Surely the science is accurate enough to rule out it being frozen CO2? They sound pretty confident it’s liquid water.
For the last 30 years I have read of new discoveries of water on Mars (under the dust, under the ground, under the ice caps, etc.) that I have grown extremely skeptical of any new discoveries. These “discoveries” result in very expensive and redundant robotic missions to Mars that seem more about financing scientists careers than making real meaningful discoveries. At this point, the only mission I care about is sending a man to Mars. They aren’t going to find anything living there other than that.