Reminds me of Sunshine.
I like this! Have you ever seen Danny Boyle's film "Sunshine". It's a film about a space mission that goes all wrong, it had the most fantasic music by John Murphy. Anyway this song reminded me of the film, and probably woundn't have been too out of place in it.
You captured what you were going for perfectly. You get the immediate feel of both beauty and sadness. But! The song doesn't break any new ground after halfway in, so it's a little too long for it's own good. I suppose that might have been what you were going for since he's forever floating though space, but it almost felt like you could have gone somewhere else with it towards the end. I'm not sure.