April 7, 1997 in Nation/World

Nasa Calls Columbia Crew Home Faulty Generator Creates Risk Of Explosion

William Harwood Washington Post

The potential for an explosion in an electrical generator forced the Columbia astronauts Sunday to cut short a planned 16-day science mission and to prepare instead for a quick flight home on Tuesday.

The decision to abort the 83rd shuttle flight was a crushing disappointment to scores of scientists and engineers who began planning the complex series of microgravity experiments more than three years ago. Only a handful of the 33 planned experiments can be undertaken on a mission that cost about $500 million.

“These experiments are important to us and we want to see them run,” said mission scientist Michael Robinson. “Hopefully, they will run in the future (on another flight) and we’re hanging on to that glimmer of hope.”

Columbia’s seven astronauts Sunday shut down the balky generator and started preparing the orbiter for a 2:35 p.m. landing Tuesday at the Kennedy Space Center.

While two other electricity-generating fuel cells are working properly, NASA flight rules require a shuttle crew to head for home when one fails, to protect against the possibility of subsequent malfunctions.

“This is not an emergency situation,” said shuttle program director Tommy Holloway. “It’s a prudent thing to do, and we’re off doing it in an orderly, methodical” manner.

It was the third time a shuttle flight had to be ended early because of a mechanical problem.

The flight of shuttle Columbia was derailed Sunday by a subtle, not-yet-understood problem in fuel cell No. 2, one of three electrical generators on the shuttle that combine hydrogen and oxygen to produce both electricity and the crew’s drinking water.

Shortly after Columbia’s launch Friday, engineers noticed a slight discrepancy in the voltage from one of the substacks in fuel cell No. 2. As the flight progressed the mismatch increased, indicating low voltage in a single cell.

Low voltage generates heat, and engineers were concerned that if the fuel cell continued to operate, enough heat could be generated to burn through membranes separating hydrogen and oxygen.

“That’s considered a crossover of our two gases and of course, that’s hydrogen and oxygen, and when they mix that’s not a nice sight,” said Jeff Bantle, a mission operations representative at the Johnson Space Center.

NASA managers say they hope the problem with Columbia’s electrical generator will not affect plans to launch the shuttle Atlantis next month on a critical flight to dock with the problem-plagued Russian Mir space station.

Along with carrying astronaut Michael Foale to Mir to replace astronaut Jerry Linenger, who will have spent 132 days in space, Atlantis also will carry a new oxygen generator to supplement a pair of similar devices that have failed in recent weeks.

A fire Feb. 23 destroyed a backup solid-fuel oxygen generator and the Mir crew - commander Vasily Tsibliev, flight engineer Alexander Lazutkin and Linenger - is relying on a single source of oxygen from the lone remaining backup.

In addition, problems with coolant loops last week raised the cabin temperature in at least two modules and forced the cosmonauts to shut down a carbon dioxide removal system. The crew is relying on yet another backup system, this one to purify the station’s air supply.

The Russians launched an unmanned Progress resupply vehicle Sunday from the Baikonur Cosmodrome in Central Asia. The vehicle was loaded with repair equipment and other supplies.

Docking is scheduled for Tuesday, and if all goes well, the Mir cosmonauts should be able to partially repair one of their oxygen generators, fix leaks in the coolant systems and get the carbon dioxide air scrubber back on line.

In addition, Progress is carrying backup supplies for Mir’s sole operational solid-fuel oxygen generator. The shuttle Atlantis will bring more supplies next month, along with the new oxygen generator.

“I believe they are dealing with more problems simultaneously than they’ve had to in the past,” said Frank Culbertson, NASA director of the shuttle-Mir docking program.

“I’ve actually been pretty impressed with the way they deal with them and keep them in balance.”

xxxx ‘HOUSTON …?’ Shuttle missions cut short by equipment failure: November 1981: A fuel cell is flooded with water aboard Columbia, cutting short the research mission by three days. November-December 1991: An inertial measurement unit fails aboard Atlantis, cutting short the Defense Department mission by three days. April 1997: A fuel cell slowly loses voltage aboard Columbia, cutting short the science mission by 12 days.

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