Oxygen generators aboard Mir break down Rescue mission to be launched Tuesday August 5, 1997 Web posted at: 6:56 a.m. EDT (1056 GMT) ATLANTA (CNN) -- Two oxygen generators aboard the stricken Russian space station Mir broke down Tuesday, only hours before a repair mission was to blast off from the Baikonur cosmodrome in Kazakstan. However, the Russian Interfax news agency said there was no immediate threat to the three-member crew on board Mir. Interfax quoted Russian ground control as saying that the crew was now using special oxygen canisters. Ground control said the crew was not facing an emergency situation since there were enough canisters to last for a minimum two months. The latest technical failure came as the two new Russian cosmonauts prepared for Tuesday's liftoff. Flight commander Anatoly Solovyov, 49, and flight engineer Pavel Vinogradov, 43, passed their final health check Monday, clearing the final hurdle for an urgent mission. They are to lift off in a Soyuz-TM-26 space capsule mounted on a 300-ton booster rocket and dock with the Mir on Thursday. CNN's John Holliman reports - Replacement cosmonaut team prepares for trip to Mir The station has been operating at about half its normal power supply since June 25 when a supply ship being used for docking practice crashed, punching a hole in the Spektr module and damaging one of the solar panels. The three-man crew aboard Mir -- cosmonauts Alexander Lazutkin and Vasily Tsibliyev and U.S. astronaut Michael Foale -- managed to close the door to Spektr, which saved their lives but cut off the main source of electricity for the station. It was decided not to have Lazutkin and Tsibliyev make the repairs when it was discovered that the latter had an irregular heartbeat, and the former was suffering from exhaustion. Holes in hull must be patched Foale offered to make repairs, but the Russians decided to send Solovyov and Vinogradov to do the work. They are expected to make six spacewalks of more than nine hours each, and to make repairs inside and outside the module. The repairs will include patching holes in Spektr's hull, an operation that will require a preliminary walk to inspect the damage and at least two more to fix it. Solovyov and Vinogradov are also taking with them a replacement hatch for the Spektr module which will allow electricity from Spektr's solar panels to flow into the rest of the space station, much of which is now without power. The new door, unlike the current one, has hermetic connections for the power cables from Spektr's three functioning solar panels. Although it sounds easy enough, replacing the hatch involves an element of danger. Vinogradov will be wearing a 300-pound spacesuit, and there is some concern that there may be debris or dangerous chemicals floating behind the door. If his suit is punctured when he opens the door, he could die swiftly. Astronaut continues to train The solar panel damaged in the crash is not among the things expected to be repaired. Mir's problems have caused the Russians and the Americans to make major changes in who they send into space. A French cosmonaut was scheduled to make the trip, but he had to give way to a second cosmonaut who had been trained in making repairs. U.S. astronaut Wendy Lawrence was to replace Foale in the space station in September when the U.S. space shuttle Atlantis pays a visit. But the 5-foot-3 Lawrence is too small for the Russian space suit she would have to wear should she be needed to go into space to make repairs. She will continue to train with her replacement, Dr. David Wolf, at Star City, the Russian training center, and will accompany him on the shuttle as his backup. Should illness or injury befall Wolf, Lawrence would remain on the Mir and participate in scientific experiments, but make no spacewalks. Correspondent John Holliman contributed to this report.