Astronaut - Air Force test pilot and any technical degree. I would suggest geology for manned missions.
Spacecraft design, Propulsions - Aerospace/Mechanical/nuclear/electrical engineering
Computer systems engineer - computer engineering
Space station engineer - Mechanical, electrical, possibly biological engineering. I think UHouston has a Master's degree in Space Architecture
Planetary scientist/engineer - Geology, Geography, Meteorology, Physics, Chemistry
Astronomer - Astronomy/Physics
Take plenty of Math classes no matter what you do.