[18] The Chinese Lunar Exploration Program was divided into three main operational phases:[17] Unlike NASA and ESA, the China National Space Administration reveals little about its missions to the public, so detailed information about Chang'e 3 is limited.During the 14-day lunar nights, the rover went into sleep mode,[23] during which heating was provided by radioisotope heater units (RHU) using plutonium-238[24] and two-phase fluid loops.[33] On 17 December 2013, it was announced that all of the scientific instruments except the spectrometers were successfully activated, with both the lander and rover "functioning as hoped, despite the unexpectedly rigorous conditions of the lunar environment".[27][35][36] In addition to successfully deploying its robotic arm, Yutu completed diagnostic checks on 23 December 2013 to ensure that it was prepared for the upcoming lunar night, and moved about 40 metres south of the lander.[9] The Planetary Society reported that the rover was not responding to commands from Earth correctly, rendering it unable to "prepare for the oncoming night properly."[40][41][42][43] It later became evident that the rover suffered a control circuit malfunction in its driving unit, which prevented it from entering normal dormancy and folding its mast and solar panels.[47][48][49] China's lunar program spokesman Pei Zhaoyu declared that although Yutu was able to communicate, "it still suffers a mechanical control abnormality," rendering it immobile.[11] The rover entered its third hibernation period on 22 February 2014 and continued to remain immobile, while serious technical difficulties persisted, further hampering science operations.[50][51] While amateur observers were unable to detect transmissions from the lander, Chinese officials reported that the craft was still operating its UV Camera and Telescope as it entered its 14th lunar night on 14 January 2015.[52][53] On 18 April 2014, Wang Jianyu, deputy secretary general of the Chinese Society of Space Research stated that the failure was not mechanical, but electrical, and they were looking to bypass it.
The planned landing site was
Sinus Iridum
, a lava-filled crater 249 km (155 mi) in diameter. The actual landing took place on
Mare Imbrium
.
LRO
image of the landing site, which is close to the transition between light and dark maria
LRO
close-up image taken on 25 December 2013. The lander (large arrow) and rover (small arrow) can be seen.
Boulders near
Ziwei
crater photographed by the
Yutu
rover