MOSCOW (AP) — Fragments of a failed Russian space probe are now expected to fall to Earth on Jan. 15, officials said Wednesday.

The unmanned Phobos-Ground probe was launched Nov. 9 on what was supposed to have been a 2 1/2-year mission to the Mars moon of Phobus to take soil samples and fly them back to Earth, but it became stuck in Earth's orbit and attempts to send commands that could propel it toward the Mars moon were unsuccessful.

As the probe's orbit slowly deteriorated, space officials predicted it would come crashing down between late December and late February.

A precise date was given Wednesday by a spokesman for the air and space defense troops, who said any fragments that do not burn up in the atmosphere are expected to fall to Earth on Jan. 15.

The date could still be affected by external factors and Defense Ministry troops are monitoring changes in the probe's orbit, Russian state news agencies quoted Alexei Zolotukin as saying.

The failed spacecraft weighs 13.2 metric tons (14.6 tons). Most of that weight, about 11 metric tons (12 tons), is highly toxic fuel. Experts have said that if the fuel has frozen, some could survive the plummet to Earth, but that if it is liquid it will likely combust from the heat of re-entering the atmosphere.