As the Opportunity rover toddles across the Martian plains, it keeps finding blueberries. They were scattered around its landing site. It found little ones on the rim and floor of a small crater, and big ones on the floor of a big crater. And just a few months ago, it found jumbled masses of them -- like blueberries smashed together by a big foot.
The "blueberries" are actually round lumps of an iron-rich material known as hematite. Most of them are about the size of BBs or peppercorns, but a few are as big as -- well, blueberries.
The blueberries tell geologists that the area Opportunity is exploring was once wet. That's because hematite forms in watery environments, and the blueberries are embedded in layers of salt that were left behind when water evaporated.
The water probably wasn't in the form of a lake or sea, though. Instead, it most likely consisted of groundwater that soaked the soil.
Opportunity is headed toward an even bigger crater. It's still miles away, and might not survive the long trek. But if it does, it'll look for more blueberries in the layers of rock around its rim. They may tell scientists how wide an area was soaked in water, and when the water evaporated -- leaving piles of dried-out blueberries.
And you can see Mars tonight. It's to the upper left of the Moon as darkness falls, and looks like an orange star. The true star Regulus stands above the Moon, completing a beautiful triangle.
Script by Damond Benningfield, Copyright 2010