In space, no one can hear you clean:
NASA's Mars rover Opportunity seems to have stumbled into something akin to a carwash that has left its solar panels much cleaner than those of its twin rover, Spirit. A Martian carwash would account for a series of unexpected boosts in the electrical power produced by Opportunity's solar panels.Opportunity's output also declined at first — to around 500 watt-hours — but over the past six months it has regained power (New Scientist print edition, 30 October). Lately, its solar cells have been delivering just over 900 watt-hours.
...Whatever the process, it has taken place while Opportunity was parked during the Martian night.
Rover team scientists believe the cleaning process may be caused by wind patterns in the crater Opportunity is currently exploring. Glenn Reynolds, meanwhile, is counting on the "Little Green Squeegee Men" theory and all its grand implications. What if it's a Martian city bum who's uninvitedly washing Opportunity's panels with a dishrag at stoplights? Just wait until he sends NASA the bill.