The failed Russian Phobos-Grunt spacecraft that has been circling the Earth since the 8th November 2011 is predicted to re-enter the Earth's atmosphere on the 14th January 2012. Officials at Roscosmos, the Russian space agency, admitted that up to 30 fragments, weighing a total of 200kg, might survive re-entry and hit the Earth. This is a small amount of the total spacecraft weight of 13.5 tonnes.
The Phobos-Grunt spacecraft is not considered by scientists to be one of the more high-risk spacecraft re-entries. Dr Heiner Klinkrad, head of the European Space Agency (ESA's) space debris office at the European Space Operations Centre (ESOC) in Darmstadt, Germany said, "It's a very delicate structure and it will break up fairly quickly. Largely it consists of propellant to take it to Mars, which is still left in the tank, and none of that is expected to survive re-entry."
Space agencies around the world have now started to step up their monitoring using radar tracking stations. As the spacecraft approaches re-entry, officials will track its descent hour by hour to improve predictions of where any debris might land. Although re-entry is likely to be on the 14th January, it could be a few days before or after this date.
The Phobos-Grunt spacecraft suffered a computer malfunction just after launch and despite repeated attempts to contact the rocket it was not possible to restart its engines and send it on the journey to Mars. In the end, Roscosmos had to abandon the mission.
Phobos-Grunt (the word "Grunt" is a translation of "soil") was a highly ambitious mission designed to land on the larger of the two Mars moons, Phobos, and scoop up about 160 grams (5.5 ounces) of soil, and bring it back to Earth.
**UPDATE: 16 Jan 2012 **
Orbital tracking reports suggest that Phobos-Grunt fell back to Earth on Sunday 15th January 2012. "According to information from mission control of the space forces, the fragments of Phobos-Grunt should have fallen into the Pacific Ocean at 1745 GMT," space forces spokesman Alexei Zolotukhin told the Interfax news agency. At this time the debris would have splashed down at a location more than 1,000km west of Chile.