The Mir space station

CAPE CANAVERAL, Florida (CNN) -- NASA officials said Sunday they can't launch Shuttle Discovery on the last planned mission to Mir until the current computer problems on the Russian space station are solved.

But the officials said they expected the problems to be corrected in time for the shuttle launch Tuesday.

The Mir crew worked under reduced electrical power Sunday to replace the failed computer with a spare one delivered on the last shuttle flight. They've also turned off the air conditioning to save power. The breakdown in the guidance system left the station adrift Saturday and astronauts were unable to aim solar panels at the sun and generate electricity.

CNN's John Holliman comments on the launch situation
	204K/15 sec. AIFF or WAV sound

NASA officials told reporters Sunday they expect the new computer to be up and running by the end of the day, and that the shuttle launch will proceed as scheduled. But in response to questions by CNN's John Holliman, they said the new Mir computer, with its "attitude control system," must be working for Discovery to dock at the space station. 230K/17 sec. AIFF or WAV sound

Discovery sits on the launch pad at Kennedy Space Center

Liftoff for Discovery is set for 6:10 p.m. EDT Tuesday. The shuttle will bring several new projects to the Mir station, including a Russian biotechnology experiment. NASA astronaut Andy Thomas, who has lived on Mir since January, is to return with the shuttle.

This will be the ninth and final time a shuttle links up with the aging Mir space station. The last year, when onboard computers frequently shut down and caused power outages, has been called the most dangerous in the station's 12-year history,.

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