At this stage of our understanding of the planet Mars, we have seen salty water flowing (recurring slope lineae), found evidence of ancient riverbeds, and seen seasonal changes in the polar caps.  But an important question is how does water behave on Mars? A bit of science here on Earth gives some insight. Water at sea level on Earth boils at 100 degrees Celsius, which actually defined the Celsius scale.  But as pressure changes, liquids boil at different temperatures.  As the atmosphere gets thinner, the boiling temperature of water decreases.  On Mars, with it’s extremely thin atmosphere, this means that water...