June 1, 2024

— China has achieved its fourth robotic moon landing, advancing a mission to combine the feats of its two prior probes: touching down on the lunar far side and bringing samples back to Earth.

The China National Space Administration's (CNSA) Chang'e-6 spacecraft landed on target in the southern part of Apollo crater, located within the moon's South Pole-Aitken basin, on Saturday (June 1). The touchdown, at 6:23 p.m. EDT (2223 GMT or 6:23 a.m. Beijing time on June 2), came 24 days after the multi-module Chang'e-6 arrived in lunar orbit.

"Chang'e-6 landed on the far side of the moon — Aitken Basin, and will carry out sampling work on the far side of the moon as planned," a CNSA statement read.

Launched on May 3 from the Wenchang Space Launch Site on the coast of China's southern island province of Hainan, the Change'6 lander, ascender, orbiter and returner were based on the previous mission's (Chang'e-5) hardware, which successfully collected about 3.8 pounds (1,731 grams) of lunar material from the near side of the moon in December 2020. If successful, Chang'e-6 will be the first mission to deliver far side material for study.

Chang'e-6 lands on the moon. Click to enlarge video in new pop-up window. (CNSA)

"Compared with the Chang'e-5 mission that achieved the sampling and return from the front side of the moon in 2020, the Chang'e-6 mission has made breakthroughs in the design and control technology of the lunar retrograde orbit, and will complete key technical nodes such as intelligent rapid sampling and takeoff and ascent from the far side of the moon," the CNSA release stated.

The far side of the moon, or the hemisphere that forever faces away from Earth, is more crater-pocked and saw less volcanic activity than the near side. Moon rocks and regolith returned from Apollo crater may help scientists better understand why the two sides differ.

On May 30, the Chang'e-6 lander and ascender separated from the orbiter and returner in lunar orbit. At 6:09 p.m. EDT on Saturday (2209 GMT or 6:09 a.m. Beijing Time on June 2), the Chang'e-6 lander and ascender combination began its powered descent to the surface.

During its approach, an autonomous obstacle avoidance system and a camera were used to select an approximate safe landing point. The probe then hovered 100 meters above the chosen area and used a laser to detect any small obstacles on the surface. With its landing point selected, a slow vertical descent began.

"When Chang'e-6 was about to reach the lunar surface, its engine was shut down and a buffer system was used as the spacecraft free fell the rest of the way down and finally landed smoothly," according to the CNSA.

The Chang'e-6 ascender is expected to spend about three days on the surface, using a drill and robotic arm mounted on the lander to scoop up and store lunar samples. The ascender will then lift off from the moon and dock with the Chang'e-6 orbiter a couple of days later.

Update: At 7:38 p.m. EDT on June 3 (2338 GMT or 7:38 a.m. Beijing Time), the Chang'e-6 ascender lifted off from the moon with lunar samples in tow.

The sample container will then be transferred to the orbiter and the ascender will separate so that orbiter can begin the journey back to Earth. The returner — a small reentry capsule — is expected to land in northern Inner Mongolia before the end of the month.

In addition to supporting sample collection, the Chang'e-6 lander also has several science experiments on board, which will function as long as solar power can be maintained. Among the research payloads are a European Space Agency (ESA) negative ions analyzer and a French instrument for detecting outgassing from the lunar regolith. The lander also has an Italian retro-reflector, a surface radar and a panoramic camera.

Chang'e-6 is also carrying a small rover of unknown specifications, though it may be equipped with a infrared imaging spectrometer.

Update: The rover or "mobile camera" was used to photograph the ascender and lander on the lunar surface.

Chang'e-6 is the sixth mission in the Chinese Lunar Exploration Program (CLEP), which was established in 2003 to ultimately land Chinese astronauts on the moon. Prior to Chang'e-6, the CLEP missions included two orbital missions, three landing missions (two including rovers) and a test (Chang'e 5-T1) that verified the ability to return a spacecraft from lunar orbit.

The Chang'e-3 and -4 landers and Chang'e-4 rover Yutu-2 continue to operate on the moon. The Chang'e-5 orbiter is also still active, testing a a distant retrograde orbit around the moon.

Before launching Chang'e-6, CNSA sent the Queqiao-2 satellite into lunar orbit to serve as a communications relay between the spacecraft on the moon's far side and Earth. Chang'e-6 also deployed ICUBE-Q (or ICUBE-QAMAR), a Pakistani lunar remote sensing observation nanosatellite, which began taking images of the Sun and moon once it was released on May 8.

Chang'e-6 is the 152nd attempt at a moon mission since 1958, including flybys, orbiters, impactors and landers. The probe is the 27th lander to successfully touch down on the lunar surface. Like the other spacecraft in its series, Chang'e-6 was named for the moon goddess from Chinese mythology.