Astronauts and SRTM equipment in wide-angle (from above the main antenna): NASA's STS-99 radar-mapping mission, set for launch on Sept. 16, 1999, aboard the space shuttle Endeavour, will yield a wealth of high-resolution topographic data of Earth's varied landscape, from its highest volcanic peaks to the deepest canyons carved millions of years ago. The radar data, which can see through clouds, thick vegetation and ground cover such as sand, will improve scientists' ability to see subtle changes in geologic features such as earthquake fault lines and river beds that have swelled and changed course. Radar data may also allow them to detect changes in some of Earth's most fragile ecological niches, such as the rain forests of South America and the unspoiled highland regions of central Africa, home to the endangered mountain gorillas. From left to right: Gerhard Thiele, European Space Agency; Mamoru Mohri, National Space Development Agency of Japan (NASDA); Dominic Gorie, STS-99 space shuttle pilot; Janice Voss, NASA; Janet Kavandi, NASA; and STS-99 mission commander Kevin Kregel, standing in center of circle facing a clean room technician (back to camera). The mechanical engineer, Howard Eisen of JPL, is explaining how the radar antenna mast, the longest structure ever to be flown in space, will be deployed from its cylindrical canister.