Is Yutu waking up after all? (Image: Imaginechina/Corbis)

Reports of the moon bunny’s death may be somewhat exaggerated. Despite earlier suggestions that China’s lunar rover, Yutu – or Jade Rabbit – had been officially declared dead, Chinese state media now say that the rabbit has phoned home. It remains unclear, though, whether the rover is healthy enough to continue its mission.

A news statement from state media agency Xinhua reports that the Chinese space agency is seeing signs of life from Yutu. And a website that records amateur monitoring of radio signals from space has received a downlink signal from Yutu, according to the Planetary Society.

Getting a signal from the rover raises hopes that all is not lost. According to Xinhua, a mission member has said: “The situation of the little rabbit is improving, with a little indication of awakening. Wait a while more.”


Early mourning

Yutu’s troubles began last month, 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 90 °C to below -180 °C.

When the second lunar night rolled around on 25 January the lander went in to hibernation but Yutu appeared to have failed. It is impossible to communicate with the vehicles during lunar night, so mission operators had to wait until the new lunar day on Monday this week to confirm whether Yutu would respond.

Communication was established with Chang’e-3 but today, the ECNS news agency reported efforts to reactive the rover were unsuccessful: “China’s first lunar rover, Yutu, could not be restored to full function on Monday as expected, and netizens mourned it on Weibo, China’s Twitter-like service.”” No other details were given at the time, leading many observers to think the rover was a goner. News of a wake-up signal is hopeful, but there are no verified reports yet on whether the rover is able to receive and carry out orders from mission controllers.

Cold, cold night

The rover’s mechanical problems are likely related to critical components that must be protected during the cold lunar night. When temperatures plunge, the rover’s 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.

China’s space agency has not released any more details, but 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 programme the sharp-edged dust grains wore through astronaut space suits, scratched up mirrors used for laser ranging experiments and caused moon buggies to overheat.

Even if it is the end of the road for Yutu, China’s race into space is just getting started. The nation has bold plans for a crewed lunar base. The rover has also helped put the moon back on the map – NASA has recently began a programme working with private companies to build robots for lunar mining.