China’s Chang’e-6 robotic mission to pluck samples from the Moon’s far side achieved another step in bringing the goods home to planet Earth, targeted for a June 25 parachute landing.
At 2:48 PM (Beijing Time) the mission’s ascender vehicle rendezvoused and docked with the Chang’e 6 orbit-return vehicle combination in lunar orbit.
The container carrying the first lunar far side samples were transferred from the ascent vehicle to the orbit-return vehicle by 3:24 PM.
The successful transfer process followed surface sampling, stowage, and ascent stage liftoff from the floor of the Apollo basin on Tuesday morning, and entering lunar orbit, during which time it made four orbital adjustments to enable rendezvous.
Holding claws
“There were two steps in the rendezvous and docking process. After the ascender took off from the far side of the moon, it made four orbital adjustments in the lunar orbit to enter the preset orbit. Then, the orbiter-returner combination caught up with and got closer to the ascender. Finally, the docking was completed. The biggest challenge therein was stability,” Lu Yuntong from the China Aerospace Science and Technology Corporation told China Central Television (CCTV).
Wang Qiong, deputy chief designer of the Chang’e-6 mission, said that the docking apparatus of the Chang’e-6 mission is capable of precisely capturing the sample container and transferring it to the orbiter-returner combination, with the three pairs of holding claws playing an important role in the process.
“A pair of holding claws equipped onto the orbiter firmly clasped a bar of the ascender, after which the two spacecrafts closely got together. During the process, the container carrying samples were transferred from the ascender into the returner capsule,” Wang told CCTV.
“The docking process went very well today with high precision because it docked at the right time. If we missed this opportunity, there would be a collision. We got one chance only,” Qiao Dezhi, a space scientist at the China Aerospace Science and Technology Corporation, told CCTV.
Next step: Moon-Earth departure
When the ascender was about 30 miles (50 kilometers) in front of, and 6 miles (10 kilometers) above the orbiter-return vehicle combination, the combination gradually approached the ascent vehicle through short-range autonomous control, and captured it with clasping claws, similar to the successful docking and transfer procedures of the Chang’e 5 nearside surface samples in 2020.
The orbiter-return combination will later separate from the ascent vehicle and prepare to return to Earth at an appropriate and optimal trans-Earth injection time.
Following the Moon-Earth transfer burn and the trip home, the orbiter and ascent vehicle carrying the sample container is scheduled to separate.
If all continues to go as planned, the sample return capsule is expected to parachute into Siziwang Banner (county) in north China’s Inner Mongolia Autonomous Region around June 25.
Note: Special thanks to James Head of Brown University for this update.
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