The Chinese rover of the Chang’e-4 mission has enabled scientists to visualize “hidden” structures beneath the surface of the far side of the Moon, a breakthrough that reveals billions of years of lunar history.
The Yudu-2 rover aided the discovery with its LPR (Lunar Sounding Radar), which picked up sound echoes bouncing off structures beneath the lunar surface, hidden from view, and imaged deep into the lunar surface.
The same rover and mission lander made history in 2019 by becoming the first manned objects to land on the far side of the Moon facing the Earth’s exterior.
Scientists have previously used the rover’s GPR (Ground Penetrating Survey), but those previous efforts were only able to map up to 40 m, or about 130 feet, of the lunar surface. Thanks to this study, they discovered “hidden” structures at a depth of about 300 m (984 ft).
New data suggest that the first 40 meters of the moon’s surface are made up of layers of dust, soil and rock.
Radar analysis revealed the presence of a buried crater formed when a large object hit the lunar surface and helped map ancient lava flows under the moon.
“GPR sends electromagnetic pulses into the lunar interior and receives echoes from the surface layers. “We used high-frequency channel data to detect structure above 40 m along the rover’s path, which is mainly composed of rock debris and soil,” the researchers explain in the study.
Scientists speculate that the broken rocks surrounding the formation may be debris from the impact.
“Through this investigation, we found several layers in the upper 300 meters, indicating a sequence of basalt eruptions that occurred billions of years ago,” they wrote.
The new study, recently published in the journal Journal of Geophysical Research: PlanetsThis reveals that the terrain of this part of the moon may have flowed lunar lava billions of years ago.
The researchers found that layers of volcanic rock are thinner as they are closer to the lunar surface.
“The variation in thickness of these lava flows indicates a decrease in eruption volume over time,” they noted.
Based on this evidence, they say that lunar volcanic activity has gradually cooled since the Moon formed 4.5 billion years ago, when a Mars-sized object collided with Earth and eventually broke off into a piece that merged with Earth.
“The thickness of the strata decreases with decreasing depth, indicating a progressively lower volcanism rate over time,” the scientists concluded.