LITTLE GREEN SQUEEGEE MEN? I linked to an earlier report of this phenomenon a while back, but it keeps happening:

An unexplained phenomenon akin to a space-borne car wash has boosted the performance of one of the two U.S. rovers probing the surface of Mars, New Scientist magazine said on Tuesday.

It said something — or someone — had regularly cleaned layers of dust from the solar panels of the Mars Opportunity vehicle while it was closed down during the Martian night.

The cleaning had boosted the panels’ power output close to their maximum 900 watt-hours per day after at one stage dropping to 500 watt-hours because of the heavy Martian dirt.

I, for one, welcome our new squeegee overlords, and when they arrive on Earth I will entrust them with the care of my Passat wagon’s windshield.