Cosmonauts have replaced a faulty component of the Mir space station's main computer which broke down early on Friday, the space flight ground control centre (TSOUP) said overnight, ITAR-TASS reported.

The breakdown had caused the orbital station's solar panels to swing away from the sun, thereby disrupting its energy supplies.

But Interfax, citing TSOUP, reported earlier that manoeuvres had begun to correct Mir's orientation using small auxiliary thrusters on the Soyuz TM-26 cargo vessel.

It said the thrusters had been ignited at 1915 GMT. TSOUP said that at no time had the breakdown jeopardised the security of the three men aboard the station, Russians Anatoly Solovyev and Pavel Vinogradov and American David Wolf.

The computer crashed at 3:45 a.m. (0045 GMT) Friday, disrupting both the craft's gyroscopic navigational system and power supply, Russian space officials told Interfax news agency.

To save power, Solovyov, Vinogradov and their NASA colleague David Wolf disconnected the electricity supply to the Kvant II, Priroda and Kristall modules, the officials said.

It was the first breakdown on board the 11-year-old Mir station this year, but the third malfunction of the new computer, which was installed on October 1.

After previous computer breakdowns and power cuts, the crew used back-up solid fuel oxygen generators and shut down all but the essential on-board systems.

A source at mission control told AFP that the faulty unit was "responsible for the interface between the main computer and peripherals".

"It is not very serious, and so far the Mir programme remains unchanged," the source said. The previous computer broke down seven times last year, and was replaced by one which had already been used on Earth. A more up-to-date system could not be installed because that would require a major technical overhaul of the station, Russian space officials said.

Mir was dogged by breakdowns and accidents in 1997, including a near-catastrophic collision with an unmanned cargo craft on June 25 which punctured the Spektr science module.

Solovyov, the station's commander, and Vinogradov will fit a new seal on the exit hatch of Kvant II during a spacewalk on January 8, and will carry out another spacewalk on January 14.

The module section, which is separated from the rest of the station by other working airlocks, has been gradually losing pressure since two spacewalks in November.

The US space shuttle Endeavour is due to dock with Mir on January 21, and on January 29 a Soyuz TM-27 craft will blast off for Mir carrying French astronaut Leopold Eyarts and two Russian cosmonauts to replace Solovyov and Vinogradov.

Despite Mir's spate of problems, Russian space officials plan to keep it in service until late 1999, when the first elements of the Alpha international space station are expected to be in orbit. The first, Russian-made component of Alpha is due to be launched on June 30.
 

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