Mars Rovers Survive the Dust, Follow the Water
The durable NASA rovers Spirit and Opportunity, nearly four years into missions originally planned for three months, continue adding to evidence about water's role in past Martian environments. This fall, Spirit is examining the top of a low plateau in the vicinity of silica-rich deposits that may have formed in hydrothermal environments similar to ones that support microbial ecosystems on Earth. Opportunity is inspecting layered deposits inside a half-mile-wide crater in the Meridiani Region. Complementary studies of the Meridiani region from orbit show that clay-rich deposits and ancient cratered terrain cut by fluvial channels underlie the thick stack of sulfate-rich layers that the rover is sampling from the top. The combined vantages tell a long history of how hydrology of this region evolved. Dust storms in mid-2007 choked Spirit and Opportunity's solar-energy supply enough to temporarily halt science observations. Spirit's solar panels remain quite dusty, making the approaching winter's low sunshine another real threat to the rover's survival.
> Mars Exploration Rovers site