Dreams of floating in zero gravity, gazing down at the vast blue and green of Earth, or stepping onto another world have captivated humanity for generations. Becoming an astronaut is a pinnacle achievement, and only a select few get to experience these wonders. But how are these few chosen? Each major space agency has its unique selection process, and in this article, we'll break down the stages for four prominent agencies: ESA, NASA, CSA, and ROSCOSMOS.

Starting Line - The Announcement and Applications

  • ESA: Prospective astronauts submit the EASA Class 2 medical certificate right at the application stage.
  • NASA: Applicants are required to undergo online assessments through the USA jobs portal.
  • CSA: An online public service entrance exam is the first hurdle for Canadian hopefuls.
  • ROSCOSMOS: The Russian space agency requires medical documentation as part of the initial application.

For more details on how the application stage works, check out the article The Journey to Becoming an Astronaut: Navigating the Application Process

Stage 1 - Setting the Foundations

  • ESA: Candidates undergo assessments testing their basic knowledge and skills.
  • NASA: The journey starts with a pre-screening history and a medical evaluation. Some may also receive a Qualifications Inquiry form, or even have their references checked.
  • CSA: Preliminary interviews combined with an initial medical examination set the tone.
  • ROSCOSMOS: Candidates experience a "Full-time stage," spending two weeks living on-site.

For more details on cognitive testing, see Mental Mastery in Space: Cognitive Skills and Training for Aspiring Astronauts

Stage 2 - Delving Deeper

  • ESA: Psychological and teamwork assessments ensure candidates are mentally prepared.
  • NASA: A more personal touch is introduced with initial interviews and activities.
  • CSA: This stage involves robotics, flight operations, and rigorous physical tests. Furthermore, an additional medical examination is conducted.
  • ROSCOSMOS: A dedicated medical commission evaluates the applicants.

Stage 3 - Advanced Assessments

  • ESA: Medical assessments are paramount at this stage.
  • NASA: Candidates undergo personal interviews, a thorough medical screening, and a one-week orientation on-site.
  • CSA: The focus shifts to survival skills and damage control tests, ensuring astronauts can handle emergencies.
  • ROSCOSMOS: No specifics mentioned for this stage.

For more details on medical assessments, you can read the articles on Astronaut Medical Selection 101 and NASA’s medical standards broken down

Stage 4 and 5 - Final Hurdles

  • ESA: The last stages involve intensive interviews.
  • NASA: Similar to ESA, NASA also emphasizes interviews during these stages.
  • CSA: The last step is a final interview complemented by medical and psychological tests.
  • ROSCOSMOS: Details are not provided for these stages.







EASA Class 2 medical submitted on application5

Online assessments with USA jobs

Online public service entrance exam

Medical documentation submitted on application

Stage 1

Basic knowledge and skill assessments

Pre-screening history and medical evaluation.  Qualifications Inquiry form may be sent to References of Highly Qualified applicants

Preliminary interviews and initial medical

"Full time stage" (two weeks living on site)

Stage 2

Psychology and teamwork

Initial interview and activities

Robotics, flight operations and physical tests. Additional medical examinations

Medical commission

Stage 3

Medical assessments4

Personal interviews, medical screening7, and orientation (one week living on site)

Survival and damage control tests


Stage 4



Final interview. Medical and psychological tests


Stage 5




While the journey to become an astronaut is a challenging one, each stage is meticulously designed to ensure that only the best-suited individuals are chosen. From assessing mental acuity and teamwork to physical stamina and medical fitness, each space agency's process, although unique, has the same end goal: selecting the best to represent humanity beyond our world.

Whether it's ESA's stringent medical requirements from the get-go or NASA's blend of interviews and hands-on activities, the path to becoming an astronaut is as diverse as the agencies themselves. So, if you've ever dreamt of reaching the stars, understanding these stages might be your first small step towards that giant leap!