Chang’e 6 brought rocks from the far side of the Moon back to Earth – a planetary scientist explains what this sample may contain

China achieved a historic feat by bringing back the first sample on the other side of the moon in June 2024. It is a lunar module, Change 6, used a robotic shovel and drill to collect approximately 5 pounds (2 kg) of rocks and soil. These samples returned to Earth on June 25, 2024.

Chang’e 6 built on the achievements of two previous Chinese missions: Change 4which softly landed on the far side of the Moon and used a rover to explore the surface, and Change 5which returned samples from the near side of the Moon.

Scientists hope that the Chang’e 6 samples will not only provide important geological knowledge about the Moon, but also improve their understanding of Earth and the early history of the solar system.

Lunar scientists like me I was fascinated with the other side of the moon since the Soviet Union Moon Mission 3 in 1959, which revealed that the far side of the Moon looks very different from its near side.

The other side of the Moon

Since the same side of the Moon always faces Earth, you can only see the other side with spacecraft. The other side is not permanently dark – it alternates between two weeks of daylight and two weeks of nightjust like any location on the Moon.

Images taken by the spacecraft show that about one-third of the Moon’s surface it is made of dark and smooth plainswhile only about 1% on the other side has these plains.

These dark plains were once volcanic lava flows, similar to those found on Earth in Hawaii, eastern washington and India.

Images taken from lunar orbit tell researchers that these plains once had volcanic vents, cones, domes, pits and collapsed channels.

Only the Chang’e 4 and Chang’e 6 missions landed on the far side of the Moon, while 25 spacecraft successfully soft-landed on the near side. A mission landed on the other side is more difficult because mission control cannot see or talk directly to the spacecraft. So what’s needed is a second spacecraft to transmit information between the lander and Earth. China used its satellite in orbit Queqiao-2which was released in March 2024.

Chang’e 6 landing

On June 6, 2024, Chang’e 6 has landed inside the colossal South Pole-Aitken Basin, which is about 1,550 miles (2,500 km) wide and 5 miles (8 km) deep. It is the largest impact structure in the solar system: a bowl-shaped structure formed when an asteroid collides with a body, causing a huge explosion.

Overlying South Pole-Aitkin is a slightly younger and much smaller impact structure called Apollo Basinabout 308 miles (492 km) in diameter.

Impact basins expose the deep interior of the Moon as a drill core. For example, the impact that created the South Pole-Aitkin basin may have removed part of the lunar crust, exposing materials deep within the Moon – up to 100 km deep. The subsequent Apollo impact would have removed even more material. Therefore, the returned samples will likely contain some different rocks than those in the current sample collection.

Chang’e 6 touched down here on some of the scattered volcanic deposits on the other side. Analysis of the composition of the volcanic rocks that Chang’e 6 brought back could help researchers figure out why the closest side so many more volcanic deposits. Scientists will also be able to compare the ages of these rocks on the far side with rocks from near-side volcanic eruptions that occurred about 3.9 to 3.2 billion years ago.

Measuring the actual age of rocks will help scientists refine other methods, how to count craterswhich are used to estimate the age of surface formations on planets.

Because planet surfaces accumulate more craters the longer they sit, researchers can estimate the age of a planetary surface by comparing the number of craters they can count with those generated by a simulated model. But crater counts aren’t very accurate — having real rock samples could help researchers figure out how improve these methods.

Uncovering secrets of the Moon’s molten past

Researchers theorize that the Moon, along with some rocky planets, used to be almost completely melted. Thus, for a brief period of time early in its history, the Moon was just lava with little or no solid rock.

Chang’e 6 landing site may contain Moon mantle materials – the layer beneath your crust. These samples can help scientists understand how the Moon evolved from a magma ocean to have geological layers – a solidified crust, mantle and core.

Data from these samples could also provide clues about the Earth’s evolution in the last stages of planetary formation. Scientists predict that about 4 billion years ago, many asteroids and comets rained down on Earth. rocky planets like Earth. We call this period Period of “lunar cataclysm”. Studying certain rocks resulting from crater impacts on the Moon could help scientists learn more about this era.

Since South Pole-Aitkin Basin is the oldest and best-preserved structure on the Moon, it could contain evidence about whether the number of basin-forming impacts occurred over a longer period of time, such as 500 million years, or a shorter period, such as 200 million years. Knowing the timescale would help assess the intensity of impacts during the formation of the solar system.

A scientific gift from the other side

Extraterrestrial materials – such as samples from the Moon, Mars, asteroids It is comets – these are gifts that keep on giving.

Scientists will curate and maintain these samples in laboratories to keep them pristine. This process will distribute some of the precious samples for analysis with state-of-the-art equipment. The rest will be stored for future generations of scientists to explore new questions that will arise decades from now.

Science progresses most when scientists share ideas, data and samples. In late 2023, the China National Space Administration made the Chang’e 5 samples available for a set of international researchers. I hope to see a similar sample sharing program for the Chang’e 6 samples.

This sharing, however, does not go both ways. NASA cannot directly share the samples it curates with Chinese researchers due to Wolf Amendmentwhich prohibits NASA from using funds to collaborate with China on any programs.

China’s future lunar exploration plans include the Change 7 and 8 missions, scheduled for 2026 and 2028, respectively. These missions will land at the south pole in search of water ice, carbon dioxide ice – also known as dry ice – and methane in the form of ice. NASA recently canceled VIPER rover had similar goals. These missions will help China figure out where to place its International Lunar Research Station, scheduled for 2030.

This article was republished from The conversation, an independent, nonprofit news organization that brings you trusted facts and analysis to help you understand our complex world. It was written by: Jeffrey Gillis-Davis, Arts and Sciences at Washington University in St.

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Jeffrey Gillis-Davis does not work for, consult with, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond his academic appointment.