The hunt for evidence of water on Mars that could support life has been a long and exciting one (depending on your definition of exciting). While there is evidence abound of water that used to be on the Martian planet, it has been of the highly acidic variety, which is not conducive to life. Now, however, NASA has discovered evidence of non-acidic water in Mars' past, a finding made by the rover Opportunity.
The evidence is various clays discovered inside a rock Opportunity was analyzing, clays that NASA says were formed with non-acidic water. The water is said to be pH-neutral, which means you could drink it if you liked. This doesn't mean that this water is present on Mars right now, however, only that there is clay that was formed by such a substance.
When speaking to media in a conference call today, Steve Squyres of Cornell University and head scientist of both the Opportunity and Spirit rover missions, said: "The tough thing about an acid environment is that it's very, very hard, we believe, to get pre-biotic chemistry, the kind of chemistry that can lead to the origin of life. What's exciting about this discovery is that it points to a neutral pH at a time very, very early in Martian history."
The clay was found in a rock called Esperance, which is located in the Endeavour Crater, a basin created by a collision on the planet. Esperance is located on its rim, and took a solid three years for Opportunity to locate. While the newer Curiosity rover is equipped with a drill, which it has used to bore into Martian rock in recent months, Opportunity has no such tool.
Because of this, Opportunity was forced to "scratch" Esperance, which required repositioning itself more than half a dozen times before it was successful. All the time and effort was worth it, however, because doing so revealed clays containing high levels of aluminum. Now Opportunity is making its way to another rock column on the crater, which it is slated to reach by the first of August.