US, WASHINGTON (ORDO NEWS) — Researchers have discovered a system of ridges scattered on the near side of the moon, crowned with fresh boulders. These crests may be evidence of active lunar tectonic processes, the researchers say, perhaps an echo of a long-time strike that nearly tore the moon apart.
“There is speculation that the moon has long been dead, but we continue to discover that it is not,” said Peter Schulz, professor of the Department of Earth, Environment and Planetary Sciences at Brown University and co-author of a study published in the journal Geology. “From this article, it follows that the moon can still creak and crack – potentially these days – and we can see evidence on these ridges.”
Most of the surface of the moon is covered with regolith – a dusty blanket of crushed rocks formed as a result of constant bombardment by tiny meteorites and other blows. Regolith-free areas where the bedrock of the moon is exposed are extremely rare. But Adomas Valantinas, a graduate student at the University of Bern who led the research, used data from NASA’s Lunar Reconnaissance Orbital Orbiter (LRO) to detect strange open areas around the ridge.
“Open areas of the surface have a relatively short observational time because the accumulation of regolith occurs continuously,” Schulz said. “So when we see them, there must be some explanation for how and why they formed in these places.”
For research, Valantinas used the LRO Diviner instrument, which measures the temperature of the lunar surface. Just as concrete-coated cities on Earth retain more heat than rural areas, open rock and block surfaces on the moon remain warmer during a moonlit night than regolith-covered surfaces. Using night observations from LRO Diviner, Valantinas discovered over 500 sections of exposed bedrock on narrow ridges.
According to Schulz, several ridges topped with exposed rock formations have been noticed before. But these ridges were located on the edges of ancient lava-filled shock basins and could be explained by the continued subsidence of the rock as a response to the weight that the lava filled. But this new study showed that the most active ridges are associated with a mysterious system of tectonic features on the near side of the moon, not associated with either lava-filled pools or other young faults crossing the highlands.
“The distribution we found here requires a different explanation,” Schultz said.
Valantinas and Schultz mapped all the recorded areas and found an interesting correlation. In 2014, a NASA GRAIL mission discovered a network of ancient cracks in the lunar crust. These cracks turned into channels through which magma flowed to the surface of the moon, forming deep intrusions. Valantinas and Schultz showed that the location of the ridges almost perfectly matched the deep intrusions discovered by GRAIL.
“This is an almost unambiguous correlation,” Schultz said. “It makes us think that what we see is a continuous process caused by events taking place in the bowels of the moon.”
Since the “bare spots” on the moon become dusty rather quickly, these crackings must have occurred very recently, perhaps even continue today.
Researchers believe that this chain of events began billions of years ago with a giant blow to the far side of the moon. In previous studies, Schulz and his colleague suggested that this is the effect that formed the 2,000-kilometer South Pole Aitken Basin. Then magma filled these cracks and created the structure of the dams found in the GRAIL mission.
“It looks as if the ridges answered something that happened 4.3 billion years ago,” Schultz said. “Giant blows have lasting consequences. The moon has a long memory. What we see today on the surface testifies to its long memory and the secrets that it still holds.”
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