Up to 400 pounds of Russia's failed Phobos-Grunt Mars space probe could fall to Earth between Jan. 10 and 21, the Roscosmos space agency said Friday.

The most probable date for its re-entry into the atmosphere is Jan. 15, Roscosmos said.

"The dynamics of the rover's braking in the Earth atmosphere depends on a variety of space and technical factors, including those beyond human control," an agency statement said.

The Phobos-Grunt mission was launched Nov. 9 but failed to set off toward Mars when its engine malfunctioned, remaining instead in Earth orbit, ITAR-Tass reported.

Around 20 to 30 fragments made of heat-proof materials with a total weight of around 400 pounds may hit the ground, Roscosmos said, but the spacecraft's highly toxic fuel will burn out in dense layers of the atmosphere at an altitude of about 60 miles.

"Judging by the world's statistics, spacecraft that go off the orbit usually burn completely in dense layers of the atmosphere and fragments that reach the ground do not make any harm," the agency said.