Nektar - Journey to The Centre of The Eye
Although their second release, "A Tab in the Ocean" is much more refined, It's more of a prog. rock album with spacey elements. Journey... takes more influences from krautrock. It's a concept album about an astronauts journey in space and half of it is instrumental. Highly layered, dreamy and quite enjoyable. The organ/Mellotron take center stage here.
I already posted a track earlier, but anyways, here are more -
YouTube - Nektar - prelude_astronauts nightmare
YouTube - NEKTAR-JOURNEY TO THE CENTRE OF THE EYE
YouTube - Nektar — Countenance
YouTube - Nektar - warp oversight(track ends at around 4:10)