How to Get Asteroid Dust Ponds in Mere Millennia

A team of U. of Colorado and MIT scientists modeled the formation of the smooth dust ponds found in some of the craters on the asteroid Eros by the NEAR spacecraft (see 02/13/2001 entry).  They calculated that micrometeoroid settling from impacts was too slow a process, and instead ran experiments with electrostatic levitation of fine particles.  Their calculations suggested this process could deposit a monolayer of micron-size particles once a day.  That would lead to the observed pond formation in 2,000 years or less; maybe as little as 100 years.  Their paper is published in Icarus.¹

¹Colwell et al., “Dust transport in photoelectron layers and the formation of dust ponds on Eros,” Icarus, Volume 175, Issue 1, May 2005, Pages 159-169, doi:10.1016/j.icarus.2004.11.001.

If that process is so efficient, why aren’t the craters overflowing with dust after 4.5 billion years?  The dust is found coating only the bottoms of some of the craters.  Explore the pictures on NASA Photojournal and see for yourself.  Calculations like this are always based on assumptions and limited data, but it seems harder to imagine so little ponding after billions of years.  Explaining the dust away seems to require more ad hoc elements in the story.  Maybe Eros just hasn’t been drifting out there all that long.