The far side of the moon and distant Earth, imaged by the 2014 Chang’e-5 T1 mission service module.
The far side of the moon and distant Earth, imaged by the 2014 Chang’e-5 T1 mission service module. Credit: Chinese Academy of Sciences

HELSINKI — China’s Chang’e-6 lunar far side sample return spacecraft entered orbit around the moon late Tuesday, in another step towards collecting lunar samples.

The Chang’e-6 orbiter completed a braking burn at 10:21 p.m. Eastern, May 7 (0221 UTC May 8), slowing the craft down to allow it to be captured by the moon’s gravity, the China National Space Administration (CNSA) announced

The mission launched May 3 and embarked on a roughly 112-hour journey to the moon. It is the first-ever attempt to collect samples from the far side of the moon, promising big scientific payoffs. 

The orbiter used its 3,000N engine for the braking burn. The Chang’e-6 spacecraft is understood to be in an elliptical lunar orbit with a periapsis of around 200 kilometers. Chang’e-6 will next release a 7-kilogram cubesat named Icube-Q into lunar orbit. The main spacecraft will then gradually circularize its orbit in preparation for landing.

The mission lander will separate from the spacecraft in the days ahead of the landing attempt in Apollo crater. The landing is expected, though not officially confirmed, to be around early June, as current lighting conditions over Apollo crater are not optimal for landing and surface operations.

The target landing area is within the vast, ancient South Pole-Aitken Basin (SPA) and is thought to contain material excavated from the moon’s mantle. Analysis of such samples could bring new insights into and understandings of the moon, in particular its history and the contrast between its near and far hemispheres.

What’s next for Chang’e-6?

The Chang’e-6 mission is expected to last 53 days from launch till landing, according to information published by the Deep Space Exploration Laboratory (DSEL) under CNSA.

A map of the lunar far side, indicating the Chang’e-6 landing zone within Apollo crater. Credit: CNSA

Sunrise over Apollo crater will occur May 28. This means Chang’e-6 will likely attempt to land around early June, once the sun is high enough in the sky over the landing area. Timing of the attempt will be dependent on the spacecraft’s orbit and constraints regarding surface lighting conditions for generating power. 

Sampling operations will—as with Chang’e-5, for which Chang’e-6 is a repurposed backup—likely be wrapped up within 48 hours of landing. Samples will be sent into lunar orbit via an ascent vehicle, which will then track the Chang’e-6 orbiter. 

Based on the earlier mission, the pair will likely rendezvous and dock around two days after launch, with the ascender to be discarded a further couple of days later. The orbiter would then prepare to leave lunar orbit at a calculated time. It would then release a reentry capsule just ahead of its return to Earth, around June 25.

The far side of the moon is never visible to Earth. This is due to our planet slowing the moon’s rotation and leaving it tidally locked. The mission is thus supported by the Queqiao-2 satellite. Queqiao-2 is operating in a specialized orbit in order to bounce communications between Chang’e-6 on the far side and ground stations on Earth. 

Further objectives

Asides from its main objective of sample return, Chang’e-6 carries payloads for further science. The mission carries international payloads from France, Sweden, Italy, as well as the aforementioned cubesat with involvement from Pakistan.

The lander also carries the Detection of Outgassing RadoN (DORN) instrument from France. This will detect radon outgassing from the lunar crust. Sweden, with ESA support, contributed the “Negative Ions at the Lunar Surface” (NILS) payload. An Italian passive laser retro-reflector is also aboard the lander.

The Chang’e-6 spacecraft stack showing, for the first time, an apparent lunar rover attached to the mission lander. Credit: CAST

Images of the spacecraft released after launch also reveal Chang’e-6 to be carrying a small rover.

Chang’e-6 is part of China’s broader lunar goals. 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.

Andrew Jones covers China's space industry for SpaceNews. Andrew has previously lived in China and reported from major space conferences there. Based in Helsinki, Finland, he has written for National Geographic, New Scientist, Smithsonian Magazine, Sky...