A Russian space probe sent to collect rock and dust from one of Mars' two moons - Phobos - has veered off course within minutes of starting its 33-month mission.
The Russian space agency says an engine designed to keep the probe on track failed to start.
It says the craft is currently stuck in an Earth orbit and engineers have three days to correct the fault before its batteries run out, the BBC reports.
The project is Russia's most ambitious space voyage in recent years.
It is called Phobos-Grunt - Grunt means soil in Russian.
The BBC reports scientists hope the dusty debris it is designed to collect will provide fresh insights into the origin of the 27 kilometre-wide moon, which many scientists suspect may actually be a captured asteroid.
The venture is also significant because it is carrying China's first Mars satellite - Yinghuo-1 - a 115 kilogram probe that will ride piggyback and should be released into an observation orbit around the Red Planet.
Phobos-Grunt craft lifted off from Baikonur cosmodrome in Kazakhstan at 00:16 local time on Wednesday.
If its course can be corrected, and everything else goes well, Martian moon samples could be back on Earth in just under three years' time.