The astronaut Chris Hadfield had a massive YouTube hit this week with his version of the song Space Oddity by David Bowie. The video was made in the ISS space station. He also appears to have a large amount of sounds which he recorded in space. He has posted these sounds on SoundCloud.
The quality of these space sounds is very good. They can be downloaded for use in your own tracks. Ideal for the production of ambient music or to spice up your tracks with some cool noises. Unfortunately I have no clue whether they can be used for free.