How to become an astronaut
Both NASA and ESA publish their minimum requirements, and they are more specific than most advice suggests: a master’s degree in a relevant field, documented professional experience, and a medical certification.
Updated on October 7, 2026
NASA astronaut candidate requirements
- Citizenship
- United States
- Education
- master's degree in engineering, biological science, physical science, computer science or mathematics
- Accepted instead of the master’s
- doctorate, medical degree, or completion of a test pilot school programme
- Professional experience
- at least 2 years of related work, or 1,000 hours of pilot-in-command time in jet aircraft
- Medical
- must pass the NASA long-duration spaceflight physical
- Selection frequency
- roughly every 4 years, by open call
- Typical competition
- over 12,000 applicants for about 10 places in recent rounds
ESA astronaut requirements
- Citizenship
- a member or associate member state of ESA
- Education
- master's degree or higher in natural sciences, medicine, engineering, mathematics or computer science
- Accepted instead
- qualification as an experimental test pilot
- Experience
- at least 3 years of relevant professional experience after the degree
- Languages
- fluent English; another language is an advantage
- Selection frequency
- rare: 1978, 1992, 2008, then 2021-22
- Parastronaut
- ESA opened a feasibility programme for candidates with certain physical disabilities in 2022
What the requirements do not tell you
Meeting the minimum gets your file read, nothing more. Selection boards look for people who have already done hard, consequential technical work in teams under pressure: field geology in difficult places, operational flying, surgery, submarine or polar deployments, running an instrument through a real mission. Among those selected, scuba qualifications, wilderness experience and a second language come up again and again, because training involves spacewalk practice underwater, survival exercises and life in Russian-language systems.
Then there is time. Once selected, basic training runs about two years, and the wait for a first flight has often been another three to seven. There are also other routes into orbit now — private missions, and national programmes in Canada, Japan, India, the UAE and China with their own calls. Check the agency’s own page before applying: these criteria change between rounds, and the versions here were taken from the official pages on the date shown.
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More about “How to become an astronaut”
The competition, by the numbers
With roughly 12,000 applicants for 10 seats, a recent NASA selection’s acceptance rate ran at about 0.08%. Meeting the requirements listed on "How to become an astronaut" gets you into the process, not a guarantee — most people who meet every requirement still aren’t called.
Words on this page
Astronomical unit
The solar system’s reference distance, fixed at exactly 149,597,870,700 metres since 2012, close to the average Earth–Sun distance. It saves writing every planet’s orbit in kilometres with ten digits.
Standard definition by IAU — International Astronomical Union · Astronomical unit
Standard uncertainty
The margin attached to a measured value, usually written in parentheses on the last digits. A constant that is "exact by definition" has zero standard uncertainty; a measured one, like the gravitational constant G, always carries some.
Standard definition by BIPM — Bureau International des Poids et Mesures (SI) · Standard uncertainty
Exoplanet
A planet orbiting a star other than the Sun. Most were found indirectly, by the star’s faint dimming as the planet crosses in front of it (transit) or by the gravitational wobble it causes in the star (radial velocity), not by direct image.
Standard definition by NASA Exoplanet Archive · Exoplanet
Launch window
The span of time in which a rocket can lift off and still reach its planned orbit or destination. For a trip to another planet that window can last only a few weeks and only returns at the next favourable alignment, so missing it costs months or years of waiting.
Mole
The SI counting unit for atoms, molecules or other entities: one mole is exactly 6.02214076 × 10²³ of them, by the definition fixed in 2019. It is what ties a mass in grams to a number of particles.
Standard definition by BIPM — Bureau International des Poids et Mesures (SI) · Mole