The Caltech Jet Propulsion Laboratory (JPL) near Pasadena, California builds and operates unmanned spacecraft for NASA. JPL-run projects include the Galileo Jupiter mission and the Mars rovers, including the 1997 Mars Pathfinder and the twin 2003 Mars Exploration Rovers. Over the years, JPL has sent unmanned missions to every planet, except Pluto. In addition, JPL has also done extensive mapping missions of the Earth. JPL also manages the world-wide Deep Space Network, with facilities in California's Mojave Desert, near Madrid, Spain, and near Canberra, Australia.
The 177-acre JPL campus is actually located in the city of La Canada Flintridge, California, but JPL maintains a Pasadena address (4800 Oak Grove Drive, Pasadena, CA 91109), for simplicity's sake. There are approximately 5,000 full-time employees, and typically a few thousand additional contractors work there on any given day. The lab has an open house once a year on a Saturday in May, when the public is invited to tour the facilities and see live demonstrations of JPL science and technology. More limited private tours are also available throughout the year if scheduled well in advance. Thousands of schoolchildren from around Southern California and elsewhere visit the lab every year.
JPL dates back to the 1930s, when Caltech professor Theodore von Karman began running rocket propulsion experiments on the site. During World War II, the United States Army Air Corp asked JPL to analyze the V2 rockets that were developed by Nazi Germany, as well as work on other projects for the war effort.
By 1958, JPL's government affiliation was transferred to the new National Aeronautics and Space Administration (NASA), and JPL's current mission of unmanned planetary exploration began. JPL retained its original name after the transition, even though any research into jet propulsion ceased after 1958.
In addition to its government work, JPL has also assisted the nearby motion picture and television industries, by advising them about scientific accuracy in their productions, For example, a science-fiction show which has consciously attempted to be true to portraying physics correctly is Babylon 5. The sequel series, "Crusade", went so far as to formally enter into a working partnership with NASA's Jet Propulsion Laboratory to ensure scientific accuracy.