After seeing the NASA footage of STS-135's rocket boosters breaking away from the shuttle and falling back to Earth, I knew I had to use the audio from those videos. It's so raw and powerful. I extracted the audio from the video feed of both the left and right booster, and then lined them up (in time) in my audio workstation. So what you hear are both boosters breaking away... and then (my guess) the remaining fuel burning away into the vacuum of space. Pretty rad. It gives me chills. The burning fuel noise increases as the boosters fall toward Earth, and line up an amazing climax..., a perfect blueprint for "song". So, I fed the space sounds through some tasty reverb, added a little bit of analog sounds... and I was done.
The original video(s) where I sourced the audio can be found here: www.youtube.com/watch?v=zxE3KBRorZI