Lunar mission to return samples expected to explain variations between Moon’s near and far sides
A mini rover released from Chang’e-6 probe on the Moon’s surface. Photo: China National Space Administration
After a nearly two-month long mission, China’s Chang’e 6 lunar lander has returned to Earth June 25, 2024, bringing with it the first-ever lunar samples collected from the moon’s far side. Scientists were eagerly awaiting the return of the robotic lunar exploration mission in hopes of solving the long-standing mystery of why the moon’s near and far sides appear so different.
The near and far sides of the Moon have distinct characteristics, including differences in the thickness of the lunar crust, past magma activity, and overall composition, according to a paper published in journal Innovation. These variations have puzzled scientists for decades.
“The CE-6 [Chang’e 6] samples, being the first obtained from the far side of the moon, are expected to answer one of the most fundamental scientific questions in lunar science research: What geologic activity is responsible for the differences between the two sides?” first author Zongyu Yue, a geologist at the Chinese Academy of Sciences, said in a statement.
Read more: A year around the moon
Chang’e 6 took off on May 3, 2024 and landed on the Moon on June 1. The landing site was within the Apollo crater, which, in turn, sits inside the largest, deepest, and oldest impact basin on the Moon — the South Polar-Aitken (SPA) basin.
Armed with a scoop and drill, the mission obtained samples from the surface and a depth of 2 meters below the surface. It collected about 2 kilogrammes of material.
The samples were then placed in the ascent vehicle, which was launched from the Moon on June 3. On June 6, the vehicle docked with Chang’e 6 orbiter-return vehicle and transferred the samples into the return vehicle.
Previous lunar sample return missions — six Apollo, three Luna spacecraft and Chang’e-5 (CE-5) missions — were from the lunar nearside.
Samples from the far side of the Moon are of great significance for a comprehensive understanding of its history, the researchers wrote in their paper.
They added the mission will answer other questions such as the age of the SPA basin, the age of the Apollo crater and the major mineral composition of the lunar mantle and volcanic eruption inside the basin.
The team expected the returned surface samples to contain 2.5-million-year-old volcanic rock combined with small amounts of material generated by nearby meteorite strikes.
The collected rocks and minerals may contain traces of early meteorite impacts. The researchers hope to find data on how far materials ejected from early collisions spread across the moon. The other goal is to also compare it with the nearside of the natural satellite.
“My greatest hope is that the CE-6 samples contain some impact melts (fragments generated when smaller bodies crashing into the moon) from the Apollo Crater and the SPA basin, which can provide crucial constraints on the early impact flux of the moon,” Yue explained.
“Once this information is obtained, it will not only help clarify the role of early lunar meteorite impacts on the moon’s evolution but also be of great significance in analysing the early impact history of the inner solar system.”
Once the samples touchdown on Earth, researchers will study the samples, including analysis of the structure, physical properties, and composition of the lunar soil, according to Ge Ping, Deputy Director, Lunar Exploration and Space Engineering Center, China National Space Administration.
Chang’e 6 also carried four international payloads and satellites, including a RadoN detector from France, a lunar surface negative ion analyser from the European Space Agency, a laser angle reflector from Italy, and a cube satellite from Pakistan, the expert said in a press statement.
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