Martian water blasts away sand, may craft features as it boils

The complex pattern left behind by liquid water flowing through sand under Martian atmospheric pressures. (credit: M. Massé)

We now know that there is liquid water on the surface of Mars. Streaks of dark material flow down crater walls, appearing and disappearing with the seasons. Imaging from orbit has confirmed that these features contain hydrated salts, leading researchers to conclude that the water took the form of a salty brine, which would prevent it from immediately evaporating into Mars' cold, thin atmosphere.

But a new paper released today argues that we might want to rethink the role of brine. The international team behind it tested what would happen if pure water were flowing through sand under Mars-like conditions. Some of the water boiled off quickly, but it managed to spread a bit further than expected and produced features similar to some that have been imaged from orbit.

There are a number of challenges with figuring out what's happening on Mars. The first is that we've got no hardware anywhere near where the watery features form; all our direct exploration has to take place from orbit. Another challenge is that we don't know the nature of the water. At Martian pressures, pure water could boil at temperatures reached in the daytime and freeze at night, while salts could keep it liquid at the prevalent temperatures.

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