Why does the dust clump together like wet sand? Everybody's seen the pictures of the astronauts' footprints, but should the dust have left any trace of the footprints? Wouldn't they have disappeared like footprints in dry sand dunes?
The lunar dust is not anything like sand. The particles are smaller and much more irregular. Sand on Earth is the result of weathering and has been rounded and smoothed by wind, water and oxidation, but dust on the moon are minuscule shards of broken rock from asteroid collisions. Consequently their surface at a molecular level is a jagged mass that won't get smoothed off and don't have any weathering to smooth them off. This means that when compressed, say by a boot, the dust particles will grip with each other very readily, using and retain the shape. All without any water.
No comments:
Post a Comment