The astronaut selection process is based on criteria matching the requirements of the various missions foreseen. Astronaut candidates are pre-selected in ESA Member States and finally selected by ESA. Major aspects taken into consideration are psychological suitability, scientific and technical competence and fulfilment of medical criteria. The selection is based on the following criteria :

General requirements

Applicants, male or female, must be nationals of an ESA Member State. The preferred age range is 27 to 37 and applicants must be within the height range of 153 to 190 cm. They must speak and read English and have a university degree (or equivalent) in Natural Sciences, Engineering or Medicine, and preferably have at least three years postgraduate professional experience in a related field. Flying experience is welcome.

Medical requirements

Applicants should be in good health, have a satisfactory medical history, be of normal weight and have a sound mental disposition. Specific tests are performed to evaluate applicants' bodily systems (muscular, cardiovascular and vestibular). These tests use facilities such as centrifuges, rotating chairs, pressure chambers and aircraft.

Psychological requirements

The general characteristics expected of applicants include good reasoning capability and memory, concentration, aptitude for spatial orientation and manual dexterity. An applicant's personality should be characterised by high motivation, flexibility, gregariousness, empathy with fellow workers, a low level of aggressiveness and emotional stability. For long-term flights on the Space Station ability to work as a team member in an intercultural environment is of high importance.

Professional requirements

The candidate should be knowledgable in scientific disciplines and should have proven outstanding ability in applicable fields, preferably including operational skills.