December 23, 2013
With Chang'e 3's lander now on the Moon, its 140-kg (310-lb.) rover deployed and instruments on both working well, China is looking ahead to a sample-return mission to Earth's natural satellite in 2017.
The next mission, Chang'e 4, will be similar to the current effort, using a backup spacecraft and rover, but it will be adapted to prove technologies for the sample-return mission, Chang'e 5, says Wu Zhijian, a spokesman for the State Administration of Science, Technology and Industry for National Defense. Wu gave no schedule for Chang'e 4, but last year it was slated for 2015.
In 2017, Chang'e 5 will be China's first space expedition to collect samples from the Moon and return them to Earth. Chang'e 6 is designed to do the same, following China's habit of planning a pair of missions for each stage of its lunar exploration program, in case of failure. Stage 2 of the program, to land and deploy a rover, has been executed. Chang'e 3 touched down at 1:11 p.m. GMT on Dec. 14 at the eastern-most edge of its target zone, just short of the Bay of Rainbows in a scientifically promising region of the Sea of Rains (Mare Imbrium). Paul Spudis, an experienced lunar scientist based at the Lunar and Planetary Institute in Houston, says the touchdown spot suggests the Chinese lander succeeded in a safe descent on its first orbit.
“My sense is, one, they landed where they wanted to and, two, they landed safely because that objective had been built into the plan,” Spudis says. “It's quite impressive. It's a real tribute to them, I think.”
The rover rolled off the lander about 7 hr. later. It is intended to examine the Moon's geological structure and surface material and look for natural resources for the next three months. The lander, unable to move, is to observe its surroundings and the Earth's plasmasphere for a year.
China's lunar exploration program began in 2007 with the launch of Chang'e 1, a spacecraft built on a DFH-3 satellite bus; it was finally crashed onto the Moon. Chang'e 2, a basically similar spacecraft built as a back-up, improved on its predecessor in 2010, when it was launched directly into a lunar transfer orbit. Among the tasks of that mission was surveying possible landing sites for Chang'e 3. That completed Stage 1, although Chang'e 2 is still operational, heading into deep space and now 60 million km (37 million mi.) from Earth.
No details are available on how Chang'e 4 will be adapted to lay groundwork for the third-phase sample-return missions, but Wu tells state news agency Xinhua: “The program's third phase will be more difficult because many breakthroughs must be made in key technologies, such as Moon surface takeoff, sampling encapsulation, rendezvous and docking in lunar orbit and high-speed Earth reentry, which are all new to China.”