New research shows that the Moon’s poles have shifted as a result of asteroid impacts over billions of years.
Astronomers have long used lunar craters to chart the history of both Moon and complete The Solar System, because the distribution of destruction left by asteroid impacts paints a picture of the violent conditions found in young solar systems. New research turns the tables on those studies by simulating the removal of thousands of craters and considering the impacts of smaller craters, thus recounting 4.25 billion years of lunar history.
Researchers based at NASA’s Goddard Space Flight Center in Maryland found that as the moon buffeted small star Attack, its north and south poles rotate about 10 degrees in latitude – the equivalent of about 186 miles (300 kilometers).
The Moon’s geographic poles are located where its axis of rotation – the imaginary line around which it spins – intersects the lunar surface. The simulation showed that when the Moon’s body moves, the rotational axis remains constant.
The discovery could shed light on how Earth’s natural satellite has evolved and help researchers locate water and other resources that could be used for future space missions.
Scientists have discovered frozen water cold, shadowy regions at the poles of the moon, but how much water there is remains a mystery. By understanding how and where the poles have moved, researchers can learn how much of the frozen water has changed directly from solid ice to gas – a process called sublimation. An extreme shift in the locations of the lunar poles – particularly toward the Moon’s warmer, less shadowy regions – resulting in water being quickly elevated and lost to space, as well as reducing new water to accumulate at the poles. gives time.
Vishnu Viswanathan, a research scientist at NASA Goddard who led the study, said, “Based on the Moon’s history of cratering, polar wander appears to be moderate enough for water near the poles to remain in shadow and enjoy stable conditions over billions of years. It happens.” At the deviating poles of the Moon, a . said in Statement (opens in new tab),
The shifting of poles is caused by a phenomenon called “true polarity”, which occurs when a spinning object encounters obstacles like a change in the distribution of its mass. In the case of the Moon, this happened when asteroid impacts carved craters deep in the lunar surface, which redistributed mass and left regions of lower mass.
The Moon re-established itself, moving these low-mass “pockets” toward the poles. As it happened, centrifugal force—the same force that propels and expands the dough into the pizza base—moves areas of higher mass toward the lunar equator.
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David E., a research scientist at the Massachusetts Institute of Technology and a co-author of the new research. “If you look at the Moon with all these craters, you can see that in the gravitational field data,” Smith said. Statement. “I thought, ‘Why can’t I just take one of those craters and suck it up, remove the sign completely?'”
Smith is the principal investigator of the Lunar Orbiter Laser Altimeter (LOLA) instrument aboard NASA’s Lunar Reconnaissance Orbiter and has experience using it gravity Data to assess changes in the lunar poles. Smith, Viswanathan and their team used LOLA data to design a computer model that took the coordinates and width of 5,200 lunar craters between 12 and 746 miles (19 to 1,200 km) in diameter.
Then, the team matched impact craters with pockets of high or low gravity found on a gravity map of the Moon created with data from NASA’s Gravity Recovery and Interior Laboratory. They ran these simulations backwards, removing these pockets of high and low gravity and thus erasing the craters in the order of their age. This repetition of the Moon’s evolution brought the poles back to the positions they occupied billions of years ago.
Researchers had previously attempted a similar process, but by focusing only on the largest lunar craters, those efforts did not consider the net effect of smaller impacts at the Moon’s poles.
“People assumed that small craters were insignificant,” Viswanathan said. “They are negligible individually, but collectively, they have a huge impact.”
The researchers will continue to simulate the removal of smaller craters from the lunar surface, and they plan to remove features that have been caused by volcanic eruptions throughout the Moon’s history. The team hopes that these additional steps will help paint a more complete picture of polar orbits on the Moon.
The findings were published on 19 September planetary science magazine (opens in new tab),