Launch of Chang’e 6, the first probe to return samples from the far side of the Moon

China’s space program is returning to the moon with the launch of Chang’e-6, the first probe to bring back samples of our moon’s hidden side. On May 3, 2024, at 09:27 UTC, the CZ-5 Y8 Long March rocket successfully took off from the LC-101 ramp of the Wenchang Space Center on Hainan Island using the Chang’e 6 (CE-) probe. 6, 嫦娥六号) on a challenging 53-day mission. After two second-stage burns, the probe was launched onto a trajectory toward the Moon and separated approximately 37 minutes after takeoff. This is the eighth launch of the CZ-5 – the three-stage version of the most powerful missile in Chinese service – and the 12th launch of the CZ-5 overall, including the two-stage CZ-5B used for low-altitude launches. orbit. This is also the third CZ-5 launch in just six months. Chang’e-6 is the second probe of the Chang’e family to use the CZ-5 heavy rocket, and the third Chinese probe to use this launcher, including the Tianwen-1 Mars probe Chang’e-6, which carries a small Icube- rocket. The Pakistan Space Agency’s (SUPARCO) Q satellite will be deployed in lunar orbit. The mission’s launch window lasted three days, with each day lasting 50 minutes.

If all goes according to plan, Chang’e 6 will enter lunar orbit on May 8, and its surface segment will land on the far side in the South Pole-Aitken Basin (43 degrees south, 154 degrees west) on June 2 next year, becoming China’s fourth probe landing on the surface of the Moon. The sample capsule is scheduled to land in Inner Mongolia on June 25. Chang’e 6 is similar in nature to Chang’e 5, launched on November 23, 2020, and which returned on December 16 of the same year with 1.73 kg of lunar samples from the Mons-Rümker region in the visible region. In fact, Chang’e 6 was originally built as a backup for the Chang’e 5 mission, just as Chang’e 4 was once a backup for Chang’e 3 (speaking of Chang’e 4, this probe has remained active on the far side since 2019 along with the Yutu 2 rover).

Chang’e 6 is a sample collection probe weighing about 8 tons and 7.2 meters high, built by CAST (Chinese Association of Science and Technology), a division of CASC—the prime contractor for the Chinese space program—for the Chinese lunar exploration program, CLEP (Chinese lunar exploration program). The probe consists of two ships, each of which is divided into two parts: an orbital segment and a surface segment. The surface segment, weighing 3.8 tons, includes a descent stage similar to the Chang’e-3 and Chang’e-4 stations, on which the take-off stage is located. The orbital segment includes a 3.2-ton orbiter and a 1-ton return capsule.

The mission architecture is similar to that of Chang’e 5 and is therefore the most complex of the automated missions. The orbiter will use its 3 kilonewton thrust YF-37 main engine to place the array into a preliminary elliptical lunar orbit with a period of 12 hours. It will then enter orbit with a period of 4 hours and reach a circular orbit at an altitude of 200 kilometers. The surface segment will be separated from the orbital segment and placed into an orbit measuring 15 x 200 kilometers. The lander will perform an automatic landing using a 7.5-kilonewton YF-36A lander engine and an autonomous navigation system using lidar and optical navigation. Once the samples are collected, the sample container will be placed on the lift stage.

The stage will take off on June 4 using an engine with a thrust of 3 kilonewtons and dock with the orbiter using a clever system (hooks on the orbiter will “hug” the three booms of the ascent stage). The descent stage will remain on the surface (it is assumed that it does not carry an RTG, like Chang’e-3 and Chang’e-4, therefore, like the Chang’e-5 descent stage, it will not survive a lunar night). The container will then be transferred from the ascent stage to a capsule located inside the orbiter. After the ascent stage enters lunar orbit, the orbiter with the capsule will head towards Earth and on June 25 will release the capsule, which will make a double entry into the atmosphere –skip re-entry– before landing by parachute.

Chang’e 6 will collect samples using a drill and a robotic arm. As with Chang’e 5, the drill will be able to collect regolith to a depth of about 2.5 meters (Chang’e 5 can only drill up to one meter), and a robotic arm will be used for collection. , in addition to regolith, surface rocks. The expected collection amount has not been disclosed, but it is expected to be between 2 and 3 kg.

The main difference from the Chang’e-5 mission is that Chang’e-6, after landing on the far side, will not be able to communicate directly with Earth, so it will require the services of the Queqiao-2 relay satellite, launched on December 21. March along with the small lunar satellites Tiandu 1 and 2 on CZ-8. Queqiao-2 will relay data from Chang’e-6 from an ELF-type inclined lunar elliptical orbit (Elliptical lunar frozen orbit), with a period of 24 hours and 200 x 16,000 kilometers, with an inclination of 62.4 degrees. Queqiao-1, still in operation at the L2 Lagrange point of the Earth-Moon system, from where it serves as a relay for Chang’e-4, will serve as a reserve for this mission.

In addition to several cameras and a flying flag of the People’s Republic of China, Chang’e 6 carries three European scientific instruments: the French DORN radon detector (Detection of outgassing Radon), provided by the French space agencies CNES and IRAP (Institute for Research in Astrophysics and Planetary Science), Italian laser retroreflector INRRI (A device for landing and moving a laser retroreflector.), the National Institute of Nuclear Physics of Italy and the Swedish solar wind sensor NILS (Negative ions on the lunar surface), provided by the European Space Agency (ESA). Chang’e 6 also carries, surprisingly, a small rover that appears to be a mobile camera for recording sample collection and ascent stage launch operations.

Chang’e 6 is part of the fourth phase of the CLEP program, approved in 2021, which includes extending the life of Chang’e 4 and the future ground probes Chang’e 7 (due to launch in 2026) and Chang’e 6. . e 8 (2028). Separately, we note that the secrecy surrounding this mission is amazing, and this despite the fact that it is similar to Chang’e-5. The exact take-off time had not been announced the day before, and only one image of the probe had been released. launched.

Stages of the Chang’e 6 mission

• May 3: launch.
• May 8: entering lunar orbit.
• June 1: Separation of the descent segment of the orbiter.
• June 2: Landing on the far side of the descent section.
• June 4: The ascent stage lifts off from the surface carrying samples.
• June 6: Ascent stage docks with the orbiter and transfers samples to the capsule.
• June 20: The orbiter sets course for Earth.
• June 25: Lunar sample capsule arrives.

Launch stages

• T+0 s: takeoff.
• T+173 s: stopping 4 blocks of Carolox accelerators.
• T+176 s: separation of 4 blocks of the Carolox accelerator.
• T+325 s: coping department.
• T+484.8 s: shutdown of the cryogenic stage of the core.
• T+488.6 s: central stage separation.
• T+489 s: second stage ignition.
• T+738.4 s: first shutdown of the second stage.
• T+1725.3 s: second ignition of the second stage.
• T+2126.5 s: second stop of the second stage.
• T+2210.6 s: separation from Chang’e 6.

Transfer to the ramp:

Ramp rocket:

Take off: