwei became China's first astronaut on the Shenzhou 5 spacecraft.

Age milestones

The youngest person to fly in space is Gherman Titov, who was 25 years old when he flew Vostok 2. (Titov was additionally the first person to suffer space sickness). The oldest person who has flown in space is John Glenn, who was 77 when he flew on STS-95.

Duration and distance milestones

The longest stay in space thus far has been 438 days, by Russian Valeri Polyakov. As of 2006, the most spaceflights by an individual astronaut is seven, a record held by both Jerry L. Ross and Franklin Chang-Diaz. The farthest distance from Earth an astronaut has travelled was 401,056 km (249,205 mi), when Jim Lovell, Jack Swigert, and Fred Haise went around the Moon throughout the Apollo 13 emergency.

Civilian and non-government milestones

The first civilian in space was Valentina Tereshkova aboard Vostok 6 (she additionally became the first woman in space on that mission). Tereshkova was only honorarily inducted into the USSR's Air Force, which had no female pilots whatsoever at that time. A month later, Joseph Albert Walker became the first American civilian in space when his X-15 Flight 90 crossed the 100 km (54 nautical miles) line, qualifying him by the international definition of spaceflight. Walker had joined the US Army Air Force but wasn't a member throughout his flight. The first people in space who had never been a member of any country's armed forces were both Konstantin Feoktistov and Boris Yegorov aboard Voskhod 1.

The first non-governmental space traveller was Byron K. Lichtenberg, a researcher from the Massachusetts Institute of Technology who flew on STS-9 in 1983. In December 1990, Toyohiro Akiyama became the first paying space traveller as a reporter for Tokyo Broadcasting System, a visit to Mir 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". Akiyama suffered severe space sickness throughout his mission, which affected his productivity.

The first self-funded space tourist was Dennis Tito on board the Russian spacecraft Soyuz TM-3 on April 28, 2001.

Self-funded travelers

The first person to fly on an entirely privately funded mission was Mike Melvill, piloting SpaceShipOne flight 15P on a suborbital journey, although he was a test pilot employed by Scaled Composites and not an actual paying space tourist. Seven others have paid the Russian Space Agency to fly into space:

  1. Dennis Tito (American): April 28 – May 6, 2001 (ISS)
  2. Mark Shuttleworth (South African): April 25 – May 5, 2002 (ISS)
  3. Gregory Olsen (American): October 1–11, 2005 (ISS)
  4. Anousheh Ansari (Iranian / American): September 18–29, 2006 (ISS)
  5. Charles Simonyi (Hungarian / American): April 7–21, 2007 (ISS), March 26 – April 8, 2009 (ISS)
  6. Richard Garriott (British / American): October 12–24, 2008 (ISS)
  7. Guy Laliberté (Canadian): September 30, 2009 – October 11, 2009 (ISS)


Elliot See throughout water egress training with NASA (1965)

The first NASA astronauts were selected for training in 1959. 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 the Mercury Seven) had any university degree, in engineering or any additional discipline at the time of their selection. Selection was initially limited to military pilots. The earliest astronauts for both America and the USSR tended to be jet fighter pilots, and were often test pilots.

Once selected, NASA astronauts go through twenty months of training in a variety of areas, including training for extravehicular activity in a facility such as NASA's Neutral Buoyancy Laboratory. Astronauts-in-training might additionally experience short periods of weightlessness in aircraft called the "vomit comet", the nickname given to a pair of modified KC-135s (retired in 2000 and 2004 respectively, and replaced in 2005 with a C-9) which perform parabolic flights. Astronauts are additionally required to build up a number of flight hours in high-performance jet aircraft. This is mostly done in T-38 jet aircraft out of Ellington Field, due to its proximity to the Johnson Space Center. Ellington Field is additionally where the Shuttle Training Aircraft is maintained and developed, although most flights of the aircraft are done out of Edwards Air Force Base.

NASA candidacy requirements

  • Be citizens of the United States.
  • Pass a strict physical examination, and have a near and distant visual acuity correctable to 20/20 (6/6). Blood pressure, while sitting, must be no greater than 140 over 90. There are currently no age restrictions.

