An astronaut (from the Ancient Greek (), meaning 'star', and (), meaning 'sailor') is a person trained, equipped, and deployed by a human spaceflight program to serve as a commander or crew member of a spacecraft. Although generally reserved for professional space travelers, the term is sometimes applied to anyone who travels into space, including scientists, politicians, journalists, and space tourists. In the United States, it is a designated term used by three agencies: NASA, the FAA, and the military. The term is also used for people who are trained to fly in a spacecraft after passing certain training courses, regardless of their experience of space travel.
"Astronaut" technically applies to all human space travelers regardless of nationality. However, astronauts fielded by Russia or the Soviet Union are typically known instead as cosmonauts (from the Russian "kosmos" (космос), meaning "space", also borrowed from Greek ). Comparatively recent successes of the China Manned Space Program have led to the rise of the informal term taikonaut (from the Mandarin "tàikōng" (), meaning "space"); Chinese official media refers to its astronauts and their foreign counterparts as hángtiānyuán (, meaning "celestial navigator" or literally "heaven-sailing staff"). The Canadian Space Agency, European Space Agency, and JAXA refer to their crew as astronauts regardless of launch vehicle; historically other nationalities launched by the Soviet Interkosmos adopted the cosmonaut term.
As of April 2026, 781 humans have flown in space, many of these to space stations. Over 290 individuals have visited the International Space Station; 105 individuals visited the Mir station. 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 funded SpaceShipOne in 2004, a new category of astronaut was created: the commercial astronaut.
Definition
The word "astronaut" is sometimes used in a strictly defined sense, such as in the United States, where it is a designated term used by three agencies: NASA, the Federal Aviation Administration, and the military, with slightly different criteria for each. NASA and the military only use the term for their own employees who meet specific criteria. In Europe, the European Astronaut Corps calls graduates of their training program "ESA astronauts", being "active ESA staff having successfully completed Basic Astronaut training recognised by ESA or who have participated in a mission to space". People who have completed this training are generally described as astronauts in the press, and the Collins and Cambridge English Dictionaries define "astronaut" as people who are trained to fly in a spacecraft.
In addition, the criteria for what constitutes human spaceflight vary, with some focus on the point where the atmosphere becomes so thin that centrifugal force, rather than aerodynamic force, carries a significant portion of the weight of the flight object. The (FAI) Sporting Code for astronautics recognizes only flights that exceed the Kármán line, at an altitude of . In the United States, professional, military, and commercial astronauts who travel above an altitude of are awarded astronaut wings.
, 781 people from 55 countries have reached or more in altitude. Of these, 28 people, all but Canadian Jeremy Hansen from the United States, have traveled beyond low Earth orbit, with three of them—Jim Lovell, John Young and Eugene Cernan—doing so twice. There have been ten crewed missions beyond low Earth orbit: Apollo 8 and Apollo 10 orbited the Moon without landing, Apollos 11–12 and 14–17 landed on the Moon, and Apollo 13 and Artemis II looped around the Moon.
, 676 humans had flown to space under the U.S. definition. Of eight X-15 pilots who exceeded 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. Space travelers have spent over 41,790 man-days (114.5-man-years) in space, including over 100 astronaut-days of spacewalks. , the man with the longest cumulative time in space is Oleg Kononenko, who has spent over 1100 days in space. Peggy A. Whitson holds the record for the most time in space by a woman, at 695 days.
Schirra definition The veteran American astronaut, Wally Schirra (1923–2007), had firm views on the criteria that should apply for membership of the Society of Experimental Test Pilots (SETP) – and on the definition of an astronaut. He devoted a whole chapter (My Ultimate Peer Group) of his 1988 autobiography, Schirra's Space, to a discussion of the subject. He argued that aircraft personnel not piloting an aircraft are not aviators, and applied the strict criterion that anyone in space not in control of the flight of the spacecraft is not an astronaut:
Terminology
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, Hugh Dryden, discussed whether spacecraft crew members should be called astronauts or cosmonauts. Dryden preferred "cosmonaut", on the grounds that flights would occur in and to the broader cosmos, while the "astro" prefix suggested flight specifically 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".
