Psychedelic, Mid-frequencies, Cavernous, Resonant, Deep
As we've established, there is no sound in the vacuum of space. But it could be these are the sounds you hear when you're on a super creepy planet that is lost in space. The planet might not be lost in space, but you certainly are. Psychedelic is certainly the primary feel of these sounds, thus being labeled as the first descriptive word. However, these ambient sounds could be used in so many ways, my suggestions would be moot. So enhance your visual environments with some super strange audio environments.