ROANOKE TIMES
Copyright (c) 1996, Roanoke Times
DATE: Saturday, November 23, 1996 TAG: 9611260069
SECTION: NATIONAL/INTERNATIONAL PAGE: A-6 EDITION: METRO
DATELINE: CAPE CANAVERAL, FLA.
SOURCE: Associated Press
Columbia's astronauts heaved another science satellite into orbit Friday night, this one to grow thin semiconductor film in the ultraclean vacuum of space.
As the space shuttle soared 220 miles above the Pacific Ocean, crewman Thomas Jones released the grip of the orbiter's robot arm on the 12-foot-diameter steel disk, called the Wake Shield Facility.
On Tuesday, the shuttle crew dropped off an ultraviolet telescope to observe stars. The telescope was about 60 miles behind Columbia when the Wake Shield was set loose for three days of free flight.
The release is the first time a space shuttle has flown in formation with two satellites.
The five astronauts will use radar and lasers to keep track of the satellites, both of which will be retrieved later in the 16-day flight. Ground stations also will monitor the spacecraft for safety reasons.
To be safe, NASA wants at least 28 miles, and preferably 58 miles, between Columbia and the telescope, with the Wake Shield in between.
Scientists will try to grow seven semiconductor-film wafers on the back of the Wake Shield in the super-pure wake created as it zooms around Earth at 17,500 mph.
Atoms of aluminum, arsenic, gallium and indium will be combined, atom by atom, atomic layer by atomic layer, to form the film. The 10,000 to 20,000 atomic layers constituting each 3-inch wafer will be just one-tenth the thickness of a human hair. The film will be tested for use in transistors and other electronic devices.
Alex Ignatiev, director of the University of Houston research center that designed the satellite, said the vacuum in the satellite's wake is cleaner than vacuum chambers on Earth, and should yield faster and better semiconductor film than that now used in computers and other electronics.
If the technique proves feasible, it could be lucrative. Ignatiev said permanently orbiting spacecraft could one day produce up to 10,000 wafers of semiconductor film a year, worth about $40 million at today's prices.
Tension at NASA will be high, given the trouble-plagued history of the satellite.
The disk could not be released from space shuttle Discovery in 1994 because of wiring and sensor problems, and all the semiconductor film was contaminated. It was deployed the following year from Endeavour but had communication problems, overheated, wobbled and even tumbled. Only three ``quality'' film wafers were grown.
``The peer pressure, so to speak, is a bit more severe this time,'' Ignatiev said. He said improvements have been made to the satellite and more rigorous testing was done this time. NASA has spent $29 million on the experiment.
At Kennedy Space Center, a preliminary check of the booster rockets used to launch Columbia revealed heat damage to the insulation of both nozzles but not as much as on the previous shuttle flight, officials said.
Columbia's mission was delayed a week because of concerns over the unusual amount of damage to nozzle insulation during the September launch of Atlantis.
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