China Chang’e-6 The mission is currently on track to recover a sample of material from the far side the moonIt will test theories about why there is such a big difference between the near and far sides of the Moon.
We take Launched on May 3, Chang’e-6 is expected to land in early June inside Apollo’s double-ring impact basin, which is located inside the larger spacecraft. Antarctic Basin – Aitken (Spa). The massive SPA is the largest impact feature of its kind in the world Solar System, extending over an area of 2,400 x 2,050 kilometers (1,490 x 1,270 mi); Formed about 4.3 billion years ago, i.e very Early in the history of the solar system. Although Apollo is younger, it is also the largest impact site ever installed on a SPA. Apollo has a double-ring structure, with an inner ring of mountaintops measuring 247 kilometers (153 miles) in diameter and an outer ring about 492 kilometers (305 miles) wide.
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As the first far-side sample return mission, Chang’e-6 aims to return about 2 kilograms (4.4 pounds) of precious lunar material to Earth. The Far Side is a relatively unknown place; Its mystery is also enhanced by the fact that we cannot see it from Earth. It was first photographed by the Soviet Luna 3 spacecraft in 1959. With this image in hand, scientists around the world were amazed to discover how different the far side of the Moon looked compared to our side. familiar. While both the near and far sides contain many craters, the near side also exposes vast areas, Volcanic plains called lunar mariawhich creates “man-in-the-moon” impressions and covers about 31% of the entire near side area.
Meanwhile, the far side is just the opposite. Only about 1% of it is covered by volcanic plains.
So, how did the near side and far side become so different? Well, the thickness of the crust seems to be a factor. In fact, in 2011, NASA the cup The Gravity Recovery and Interior Laboratory mission found that the far-side crust is, on average, 20 kilometers (12 miles) thicker than the near-side crust.
This is thought to go back to when our Moon formed from debris ejected when a Mars-sized protoplanet struck Earth about 4.5 billion years ago. As the Moon gathered debris around the wounded Earth, it became tidally locked, meaning it would always show the same face to our planet. The Earth’s surface became completely molten due to the giant impact, sending heat to the near side of the Moon, and actually staying molten for much longer. Scientists suggest that the rocks will evaporate on the near side and condense on the cooler far side, making the crust on the far side thicker.
“The basic result suggests that the discrepancy in crustal thickness between the near side and the far side may be the main reason for the asymmetric volcanic activity on the moon’s surface,” said Yuki Qian of the University of Hong Kong in a study. statement.
Qian is one of the lead authors of a new study that suggests a sample of material to be returned to Earth by Chang’e-6 could test this theory.
The logic is as follows.
When the lunar crust is thick, as it is on most of the far side, magma rising through cracks in the rock cannot reach the surface. When the crust is thin, such as on the near side, these fractures can allow magma to actually break through, and lava can erupt.
Although both the SPA and the Apollo Basin are located on the far side of the Moon, they pose a bit of a contrast. This is because they have drilled deep into the lunar crust, and at the base of these giant impact sites, the crust is thinner than elsewhere on the far side. And yes, there are volcanic plains within these basins, but still only 5% of their area is covered by basalt lava flows. This limited amount of volcanoes seems to contradict the idea that the thickness of the Earth’s crust determines volcanic activity, a paradox in lunar science that has long been known.
One alternative possibility suggests that the near side could contain more radioactive elements than the far side. These elements may have produced heat, causing the lower mantle to melt, creating more magma as well as a thinner crust on the near side. Hence more volcanoes.
However, by landing on one of the few volcanic plains on the far side, Chang’e-6 could bring back samples to test these theories directly. In particular, the Apollo Basin area, where Chang’e-6 will land, contains diverse materials that require investigation.
Some evidence also suggests that two major volcanic eruptions occurred in the area. The first, about 3.35 billion years ago, scientists believe covered the entire area with magma containing a low abundance of titanium. The other, which would have occurred 3.07 billion years ago, likely contained titanium-rich magma and was more localized, erupting near the Chaffee S crater (named after Roger Chaffee, one of the astronauts who died tragically in the crater Chaffee S). Apollo 1 disaster) and spreads eastward with decreasing thickness.
The new study suggests that retrieving a sample from a site near Chaffee S would provide the greatest scientific benefits. This area contains titanium-rich basalt above, titanium-poor basalt below, and various pieces of ejecta resulting from impacts.
“Diverse sample sources will provide important insights to solve a series of lunar scientific questions hidden in the Apollo Basin,” said Joseph Michalski of Hong Kong, a co-author of the new study with Yuki Qian, also of Hong Kong. His colleague Guochun Zhao and researchers from elsewhere in China, Germany and the United States.
These diverse samples can tell scientists something about the magmatic processes that occurred on the far side, and by comparing them with near-side samples returned by the Apollo missions, could hold the answer to why volcanic activity on the far side is limited.
“The result of our research represents a major contribution to the Chang’e-6 lunar mission,” Zhao said. “It establishes a geological framework for fully understanding the soon-to-be-returned Chang’e-6 samples, and will be a key reference for Chinese scientists’ upcoming sample analysis.”
The team’s paper was published in the journal Earth and planetary sciences letters; You can continue to follow Space.com for more updates about the Chang’e-6 mission.
