© Chinese Academy of SciencesThe far side of the moon and distant Earth, imaged by the 2014 Chang’e-5 T1 mission service module.
HELSINKI — China's Chang'e-6 mission lander made a successful soft landing on the far side of the moon late Saturday and will soon begin collecting unique lunar samples.

The Chang'e-6 lander made a soft landing at 6:23 p.m. Eastern June 1 (2223 UTC), the China National Space Administration (CNSA) announced shortly after the event. The lander targeted a southern portion of Apollo crater within the South Pole-Aitken (SPA) Basin on the lunar far side.

The landing is a critical step towards bringing unique and scientifically invaluable lunar samples to Earth for analysis. U.S. decadal surveys have highlighted an SPA sample return as a highest priority science objective.

The Chang'e-6 lander used a variable 7,500-newton-thrust engine to slow its velocity in lunar orbit and begin its descent. The lander was scheduled to make rapid positional adjustments at an altitude of around 2.5 kilometers above the lunar surface before continuing its descent. The spacecraft entered a hovering phase for fine hazard avoidance at approximately 100 meters above the surface. It used light detection and ranging (LiDAR) and optical cameras to find a safe landing spot.

Chang'e-6 is China's fourth successful lunar landing from four attempts, and the second on the far side of the moon. It is also the third lunar landing in 2024. It follows Japan's SLIM in January and Intuitive Machines' IM-1 Odysseus lander in February.

Teams will now begin initial checks of the lander's systems and soon begin collecting samples. The lander will collect up to 2,000 grams of samples, using a scoop to grab surface regolith and a drill for subsurface material. Samples are expected to be sent into lunar orbit within around 48 hours. Chinese space authorities have yet to publish a timeline for the mission and its steps, however.

There are complex stages remaining before samples can be returned to Earth for analysis. Yet the success of this critical stage of the mission will be celebrated.

Xu Yi, an assistant professor at the Macau University of Science and Technology, told SpaceNews earlier in the week:
"I have been analyzing the scientific data of the Chang'e-4 mission that landed on the far side of the moon, and I am constantly excited to have new findings from the ongoing rover data. Therefore, I am particularly excited about the Chang'e-6 mission.

"The reasons for the asymmetry in the scale of volcanic activity between the lunar nearside and farside are still subject to different hypotheses. Chang'e-6 will probably collect lunar samples from various sources, including products of local volcanic activity. Dating and compositional analysis of these samples will provide more ground truth information about volcanic activity on the far side."
Samples could contain material ejected from the lunar mantle. These would provide insights not only into the depths of the moon, its composition and its evolution, but also for the Earth the wider history of the early solar system.

Chang'e-6 next steps

Following sampling, an ascent vehicle will be expected to launch itself and the samples from atop the Chang'e-6 lander. The launch is expected within around 48 hours of landing, taking the samples into lunar orbit. The ascender will need to rendezvous and dock with the waiting Chang'e-6 orbiter.

Samples would then be transferred to a reentry capsule and ahead of the journey back to Earth. Departure from the moon will take place at a calculated time. The orbiter would then release a reentry capsule just ahead of its return to Earth, around June 25. The capsule will first bounce off the atmosphere once and target a landing in grasslands of Inner Mongolia. Samples would then be transferred to special facilities for handling, analyzing and storing the lunar material.

The Chang'e-6 mission also uses support from the Queqiao-2 relay satellite. This allows communications with the otherwise hidden far side of the moon.

Lunar rover, science payloads

Beyond the precious samples, the Chang'e-6 lander also carries further payloads for conducting a range of science objectives. A small rover is expected to be deployed onto the surface for short term operations.

International payloads include the Negative Ions at the Lunar Surface (NILS) payload developed by the Swedish Institute of Space physics and the Detection of Outgassing RadoN (DORN) instrument from France. An Italian passive laser retro-reflector is aboard the lander. The lander will then suffer damage from the launch of the ascent module, likely ending surface operations.

Chang'e-6 is part of China's broader lunar program. The country will follow up with two missions to the south pole of the moon. These are Chang'e-7 in 2026 and Chang'e-8 around 2028. The country aims to launch its first crewed lunar mission by 2030.

Both sets of missions are part of a plan to establish a permanent lunar base. This project is known as the International Lunar Research Station (ILRS) program, planned for the 2030s. A number of countries and organizations have signed up to the project.