NASA\'s Jet Propulsion Laboratory in Pasadena, Calif., has announced former JPL Director Bruce C. Murray died Thursday at the age of 81 after a long illness. Murray headed the lab from 1976 to 1982, during an era of intense planetary exploration when the Viking spacecraft landed on Mars, and Voyager 1 and 2 were launched and flew by Jupiter and Saturn, JPL said. After leaving JPL, Murray was a professor of planetary science and geology at the California Institute of Technology in Pasadena, which manages JPL for NASA. During his tenure at JPL Murray had to fight for programs threatened by a rapidly shrinking budget. \"He worked tirelessly to save our nation\'s planetary exploration capability at a tumultuous time when there was serious consideration for curtailing future missions,\" current JPL Director Charles Elachi said. \"Long after returning to Caltech as a professor he continued to be an important voice in expressing the importance of space exploration.\" Murray, who earned his doctorate in geology at the Massachusetts Institute of Technology, worked as a geologist for Standard Oil until 1958, then served two years in the U.S. Air Force before coming to Caltech in 1960. He worked on planetary astronomy became part of the imaging science team for JPL\'s first two missions to Mars, Mariners 3 and 4 and served in a served a similar role on Mariners 6, 7 and 9. After retiring as director in late 1982, Murray returned to Caltech and was later named an emeritus professor at the campus. Flags at JPL have been lowered to half staff in his honor, the lab said.