After over 7 months on the Moon, China's 'Jade Rabbit' rover still lives

Friday, July 25, 2014, 1:45 PM - Yutu, China's little lunar rover, hasn't been having the easiest time of it on the Moon since it arrived back in December 2013. It's been stationary for months now and suffers problems with each lunar night, but remarkably, the tenacious little robot continues to survive, even after going through its 8th lunar day!

With the Moon always showing the same face to Earth, its days and nights last a lot longer than they do here. A day there is typically between 9 and 13 Earth-days long, while a lunar night can last anywhere between 17 and 20 Earth-days. Also, without an atmosphere, there are wild temperatures swings from day to night, climbing up to over 100 degrees C when the Sun is up, and dropping down to around -180 degrees C in the dark.

Yutu - Chinese for Jade Rabbit - was designed with this in mind, of course. When each lunar night came around, it would be able to stow away its camera mast, fold one of its solar panels over its inner workings, so that they would be warmed by radioisotope heaters, and its other solar panel would be aimed at the horizon, to wait the coming dawn. This worked fine for its first lunar night, which lasted from December 26 to January 11. However, just before it entered its second lunar night, on January 25, the rover experienced a problem, possibly due to the abundance of dust at its location, that prevented its solar panel from folding down properly. This situation left its sensitive electronics exposed to the cold, and originally it was thought that the rover would not wake up again.

When the Sun rose again on its location, on February 12, it seemed the space agency's fears were confirmed, as they could not contact the rover, but slowly, over the next few days, the plucky little robot came back to life. Since then, the rover has been going to sleep each night, with a very good chance that we'll never hear from it again, but each time the Sun shines on its solar panels, it slowly, sluggishly reports in and starts sending data again.

Yutu has now gone though its 8th lunar day, which ran from July 9-19, and it is down for another night, which will end on August 8 (click here for a timeline of Yutu's day/night schedule, c/o of the International Lunar Observatory Association).

It's really quite remarkable that it continues to survive night after night, despite the extremes it endures and now four months after its original three-month-long mission has ended.

Zhang Yuhua, the deputy chief designer of the lunar probe system for the Chang'e-3 mission (Chang'e-3 being the lander that delivered Yutu to the lunar surface), has been quoted by the Chinese state news agency as saying that Yutu is "much stronger than expected."

Even with this amazing tenacity, the rover still isn't doing all that well. Each dip into the frigid cold of the lunar night takes a toll on Yutu's electronics, plus the rover hasn't actually been roving since January. Apparently, the surface where the Chang'e-3 lander touched down is much rockier than anticipated.

"It is almost like a gravel field," Zhang told the Xinhua news agency, adding that the rover was "'wounded' by colliding with stones while moving."

Still, despite the problems it has been suffering, Yutu has sent back a great amount of data to Earth, which according to Emily Lakdawalla of The Planetary Society and Nature magazine, should be appearing in an upcoming issue of the journal Research in Astronomy and Astrophysics.

"Yutu has 'over-served' its time on the moon and sent lots of data back to Earth," Zhang said in her Xinhua interview. "We hope it can continue to work miracles."