Monday, May 20, 2024

China’s Chang’e 6 Mission Heads to the Moon – Sky & Telescope

AstronomyChina's Chang'e 6 Mission Heads to the Moon - Sky & Telescope


The Chang’e 6 team with the Long March 5 rocket ahead of launch.
CNSA

A massive Long March 5 rocket lit up the skies over Wenchang Space Center on Hainan Island in China early this morning, carrying China’s 2024 lunar bid: the Chang’e 6 sample-return mission. Watch the launch here:

Liftoff occurred at 5:27 a.m. EDT / 9:27 UT, and Chang’e 6 and the upper stage booster separated shortly after launch. Controllers report the mission is in good health.

Chang'e 6 inside building with blue, spiky walls and bright overhead lights
Chang’e 6, stacked in the clean room on Earth.
CASC / CAS

The Mission Timeline

The plan for Chang’e 6 is a 53-day long mission with the goal of returning 2 kilograms (4.4 pounds) of soil by June. The targeted landing site is the Apollo Basin on the lunar farside.

Scientists obtained their first blurry views of the lunar farside with USSR’s Luna 3 flyby in 1959, which revealed a region decidedly different from the nearside: There were almost no maria or ancient lava flows, and far more craters than expected. NASA’s GRAIL missions showed that the farside’s crust is actually thicker than the nearside crust by about 20 kilometers.

Most recently, China’s Chang’e 4 mission performed the first soft landing on the farside, exploring the area near the lunar south pole with a rover and returning images of its landing site in Von Kármán Crater in the South Pole-Aitken Basin. Now, with Chang’e 6’s sample return,scientists hope to better understand the history and formation of the Moon.

Landing Site
The Lunar South Pole region, and the proposed Chang’e 6 landing site. The Planetary Society

The Chang’e Program

The Chang’e series takes its name from the Chinese moon goddess. China has taken a slow, incremental approach to space missions, and the Moon is no exception. The first two missions in the lunar series, Chang’e 1 and 2, were orbiters, followed by the nation’s first lander and rovers, Chang’e 3 and 4. Then, in 2020, China completed its first automated lunar sample return with Chang’e 5, which touched down at Mons Rümker (on the nearside) and brought back a sample in a whirlwind 24-day mission.

Diagram of Chang'e 5 ground support
ESA’s basic architecture for communicating with Chang’e 5, which followed a similar flight trajectory to the Moon as the Chang’e 6 mission will.
ESA

Now, Chang’e 6 will synthesize the lessons learned on previous missions, entering orbit around the Moon in preparation for a landing and sample return from the farside. Earlier this year, China also launched the Queqiao 2 relay orbiter to the Earth-Moon L2 Lagrange point, where it has line of sight contact with both the lander and Earth to facilitate communications with the Moon’s farside.

Chang'e
The lunar ascent vehicle, lifting off from the surface of the Moon.
CNSA

The scenario for sample return is complex. Unlike automated Soviet returns in the Luna program, which simply returned directly to Earth, the ascent stage for Chang’e 6 will rendezvous with the mission’s service module, which remains in lunar orbit. The precious cargo will then be transferred to that return capsule, before it detach for return to Earth and atmospheric reentry over outer Mongolia.

CNSA
Change 5’s sample return capsule back on Earth. CNSA

It’s quite possible that China could repurpose Chang’e 6’s service module for more science after its Earth flyby. The previous Chang’e 5 mission passed thru the Sun-Earth L1 point, before entering a distant lunar retrograde orbit to conduct long-baseline radio experiments.

International Contributions

Unlike previous Chang’e missions, this one features international cooperation: The French space agency (CNES) has contributed the Detection of Outgassing Radon instrument, which seeks to measure the exchange of dust and volatiles between the lunar regolith and the Moon’s tenuous exosphere. Sweden also has its Negative Ions on the Lunar Surface instrument on board; it’s designed to study the reflection of negative ions off of the lunar surface. Italy has also sent a passive laser reflector on the mission.

Finally, Pakistan’s ICUBE-Q cubesat mission is hitching a ride to lunar orbit with Chang’e 6. ICUBE-Q will search for lunar water ice in permanently shadowed polar regions of the Moon.

Watch for Chang’e 6 to land on the Moon later this month, and the sample-return to Earth return in June.



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