Lunar regolith

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.

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.

According to a model proposed in 2005 by the Laboratory for Extraterrestrial Physics at NASA's Goddard Space Flight Center,[3] 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.

LEAM saw a large number of particles every morning, mostly coming from the east or west—rather than above or below—and mostly slower than speeds expected for lunar ejecta.

In addition, the experiment's temperature increased to near 100 degrees Celsius a few hours after each lunar sunrise, so the unit had to be turned off temporarily because it was overheating.

It is speculated that this could have been a result of electrically charged moondust sticking to LEAM, darkening its surface so the experiment package absorbed rather than reflected sunlight.

[6] However, scientists were unable to make a definite determination of the source of the problem, as LEAM operated only briefly before the Apollo program ended.

[8] It is possible that these storms have been spotted from Earth: For centuries, there have been reports of strange glowing lights on the Moon, known as "transient lunar phenomena" or TLPs.

Some TLPs have been observed as momentary flashes, now generally accepted to be visible evidence of meteoroids impacting the lunar surface.

But others have appeared as amorphous reddish or whitish glows or even as dusky hazy regions that change shape or disappear over seconds or minutes.

The primary minerals identified in Lunar regolith are plagioclase, olivine, augite, orthopyroxene, pigeonite, ilmenite, chromite, quartz, cristobalite, and whitlockite.

[15] The agglutinates form at the lunar surface by micrometeorite impacts that cause small-scale melting which fuses adjacent materials together with tiny specks of elemental iron embedded in each dust particle's glassy shell.

The methods used to mitigate exposure will include providing high air recirculation rates in the airlock, the use of a "Double Shell Spacesuit", the use of dust shields, the use of high–grade magnetic separation, and the use of solar flux to sinter and melt the regolith.

After each EVA, the crew modules were heavily contaminated with dust; many astronauts reported coughs, throat irritation, watery eyes, and blurred vision that likely reduced their performance.

A flight surgeon exposed to the capsule interiors after recovery developed what appeared to be allergic reactions to lunar dust that worsened after each exposure.

[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 regolith to remove heavy metals and oxidize iron atoms, and selectively breeding strains of plants that are adapted to the inhospitable lunar regolith.

[8] Moon dust-contaminated items finally became available to the public in 2014, when the US government approved[35] the sale of private material owned, and collected, by astronauts.

A luggage strap, exposed to the elements of the Moon for 32 hours, a piece of Charles "Pete" Conrad's spacesuit on the Apollo 12 mission, was sold by his estate to a private purchaser at auction.

On 11 September 2020, NASA announced that it is willing to create a market for lunar regolith by calling for proposals to purchase it from commercial suppliers.