A Patch of Spherules on Mars

Some patches of Mars are full of mysterious tiny spherules . The microscopic imager on board the Opportunity rover on Mars recorded, last week, the above image showing over a dozen. The image was taken near a rock outcrop called Stone Mountain and spans roughly 6 centimeters across. A typical diameter for one of the pictured spherules is only about 4 millimeters, roughly the size of a small blueberry . The spherules appear to be much grayer and harder than surrounding rock. Debate rages on the origin of the tiny spherules , and whether their shape has to do with a slow accumulation of sediments suspended in water, or flash-frozen rock expelled during a meteor impact or volcanic eruption. A layered spherule, if ever found, would favor a water-based origin. Meanwhile, Opportunity is being programmed to dig into the Martian surface of Meridiani Planum to see what is there.