This is Mir to ground control - we've had a bit of a bump ...

Crash had its premiere in space yesterday. Unfortunately for the three astronauts involved, it was not the film - but the first time that two spacecraft have collided.

None of the three astronauts on board the Mir space station was hurt after a collision with an unmanned cargo ship, Progress, at about 10.20 am BST. But last night the trio, including British-born Michael Foale, 40, were struggling to cope, having lost a third of their power supplies and forced to shut off one of Mir's six modules, used for scientific experiments, when its air pressure began falling.

A spokeswoman for the US space agency Nasa said: "When the crew closed a hatch on the "Spektr" module they were forced to cut some cables resulting in 45 per cent of Mir's power being lost."

Last night the crew and ground control were still assessing whether this will force an evacuation.

The cause of the crash was not immediately clear, though it occurred while cosmonauts Vasily Tsibliyev and Alexander Lazutkin from Russia, and Dr Foale, for the US space agency Nasa, were using manual controls to practice docking Progress - described by Nasa as "the space equivalent of a garbage truck". Progress is gradually moving away from Mir, and is expected to fall to Earth and sink into the Pacific Ocean on Friday. The crew was experimenting with ways of disconnecting it manually because the automatic docking equipment had been failing repeatedly.

During one run it hit the solar battery of Mir's newest module, the scientific experimentation area called Spektr, added only two years ago. As Spektr slowly began losing air pressure - almost certainly due to solar panel damage rather than a breach of the hull - the crew shut the hatch linking it to the rest of the station.

The incident follows a string of setbacks for the 11-year-old station, which was first put into orbit 250 miles above Earth in February 1986, and expected to be in use for only five years.

In February a fire broke out. In March the main oxygen generator failed, forcing the crew to rely on a chemical generator; then leaks in the cooling system sent temperatures soaring to 35.5 Celsius, while leaking antifreeze made crew cough and their eyes swell. At the same time a carbon dioxide "scrubber" failed, causing condensation to build up and forcing the astronauts to stop exercising. And on 4 March, the crew lost control of another approaching cargo craft.

Russian space chiefs were last night working out how Spektr could be repaired, as well as considering what to do with the Progress ship, left orbiting the earth close to Mir itself. Cost will be an important factor: The Russian space program is severely strapped for cash, which has restricted the number of relief flights to the station. Consequently, cosmonauts have found themselves breaking space endurance records whether they wanted to or not.

US officials involved in various joint projects with the Russians, have questioned Mir's safety but Moscow insists there is no serious danger.