Space rape is a simple action when some dumb ass alien hobos rape you for fun.
It is not mandatory that they are hobos, but it most situations that is the case.
A very very common situation you can get yourself in while sucking your won dick.
Quite literally means being raped by Russian Cosmonauts and or other space-residing entities. However an alternative meaning could mean being raped by space itself (asteroids, high levels of radiation, no oxygen, etc).
a) John hasn't been the same since he was space raped by that Cosmonaut. Now he doesn't go to bed without his waxed replica doll of Lenin.
b) A sure-fire way to get space-raped is stepping outside the space station for a walk without a helmet.