Space station crew must use backup oxygen

International space station

MOSCOW (CNN) -- The residents of the international space station are using a secondary oxygen supply after their main oxygen generator stopped working, Russia's mission control center said Thursday.

The crew will have enough oxygen for at least three months and the main generator could be repaired within days, according to the Russian space agency.

The Russian-made Elektron generator, which creates oxygen from water, started malfunctioning last week, a mission control spokesman said.

Flight controllers in Moscow suspect a faulty sensor in the oxygen generator and are developing computer software to work around the problem.

Russian skipper Yuri Onufrienko and his U.S. crewmates Carl Walz and Dan Bursch are relying on solid-fuel canisters to generate oxygen. A mishap with a similar oxygen "candle" ignited a nearly disastrous fire on Russia's Mir space station in 1997.

Despite the glitch, the trio proceeded with their normal daily routine. During a live interview with a radio station on Thursday, the topic was hardly mentioned.

Bursch did comment favorably on a visit earlier this month from South African Mark Shuttleworth, the second paying tourist in space.

"He was a low maintenance visitor," Bursch said.

The crewmembers conducted their regular scientific duties as well. The tasks this week include growing industrial crystals, cultivating wheat sprouts and taking photographs of environmentally sensitive spots on Earth.

The space shuttle Endevour is expected to launch May 30 with a fresh oxygen supply and a new space station crew.