In the world of space and ambient music, the German group called Cluster are eccentric wizards, musical alchemists who defied traditions, even the ones they helped create in 1970s Berlin. One half of this influential band, Dieter Moebius, died on July 20 at the age of 71. We listen back to an interview with Cluster from 1997, and hear some music from Cluster, Harmonia, and Cluster and Eno.