From 1978 to 1982, he worked at the DFVLR (the precursor of the DLR) in the Institute of Communications Technology in Oberpfaffenhofen on space-borne communications. In 1983, he was selected as one of the astronauts for the first German Spacelab mission D-1. He flew as payload specialist on STS-61-A in 1985, spending over 168 hours in space.
After his spaceflight he became a professor at the Institut für Raumfahrtsysteme at the University of Stuttgart. Since 1999, he is head of the European Astronaut Center in Cologne. In January 2005, he returned to the University of Stuttgart teaching on subjects of Astronautics and Space Stations.