At least 10 days till hot Phobos-Grunt chunks rain down

Earliest estimate for fallout from doomed Russian Mars probe 'may change'

Any fragments of the doomed Russian Mars probe Phobos-Grunt that don't burn up in the fiery explosion of its fuel tanks hitting the atmosphere are likely to fall to Earth on 15 January.

Russian Air and Space Defence Troops' spokesman Alexei Zolotukhin gave Russian news agency Itar-Tass the date but added that it might still change.

No landing site was given for the rogue fragments, but Zolotukhin said that as of today, the stalled spacecraft was in an orbit with a period of 88.57 minutes and an inclination of 51.41 degrees, and its apogee was now 224km while its perigee is 184km.

Since the probe got stuck in Earth's orbit instead of firing its engines to send it on its mission to Mars and Martian moon Phobos, there has been concern about what will happen when it drops unguided back through the atmosphere.

The craft is carrying around 7.5 metric tons of fuel, which is likely to help Phobos-Grunt to disintegrate as soon as it hits the atmosphere, but Russian space agency Roscosmos has warned that 20 to 30 pieces with a total weight of less than 200kg could survive to impact the surface.

Roscosmos has also said that it won't be possible to be certain about the time and place of any fragmentary impacts until within a few days of the probe's plunge through the atmosphere.

Specialists at the Russian Air and Space Defence Troops' space situation are currently monitoring the probe's changes and will be able to give a preliminary forecast of when and where the bits of debris will land once Phobos-Grunt drops out of orbit.

Zolotukhin said that information about orbit changes was being "provided for all the parties concerned".