We’ve known for some time that water exists in some forms on Mars. The Viking program, which consisted of both orbiter and lander craft, showed that Mars’ surface had many characteristics that must have been shaped by water. Further probes such as Mars Odyssey and the Phoenix Lander showed that much of the present day water that Mars holds is present at the poles, trapped in the vast frozen tundra. There’s been a lot of speculation about how liquid water could exist on Mars today however no conclusive proof had been found. That was until today when NASA announced it had proof that liquid water flows on Mars, albeit in a very salty form.
The report comes out of the Georgia Institute of Technology with collaborators from NASA’s Ames Research Center, Johns Hopkins University, University of Arizona and the Laboratoire de Planétologie et Géodynamique. Using data gathered from the Mars Reconnaissance Orbiter the researchers had identified that there were seasonal geologic features on Mars’ surface. These dark lines (pictured above) were dubbed recurring slope lineae would change over time, darkening and appearing to flow during the warmer months and then fading during the colder months. It has been thought for some time that these slopes were indicative of liquid water flows however there wasn’t any evidence to support that theory.
This is where the MRO’s Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) comes into play. This instrument was specifically designed to detect water on Mars by looking at varying wavelengths of light emitted from the planet’s surface. Once the target sites were identified CRISM was then pointed at them and their surface composition analysed. What was found at the RSL sites were minerals called hydrated salts which, when mixed with water, would lower the freezing point of the water significantly. Interestingly these hydrated salts were only detected in places were the RSL features were particularly wide as other places, where the RSLs were slimmer, did not show any signs of hydrated salts.
These salts, called perchlorates, have been seen before by several other Mars missions although they’ve never been witnessed in hydrated form before. These perchlorates can potentially keep water from freezing at temperatures down to -70°C. Additionally some of these perchlorates can be used in the manufacturing of rocket fuel, something which could prove to be quite valuable for future missions to Mars. Of course they’re likely not in their readily usable form, requiring some processing on site before they can be utilized.
Data like this presents many new opportunities for further research on Mars. It’s currently postulated that these RSLs are likely the result of a shallow subsurface flow which is wicking up to the surface when the conditions are warmer. If this is the case then these sites would be the perfect place for a rover to investigate as there’s every chance it could directly sample martian water at these sites. Considering that wherever we find liquid water on Earth we find life then there’s great potential for the same thing to happen on Mars. If there isn’t then that will also tell us a lot which means its very much worth investigating.