Chang’e-5 leg of lunar lander.
Credit: CNSA/CLEP

 

Lunar samples returned to Earth by China’s Chang’e-5 mission are undergoing intensive study and offer revealing details about the Moon.

China’s Chang’e-5 (CE-5) mission was the first robotic Earth-Moon round-trip collection of lunar bits and pieces since the Soviet Union’s Luna 24 mission in 1976.

Regional context of the Chang’e-5 Moon landing site (green triangle).
Credit: Yuqi Qian, et al.

A new research paper indicates that samples returned by the Chinese Moon sample mission will address fundamental questions such as lunar chronology, thermal evolution, as well as provide key calibration for lunar and planetary chronologies and remote sensing data.

The paper – “China’s Chang’e-5 landing site: Geology, stratigraphy, and provenance of materials” – has been published in the Earth and Planetary Science Letters journal. Lead author of the paper is Yuqi Qian of the State Key Laboratory of Geological Processes and Mineral Resources, Planetary Science Institute, School of Earth Sciences, China University of Geosciences in Wuhan, China.

NASA Lunar Reconnaissance Orbiter’s powerful LROC system captured these images. Left: Chang’e 5 spacecraft before departure of ascent stage. Right: After departure of ascent stage. Both images sampled at 1.2 meter pixels, north is up. Credit: NASA/GSFC/Arizona State University

Topside and subsurface samples

China’s highly successful Chang’e-5 lunar mission retrieved about 4 pounds (1,731 grams) of samples from the basaltic plains of Northern Oceanus Procellarum (“Ocean of Storms”). Its lander-ascender combination touched down on the near side of the Moon on December 1, 2020, collecting samples from both the lunar surface and beneath.

Chang’e-5 cannister holding lunar specimens is carefully removed by technicians.
Credit: National Astronomical Observatories, CAS

 

The ascender later rocketed the specimens off the Moon for transfer to an orbiter/returner for transport back to Earth.

A return capsule containing the lunar collectibles landed in Inner Mongolia Autonomous Region in the early hours of December 17, 2020.

 

Stratigraphic assessment

Regolith and rock fragments sampled by Chang’e-5, the paper explains, “come from some of the youngest mare basalts on the Moon, near Rima Sharp [the longest sinuous rille on the Moon] and from the center of the globally anomalous Procellarum KREEP Terrane (PKT), hypothesized to be responsible for the generation of the young volcanism.”

A detailed geologic map and stratigraphic assessment of the landing site of Chang’e-5 has been created. The stratigraphy consists of ancient highland materials, local silica-rich volcanism, overlain by a sequence of mare basalts, capped by post-mare bombardment ejecta from distant sources, mainly from Harpalus (a young lunar impact crater), Copernicus (one of the most prominent craters on the Moon) and Aristarchus (one of the most geologically complex areas on the Moon).

Credit: Yuqi Qian, et al.

Chinese President Xi Jinping inspects specimens from the Moon brought back by the return sample mission.
Credit: CCTV/Inside Outer Space screengrab

Different layers

There are at least 9 different layers in the Chang’e-5 landing site, the paper explains, including impact ejecta, regolith, moderate- titanium (Ti) basalts, paleo-ejecta, paleo-regolith, low-Ti mare basalts, and Procellarum KREEP Terrane crust, which can be tested by the Lunar Penetrating Radar carried onboard the Chang’e-5 lunar lander. That radar provided information support for lunar drilling and sampling.

The mare basalts whisked back to Earth by the Chang’e-5 mission, “have enormous potential for improving our understanding of the recent thermal evolution and impact history of the Moon,” the research paper notes. Soil and rock fragments returned are to be carefully studied in laboratories using cutting-edge techniques.

To access the paper — “China’s Chang’e-5 landing site: Geology, stratigraphy, and provenance of materials” – go to:

https://www.sciencedirect.com/science/article/abs/pii/S0012821X2100114X

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