If you really like Carl Sagan, you should check out Vangelis; Movement 3 from the album "Heaven and Hell" is the opening theme from the Cosmos TV series. "L'Apocalypse des Animaux" is another great Vangelis album. I also highly recommend "Does It Look Like I'm Here?" by Emeralds and "Ambient 1: Music for Airports" by Brian Eno. Excellent space music.