Having recently discussed sound in film, I thought this would make a good followup. Check out this article from CreateDigitalMusic.com about NASA’s recently released sound library:
http://createdigitalmusic.com/2014/10/nasa-posts-huge-library-space-sounds-youre-free-use/
https://soundcloud.com/nasa
The quality of some of these sounds is questionable – they all have a sort of low-fi transistor radio feel to them – but I’m imagining them being used precisely for that atmosphere (pardon the pun). These will make great background sound effects or ambiance for space-themed scenes, particularly where the sounds are supposed to feel like radio transmissions.
Create Digital Music’s article also touches on a legal discussion, which is always enlightening. Nasa’s page on SoundCloud has links to their “Use Policy,” which is probably the most important thing you should look for any time you’re using content you didn’t create personally.