This figure shows the distribution of permanently shadowed regions (blue) toward the moon’s poles at 80 degrees south latitude. They are overlaid on a digital elevation map of the lunar surface (gray) from the Lunar Orbiter Laser Altimeter Instrument aboard NASA’s Lunar Reconnaissance Orbiter. Image credit: NASA / GSFC / Timothy P. McClanahan.
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.
Permanently shadowed regions (PSRs) typically occur 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.
“Our models and analysis show that the largest ice concentrations are near the coldest parts of the PSR below 75 Kelvin (minus 198 degrees Celsius, or minus 325 degrees Fahrenheit) and on poleward-facing slopes of the PSR. It is expected to occur near the base of the Dr. Timothy McClanahan, researcher at NASA Goddard Space Flight Center.
“It is not possible to accurately measure the volume of ice deposits in the PSR or determine whether they are buried beneath a dry layer of regolith.”
“However, we expect it to be 1 m for each surface.2 If present above these deposits, there should be at least about 5 liters of ice within the top meter of the surface compared to the surrounding area. ”
McClanahan and his colleagues used LRO’s Lunar Exploration Neutron Detector (LEND) instrument to detect signs of ice deposits by measuring moderately energetic “exothermal” neutrons.
Specifically, they used LEND’s Collimating Sensor for Exothermal Neutrons (CSETN), which has a fixed field of view of 30 km (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 1 meter (3.3 feet) and ping-pong through the regolith, colliding with other atoms. Some are guided into space and 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 hydrogen concentrations proportionally depending on their area,” Dr. McClanahan said.
“Therefore, more hydrogen should be observed towards the larger area of the PSR.”
of findings this week, Planetary Science Journal.
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TP McClanahan others. 2024. Evidence of widespread hydrogen sequestration within the lunar south pole cold trap. planet. Science. J 5, 217; doi: 10.3847/PSJ/ad5b55
This article has been adapted from the original release by NASA.
Source: www.sci.news
