Bruce Murray, the former director of NASA’s Jet Propulsion Laboratory (JPL) who went on to co-found the Planetary Society with Carl Sagan in 1980, died Aug. 29. He was 81 and had Alzheimer’s disease.

Murray ran JPL from 1976 to 1982, a period that included the landing of a pair of Viking probes on Mars and the launch of Voyagers 1 and 2 on deep-space treks still underway 36 years later.