Twitter is abuzz with rumors of the Yutu rover being dead. This article mentions that it might not have been able to prepare for night properly:

More details are available from the unofficial Twitter account of the mission. Links take you to original Chinese, with Google translation below it. It sounds like the rover is not responding properly to commands from Earth, and couldn't prepare for the oncoming night properly. It doesn't sound good; Yutu appears to be saying farewell to us.

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Artist's rendition of a lonely Yutu. Img credit @ShuttleAlmanac

What, exactly, does the rover need to do to prepare?

  • $\begingroup$ I hope someone here knows! "Rumors" in English online claim that it needs to fold its solar panels to protect its mast on which its cameras and high gain antennas are mounted. However, if it can still get some power from the photovoltaics, the internal chassi of the rover is heated by a plutonium source and it might continue operations by driving around with its ground penetrating radar. Given there is a secondary radio communications antenna, and navigation using the stationary lander cameras. That's speculation lacking better Chinese info. $\endgroup$
    – LocalFluff
    Commented Jan 27, 2014 at 14:49
  • 2
    $\begingroup$ Read Emily Lakdawalla's post on this. She does a good job collecting and interpreting what little actual information is available. $\endgroup$
    – Mark Adler
    Commented Jan 27, 2014 at 23:10

1 Answer 1


Like @LocalFluff mentions in the comment, much of what is circulating the western media in the last few days since news broke out that Yutu is in trouble is unsourced information, but those speculations, however substantiated they might or mightn't be, are regarding its fate and possible procedures to mitigate problems that it encountered, not what the rover would actually have to do to prepare for Lunar night, like I read the question.

Procedures to prepare the rover for the Lunar night, that lasts roughly 354 hours, are well known and understood. For example, Spaceflight 101 puts it like this:

For lunar night, the Yutu rover retracts its mast that carries panoramic cameras and the high gain antenna. In is retracted position, the mast is protected by a box located on the rover deck. Then, one of the two solar panels of the rover would be folded up to cover the mast and prevent heat from radiating into space.

Radioisotope Heater Units are mounted in the vicinity to keep the equipment warm during lunar night, but they are only effective when the mast is shielded by the solar panel. The other solar panel would be oriented towards sunrise to trigger the wake up sequence when the next lunar day begins.

This is in accord with reports from other sources, and also how it was explained on China's national broadcasting service CNTV during live webcast of the Chang'e 3 lander's Lunar descent, which some of us followed and commented on in our main chat room. Some of these webcast streams might have been recorded and hosted online somewhere, but I wouldn't hold my breath, since the live event lasted for several hours, and most videos I can find aren't longer than perhaps a quarter of an hour.

Still, no rumours are actually required to understand what the little rover would have to do to protect its equipment during long Lunar nights, but there isn't any end to speculations on what it is to do now, when it experienced problems that aren't well understood at all. But that wasn't the question. ;)


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