Atem is more melodic and less dissonant than Tangerine Dream's other early works. The lineup of Edgar Froese, Christopher Franke, and Steve Schroyder puts a nice topspin on the old prog rock sound. They take it to the edge -- as in cutting -- and beyond. While it is still very common to see TD listed as progressive rock and art rock, this album is pure space music. It goes beyond the confines of rock & roll.