As a new crew prepares to lift off tomorrow for the international space station, NASA officials say they are less worried than they were two weeks ago about problems with its oxygen generator and growing shortages of food and spare parts.
NASA's Oct. 1 announcement that the planned return to flight of the space shuttle fleet would be delayed at least until May of next year had triggered fears that the $39 billion orbiting laboratory's chronic problems with breakdowns and supplies could get worse.
NASA officials now say jury-rigged repairs are keeping the vital but balky Elektron oxygen generator running part time, building up a reserve so that the new crew will not face a shortage by year's end.
Space station Program Manager William Gerstenmaier said, however, that engineers will need to monitor food consumption carefully to ensure that astronaut Leroy Chiao and cosmonaut Salizhan Sharipov will be well supplied until a scheduled Russian cargo flight arrives Christmas Day.
Overall, Gerstenmaier sounded considerably more upbeat than he did in late September when he suggested that food shortages and continued problems with the Russian-built oxygen generator could force evacuation of the station if resupply were delayed.
"We're watching our consumables closely, and we're in pretty good shape," Gerstenmaier said in a recent telephone interview. "Every day we run the Elektron helps us. I don't see any game breakers out there."
"Expedition 10" Commander Chiao, 44, a chemical engineer from Danville, Calif., and Flight Engineer Sharipov, 40, a colonel in the Russian air force, are scheduled to lift off from the Cosmodrome in Baikonur, Kazakhstan, aboard a Russian Soyuz spacecraft at 11:06 p.m. Eastern time tomorrow. Docking at the station is planned for 12:14 a.m. Eastern time Saturday.
Chiao is a three-time space shuttle veteran, while Sharipov has flown aboard the shuttle once. Barring catastrophe, the pair will spend slightly more than six months aboard the station, marking the first time that both crew members are of Asian extraction.
Russian Space Forces Test Cosmonaut Yuri Shargin, 44, will accompany Chiao and Sharipov on the Soyuz flight and perform experiments aboard the station for eight days before returning with the current crew: Russian Commander Gennady Padalka and U.S. Flight Engineer Edward "Mike" Fincke.
During planning for Expedition 10, it appeared that the space shuttle, grounded since last year's Columbia tragedy, would make its first post-Columbia flight in March, while Chiao and Sharipov were still aboard. But hurricane-aggravated delays in implementing new shuttle safety measures forced NASA to push the launch date back to May, at the earliest.
NASA officials said Chiao and Sharipov will spend considerable time preparing the station to receive the shuttle: "They will pre-pack cargos for the shuttle to take back," Expedition 10 manager Susan Brand said in a telephone news conference. "They will also reconfigure stowage spaces."
The station depends on the shuttle for the majority of its spare parts and resupply, and engineers have delayed some major repairs because the Russian cargo craft currently handling replenishment are too small to carry major equipment. The station for more than two years has needed a new "control moment" gyroscope to help keep it positioned properly in space.
Gerstenmaier, however, welcomed the shuttle delay as an opportunity to prepare the station better for its eventual arrival. Further delays, he added, should not harm the station's ability to function. "We've done the consumables analysis both ways," Gerstenmaier said. "Whether the shuttle launches or doesn't launch, we look stable with what we have."
Still, the new crew, like the old, is likely to spend lots of hours on nagging maintenance problems that have plagued the station. For example, Fincke will have to show Chiao how to repair cooling units in non-functioning U.S. space suits, Gerstenmaier said.
But the lingering headache is the erratic Elektron, which generates the station's primary oxygen supply by separating waste water into hydrogen and oxygen and venting the hydrogen into space.
For nearly a year, the Elektron has provoked periodic crises with irritating malfunctions that have forced astronauts to rely on auxiliary oxygen stored in tanks.
On Sept. 4, the unit tripped off-line altogether, and nearly three weeks of troubleshooting failed to produce an enduring repair. On Sept. 24, Gerstenmaier told reporters that while auxiliary oxygen was keeping Padalka and Fincke out of any danger, those supplies, as well as the station's solid fuel oxygen "candles," would deplete to such an extent that if a scheduled Russian cargo shipment failed to show up on Christmas Day, Chiao and Sharipov would have to consider abandoning the station.
Since then, however, NASA said Padalka took the advice of Russian ground controllers and hooked up the hydrogen venting line to a different overboard valve, temporarily fixing the problem.
The Elektron went back online Sept. 30 and runs while the astronauts are awake, Gerstenmaier said, with Padalka and Fincke checking it hourly. Chiao and Sharipov are bringing up a new sensor that will allow the crew to operate the unit constantly, he added.
"If this occurs, we will not use any solid fuel oxygen generators or any air lock [auxiliary] oxygen," Gerstenmaier said. More important, a working Elektron will leave the station with enough oxygen for about 160 days by the time the Christmas flight arrives -- "roughly the same condition as now."
Engineers have drawn a "red line" at 45 days' supply of consumables before they will consider buttoning up the station and sending the astronauts home aboard the station's lifeboat Soyuz, leaving the lab operating in an autonomous mode.
Food remains a worry. "We'll have slightly above the 45-day value" when the Christmas cargo ship arrives, Gerstenmaier said. "We did a detailed food inventory, and the numbers improved. No real concerns, but we need to track this carefully."