Perchlorate Brine On Mars?

It's funny, I had thought the properties of inorganic salts had long been known, but maybe it's not true. Certainly space exploration allows one to formulate questions that might not seem obvious at first, but are more and more plausible:

“They do seem to depress the freezing temperature to the point where you could have stable liquid on the surface,” said Selby Cull of Bryn Mawr College.

What is more, salts such as perchlorates provide a way for Martian soils to take up water from the atmosphere. When the Martian atmosphere becomes more humid during its daily cycle, perchlorates can undergo a process called deliquescence, pulling water from the air and essentially transforming from a crystal to a droplet. As the humidity decreases again, the salts effloresce, releasing the water vapor back into the atmosphere. Intriguingly, the process is asymmetrical—preliminary laboratory data presented at the conference demonstrated that perchlorate salts deliquesce and effloresce at very different humidity levels. Once a perchlorate has taken in water via deliquescence, which occurs as moderate humidities, it will retain that water until the humidity drops to very low levels. “The salt really likes to maintain its aqueous state,” said Raina Gough of the University of Colorado at Boulder. The ready uptake of water by perchlorate salts points the way to the regular emergence of pockets of liquid under typical Martian conditions. “We’ve expanded the region where you can have an aqueous phase to lower temperatures and lower humidities,” Gough said.

...All the same, McEwen and his colleagues have recently found what appears to be the best evidence for present-day flowing liquid on Mars. In 2011 the researchers used the Mars Reconnaissance Orbiter’s HiRISE camera to identify several sites where warm slopes are periodically darkened by linear streaks. Flowing briny water was, and still is, the best explanation for the seasonal appearance of the so-called recurring slope lineae—although McEwen noted that non-perchlorate salts, with less extreme properties, could be in play.