ROANOKE TIMES
Copyright (c) 1997, Roanoke Times
DATE: Monday, April 7, 1997 TAG: 9704070114
SECTION: NATIONAL/INTERNATIONAL PAGE: A-3 EDITION: METRO
SOURCE: THE NEW YORK TIMES
There are no immediate fears for the safety of the crew, NASA said.
After two days of wrestling with a power supply problem, space agency officials decided Sunday to bring the space shuttle Columbia home Tuesday afternoon, ending the mission 12 days early.
NASA officials said that there were no immediate concerns for the safety of the seven-member crew on the shuttle but that ending the planned 16-day mission was ``prudent'' because of problems with one of three essential fuel cells that produce electricity for Columbia.
``The conservative thing to do is land on Tuesday,'' Thomas Holloway, the shuttle program manager, said at a news conference at the Johnson Spaceflight Center in Houston, where missions are controlled.
Holloway said an emergency landing today was ruled out because there was no immediate concern for crew safety and because Columbia's two other fuel cells were working well. Although the problem is serious and flight rules require that a shuttle come home if it does not have three working fuel cells, he said, the situation is not so bad that undue haste is required.
The decision is only the third time since space shuttle flights began in 1981 that a mission has been ended early by the National Aeronautics and Space Administration. On the second mission of the program, in November 1981, Columbia was called back three days early because of a fuel cell problem. And in December 1991, Atlantis also returned three days ahead of schedule, on the 44th mission, because of malfunctioning navigational equipment.
Fuel cells are at the heart of a shuttle's operations. The devices combine supercold liquid hydrogen and liquid oxygen to generate electrical power. The cells also produce the crew's drinking water as a byproduct of the system.
Holloway, the program manager, said that ``with 20-20 hindsight,'' the countdown should have been delayed and the unit swapped with a spare. But at the time, he said, the decision was sound and based on the information at hand. He said the behavior of the troubled fuel cell was unlike any ever seen before in operations or in tests.
``We really do not have enough data to really understand the situation,'' said Holloway, the program manager.
LENGTH: Short : 48 linesby CNB