Aerospace engineering
The corps' native languageVehicle systems, orbital mechanics and failure analysis are the daily substance of training; engineering remains the single most common background across NASA, ESA and China's post-2020 selections.
Becoming an astronaut is unique among career paths: it is a second profession stacked on a first. Agencies do not hire promising students; they hire finished pilots, engineers, physicians and scientists — usually in their mid-thirties — and then spend years retraining them. The single most useful preparation is a decade of being genuinely excellent at something an agency needs.
The bottleneck is not the training but the door. Selections open rarely — NASA every four years or so, ESA roughly once a decade — and each draws ten to twenty thousand applicants for a handful of places. Everything before the interview rounds exists to filter: degrees, flight hours, publications, medical history. Everything after exists to answer one question — can this person live and work, calmly and agreeably, in a small can with others for months?
The route in
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1
A STEM degree
3–4 yrsEngineering, physical or biological science, mathematics or medicine at a rigorous university — the non-negotiable floor for every agency corps in the world. Military academies serve the same function for the pilot route.
The filterNo formal gate yet, but grades and the choice of field decide whether the later CV survives its first thirty-second screening.
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2
Go deep: advanced degree or the cockpit
4–10 yrsNASA requires a STEM master's (or MD, test-pilot school, or substantial doctoral work) plus professional experience — or 1,000 hours as pilot-in-command of jet aircraft. Most successful candidates bring far more: PhDs, operational military careers, expedition science, or all three.
The filterThe paper filter: NASA's 2021 round cut over 12,000 applications to a few hundred interviews mostly on this record alone.
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3
The selection campaign
~1 yrWaves of cognitive and psychomotor testing, medical screening to a long-duration flight standard, team exercises and panel interviews, thinning thousands to dozens. ESA's 2021–22 campaign processed 22,523 applications through six stages to reach 17 names; NASA's 2021 round picked 10.
The filterEverything at once — the medical commission alone eliminates a large share, and overall odds run near one in a thousand.
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4
Basic training (astronaut candidate)
≈2 yrsSpacecraft systems, spacewalk qualification in the Neutral Buoyancy Laboratory's 12-metre-deep pool, robotics on Canadarm2 simulators, T-38 jet operations, wilderness and water survival, and Russian language study — ending, at NASA, with the silver astronaut pin.
The filterContinuous evaluation; a medical flag or a failed spacewalk qualification can end a career that survived thousand-to-one odds.
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5
Ground rotations and the wait
2–10+ yrsCertified astronauts work as capsule communicators in mission control, serve on backup crews, test hardware and live in undersea NEEMO habitats while waiting for assignment. The wait is real: Jeanette Epps was selected in 2009 and first flew in 2024.
The filterThe flight assignment board — an opaque judgment by the chief astronaut weighing skills, mission needs and how well you wear the wait.
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6
Mission training and flight
1.5–2.5 yrs per missionA named crew trains together across Houston, Star City, Cologne and Tsukuba for a specific increment: every experiment, every emergency drill, every spacewalk choreographed underwater first. Then six months in orbit, followed by months of physical rehabilitation and debriefs.
The filterCrew medical certification, re-checked until days before launch — every prime crew trains alongside a backup ready to take the seat.
Cost of entry
≈$0 in fees — a career in time
No agency charges for astronaut training; candidates are salaried from day one. The real price is everything before: the degrees (free in much of Europe, $200,000+ in the US), a decade of a first career, and odds near one in a thousand at the door. The only way to buy past the queue is the private route, where an orbital seat has sold for tens of millions of dollars.
What to study
Physics & astronomy
Depth agencies can retrainPhysicists arrive with the mathematical core the job's systems knowledge hangs on; ESA's 2022 class included astrophysicist Rosemary Coogan, and physics PhDs recur throughout NASA's scientist-astronaut lineage.
Medicine
Every long crew wants a doctorPhysicians double as crew medical officers and as investigators on the human-body experiments that justify the station; Valeri Polyakov, the 437-day endurance record holder, was a physician studying his own mission.
