Having listened to Ashra's "Blackouts"(1977) and "New Age of Earth"(1976) again recently, I would highly recommend both these albums for inclusion on the Moon. Both have quite a layered ambient feel, with some of the longer tracks reminiscent of Tangerine Dream. While NAOE is more synth-based, Blackouts features some beautiful melodic guitar. For anyone who doesn't know these albums you can hear some mp3 samples at:
http://www.ashra.com/disco/welcome.htm