How long does it take to become an astronaut?

The clock starts well before a selection campaign opens. ESA requires at minimum a university master's degree in natural sciences, medicine, engineering, mathematics or computer science, along with relevant professional experience or a doctorate; a test pilot qualification is an equivalent entry route. In practice, this already represents five to ten years of study and career, depending on the path taken.

A scheduling constraint beyond the candidate's control adds to this: European selection campaigns are spaced more than a decade apart. The 2008-2009 campaign preceded the 2021-2022 one, leaving few windows within a career.

The campaign opened by ESA in 2021 concluded with the presentation of the selected candidates in November 2022, after several rounds of psychological, cognitive, practical and medical tests. Next comes basic training, lasting about a year, covering the station's systems, robotics, emergency procedures, survival, scuba diving and languages, including Russian.

This is followed by advanced training, then mission-specific training, carried out at partner centers in Europe, the United States, Japan and Russia.

The last stage is the most unpredictable: it depends on available crew slots, which in turn depend on agreements between agencies and the number of flights. Some selected candidates fly a few years after their appointment, others wait much longer. Thomas Pesquet, selected in 2009, didn't launch until November 2016, seven years later. In the meantime, unassigned astronauts take on support roles: monitoring experiments from the ground, communicating with crews in flight, and contributing to the development of future vehicles.