Commander and Pilot

  • A bachelor's degree in engineering, biological science, physical science or mathematics is required.
  • At least 1,000 hours' flying time as pilot-in-command in jet aircraft. Experience as a test pilot is desirable.
  • Height must be 5 ft 2 in to 6 ft 2 in (1.58 m to 1.88 m).
  • Distant visual acuity must be correctable to 20/20 in each eye.
  • The refractive surgical procedures of the eye, PRK (Photorefractive keratectomy) and LASIK, are now allowed, providing at least 1 year has passed after the date of the procedure with no permanent adverse after effects. For those applicants under final consideration, an operative report on the surgical procedure will be requested.

Mission Specialist

  • A bachelor's degree in engineering, biological science, physical science or mathematics, as well as at least three years of related professional experience (graduate work or studies) and an advanced degree, such as a master's degree (one to three years) or a doctoral degree (three years or more).
  • Applicant's height must be between 4 ft 10.5 in and 6 ft 4 in (1.49 m and 1.93 m).

Mission Specialist Educator

  • 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, isn't required, but is strongly desired.

Mission Specialist Educators, or "Educator Astronauts", were first selected in 2004, and as of 2007, there are three NASA Educator astronauts: Joseph M. Acaba, Richard R. Arnold, and Dorothy Metcalf-Lindenburger. Barbara Morgan, selected as back-up teacher to Christa McAuliffe in 1985, is considered to be the first Educator astronaut by the media, but she trained as a mission specialist. The Educator Astronaut programme is a successor to the Teacher in Space programme from the 1980s.

Health risks of space travel

Astronauts are susceptible to a variety of health risks including decompression sickness, barotrauma, immunodeficiencies, loss of bone and muscle, loss of eyesight, orthostatic intolerance, sleep disturbances, and radiation injury. A variety of large scale medical studies are being conducted in space via the National Space and Biomedical Research Institute (NSBRI) to address these issues. Prominent among these is the Advanced Diagnostic Ultrasound in Microgravity Study in which astronauts (including former ISS commanders Leroy Chiao and Gennady Padalka) perform ultrasound scans under the guidance of remote experts to diagnose and potentially treat hundreds of medical conditions in space. This study's techniques are now being applied to cover professional and Olympic sports injuries as well as ultrasound performed by non-expert operators in medical and high school students. It is anticipated that remote guided ultrasound will have application on Earth in emergency and rural care situations, where access to a trained physician is often rare.

On December 31, 2012, a NASA-supported study reported that manned spaceflight might harm the brain and accelerate the onset of Alzheimer's disease.

In October 2015, the NASA Office of Inspector General issued a health hazards report related to space exploration, including a human mission to Mars.

Food and drink

An astronaut on the International Space Station requires about 0.83 kilogrammes (1.83 pounds) weight of food inclusive of food packaging per meal each day. (The packaging for each meal weighs around 0.12 kilogrammes - 0.27 pounds) Longer-duration missions require more food.

Shuttle astronauts worked with nutritionists to select menus that appeal to their individual tastes. Five months before flight, menus are selected and analysed for nutritional content by the shuttle dietician. Foods are tested to see how they'll 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 gallons (132 liters) of water every day. On board the ISS astronauts limit water use to only about three gallons (11 liters) per day.


In Russia, cosmonauts are awarded Pilot-Cosmonaut of the Russian Federation upon completion of their missions, often accompanied with the award of Hero of the Russian Federation. This follows the practise established in the USSR where cosmonauts were usually awarded the title Hero of the Soviet Union.

At NASA, those who complete astronaut candidate training receive a silver lapel pin. Once they have flown in space, they receive a gold pin. U.S. astronauts who additionally have active-duty military status receive a special qualification badge, known as the Astronaut Badge, after participation on a spaceflight. The United States Air Force additionally presents an Astronaut Badge to its pilots who exceed 50 miles (80 km) in altitude.

Space Mirror Memorial


Eighteen astronauts (fourteen men and four women) have lost their lives throughout four space flights. By nationality, thirteen were American (including one born in India), four were Russian (Soviet Union), and one was Israeli.

Eleven people (all men) have lost their lives training for spaceflight: eight Americans and three Russians. Six of these were in crashes of training jet aircraft, one drowned throughout water recovery training, and four were due to fires in pure oxygen environments.

The Space Mirror Memorial, which stands on the grounds of the John F. Kennedy Space Center Visitor Complex, commemorates the lives of the men and women who have died throughout spaceflight and throughout training in the space programmes of the United States. In addition to twenty NASA career astronauts, the memorial includes the names of a U.S. Air Force X-15 test pilot, a U.S. Air Force officer who died while training for a then-classified military space program, and a civilian spaceflight participant.