NASA has released a full library on Soundcloud dedicated to their sounds of space, commentary, and shuttle take offs. Even though many of the sounds have been available already, they have made it easier compiling them on their own Soundcloud that is free to use by anyone. Best part is that they are completely copyright free (hopefully you won't be bothered by Soundclouds policy if anyone chooses to use them.)
All available as free downloads, although if anyone plans on using them for their own songs you might be a little let down as they are MP3 format. We are really interested to see what people come up with this NASA release. Everything from rocket engine sounds, John F. Kennedy commentary, even lightning on Jupiter are all at your fingertips.