Augusta Georgia: still@ugusta: NASA hopes to avoid problems of STS-83 6/28/97

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Still's First Mission

STS-94 Payload Commander Janice Voss, left, from South Bend, Ind., and Pilot Susan Still, fix their hair after taking of their flight helmets at Kennedy Space Center Saturday. The seven crew members are preparing to refly mission STS-83 after it was cut short by a faulty fueld cell back in April. AP Photo/Paul Kizzle
NASA hopes to avoid problems of STS-83

Web posted June 29, 1997

By Amy Joyner
Staff Writer

STS-83 and STS-94.

They'll be as alike as any two space shuttle missions can be, except for one important detail.

After Tuesday's 2:37 p.m. launch, NASA officials hope to avoid another fuel cell problem and keep Columbia in orbit for 16 days, so astronauts can complete 33 microgravity science experiments.

In April, a faulty fuel cell on the shuttle Columbia forced Augusta astronaut Lt. Cmdr. Susan Still and six crew members to abandon mission STS-83 and return to Earth 12 days early.

Officials at the space agency still don't know what caused the malfunction, and they've made no mechanical changes to those fuel cells for Tuesday's reflight. There's a chance - however slim - that a fuel cell might malfunction again, making the STS-94 too much like the original mission.

But to prevent a similar problem on STS-94, engineers will power up the shuttle's three fuel cells hours before the fueling of the external tanks.

``We're going to make sure that they're up and running before we start loading the external tank, however much time we need for that,'' NASA spokesman Bruce Buckingham said.

Engineers will also keep a closer watch on the performance of the fuel cells, which provide electrical power for the shuttle, lead flight director Rob Kelso said.

These same precautions were taken before the May 15 launch of STS-84 aboard the shuttle Atlantis.

Before the launch of STS-83, flight engineers detected slight fluctuations in voltage readings from the fuel cells, but considered the problem inconsequential.

Once the crew reached orbit, however, it became clear the cell was malfunctioning. Flight directors feared it would explode or cause a fire onboard, so they shut down the defective power generator and ordered the crew home.

The space shuttle has three fuel cells, which use a reaction of liquid hydrogen and oxygen to generate electricity and produce drinking water. A single fuel cell provides enough electricity to conduct on-orbit and landing procedures, but NASA safety rules require all three must be working to continue a flight.

Shortly after Columbia landed April 8, the defective fuel cell was removed. It has been studied by the manufacturer and engineers with the National Aeronautics and Safety Administration. But they still can't definitively say what caused the mission-ending malfunction, Mr. Kelso said.

Still, the astronauts and the flight management team aren't overly concerned that a similar problem will ground STS-94. They are viewing Columbia's earlier fuel cell problem as a rare ``anomaly,'' not an inherent equipment flaw.

The same type of fuel cells have been used since the beginning of the space shuttle program in 1981, logging more than 60,000 flight hours.

The same cell that grounded Columbia in April had flown more than 1,200 problem-free hours in three previous missions, Mr. Buckingham said. It was last serviced in Augusta 1995; most fuel cells can fly 2,400 hours before they need servicing, he said.

Only once before STS-83, engineers detected fluctuating voltage in a fuel cell, but the problem was fleeting and didn't affect the mission.

If something goes wrong with Columbia's fuel cells Tuesday, NASA may have to delay the launch several weeks, if not longer, Mr. Buckingham said.

Because of the position of the microgravity science lab in the orbiter, Columbia's fuel cells cannot be replaced at the Launch Pad. The shuttle would have to be moved on a large-track vehicle back to the Orbiter Processing Facility, where the fuel cells could be changed out. The replacement process takes several weeks, Mr. Buckingham said.

If the cell malfunctions in orbit, the crew would have to return to Earth. Studies of the defective fuel cell revealed it wouldn't have exploded, Mr. Buckingham said, but NASA flight safety rules haven't been revised.

Beyond the concerns over a cell malfunction, unfavorable weather was in the forecast.

Thunderstorms are expected most of the week, putting the chance of favorable launch weather at a mere 10 percent on Tuesday and only slightly better the next two days.