China Clarifies Yutu's Problem, But Not Its Future

China finally added some clarity to the problem that befell its Yutu lunar rover, but not to what its fate will be.

Yutu and its associated Chang’e-3 lander are China’s first spacecraft to make a survivable landing on the Moon.   They arrived on December 14, 2013 and Yutu rolled off the lander the next day.  It was designed to work for three lunar cycles — 14 days of sunlight and 14 days of darkness (the lunar night) — remaining dormant at nighttime until its solar arrays could be recharged by the Sun.

As it entered the second lunar night, something went wrong.  China promptly announced there was a mechanical problem on January 25, but gave no details.  Western experts speculated that the process of stowing Yutu’s mast (with camera and antenna) and one of its solar arrays did not take place as planned, leaving the interior of the rover unprotected from the bitter cold.  

As lunar night turned into lunar day two weeks later, scientists waited with baited breath to see if Yutu awakened.   China announced the good news on February 12 — yes, Yutu was alive.

Not much has been said about Yutu by the Chinese since then, however, other than a February 23 report that the mechanical problems were not resolved, but the scientific instruments were working normally.  

The rover has now entered another period of dormancy.   Today, China’s official Xinhua news agency provided an update.   Yutu’s problem, it said, is a malfunctioning control circuit in its driving unit.   Ye Peijian, chief scientist for the Chang’e-3 program, was quoted as saying “Normal dormancy needs Yutu to fold its mast and solar panels” and “The driving unit malfunction prevented” that.  Yutu’s awakening on February 12 was “two days behind schedule,” Xinhua added.

The Xinhua report is obscure about what is next for Yutu, sounding both optimistic and pessimistic at the same time:  “At present every piece of equipment of Yutu is undergoing another dormancy, is getting back to normal, the state of the rover is not encouraging, Ye said.  ‘We all wish it would be able to wake up again,’ said Ye…”

The issue does not affect the stationary Chang’e-3 lander, which remains where it set down on the Moon in December.   China has said little about the lander since then.  On February 13 It did distribute a photo of the lander taken by Yutu, but did not indicate when the photo was shot.  The proximity of the camera to the lander suggests it was taken soon after Yutu separated from the lander back then.

China’s Yutu lunar rover as seen from the Chang’e-3 lander on December 22, 2013.   Credit:  Tweet from Xinhua (@XHNews) December 22, 2013.

Chang’e is China’s mythological goddess of the Moon and Yutu is her companion Jade Rabbit.   As its name implies, Chang’e-3 is the third of China’s lunar probes and more are planned.