Water, Water Everywhere

As a review of some of the recent postings shows, the accumulating evidence for liquid water on Mars, both past and present, is getting hard to keep up with, as well as a bit confusing.

While some studies suggest that a "warmer, wetter Mars" was a brief occurrence early in the planet's history, others argue it lasted much longer, while still others continue to claim it never happened. Some findings indicate groundwater / aquifers, others suggest surface water, including rivers, lakes, playas and perhaps even oceans. Some findings show evidence for acidic and salty water (the sulphates), others show evidence for less acidic or "normal" water (the gypsum and clay minerals).

At present, we do know that Mars currently has water vapour, frost, fog, and a lot of ice, both underground and on the surface. The new images from Mars Global Surveyor apparently indicate water periodically leaking to the surface from aquifers, and the search is on right now for direct evidence of them from Mars Reconnaissance Orbiter and Mars Express.

The pieces of the puzzle are slowly being put together, but the history of water on Mars is complicated and still highly debated among scientists with no overall consensus as yet. How to make sense of all this?

Some additional new studies and articles this week:

The Geological Society of America
Science
Physics News Update