Lunar soil
Lunar soil is the fine fraction of lunar regolith found on the surface of the Moon and in the Moon's tenuous atmosphere. Lunar soil differs in its origin and properties significantly from terrestrial soil.
"Moondust" redirects here. For the 1983 video game, see Moondust (video game). For the album by The Pillows, see Moondust (album).
As the Moon's fine surface layer, lunar soil 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 soil is made of sharp and very adhesive particles, with a distinct gunpowder taste and smell. That said, lunar soil is prospected as a lunar resource, particularly for lunar in situ utilization, such as a lunar building material and soil for growing plants on the Moon.
Lunar soil 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 the progressively finer lunar soil. 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.
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.[1] Lunar dust generally connotes even finer materials than lunar soil. There is no official definition as to what size fraction constitutes "dust"; some place the cutoff at less than 50 μm in diameter, while others put it at less than 10 μm.
The major processes involved in the formation of lunar soil are:
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. Deposits of volcanic beads are also thought to be the origin of Dark Mantle Deposits (DMD) in other locations around the Moon.[2]
Use[edit]
The potential of lunar soil for construction of structures has been proposed at least since the proposal of lunarcrete and increasingly tested.[30][31]
The differences between Earth's soil and lunar soil mean that plants struggle to grow in it.[32][33] As a result long-term space missions could require complicated and expensive efforts to provide food, such as importing Earth soil, chemically treating lunar soil to remove heavy metals and oxidize iron atoms, and selectively breeding strains of plants that are adapted to the inhospitable lunar regolith.[32][33]
Therefore lunar soil has been tested, successfully growing plants from it in a laboratory on Earth.[34]