Number 163 (Story #4), February 4, 1994 by Phillip F. Schewe and Ben Stein COBE RETIRES. Launched in November 1989, the Cosmic Background Explorer was the first to discover fluctuations in the microwave background. A backlog of data is still being analyzed, but the spacecraft was turned off 23 December 1993. (Sky & Telescope, March 1994.)