Regional Martian Landscape Carved Out by Water

After driving around Mars' Victoria Crater for a good part of its mission, the rover Opportunity was finally able to beam back sufficient images for experts to piece together and propose a hypothesis on how the entire area came to look the way it does now. Two years of observations by the persistent rover have shown that the entire crater may have been shaped by the influence of flowing water, such as rivers or creeks. Victoria is the third such formation Opportunity investigated, after it took hard looks at the Eagle and Endurance craters as well.

With a depth of 400 feet (125 meters), Victoria is the largest impact zone that the rover could have gotten to before its batteries, wheels, solar panels or antennas would have failed. At that point in the mission, when the robot had already exceeded its expected operating time several times over, the experts at Mission Control wanted to squeeze as much scientific data out of it as possible. As a result, the rover spent the next two years driving alongside the edges of the crater, sometimes exposing itself to the dangers of falling inside.

One of the main purposes of the investigation was to check and see if the Victoria crater exposed the same layers of sedimentation that the team at the Jet Propulsion Laboratory (JPL) saw in Endurance. Such exposed layers could have hinted at a number of geological processes that might have affected the Red Planet several millions of years ago. The robot found important traces of sulfate-rich sandstone, the same rocky formation found in the other two craters as well. This is a clear indicator of the fact that passing water had removed the minerals from the rocks, geology experts said at the time.

After taking numerous pictures of the sediments, and even driving a bit into the Victoria itself, to see if it held any more mysteries, the Opportunity rover is currently on its way to the Endeavor crater, located some seven miles (12 kilometers away). The reason why this was selected as the next target is because it's a lot older than any of the others, and thus it could provide a window into Mars' more distant past, before the sediments started depositing. Following the study of the three craters, and of the sediment layers they revealed, experts concluded that water played a fundamental role in the Meridiani Planum region, an area about the size of the state of Oklahoma.

According to a new scientific paper detailing the finds, published in the May 22nd issue of the journal Science, it would appear that salts and other minerals in the Martian water were directly responsible for keeping it liquid, despite the fact that the average temperature on the Red Planet is well below the freezing point. But researchers know from Earth that, by mixing salt with water, for example, the slush no longer freezes at zero degrees Celsius. Some hypothesize that this type of mix may have existed on the Martian surface as recent as one million years ago.