3 ms·Why wouldn't they spin instead in a near-vacuum, instead of an environment of hydrogen?by nakedrobot2 13y agoWhy wouldn't they spin instead in a near-vacuum, instead of an environment of hydrogen?bronson 13y agoBecause near vacuum is a terrible heat conductor.kragen 13y agoVacuum has no drag but also no thermal conductivity, so you'd have to cool the generators some other way.