View Full Version : Why is Moondust So Clingy?

2005-Nov-21, 07:35 PM
SUMMARY: One of the main challenges of returning humans to the Moon will be how to deal with all that gritty, clingy moondust. Scientists believe that ultraviolet radiation charges individual grains of dust, giving them a static charge. NASA is studying individual grains of moondust returned by Apollo astronauts to how much charge they can build up, and the results have been surprising. Ultraviolet radiation can give a grain of moondust 10 times more charge than the theories had calculated.

View full article (http://www.universetoday.com/am/publish/mesmerized_by_moondust.html)
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2005-Nov-22, 04:40 AM
Not merely charged, but supercharged!

I wonder if that's a potential dc energy source?

"Yeah, fill up the moonbuggy with supercharged dust, thanks ... oh and don't bother washing the vacuum-screen - I might need the extra to get back!" :D

2005-Nov-23, 12:58 AM

I remember reports that when the NEAR probe examined the Eros asteroid in close-ups pictures some years ago, it found "lakes" of floating dust which were covering the bottom of some of Eros´meteor craters. I read that the UV radiation of the sun seems to charge Eros dust particles such that their uniform charge pushes one away from the other, such that they are lifted off the ground.
But this charged dust stays on Eros. It does not disappear into space, perhaps because Eros´weak gravity prevents the dust from doing so.

If Eros had the mass of our moon, the resulting gravity pull on the dust would be much stronger than it is now on Eros. The electric charge of the dust particles would not make that dust to move off the moon surface.
It is evident that the moon is not enshrouded by clouds of charged moon dust.

The sun´s UV radiation can build up electric charge on dust particles, causing that dust to cling to everything. But the intensity of solar UV radiation cannot compete with the intensive light coming from a UV laser. So such a the laser beam can create a higher electric charge on moon dust particles.

As the electric charge resides on the surface, and as larger dust particles have a larger surface than smaller particles, the larger particles can be charged higher than the smaller ones. Further, larger particles have greater surface radii, and so they can accept more streamlines of the electric field, and attain higher voltage levels than smaller particles can.

The electric charge on a dust particle produces high voltage, but does not produce a continuous electric current flow. Such, it is not useful as a current source. A solar cell is much more efficient for that kind of job.
Our high-tech equipment would be ruined by the lunar dust environment. It will be necessary to cover everything by flexible, transparent and tight layers of protective non-conductive wide-temperature-range plastics. A nice job.



Ray Bingham
2005-Nov-24, 08:37 PM
Just wondering. I remember reading not too long ago about someone photographing water droplets falling onto the surface of water, but in a vaccuum and noting that there was a difference in the way it splashed. Is it possible that dust simply moves in a different manner in a vaccuum than we are used to seeing it move in a pressureized atmosphere? Have we done experiments on dust movement in vaccuum?


2005-Nov-24, 08:48 PM
Why is it clingy? Because it's lonely and luvs u.