Scientists have discovered what could be signs of flowing water on Mars, a development that could amend previous theories that liquid Martian water is a thing of the distant past.
According to Georgia Tech researchers Lujendra Ojha and colleagues, they have discovered dark, finger-shaped areas on the surface of Mars, that change with season and could indicate streams of running saltwater. The newly published images were created using the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM).
Ojha initially noticed the darkened spots as an undergraduate in 2011, using the High Resolution Imaging Science Experiment. CNN reported on his discovery at the time:
Using a computer algorithm to examine images taken in the same crater as the gullies Dundas had examined, Ojha removed visual distortions, such as shadows, from images of a crater taken at different points in time. With that technique, he compared the images to identify the changes over time.
Ojha and his team published that hypothesis in a scientific journal upon making the initial discovery. In a press release, NASA describes what the new images could mean:
The features are dark, finger-like markings that advance down some Martian slopes when temperatures rise. The new clues include corresponding seasonal changes in iron minerals on the same slopes and a survey of ground temperatures and other traits at active sites. These support a suggestion that brines with an iron-mineral antifreeze, such as ferric sulfate, may flow seasonally, though there are still other possible explanations.
According to NASA, the researchers have confirmed 13 "recurring slope linae," or RSL, sites on the Martian surface. The CRISM images didn't show any spectral signature to either water or salt, but they confirmed signatures of ferric and ferrous minerals at most sites. The presence of these salty minerals, which would warm water's temperature and keep it liquid, suggests that the dark areas are streams of briny H2O.
Next month, the Georgia Tech and other scientists will publish a follow up in Geophysical Research Letters that will delve deeper into their understanding of RSL, including the observation that RSL sites differ over years — suggesting that water, if it does exist on Mars, is a seasonal occurrence.
The scientists are still not able to confirm whether or not the red planet harbors water. According to Ojha, "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." Even if researchers confirm that water exists on Mars, the planet would remain basically inhospitable to human life. One of the report authors told CNN that ferric-sulfate-infused water is undrinkable, but "if there's enough water initially to form a dilute solution, maybe it would be OK. Personally I wouldn't want to risk it!" We hope all of those people booking a one-way trip to Mars will keep that in mind.