So long moon bunny, we hardly knew you. China's lunar rover, Yutu – or Jade Rabbit – was officially declared dead in a terse statement posted on a Chinese state news agency website.
Yutu's troubles began last month, just six week 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.
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 this Monday 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. Yutu experienced mechanical problems on Jan 25 and has been unable to function since then." No other details were given.
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 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.
Yutu's demise does not mean the end of China's space ambitions, which include a crewed lunar base, and 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.
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