Chang'e III - Rover
The Chang´e-3, named after a Chinese lunar goddess, is China’s first spacecraft to make a soft landing on the moon. It comprises a lander and a moon rover called "Yutu" (Jade Rabbit). The Chang´e-3 mission is the second phase of China´s lunar program, which includes orbiting, landing and returning to Earth. It follows the success of the Chang´e-1 and Chang´e-2 missions in 2007 and 2010. The launch of China´s lunar probe Chang´e-3 was "successful".
Chang'e-III was the second step of the three phase Chang'e program, expected to demonstrate unmanned lunar soft lunar landing and various remote scientific operations on or before 2013. The landing of the 3,750 kilogram spacecraft was expected some time between 2012 - 2013. It would at first be placed in a 100 kilometer circular orbit that will be modified to a 100 by 15 kilometer orbit before powered descent begins. It would not merely utilize a lunar landing spacecraft but it would also carry a six wheeled Lunar rover spacecraft utilizing a Isotopic thermal generator for heat and power system probably utilizing solar arrays. It is expected to be targeted for landing in the Sinus Iridium (Bay of Rainbows) region of the lunar surface. Up to two rovers may be utilized in the program. Both vehicles would be launched from Xichang on the Long March CZ-3B booster because the Long March CZ-5E would not be ready in time for this phase of the program.
Chang’e-3 was launched from the Xichang Satellite Launch Center at 1:30 a.m. on 02 December 2013, Beijing time. The lunar probe flew for five days in an Earth-moon transfer orbit, making slight adjustments along the way to set its route. Chang’e-3 then entered a 100-kilometer lunar orbit after slowing down when approaching the moon. Four days later, Chang’e-3 transferred its orbit into an elliptical one. After another four days, Chang’e-3 went through six stages of deceleration until it was 15 kilometers from the moon’s surface.
China's lunar probe Chang'e-3, with the country's first moon rover onboard, landed on the moon 14 December 2013, marking the first time that China has sent a spacecraft to soft land on the surface of an extraterrestrial body. The lunar probe began to carry out soft-landing on the moon at about 21:00 p.m., Saturday and touched down in Sinus Iridum, or the Bay of Rainbows, about 12 minutes later, according to Beijing Aerospace Control Center. During the process, the probe decelerated from 15 km above the moon, stayed hovering at 100 meters from the lunar surface to use sensors to assess the landing area to avoid obstacles and locate the final landing spot, and descended slowly onto the surface. The soft-landing was carried out 12 days after the probe blasted off on an enhanced Long March-3B carrier rocket.
Chang'e-3 is the world's first soft-landing of a probe on the moon in nearly four decades. The last such soft-landing was carried out by the Soviet Union in 1976. The success made China the third country, after the United States and the Soviet Union, to soft-land on the moon. Compared to those other two countries, which have successfully conducted 13 soft-landings on the moon, China's soft-landing mission designed the suspension and obstacle-avoiding phases to survey the landing area much more precisely through fitted detectors, scientists said. The probe's soft-landing is the most difficult task during the mission, said Wu Weiren, the lunar program's chief designer. Chang'e-3 relied on auto-control for descent, range and velocity measurements, finding the proper landing point, and free-falling. The probe is equipped with shock absorbers in its four "legs" to cushion the impact of the landing, making Chang'e-3 the first Chinese spacecraft with "legs." Chang'e-3 adopted a variable thrust engine completely designed and made by Chinese scientists. It can realize continuous variation of thrust power ranging from 1,500 to 7,500 newtons.
China chose the name "Yutu" (Jade Rabbit) for its first moon rover, after a worldwide online poll challenged people to come up with names. In Chinese folklore, Yutu is the white pet rabbit of Chang´e, the moon goddess who has lent her name to the Chinese lunar mission. Legend has it that, after swallowing a magic pill, Chang´e took her pet and flew toward the moon, where she became a goddess, and has lived there with the white jade rabbit ever since. Domestic and overseas compatriots submitted their proposed names for the rover through the Internet and the official name was announced in November after an online poll on the selected proposals.
The rover has two wings, stands on six wheels, weighs 140 kg and is powered by solar energy. When it arrived in lunar orbit on board a lander, the rover chose the best landing site and gently touched down on the moon's surface, using optical and microwave sensors to avoid rocks and craters. The rover would select the best route, use minimal fuel and make the smallest possible error during landing and is capable of hovering to steer clear of obstacles.
The rover can recognize obstacles on the moon's surface, and plot a path of least resistance by a combination of onboard navigation systems and remote control from the command center. The rover can "rest", automatically entering a dormant state to recharge its batteries, and return to work after a while. It can endure a vacuum, intense radiation and extremes of temperature. Temperatures on the moon's surface can range from minus 180 to plus 150 degrees Celsius, said Wu Weiren, the program's chief designer.
The rover is equipped with numerous detectors and information gathering systems such as a panoramic camera and radar measurement devices. The rover will patrol the Earth's natural satellite for about three months. The data collected by the rover, such as 3D images, infrared spectrums and lunar soil analysis, will directly and accurately lead to greater understanding of the moon.
China hailed its Chang'e-3 lunar probe mission "a complete success" 15 December 2013, after its first moon rover Yutu, or Jade Rabbit, and lander took photos of each other on lunar surface. The one-minute photographing, a day after the country finished its first lunar soft landing, showed that both the lander and moon rover functioned well and marked the completion of soft landing, in-situ and patrol explorations, said Pei Zhaoyu, spokesman for China's lunar probe program.
Ma Xingrui, chief commander of the lunar program, declared the success of Chang'e-3 mission at the Beijing Aerospace Control Center (BACC), where Chinese President Xi Jinping and Premier Li Keqiang were present. In a congratulatory message sent by the Communist Party of China Central Committee, the State Council, and the Central Military Commission, the success of Chang'e-3 mission was hailed as a "milestone" in the development of China's space programs, a "new glory" of the Chinese people in their exploration of the frontiers of science and technology and "outstanding contribution" of the Chinese nation in the mankind's peaceful use of the space.
China's first lunar robotic vehicle showed signs of a mechanical control abnormality 25 January 2014, as scientists worked to organize repairs. According to the Chinese State Administration of Science, Technology and Industry for National Defense, the malfunction was due to the "complicated lunar surface environment." The administration gave no other details. Jade Rabbit and its lander draw power from onboard solar cells that charge their batteries. During the frigid lunar night, which lasts about 14 Earth days, there is no sunlight to provide power, so both parts of the probe go into sleep mode. The abnormality occurred before the rover's second scheduled dormancy, on 25 January 2014. The lander also went dormant one day earlier. The rover and the lander have carried out several observations and tests. The mission was planned to last three months.
The Chang'e-3 moon probe is part of the second stage of China's three-stage lunar mission, orbiting, landing, and analyzing lunar soil and stone samples. Chang’e-4 is the back-up lunar soft Lander spacecraft with its small lunar rover, mimicking Soviets practices.
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