Astronaut
A professional space traveler is called an astronaut. The first known use of the term "astronaut" in the modern sense was by Neil R. Jones in his 1930 short story "The Death's Head Meteor". 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) by J.-H. Rosny aîné, the word astronautique (astronautics) was used. The word may have been inspired by "aeronaut", an older term for an air traveler first applied in 1784 to balloonists. An early use of "astronaut" in a non-fiction publication is Eric Frank Russell's poem "The Astronaut", appearing in the November 1934 Bulletin of the British Interplanetary Society.Ingham, John L.: Into Your Tent, Plantech (2010): page 82.
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 also 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.
Cosmonaut
An astronaut employed by the Russian Federal Space Agency (or its predecessor, the Soviet space program) is called a cosmonaut, an Anglicization of kosmonavt ( ). Other countries of the former Eastern Bloc use variations of the Russian kosmonavt, such as the (Poles also used as a synonym).
Coinage of the term has been credited to Soviet aeronautics (or "cosmonautics") pioneer Mikhail Tikhonravov (1900–1974). The first cosmonaut was Soviet Air Force pilot Yuri Gagarin, the first person in space. He was part of the first six Soviet citizens, with German Titov, Yevgeny Khrunov, Andriyan Nikolayev, Pavel Popovich, and Grigoriy Nelyubov, who were given the title of pilot-cosmonaut in January 1961. Valentina Tereshkova was the first female cosmonaut and the first and youngest woman to have flown in space with a solo mission on the Vostok 6 in 1963. On 14 March 1995, Norman Thagard became the first American to ride to space on board a Russian launch vehicle, and thus became the first "American cosmonaut".
Taikonaut
In Chinese, the term (, "cosmos navigating personnel") is used for astronauts and cosmonauts in general, while (, "Tian-navigating personnel") is used for Chinese astronauts. Here, ( or spaceflight) is strictly defined as the navigation of outer space within the local star system, i.e. Solar System. The phrase (, "spaceman") is often used in Hong Kong and Taiwan.
The term taikonaut is used by some English-language news media organizations for professional space travelers from China. The word has featured in the Longman and Oxford English dictionaries, and 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 since the advent of the Chinese space program. The origin of the term is unclear; as early as May 1998, Chiew Lee Yih () 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 travelers from professional astronauts on missions coordinated by those two agencies.
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-led Interkosmos program. Inspired partly by these missions, other synonyms for astronaut have entered occasional English usage. For example, the term spationaut () is sometimes used to describe French space travelers, from the Latin word for "space". The Malay term (deriving from angkasa meaning 'space') was used to describe participants in the Angkasawan program (note its similarity with the Indonesian term antariksawan). Plans of the Indian Space Research Organisation to launch its crewed Gaganyaan spacecraft have spurred at times public discussion if another term than astronaut should be used for the crew members, suggesting vyomanaut (from the Sanskrit word meaning 'sky' or 'space') or gagannaut (from the Sanskrit word for 'sky'). In Finland, the NASA astronaut Timothy Kopra, a Finnish American, has sometimes been referred to as , from the Finnish word . Across Germanic languages, the word for "astronaut" typically translates to "space traveler", as it does with German's Raumfahrer, Dutch's ruimtevaarder, Swedish's rymdfarare, and Norwegian's romfarer.
For its 2022 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. 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 ). On 23 November 2022, John McFall was selected to be the first ESA parastronaut; he has rejected the use of the term.
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 for NASA or the military is considered an astronaut (with no qualifier) one who flies in a vehicle to the International Space Station in a mission coordinated by NASA and Roscosmos is a spaceflight participant one who flies above 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 a commercial astronaut by the Federal Aviation Administration