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February 23, 1996
Web posted at: 9:45 a.m. EST
SPACE CENTER, Houston (CNN) -- On the first full day of their mission to make electricity in space, the astronauts of space shuttle Columbia prepared Friday for the tricky and dangerous task of releasing a half-ton satellite on a 13-mile leash. (363K QuickTime Movie)
The $443 million tethered satellite, a U.S.-Italian project, is making its second space voyage. The first, in 1992, was a flop. The second try comes Saturday, when astronauts attempt to reel out the satellite on a slender cord resembling a boot lace. If all goes well, the satellite- tether assembly will generate electricity as it sweeps through Earth's magnetic field at 17,500 mph.
Soon after Thursday's liftoff, NASA said a light showed Columbia's main engine was not working at full power. But the engine responded to commands from Johnson Space Center in Houston and was found to be functioning properly. Until all the data was examined, launch officials said engineers would not know the cause of the indicator light problem.
The most demanding tasks for Columbia's seven-member crew was to begin at about 3:37 P.M. (2037 GMT) on Saturday when the satellite is reeled out to a distance of almost 13 miles. Plans call for Columbia to tow the satellite for about 48 hours.
The riskiest part of the satellite deployment will begin at about 12:38 p.m. (1738 GMT) on Monday when the crew starts to reel it in. The operation is expected to be difficult because the thin tether could break and snap back at the spacecraft.
Four years ago, astronauts were able to unreel only 840 feet of the tether when it snagged on a bolt and tangled in the cargo bay. Hardly any electricity was produced. The bolt and other problems with the satellite have been fixed. NASA officials are confident of success this time around, though they acknowledge release and retrieval of the satellite will be tricky.
The tether is narrower than a shoelace but stiffer than a fishing line. If all goes well, it will be cast out like a long line on a fly-fishing rod. If the experiment is successful, NASA has high hopes for tethered satellites. NASA engineers said a tether dragged through Earth's ionosphere generates electricity, which could be used to power the planned international space station.
Once the tether test is over, the crew will focus on crystal, metal and fire experiments for the remainder of the two-week flight. Columbia is due back at Cape Canaveral, Florida on March 7.
Associated Press and Reuters contributed to this report.
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