Duff Mars probe's flaming shards to rain down mid-January

Up to 30 bits of Phobos-Grunt to hit Earth

The remains of dud Martian probe Phobos-Grunt will fall to Earth next month, the Russian space agency announced.

Roscosmos said that the exact time or place couldn't be forecast until a few days before it falls, but "according to expert estimations", it would hit the ground sometime between January 6 and January 19.

"Between 20 and 30 pieces of the remains of the probe with a total weight of less than 200kg could hit the Earth's surface," Roscosmos warned in a statement on its website.

Last month, the Russian space agency chief Vladimir Popovkin said that the 7.5 metric tons of fuel aboard the craft would explode on re-entry and take most of the probe with it.

"It is highly unlikely that its parts would reach Earth," he said.

Despite now warning that remnants could reach the ground somewhere between the 51.4 degrees north line of latitude and 51.4 degrees south, Roscosmos is still confident that all the fuel will be burnt up.

"The fuel of the spacecraft will burn in the dense atmosphere of the Earth at an altitude of approximately 100km," the agency said.

It added that a small amount of the radioisotope cobalt-57, which is set in one of the scientific instruments, has a mass of just ten micrograms and "a small half-life", so it "will not cause dangerous contamination".

At the moment, Phobos-Grunt is in a low Earth orbit with an apogee of 275.7km and a perigee of 201.3km, an orbit it has descended to after over five weeks of being stuck without engines.

The probe was launched on November 8, but on reaching space, failed to fire its engines to send it on its mission to Mars and the Martian moon of Phobos. Since then, its been circling the planet in an ever-decreasing orbit.

Both Roscosmos and the European Space Agency managed some contact with the craft, after weeks of trying, but only got to chat to the probe once or twice before it stopped answering.

There's still no explanation as to why the Phobos-Grunt's engines clapped out, apart from some wild theories, but the failure tacks on to a long list of unsuccessful Russian attempts to study the Red Planet.

According to Popovkin, Mars is a planet that "doesn't like Earthlings". He claims that only 30 per cent of Soviet-Russian launches to the planet were successful, although NASA alleges that all 17 of Russia's attempts have failed. ®