"It is not always associated with water, but it often is." Deposits of grey hematite are typically found in places where there has been standing water or mineral hot springs, such as those in Yellowstone. The mineral can precipitate out of water and collect in layers at the bottom of a lake, spring, or other standing water. But hematite can also occur without water, as the result of volcanic activity.Since the Mars Global Surveyor spotted large concentrations of Grey Hematite on Mars in 1998 scientists have wanted to found out which process created the grey hematite on Mars. And that's exactly the mission of the Opportunity.
"We want to know if the grains of hematite appear to be rounded and cemented together by the action of liquid water or if they're crystals that grew from a volcanic melt," says Crisp. "Is the hematite in layers, which would suggest that it was laid down by water, or in veins in the rock, which would be more characteristic of water having flowed through the rocks."
"The area where we are going has 10 to 15 percent grey hematite," Crisp says. "What are the other materials found with the hematite? Clays and carbonates would indicate there had been water in the area. If the area had been volcanic, you would expect to see other types of minerals like olivine and pyroxene."
"We're very interested to know if this region could have been like Yellowstone, with hot springs, so we'll be looking to see if there are other minerals in the area such as those at Yellowstone."
"Knowing just how the hematite on Mars was formed will help us characterize the past environment and determine whether that environment was favorable for life," says Crisp. "One big question, of course, is whether life ever started on Mars. This mission probably won't tell us that, but it may well lead to future mission that can answer that question."
This is the first color picture beamed back from the Opportunity mars rover showing the martian landscape at Meridiani Planum. The image was captured by the rover's panoramic camera.
All pictures made by Opportunity can be found here, and the best (sometimes color) pictures can be found here