China's first lunar rover, the Jade Rabbit, appears to have broken down halfway through its three-month mission to the moon.
Jade Rabbit experienced a "mechanical control abnormality" and scientists were examining the best ways to carry out repairs, Xinhua reported.
The problem was the result of a "complicated lunar surface environment", Xinhua cited the State Administration of Science, Technology and Industry for National Defence as saying.
The solar-powered Jade Rabbit, or Yutu, was supposed to carry out geological surveys and astronomical observations for three months after the Beijing Aerospace Control Centre announced its soft landing on the moon on December 14.
"Reading between the lines, I think the Chinese are preparing for the loss of their rover," said Lutz Richter, a planetary rover specialist with Kayser-Threde, a German aerospace company that works with Nasa and the European Space Agency.
"This is speculation, but I think there's a problem with the electrical motors that close the solar panels," he added.
If the solar panels were not able to close, internal electrical components sensitive to temperature that would normally be shielded would freeze during the lunar night and become damaged beyond repair, said Richter.
The problem arose before Jade Rabbit went into its second dormancy at dawn yesterday - the start of the lunar night, which lasts the equivalent of about two weeks on earth. The lunar daytime temperature can reach 100 degrees Celsius, while at night it plunges to minus 180C.
Jade Rabbit and the Chang'e-3 lunar lander "woke up" two weeks ago after the first two-week dormancy.
"It might be dust blocking the mechanism," Richter said, adding that extreme temperatures could also damage its hinges and motors.
But Professor Jiao Weixin , deputy director of the China Society of Space Research's space probe committee, said it was surprising that problems should occur so soon.
"Despite some minor problems, Opportunity, the US Mars rover that also had a design lifespan of three months, is still working after almost 10 years," Jiao said.
"It is quite surprising that Yutu should experience problems at such an early stage."