This figure shows the distribution of permanently shadowed regions (blue) toward the moon’s poles at 80 degrees south latitude. These are overlaid on a digital elevation map (in grey) of the lunar surface from the Lunar Orbiter laser altimeter instrument aboard NASA’s Lunar Reconnaissance Orbiter spacecraft. Credit: NASA/GSFC/Timothy P. McClanahan
Ice deposits in the moon’s dust and rock (regolith) are more widespread than previously thought, according to a new analysis of data from NASA’s LRO mission. Understood. Ice will be a valuable resource for future lunar exploration. Water can be used for radiation protection and to support human explorers, or broken down into its hydrogen and oxygen components to produce rocket fuel, energy, and breathable air.
Previous studies have found signs of ice in the larger permanently shadowed region (PSR) near the moon’s south pole, including areas within the Cabeus, Howarth, Shoemaker, and Faustini craters. The new study “found widespread evidence of water ice within the PSR outside of Antarctica, at least toward 77 degrees south latitude,” said Timothy Sr. of NASA’s Goddard Space Flight Center in Greenbelt, Maryland. said Dr. P. McClanahan. He is also the lead author of a paper on the study published in The Planetary Science Journal on October 2nd.
The study also helps planners of lunar missions by providing a map, identifying surface features that indicate where ice is likely to be found and where it is less likely, and providing evidence why. I will support you. McClanahan said: “Our models and analysis show that the greatest ice concentrations are near the coldest parts of the PSR below 75 Kelvin (-198°C or -325°F) and facing poleward in the PSR. It is expected that this will occur near the base of the slope.” .
“We cannot precisely determine the volume of ice deposits in the PSR or determine whether they may be buried beneath a dry layer of regolith. However, these deposits We expect there to be 1.2 square yards (square meters) of each surface on top of the object, at least about 5 quarts (about 5 liters) more ice within the top 3.3 feet (meters) of the surface. “There are,” McClanahan said. The study also mapped where fewer, smaller, or lower concentrations of ice accumulation are expected, with ice accumulation occurring primarily toward warmer and regularly illuminated areas.
Ice may have been embedded in the lunar regolith by comet or meteor impacts, emitted as steam (gas) from the moon’s interior, or formed by chemical reactions between hydrogen in the solar wind and oxygen in the regolith. there is. PSR typically occurs in topographic depressions near the moon’s poles. Due to the low angle of the sun, these regions have not seen sunlight for billions of years and are constantly in extremely cold conditions.
Ice molecules are thought to be repeatedly stripped from the regolith by meteorites, cosmic radiation, or sunlight, traveling across the lunar surface and landing on the PSR, where they become trapped in the extreme cold. The PSR’s continuously cold surface could store ice molecules near the surface for perhaps billions of years, accumulating in sediments large enough for mining. It is believed that ice is quickly lost on surfaces exposed to direct sunlight, preventing ice accumulation.
The researchers used LRO’s Lunar Exploration Neutron Detector (LEND) instrument to detect signs of ice deposits by measuring moderately energetic “ectothermal” neutrons. Specifically, the researchers used LEND’s Collimating Sensor for Exothermal Neutrons (CSETN), which has a fixed field of view of 30 kilometers (18.6 miles) in diameter.
Neutrons are produced by high-energy galactic cosmic rays that come from powerful deep space events, such as exploding stars, and impact the moon’s surface, destroying regolith atoms and scattering subatomic particles called neutrons. Neutrons originate from depths of up to about 3.3 feet (meters) and ping-pong through the regolith, hitting other atoms. Some are guided into space, where they are detected by LEND.
Since hydrogen has approximately the same mass as a neutron, neutrons lose relatively more energy in collisions with hydrogen than in collisions with the most common regolith elements. Therefore, if hydrogen is present in the regolith, its concentration will correspondingly reduce the number of medium-energy neutrons observed.
“We hypothesized that if all PSRs had the same hydrogen concentration, CSETN should detect the hydrogen concentration proportionally depending on their area. Therefore, the larger the PSR, the more hydrogen could be observed. “It should be done,” McClanahan said.
This model was developed from theoretical studies that demonstrated how hydrogen-enhanced PSR is detected by the fixed-area field of view of CSETN. This correlation was demonstrated using neutron emissions from 502 PSRs with areas ranging from 1.5 square miles (4 km2) to 417 square miles (1079 km2), contrasted with surrounding areas with less hydrogen enhancement. I did. The correlation was expected to be weak at small PSRs, but increased as larger area PSRs were approached.
Further information: TP McClanahan et al, “Evidence for widespread hydrogen sequestration within the Moon’s South Pole cold trap”, The Planetary Science Journal (2024). DOI: 10.3847/PSJ/ad5b55
Citation: Lunar mission data analysis finds extensive evidence of ice deposits (October 3, 2024) https://phys.org/news/2024-10-lunar-mission-analysis- Retrieved October 6, 2024 from widespread-evidence.html
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