China's moon rover Yutu — also known as the Jade Rabbit — was supposed to go into hibernation before night fell. Now Chinese officials fear the rover is frozen. (Xinhua/Associated Press)

China is worried that its unmanned lunar rover known as Yutu, or Jade Rabbit, is frozen on the moon’s dark side.

On December 14, Yutu became China’s first rover to land on the moon. As the first lunar landing of any kind since 1976, it was a major triumph for the Chinese. Then last week came the bad news: The rover had experienced a problem that may have prevented it from going into hibernation before entering the lunar night.

During the lunar night, which lasts roughly 14 Earth days, the moon’s temperature can drop to 290 degrees below zero. If a rover isn’t prepared for that, experts say, it has little chance of recovering. The Chinese will know Thursday, when the night ends.

“It looks like the Chinese engineers have lost confidence that they will be able to get it working again,” said Joan Johnson-Freese, an aerospace specialist at the U.S. Naval War College in Rhode Island.

The rover, she said, was intended to operate through three lunar periods of hibernation. “Now it appears that there were mechanical difficulties before it went into this second hibernation, and if hibernation does not occur normally, the Jade Rabbit could freeze,” Johnson-Freese said.

Researchers worldwide have had high expectations for Yutu. The lunar rover is equipped with technology that didn’t exist in 1976, including radar that scientists hoped would reveal what makes up the layers of minerals and gases 100 feet or more beneath the moon’s surface.

— MCT Information Services