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Lunar regolith
Lunar regolith is the unconsolidated material found on the surface of the Moon and in the Moon's tenuous atmosphere. Lunar soil typically refers to only the finer fraction of lunar regolith, which is composed of grains 1 cm in diameter or less, but is often used interchangeably. Lunar soil differs substantially in properties from terrestrial soil. Lunar dust is even finer regolith than lunar soil, with grain sizes less than one millimeter.
Lunar regolith is primarily the result of mechanical weathering. Continual meteoric impacts and bombardment by solar and interstellar charged atomic particles of the lunar surface over billions of years ground the basaltic and anorthositic rock, the regolith of the Moon, into progressively finer material. This situation contrasts fundamentally to terrestrial soil formation, mediated by the presence of molecular oxygen (O2), humidity, atmospheric wind, and a robust array of contributing biological processes.
As the Moon's fine surface layer, lunar regolith is picked up by even weak natural phenomena active at the Moon's surface, allowing it to be part of the Moon's scant atmosphere. It is easily disturbed and poses a significant hazard to exposed equipment and human health. The fine lunar regolith is made of sharp and very adhesive particles, with a distinct gunpowder taste and smell. Lunar regolith is prospected as a lunar resource, particularly for lunar in situ utilization, such as a lunar building material and regolith for growing plants on the Moon.
The major processes involved in the formation of lunar regolith are:[citation needed]
These processes continue to change the physical and optical properties of the dirt over time, and it is known as space weathering.
In addition, fire fountaining, whereby volcanic lava is lofted and cools into small glass beads before falling back to the surface, can create small but important deposits in some locations, such as the orange dirt found at Shorty Crater in the Taurus-Littrow valley by Apollo 17, and the green glass found at Hadley–Apennine by Apollo 15.[citation needed] Deposits of volcanic beads are also thought to be the origin of Dark Mantle Deposits (DMD) in other locations around the Moon.
There is some evidence that the Moon has a tenuous layer of moving dust particles constantly leaping up from and falling back to the Moon's surface, giving rise to a "dust atmosphere" that looks static but is composed of dust particles in constant motion. The term "Moon fountain" has been used to describe this effect by analogy with the stream of molecules of water in a fountain following a ballistic trajectory while appearing static due to the constancy of the stream. According to a model proposed in 2005 by the Laboratory for Extraterrestrial Physics at NASA's Goddard Space Flight Center, this is caused by electrostatic levitation. On the daylit side of the Moon, solar hard ultraviolet and X-ray radiation is energetic enough to knock electrons out of atoms and molecules in the lunar regolith. Positive charges build up until the tiniest particles of lunar dust (measuring 1 micrometre and smaller) are repelled from the surface and lofted anywhere from metres to kilometres high, with the smallest particles reaching the highest altitudes. Eventually they fall back toward the surface where the process is repeated. On the night side, the dust is negatively charged by electrons from the solar wind. Indeed, the fountain model suggests that the night side would achieve greater electrical tension differences than the day side, possibly launching dust particles to even higher altitudes. This effect could be further enhanced during the portion of the Moon's orbit where it passes through Earth's magnetotail, part of the magnetic field of the Moon. On the terminator there could be significant horizontal electric fields forming between the day and night areas, resulting in horizontal dust transport—a form of "Moon storm".
This effect was anticipated in 1956 by science fiction author Hal Clement in his short story "Dust Rag", published in Astounding Science Fiction.
Hub AI
Lunar regolith AI simulator
(@Lunar regolith_simulator)
Lunar regolith
Lunar regolith is the unconsolidated material found on the surface of the Moon and in the Moon's tenuous atmosphere. Lunar soil typically refers to only the finer fraction of lunar regolith, which is composed of grains 1 cm in diameter or less, but is often used interchangeably. Lunar soil differs substantially in properties from terrestrial soil. Lunar dust is even finer regolith than lunar soil, with grain sizes less than one millimeter.
Lunar regolith is primarily the result of mechanical weathering. Continual meteoric impacts and bombardment by solar and interstellar charged atomic particles of the lunar surface over billions of years ground the basaltic and anorthositic rock, the regolith of the Moon, into progressively finer material. This situation contrasts fundamentally to terrestrial soil formation, mediated by the presence of molecular oxygen (O2), humidity, atmospheric wind, and a robust array of contributing biological processes.
As the Moon's fine surface layer, lunar regolith is picked up by even weak natural phenomena active at the Moon's surface, allowing it to be part of the Moon's scant atmosphere. It is easily disturbed and poses a significant hazard to exposed equipment and human health. The fine lunar regolith is made of sharp and very adhesive particles, with a distinct gunpowder taste and smell. Lunar regolith is prospected as a lunar resource, particularly for lunar in situ utilization, such as a lunar building material and regolith for growing plants on the Moon.
The major processes involved in the formation of lunar regolith are:[citation needed]
These processes continue to change the physical and optical properties of the dirt over time, and it is known as space weathering.
In addition, fire fountaining, whereby volcanic lava is lofted and cools into small glass beads before falling back to the surface, can create small but important deposits in some locations, such as the orange dirt found at Shorty Crater in the Taurus-Littrow valley by Apollo 17, and the green glass found at Hadley–Apennine by Apollo 15.[citation needed] Deposits of volcanic beads are also thought to be the origin of Dark Mantle Deposits (DMD) in other locations around the Moon.
There is some evidence that the Moon has a tenuous layer of moving dust particles constantly leaping up from and falling back to the Moon's surface, giving rise to a "dust atmosphere" that looks static but is composed of dust particles in constant motion. The term "Moon fountain" has been used to describe this effect by analogy with the stream of molecules of water in a fountain following a ballistic trajectory while appearing static due to the constancy of the stream. According to a model proposed in 2005 by the Laboratory for Extraterrestrial Physics at NASA's Goddard Space Flight Center, this is caused by electrostatic levitation. On the daylit side of the Moon, solar hard ultraviolet and X-ray radiation is energetic enough to knock electrons out of atoms and molecules in the lunar regolith. Positive charges build up until the tiniest particles of lunar dust (measuring 1 micrometre and smaller) are repelled from the surface and lofted anywhere from metres to kilometres high, with the smallest particles reaching the highest altitudes. Eventually they fall back toward the surface where the process is repeated. On the night side, the dust is negatively charged by electrons from the solar wind. Indeed, the fountain model suggests that the night side would achieve greater electrical tension differences than the day side, possibly launching dust particles to even higher altitudes. This effect could be further enhanced during the portion of the Moon's orbit where it passes through Earth's magnetotail, part of the magnetic field of the Moon. On the terminator there could be significant horizontal electric fields forming between the day and night areas, resulting in horizontal dust transport—a form of "Moon storm".
This effect was anticipated in 1956 by science fiction author Hal Clement in his short story "Dust Rag", published in Astounding Science Fiction.