Russia's latest shot at Mars suffered a setback shortly after launch yesterday when its upper-stage thrusters failed to fire, leaving the Phobos-Grunt probe stuck in orbit around Earth instead of on its way into deep space.
Details are still hazy about what went wrong, but the problem appears to lie with an instrument called a star sensor.
The spacecraft should have "known" when to fire its engines after using the sensor to orient itself to the stars, thereby setting its course for Mars. Either a software problem stopped the star sensor from working, or the sensor itself failed.
The craft is scheduled to pass over Russia's Baikonur Cosmodrome in Kazakhstan shortly, and technicians there will attempt to communicate with Phobos-Grunt to determine whether the failure is fixable.
The Russian space agency, Roscosmos, originally said they had three days to get the stranded craft working, but mission managers have since changed that estimate to two weeks, giving them more time to fix the problem.
It's unclear what will happen to Phobos-Grunt if the probe can't be saved. At some point, however, the probe's elliptical orbit will move it off course and, even if it could escape Earth's gravity, it will no longer be able to take aim at Mars.
(Related pictures: "Space Debris-Five Unexpected Objects That Fell to Earth.")
A Problem With Tracking
Difficulties in determining the problem were compounded because the thruster firing should have occurred over South America, where Roscosmos was unable to track the craft.
"They asked for amateur astronomers to look for the glint of the spacecraft as it was passing overhead," said the Planetary Society's Emily Lakdawalla, who has been tracking news of Phobos-Grunt since the launch.
It's common for spacecraft in low-Earth orbit to go temporarily out of contact with the ground—NASA lost its comet-probing CONTOUR spacecraft in a similar situation in 2002.
But "I think the thing [Roscosmos] could most be criticized for is that an important rocket burn was happening over a location where they did not have tracking capability," Lakdawalla said.
Roscosmos could have set up a portable, temporary tracking station like those used on ships, she added.
As it turned out, few observers saw the rocket, said Ted Molczan, an amateur satellite tracker.
During the flyover of South America, the spacecraft was in Earth's shadow, "therefore, observers would only have seen something if the engines had fired and produced a sufficiently bright plume," he said.
"The project learned that the burns had not been performed when Russia's space surveillance system detected the spacecraft, still in the original parking orbit, sometime after the first burn should have occurred."
Still a Chance for "Major" Success?
If it can be saved, Phobos-Grunt is intended to travel to Phobos, the larger of Mars's two moons, and return a handful of surface material to Earth—grunt means "soil" in Russian. (See Phobos pictures.)
Also tagging along are a Chinese-designed Mars orbiter and a canister of microbes sent by the Planetary Society to test whether life can survive in deep space.
"There are so many things that are new and complex about this mission," the Planetary Society's Lakdawalla said.
If the probe can be fixed and "they manage to set the landing craft down on Phobos, then they've achieved major success with this mission."