The Moon has quakes similar to Earth but with different causes. Apollo astronauts placed seismometers on the Moon, revealing various moonquake types, including a newly discovered fifth type linked to the Apollo 17 base.
Apollo 17 Base Caused Moonquakes
In December 1972, the Apollo 17 mission took off, carrying NASA astronauts Gene Cernan and Harrison Schmitt. During their visit, they left several items behind, including a United States flag, a lunar rover, and the descent stage of the lunar module.
Meanwhile, the Moon's surface undergoes significant temperature fluctuations, ranging from 250 degrees to -208 degrees Fahrenheit due to its lack of an insulating atmosphere. During the Apollo 17 mission, scientists positioned seismometers to capture thermal earthquakes on the Moon, occurring during its transition from lunar day to lunar night.
This period entails drastic temperature changes from 250 degrees Fahrenheit to -208 degrees Fahrenheit. Recently, researchers from the California Institute of Technology (Caltech) utilized modern techniques, including machine learning, to reanalyze data collected from October 1976 to May 1977.
Their study, titled "Thermal Moonquake Characterization and Cataloging Using Frequency-Based Algorithms and Stochastic Gradient Descent" published in the Journal of Geophysical Research - Planets, unveiled precise and regular thermal quakes on the Moon's surface.
Intriguingly, the tremors appeared to originate from the Apollo 17 base itself, which experienced similar expansions and contractions as the lunar surface.
Allen Husker, a Caltech research professor of geophysics and co-author of the study, explained that the base began "popping off" with these tremors each lunar morning when the Sun illuminated it, occurring every five to six minutes over five to seven Earth hours.
Although these moonquakes may not be natural lunar quakes, they significantly contribute to our understanding of lunar seismic activity. This knowledge is particularly valuable for future lunar exploration and development, as it aids in designing experiments and missions to explore the Moon thoroughly.
The Moon's status as the only planetary body besides Earth to host multiple seismometers offers a unique opportunity to comprehensively study another celestial body.
Lunar Missions To Measure Moonquakes
Strategically deploying additional seismometers on the Moon, particularly in its shadowy south pole region, could yield valuable insights about our desolate natural satellite, Husker noted.
Such instruments could help in the quest to uncover potential subsurface water ice deposits, as seismic waves move more slowly through water. India's recent uncrewed lunar mission, Chandrayaan-3, included another seismometer that is designed to detect seismic activity before entering sleep mode on September 2.
Husker emphasized the unique opportunity the Moon presents for comprehensive seismic research, being the only planetary body, aside from Earth, to host multiple seismometers simultaneously. He further pointed out that by conducting further lunar seismic studies, scientists hope to map out subsurface cratering and search for various deposits.
Additionally, the permanently shadowed regions within craters at the Moon's South Pole, which never receive sunlight, hold potential for seismometer deployment to investigate the possibility of trapped subsurface water ice, given the slower transmission of seismic waves through water.
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