Geology & planetary science
The Moon is the destination againApollo 17's Harrison Schmitt, a geologist, remains the only scientist to walk the Moon; with Artemis planning lunar fieldwork, agencies are again screening for people who can read a landscape through a visor.
Biochemistry & biology
The station is a life-sciences labMuch of ISS research is biological — protein crystals, plant growth, the crew's own physiology — and the route works: biochemist Peggy Whitson became NASA's most experienced astronaut ever.
Where it is taught best
United States Naval Academy
United StatesMore astronaut alumni than any other US institution — over fifty, including Alan Shepard and Jim Lovell — via the naval aviation and test-pilot pipeline.
Purdue University
United StatesThe self-styled "Cradle of Astronauts": more than 25 astronaut alumni, including the first and last people to walk on the Moon, Neil Armstrong and Eugene Cernan.
Massachusetts Institute of Technology
United StatesBuzz Aldrin's 1963 doctoral thesis on orbital rendezvous was applied on his own Gemini and Apollo flights; MIT counts dozens of astronaut alumni, mostly at graduate level.
Moscow Aviation Institute
RussiaThe classic cosmonaut-engineer school, feeding Energia and the corps for decades; alumna Svetlana Savitskaya became the first woman to walk in space in 1984.
ISAE-SUPAERO
FranceEurope's leading aerospace grande école in Toulouse; alumnus Thomas Pesquet became ESA's most-flown active astronaut and commanded the ISS in 2021.
University of Tokyo
JapanIts aeronautics department trained JAXA astronauts including three-flight veteran Soichi Noguchi and Naoko Yamazaki; the standard academic gateway to Japan's corps.
Beihang University
ChinaBeijing's aerospace university supplies the engineers behind Shenzhou and Tiangong; professor Gui Haichao flew on Shenzhou 16 in 2023 as China's first civilian in space.
Karlsruhe Institute of Technology
GermanyWhere ESA's Alexander Gerst — volcano geophysicist turned two-mission ISS commander — took his geophysics degree before the 2009 ESA selection.
Licences and exams
NASA astronaut selection
United StatesRequires US citizenship, a STEM master's degree (or MD, test-pilot school, or doctoral progress), professional experience or 1,000 jet pilot-in-command hours, and passing the NASA long-duration flight astronaut physical. Roughly every four years; 10 chosen from over 12,000 in 2021.
ESA astronaut selection
EuropeOpen to citizens of ESA member states roughly once a decade. The 2021–22 campaign drew 22,523 applications and produced 5 career astronauts, 11 reserves and 1 parastronaut through six elimination stages, from cognitive batteries to medical boards at Cologne.
Roscosmos cosmonaut selection
RussiaRun through the Gagarin Cosmonaut Training Center at Star City, open since 2012 to civilian engineers as well as military pilots. Candidates must pass the state medical commission and years of examinations before earning the title of cosmonaut.
China Manned Space Agency selection
ChinaBatches selected since 1998, originally only PLA fighter pilots; the third and fourth batches added civilian flight engineers and payload specialists, with the 2024 round including candidates from Hong Kong and Macau for the first time.
The other way in
The paying passenger route
Dennis Tito opened it in 2001, paying a reported $20 million for a Soyuz seat; Axiom's ISS missions have sold seats reported around $55 million, and Inspiration4 in 2021 flew physician assistant Hayley Arceneaux — a childhood cancer survivor with no aviation background — proving orbital flight no longer requires a corps career, only a sponsor.
The partner-nation door
Since the Soviet Interkosmos program flew Czechoslovakia's Vladimír Remek in 1978, small nations have flown astronauts through bilateral deals rather than standing corps: the UAE sent Hazza Al Mansouri to the ISS in 2019 and Sultan Al Neyadi for six months in 2023 under agreements with Roscosmos and NASA/Axiom.
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