Russia's first interplanetary mission in more than two decades has suffered a malfunction.
The "Phobos-Grunt" was meant to travel millions of kilometers to the Mars moon, Phobos, and return to Earth in 2014 with a soil sample.
However, the mission is now in doubt.
Quoted by Interfax, Roskosmos chief Vladimir Popovkin said an engine failed to fire on the "Phobos-Grunt" probe after it reached Earth's orbit.
Popovkin said space officials were in contact with the craft and have three days to put it on course before the batteries run out.
The "Phobos-Grunt" was originally due to blast off in October 2009, but its launch was postponed because the craft wasn't ready.
The 13.2-metric ton craft is the heaviest interplanetary probe ever, with fuel accounting for most of its weight.
It was manufactured by the Moscow-based NPO Lavochkin that has specialized in interplanetary vehicles since the start of the space era.
compiled from agency reports