Astronauts Begin Bouncing Radar Beams Off Planet's Surface

CANAVERAL, Fla. (AP) â€“ Space shuttle Endeavour's astronauts fired up their radar and began bouncing beams off Earth on Saturday to create the ultimate map of the planet's peaks and valleys.

Saturday, February 12th 2000, 12:00 am

By: News On 6

CANAVERAL, Fla. (AP) â€“ Space shuttle Endeavour's astronauts fired up their radar and began bouncing beams off Earth on Saturday to create the ultimate map of the planet's peaks and valleys.

Mapping got under way as Endeavour orbited high above the Maldives and then Sri Lanka. If all goes well, more than 70 percent of Earth's terrain will be mapped over the next week, as far north as Alaska and as far south as the tip of South America. Scientists were thrilled with the early results.

"Can you all hear my heart beating? You ought to be able to, because I can tell you, this has been the best 25 hours and 19minutes of my life so far," said Michael Kobrick, a scientist working at Mission Control.

That's how long Endeavour had been in orbit. NASA half expected problems in deploying the 197-foot radar antenna mast from a can in the shuttle cargo bay. But Friday evening's extension of the mast went smoothly -- so smoothly that the astronauts were able to start mapping a little early. The mast -- a series of 87 stacked cubes made of steel, titanium and plastic -- is the longest rigid structure ever flown in space.

Attached to the far end, like the cross on a T, is a 26-foot radar antenna.

For astronaut Janice Voss, who's in charge of the payload, the outstretched mast was a welcome sight. Because Endeavour's six astronauts are split into two teams working day and night, she was asleep when the mast went out.

"As much as I would have loved to have been here when this came out, it was also pretty fun to go zooming up out of my bunk up here and peer out the commander's window and see the mast shining in the sunlight glittering all the way down like a really, really tall Christmas tree with icicles on it," Voss said.

Here's how the radar mapping works: As Endeavour orbits 145 miles high, a 39-foot antenna in the cargo bay beams radar signals at the Earth. The beams sweep across the Earth in a swath 140 miles wide. The signals bouncing back are received by both the cargo-bay antenna and the antenna 197 feet away at the tip of the mast. By combining the two sets of images, scientists hope to compile3-D snapshots of Earth's terrain with unprecedented accuracy and clarity. All the radar information is stored on tape aboard Endeavour.

The crew's main job, in fact, is to keep putting new tapes into the recorders and keep the machines running. However, snippets of data were sent down for analysis, and NASA and its partner, the National Imagery and Mapping Agency, said they appeared to be of excellent quality.

"Things have gone so well it's almost a little spooky, "Kobrick said. "I kept looking behind me trying to figure out what's going to go wrong and, basically, nothing has that's going to affect our mission in any extent."

After nine days of mapping, the astronauts hope to fill nearly300 data tapes, or the equivalent of 13,500 compact discs. Scientists expect it will take one to two years to analyze all the information.