NASA's Mars orbiters have sent back photographs that may point to the existence of flowing water on Mars. To date, these images provide the most convincing evidence of liquid water on the Red Planet.
The images sent back by the Mars Reconnaissance orbiter show dark markings that can be seen running down a number of Martian slopes. These markings were photographed during times that coincided with rising temperatures on the Martian surface. Moreover, NASA scientists also noted that the images corresponded to seasonal changes on the Red Planet. The data is further supported by ground temperature surveys and recorded changes in the iron minerals found in the target sites.
The evidence gathered by NASA seems to support the theory that brines containing iron-mineral antifreeze may flow down the slopes on a seasonal basis. While NASA is also exploring other possible explanations for the markings, there is a good chance that these markings are caused by flowing water. NASA scientists currently refer to these flows as "recurring slope lineae" or RSL for short.
While the images are promising, NASA scientists are still hesitating about confirming the existence of flowing water on the Red Planet.
"We still don't have a smoking gun for existence of water in RSL, although we're not sure how this process would take place without water," said Georgia Institute of Technology graduate student Lujen Ojha. Ohja is the lead author of two new reports regarding these potential water flows on Mars.
Ohja initially discovered the flows three years ago when he was still a University of Arizona undergraduate student. He found the flows in a number of images taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance orbiter.
Along with Georgia Tech assistant professor James Wray, Ojha took a peek at 13 RSL sites captured by the Reconnaissance orbiter's Compact Reconnaissance Imaging Spectrometer for Mars (CRISM). To determine whether the RSL's were caused by flowing water, Ojha and Wray looked for certain minerals that would indicate the presence of liquid water. While the pair didn't find the right type of spectral signatures associated with salts and water, they were able to find the spectral signatures of iron-based minerals at a majority of the confirmed RSL sites.
"Just like the RSL themselves, the strength of the spectral signatures varies according to the seasons," said Ohja "They're stronger when it's warmer and less significant when it's colder."
The body of evidence that Ohja and Wray have gathered seems compelling. However, further studies are required before anything conclusive can be announced. NASA scientists will likely continue to look for more evidence to back up the theory of the existence of flowing water on Mars.
