There's no set requirement - it depends entirely on the mission requirements (EVA, satellite deployment or recovery, ISS docking, etc.) as to what they'll do an how many they'll perform.
However, it's not unusual for them to train for hundreds or thousands of hours prior to their missions. Remember that mission crews are typically selected several years in advance of the actual mission, so they have plenty of time to train.
456
None. You cannot land in space.
The astronauts have been aboarding it since 1998.
i think but i am am not sure but i think it was 1-3 astronauts
6
I'm a professional but even i don't know how many astronauts go into space a year too many to count
456
None. You cannot land in space.
Space Adaptation Syndrome
The astronauts have been aboarding it since 1998.
6 went with her
there is 8 million astronauts that live in space
30 years
15
3-5
There were 2 astronauts on each Project Gemini mission.
i think but i am am not sure but i think it was 1-3 astronauts