Maneuver Saves Shuttle Mission.

Astronauts on the space shuttle Endeavour did a tricky piece of flying dubbed a ``fly cast'' on Sunday to boost the shuttle_s orbit without too much jiggling of a 20-story radar mast being used to make the world_s finest three-dimensional map of Earth_s surface. The astronauts were in their third day of orbit and their second day of map-making, using sophisticated radar gear aboard the orbiter and at the end of the 197-foot mast. The radar mast, a truss made of stainless steel, titanium and plastic, is lightweight and resilient, just like the fly-fishing rods used by fishermen in trout streams. As with the fly rod, a gentle touch gets the best results. Unlike a fly rod, Endeavour_s crew doesn_t want to see its mast whipping back and forth, since that would upset the radar readings. The maneuver began with a short forward firing of the orbiter_s control jets, which causes the radar mast to bend back as the shuttle accelerates. As the mast whipped back forward, the crew caught it at its vertical point by firing the thrusters again, offsetting the mast_s forward momentum. They continued to fire until the shuttle reached the desired orbit. Since Endeavour is flying in a rather low orbit for this mapping mission, the upper fringes of Earth_s atmosphere slow it down and cause it to lose altitude. The maneuver_s success was one of the critical milestones for the 11-day mission. ``We_ve already got about 15 percent'' of Earth, said Mamoru Mohri, an astronaut with the NASDA, the Japanese space agency and a mission specialist on Endeavour. The crew is expected to record about 72 percent of the planet in nine days of mapping. The National Aeronautics and Space Administration (NASA) has said the topographical data collected by Endeavour will result in a map that is 30 times better than existing whole-Earth maps, but most of it will remain classified.