Greetings !! You are aiming for such a good profession.

To be an Astronaut in NASA you need to fulfill these general criterias

1. You need to have a Master's degree in STEM field including Engineering or Computer Science or Mathematics or Biological Sciences from an institution with proper accreditation.

2. 2 years professional experience after degree completion or minimum 1000 hr Pilot-in-command time on jet aircraft.

3. Should pass the long duration NASA Flight Astronaut  Physical.

Hope it helps!!