What kind of Astronaut wouldnt know how far up the Van Allen Belt begins and ends ?
Why would he? The astronaut isnt necessairly an astrophysicist.
Why would one Astronaut say the Lunar Module Rocket is loud and the other say say you cant hear it in the vacuum of space ?
Because you cant hear it in the vacuum of space. Remember how the first one said its hard to explain the difference between hearing the sound and feeling the sound, btw?