Lunar rover reveals hidden layers beneath the lunar surface: ScienceAlert

The moon is famous for its many craters that keep the scars of turbulence from above. But just below the shattered surface of the Moon is evidence of a series of pyroclastic flows, which detail a different kind of chaos in the Moon’s past emerging from below.

Jianqing Feng, an astrophysicist at the Planetary Science Institute in Arizona, and colleagues in China and the United Kingdom wanted to expand on previous studies of the surface beneath the moon’s surface, which fell slightly flat.

Like those previous studies, Feng and his colleagues analyzed data from the Chang’e-4 rover, which landed on the far side of the moon in 2019. Only this time they had more data to work with than the first Chang’e-4 mission. A few lunar days, and I looked deeper into the lunar surface using low-frequency ground-penetrating radar.

The Moon Penetrating Radar is an instrument aboard Chang’e-4. They emit pulsating signals beneath the lunar surface as the rover moves. If these radar signals show a clear contrast between two subsurface materials that have different properties, they are reflected back to the surface where the receiver is waiting.

Aside from an ancient crater hidden by debris and soil spewed from nearby impacts, Feng and his colleagues found nothing unusual in the upper 40 meters (131 feet) of the moon.

Below 90 meters (295 ft) things get a lot more interesting.

“Through this investigation, we have discovered multiple layers in the upper 300 meters, which likely indicate a series of basaltic eruptions that occurred billions of years ago,” said Feng and colleagues. Write in their paper.

Lunar volcanism has been a hot topic lately. Last month, scientists discovered a strange hotspot on the far side of our satellite, which could be a buried mass of solidified magma from a type of volcano never before seen on the moon.

Thanks to the first lunar rocks Retrieved in more than four decadesWe also learned that lava has been flowing from volcanoes on the Moon for a billion years longer than we previously thought.

The solidified lava layers discovered by Feng and his colleagues are another record of this long history. Thicker layers are found at depth, although they become thinner towards the surface. suggestion “gradual depletion of internal thermal energy leading to (lunar) volcanism” and “decreasing eruption volume over time”.

The thickest layers were about 70 meters (or 230 feet) wide, and the lava flows dwindled to about 5 meters at shallower depths near the landing site.

Overall, Feng and his colleagues think they’ve identified at least three or four large pyroclastic flow events, some of which appear very close together, sprinkling a thin layer of lunar soil between solidified rocks.

After checking their measurements against data from the previous lunar module, Changye 3Researchers say that these layers exist actor A subterranean feature across the Von Kármán crater is where Chang’e 4 has been roaming, as rovers do.

However, remote sensing data can’t tell us anything about the timing of lunar volcanic events, but they do appear to get smaller over time until the moon’s thermal energy has died away. Other recent studies have attempted to solve the shortcomings in our understanding of the moon Latest eruptions of volcanic activity.

Astronomers also discuss how to interpret low-frequency, penetrating lunar radar data. Some say that the subsurface layers discovered in previous studies are the same Just system noise. So expect these new findings to be scrutinized as well.

The study was published in Journal of Geophysical Research: Planets.