Sure, the Mars Curiosity rover is an incredible technological accomplishment that has been bringing new insights into the red planet since it landed late last summer, but don't count out its older sibling, NASA's Mars rover Opportunity. The little rover that could recently proved it still can. In its ninth year of operation, the Opportunity recently found new evidence of water on Mars, which was once suitable to support life.
The discovery takes the form of a rock that Opportunity, and its operators, have found on the surface of the planet at a site known as Cape York. There, researchers guiding Opportunity have discovered a rock that is cracked and laden with clay minerals, which suggests evidence of once running water that could have supported precursors of life on Mars. The rock, called Esperance, has clay indicating the presence of a fluid inset in it, which is nothing new. What is special about Esperance is that the clay minerals indicate rich, possibly life-supporting water.
"If you look at all of the water-related discoveries that have been made by Opportunity, the vast majority of them point to water that was a very low pH - it was acid," said Steve Squyres, the principal investigator for the Opportunity rover, to the BBC. "We run around talking about water on Mars. In fact, what Opportunity has mostly discovered, or found evidence for, was sulphuric acid."
Life on Earth has been found to exist in extremes including both high and low temperature environments, as well as low or high pH (acidic or basic) environments, but what Opportunity has most recently discovered is clay minerals that could have been formed by the routine water that we know so well. "Clay minerals only tend to form at a more neutral pH. This is water you could drink. This is water that was much more favorable for things like pre-biotic chemistry - the kind of chemistry that could lead to the origin of life," said Squyres.
Making this discovery wasn't the easiest thing for Opportunity's operators. NASA needed to get Opportunity started on a drive toward a place called "Solander Point," where there's enough tilt for the rover to collect the sunlight the team needs to keep Opportunity working during the next Martian winter, but Esperance proved so enticing that they decided to stay until they could fully investigate it. "Esperance was so important, we committed several weeks to getting this one measurement of it, even though we knew the clock was ticking."
For years, Opportunity has found evidence of ancient Martian wet environments, but they were very acidic. Esperance, which the team examined with Opportunity's camera and spectrometer, was quite a change from the usual. "Water that moved through the fractures during this rock's history would have provided more favorable conditions for biology than any other wet environment in rocks Opportunity has seen," said Squyres in NASA's statement.
According to the BBC, Squyres, a professor from Cornell University in New York State, puts this discovery in his top five Mars discoveries made by Opportunity and Spirit, the other Mars rover which landed in 2004, but whose last communication was sent in March of 2010. NASA intends on continuing with Opportunity as long as the rover can maintain operations on the red planet, which may end at any moment. The Mars Curiosity rover, meanwhile, has been busily exploring the planet, recently finding rounded pebbles that indicate flowing water and a "Mars rat," which has driven UFOlogists to scour Curiosity's images for more pareidolia-inducing stones.