Primary and Backup Oxygen Generators Aboard Mir FailBy David Hoffman
The Washington Post
The crew of the space station Mir was working Monday to repair both primary and secondary oxygen supply systems on the problem-ridden craft, just two days after Russian cosmonauts aboard undertook a delicate operation to try to restore full electrical power to the 11-year-old orbiting research complex.
NASA officials monitoring the Mir mission said the oxygen problems became apparent when Russian ground controllers ordered the crew - two Russians and American astronaut Michael Foale - to restart one of the space station's two principal oxygen generators, one that had been shut down since Aug. 18 to conserve power. The other main generator had been idle since an unmanned cargo vessel crashed into Mir on June 25, puncturing the space station's Spektr research module and forcing the crew to disconnect electrical cables within the module that had supplied Mir with about 50 percent of its power.
As soon as the crew turned on the generator Monday, however, it shut itself down, NASA officials said. "This is not an uncommon occurrence when (it) is reactivated after having been shut off," NASA said in a status report from Russian Mission Control outside Moscow, adding that the unit may have to be reinstalled to correct a problem with its cooling unit.
The crew also spent part of the day trying to troubleshoot the backup oxygen system, in which solid-fuel canisters, or "candles," are burned to produce oxygen by chemical interaction.
This process, which caused a major fire aboard Mir earlier this year, had been in use for a week because the two main generators had been shut down.
Few details about the canister problem were available Monday night, and there was no confirmation of it by Russian space officials. NASA did not say specifically what was wrong with the backup system but reported that the crew will have to replace parts of the apparatus that activates the oxygen candles.
If both the primary and backup oxygen systems fail for a substantial period, experts say, the crew would face a potentially serious problem and might have to abandon the space station for lack of air. It was not immediately clear, however, how long the crew could remain aboard without either system functioning properly. NASA said the three men are in no immediate danger.
Both the main and supplementary oxygen systems have been rife with problems over the past two months, in part because of the power shortage aboard the space station since the June 25 collision forced the crew to seal off the Spektr module from Mir's core compartment and sever links with its solar panels.
The crew has since been struggling to restore electricity to the stricken orbiter, conducting a complex spacewalk inside the airless Spektr on Friday to reconnect power cables and plan an external spacewalk for next week.
The crew learned Monday that Friday's repair mission was at least partially successful. Mir commander Anatoly Solovyev and flight engineer Pavel Vinogradov told ground controllers that they tested the reconnected cables and found additional electricity flowing into Mir's power storage cells. The cosmonauts also found, however, that a cable installed to help keep Spektr's solar panels properly aligned with the sun - and thus produce more power - was apparently not functioning, NASA said. The space agency said it may take several days to determine how great a power boost the repair mission may stimulate.
The crew also began preparations Monday for a scheduled Sept. 3 spacewalk during which they will try to locate any punctures in the Spektr module caused by the June 25 collision. Yuri Koptev, director of the Russian space program, was quoted as saying in an interview with the Tass news agency that the errant cargo vessel struck Spektr like a bouncing ball, punching seven holes in the hull.
It was not clear how Koptev learned this, but his comment suggests the damage may be more serious than initially estimated. During Friday's repair operation, the two cosmonauts were unable to spot any holes from inside the module; previously, officials had said that the rate of decompression inside Spektr after the collision suggested a small hole, about an inch and a half in diameter, in the hull.
Koptev was quoted as saying the cosmonauts could not see the damage from inside Spektr because they were working in the dark but that the punctures would be evident from outside the craft. He said the holes could be patched only on subsequent spacewalks, perhaps with a special space-age glue.