A plucky bunny on the moon may have just met an untimely end. Reports from Chinese state media suggest the country's Yutu – or Jade Rabbit – lunar rover has stopped working just six weeks into its three-month mission.
China's Chang'e-3 lander touched down on the moon on 14 December and released the Yutu rover about 7 hours later. Both machines successfully entered hibernation mode during their first lunar night. On the moon, night lasts for half of each Earthly month and plunges surface temperatures from daytime highs of about 90ºC to below -180ºC.
The second lunar night rolled around on Saturday, and while the lander is once again successfully sleeping, Yutu appears to have failed. The Xinhua news agency reports that the rover has experienced a mechanical control fault due to the "complicated lunar surface environment". No further details were given by China's State Administration for Science, Technology and Industry for National Defence.
During the deep freeze of lunar night, the most critical moving parts on Yutu are its mast and solar panels. When temperatures plunge, the mast is designed to fold down to protect delicate instruments, which can then be kept warm by a radioactive heat source. Yutu also needs to angle a solar panel towards the point where the sun will rise to maintain power levels. A mechanical fault in these systems could leave the rover fatally exposed to the dark and bitter cold.
Long, hard wait
As for what caused the malfunction, abrasive lunar dust is a top suspect. Moon soil gets ground up by micrometeoroid impacts into a glassy dust that can then become charged as it is bombarded by solar particles. During the Apollo program the sharp-edged dust grains wore through astronaut space suits, scratched up mirrors used for laser ranging experiments and caused moon buggies to overheat.
Rover designers can take measures to avoid getting this damaging dust inside important systems, says Bernard Foing, director of the International Lunar Exploration Working Group. "However, lunar dust can be electrostatically charged and can stick on sensitive parts," he says. The abrupt temperature change when the airless moon goes from day to night can also put a huge stress on mechanical systems and could have damaged the rover's moving parts, says Foing.
It is not possible to communicate with the rover during lunar night, so mission operators will have to wait until about 8 February to determine the extent of the damage. "I am sure that they are not going to give up," says Foing. "They are analysing the problem in depth and are working hard to assess safe recovery strategies."
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