In 2000, the Space Shuttle Endeavour carried the Shuttle Radar Topography Mission (SRTM) payload into orbit. Shuttle astronauts used the payload, manufactured by the AEC-Able Engineering Co., to map in high detail and three dimensions more than 70 percent of the Earth's surface--the most complete and accurate rendering of the planet's land masses ever attempted. To acquire this data, the SRTM used a novel hardware system that featured a main antenna located in the Shuttle payload bay, a folding mast (in the mast canister) that extended 60 meters from the Shuttle, and then another antenna system that was positioned at the end of the mast (the outboard structure). It was this dual antenna system — the largest rigid structure then flown in space — that produced, through interferometry (a technique for combining the information obtained from the two, separate antennas), a three-dimensional mapping of the Earth. The mission was a joint undertaking of NASA's Jet Propulsion Laboratory (JPL) and the Department of Defense's National Imagery and Mapping Agency. The military will use the highest resolution data from SRTM for terrain navigation for planes and cruise missiles. A lower resolution data set will be made available to civilian scientists and other users.