NASA scientists may have found a plausible explanation as to why dust particles appear to "levitate" above the surface of the moon without the presence of flowing water or wind that pick up the material.
In a study featured in the journal Geophysical Research Letters, researchers from the American space agency described how ultraviolet radiation can cause minute particles on the moon to seemingly float several centimeters above its surface. This phenomenon can also occur if the moon dust is exposed to electrically-charged gases known as plasmas.
Scientists have been trying to understand how dust particles can end up in different parts of space despite not having any form of air or water to transport them. The latest NASA discovery could help them finally unlock the secret behind it.
'Levitating' Dust Particles
One particular mystery that the new finding could help solve is that of the moon's "horizontal glow". Astronauts from the Apollo missions reported that they were able to see a bright, crescent cloud that appeared to float just above the moon's surface.
Earlier studies have suggested that dust particles are capable of producing high levels of electrical charges and particle repulsive forces when they get near each other. The resulting force could then lift the material above the moon's surface.
NASA researchers built on these previous findings and determined that the horizontal glow that the astronauts spotted decades ago may actually be a collection of moon dust that was electrostatically lofted and then exposed to sunlight.
In their observations, they were able to record micron-sized particles jumping a few centimeters high after being exposed to plasmas or UV radiation. If this same action occurred on the moon, the researchers believe the dust particles would have been lifted as high as 4 inches (10 centimeters) above its surface.
Xu Wang, a researcher from the University of Colorado Boulder and one of the authors of the study, said the 'patched charge model' they used allowed them to understand a basic mechanism behind dust charging and transport that had puzzled fellow scientists before.
He said that they expect particles of moon dust to mobilize electrostatically across the entire surface of the moon. This is also true for surfaces on other planetary bodies that do not have air.
The Comet 67P/Churyumov-Gerasimenko and the asteroid Eros are two such airless celestial bodies that could have the same electrostatic movement of dust particles. The phenomenon may help explain how "dust ponds" came to be formed on them.
The researchers believe that Atlas, Saturn's icy moon, may exhibit a similar lofting of dust particles on its surface similar to the one seen on the Earth's moon.
The findings of the NASA study help establish the possibility that dust mobilization in space causes dusty surfaces to become smooth, leading to the formation of dust ponds on these airless planetary bodies.
The movement of moon dust has been a particular concern for NASA astronauts. Some of those who journeyed to the moon said dust particles caused problems with their space suits while they were on the lunar surface.
