Dusty rejuvenation
By Ron Cowen
The Mars rover Spirit just got a windblown reprieve. In January 2004, the rover landed in a dusty crater. Ever since, its solar arrays—its main power source—have been getting dirtier and thus less efficient, limiting Spirit’s performance. For instance, the robot typically drove for fewer hours each day or took in less data than its cleaner twin rover Opportunity did.
When Spirit landed, it could generate 900 watt-hours of energy, but its solar-array output has since dropped to less than half that amount. As recently as March 9, “the solar arrays [were] just filthy,” notes chief rover scientist Steve Squyres of Cornell University.