On June 25, 2024, China’s Chang’e 6 mission came to an end when a reentry capsule touched down in the Siziwang Banner Province in Mongolia. The capsule contained truly precious cargo: just under 2 kilograms (4.4 pounds) of lunar samples from the farside of the Moon. No mission had ever retrieved material from the farside of the Moon before, giving China a historic first and furthering the momentum of their lunar program.
From a modest start 20 years ago, China’s lunar program has slowly grown to become a juggernaut of research and technological innovation, watched with some degree of wariness by NASA, Japan, and the European Space Agency. Unlike NASA, which is a civilian agency, the Chinese space program is closely related to, and to some extent integrated with, its national military forces. Beginning with lunar orbiters and progressing to lunar landers and rovers, the program has now reached the point of being able to mount a series of sample-return missions of remarkable complexity. Chang’e 6 comes on the heels of 2020’s successful Chang’e 5 mission, which returned samples from the near side of the Moon.
Chang’e 6’s epic voyage
Chang’e 6 launched on May 3 of this year aboard a heavy-lift Long March 5 rocket — China’s equivalent to a Delta 4 or Falcon 9 rocket — and then proceeded through several discrete phases. Entering a highly elliptical lunar orbit (measuring 124 by 236,000 miles [200 by 380,000 km]) on May 8, Chang’e 6 spent about 20 days mapping the lunar surface in search of an acceptable landing location while at the same time slowly circularizing its orbit.
On June 1, the stacked lander and ascent stage separated from the orbiter and, after a 15-minute descent, touched down autonomously on the farside of the Moon. The lander was able to obtain lunar surface and core samples, all the while being photographed by a mini-rover it had carried to the surface. Released to trundle a few meters away from the lander, the mini-rover, known as Jinchan and weighing only around 11 pounds (5 kilograms), captured some truly breathtaking images of the main lander, sitting on the lunar surface and flying a Chinese flag.
Related: Exploring the Moon: China’s Chang’e missions
Once secured, the samples lifted off from the lunar surface aboard the ascent module, which the Chinese call an “ascender.” The ascender deployed solar panels and made multiple adjustments to its orbit around the Moon before it rendezvoused with the orbiter. After the delicate rendezvous and docking was completed, the lunar samples were internally transferred to the so-called “returner” module. Once this was complete, the ascender was discarded. The orbiter and returner circled the Moon for approximately 14 more days until the proper window opened up for a return to the Earth. At this point the orbiter/returner complex fired its engine and headed home.
Around 3,000 miles (5,000 kilometers) from Earth, the returner module detached and began its reentry. Looking very much like a miniature Soyuz descent module, the returner performed a non-ballistic reentry, also known as a skip reentry. This allowed the returner to burn off speed and dissipate energy as it dipped into and out of the atmosphere before making its final plunge to the surface for a gentle landing under a parachute. The returner module was quickly reached by recovery forces after touchdown.
A coveted scientific bounty
The samples were flown to the China Academy of Space Technology in Beijing and, after a brief ceremony, handed over to scientists. The farside of the Moon is of particular interest to lunar scientists as it is distinctly different than the nearside, which is dominated by volcanic plains known as maria. The nearside is heavily covered in maria, while the farside has virtually none to speak of. The reasons for this disparity between the near and far sides of the Moon are currently up for debate. Rocks from the farside of the Moon also have a different chemical composition than those on the nearside. Scientists hope that the samples returned from the Chang’e 6 mission will address some of these discrepancies.
As in the past, Chinese scientists will get the first crack at studying the returned samples. It may be years before China allows international researchers to apply for access to them; samples recovered by Chang’e 5 in December 2020 were not offered to international labs until August 2023, and NASA did not give its scientists a green light to apply until December of that year. (Under U.S. law, NASA is banned from collaborating bilaterally with China; to be granted an exception, the agency had to certify to Congress that there was no technology transfer or security risk in studying the Moon rocks.)
The success of the Chang’e 6 mission puts China one step closer to its ultimate goal: putting Chinese astronauts (“taikonauts”) on the Moon. China plans to someday have a lunar outpost near the south pole and hopes to carry out a crewed landing by 2030. While NASA administrators are keen to state that they are not in a space race with China, the U.S. is angling to return astronauts to the Moon via the Artemis program before China makes its own first landing, and the two space agencies are clearly keeping an eye on each other. Time will tell who sets foot on the Moon next.
