Russia's unsuccessful Phobos-Grunt Mars probe to hit Earth in January

London, Dec 17 (ANI): Russia's space agency has said that its unsuccessful Mars probe will be falling back on Earth next month.

Roscosmos' unmanned Phobos-Grunt spacecraft became stranded in orbit in November, the BBC reported.

According to the agency, the toxic fuel on board is expected to burn up on re-entry, but 20-30 fragments of the spacecraft will survive to the surface.

Current Roscosmos estimates for the timing of the fall are between 6 and 19 January , but this window will be narrowed as the event comes nearer.

Professional and amateur groups around the world will also be modelling the decay in the orbit in an attempt to determine precisely where and when Phobos-Grunt might come down.

Phobos-Grunt is currently moving around the Earth at an altitude that varies between 201km and 275km.

The maximum latitudes are 51 degrees North and South, encompassing London in the Northern Hemisphere and Punta Arenas, Chile, in the Southern Hemisphere.

The spacecraft's mass at launch was some 13 tonnes, most of which was the propellants unsymmetrical dimethylhydrazine (UDMH) and dinitrogen tetroxide (DTO).

These are extremely unpleasant substances and the Russian authorities are hoping that they are destroyed during the descent.

With more than 70 percent of the Earth's surface covered by water, the chances are that any fragments that do survive the fiery re-entry will end up in the ocean.

Roscosmos expects only about 200 kilograms to make it all the way through.

Phobos-Grunt was built to land on the larger of Mars' two moons, Phobos, to scoop up rock and bring it back to the Earth. (ANI)