[2] The group joined the continuing corps of ESA astronauts, those selected in 2009, to perform both long and short-duration spaceflight missions aboard the International Space Station, and as part of the Artemis program.

[5][6][4] The announcement of the selected candidates took place in Paris on 23 November 2022 at the Grand Palais Éphémère, at the conclusion of the triennial ESA Ministerial Council meeting.

[7] Basic training for some of the group began throughout 2023 at the European Astronaut Centre (EAC) facilities in Cologne, with a duration of approximately a year.

Although the agreement did no specify who would fly or when that mission would take place,[32] the Polish minister for Economic Development and Technology stated the intent was "to submit the candidature" of Uznański for a flight in 2024.

[33] After being initially announced as a reserve Marcus Wandt became the first of the class to be assigned to a spaceflight, as "mission specialist" aboard Axiom-3, to the International Space Station.

[43][44] In September was announced that all the reserves (other than Wandt and Uznański) would receive "selected modules of ESA’s one-year basic training programme", to be conducted in three blocks of two-month duration over the next two years – with the first beginning the following month.

[5][52] The minimum formal criteria included: being a citizen of an ESA member (or associate member) state under the age of 50; being between 150 and 190 cm tall (with possible exception under the astronaut with a disability category); a "normal weight" BMI range; fluency in English and another language; a master's degree in the Natural Sciences, Medicine, Engineering, Mathematics/Computer Sciences (plus three years of professional experience), or accreditation as an experimental test pilot; a "hearing capacity of 25 dB or better per ear"; and a current class 2 pilot's medical certificate.