The Proof is in the Craters

A neat piece of news caught my eye this week — an announcement from the European Space Agency that mineral studies of Mars taken by ESA’s Mars Express mission and NASA’s Mars Reconnaissance Mission show that liquid water was once very widespread on Mars.  The evidence lies inside craters spread around the planet, apparently just beneath the surface. It’s in the form of deposits of what are called hydrated silicates — minerals that have been in contact with water sometime in the past.

Lyot Crater (at left) was one of 91 impact craters the missions studied in a search for evidence of water. At least nine of the craters have strong evidence of hydrated silicates. Those minerals form in wet environments either on the surface or underground — and they have now been identified in both the north and south parts of Mars.

Why study craters?  Because the impacting objects (asteroid chunks, for example) punched down through the surface of the planet and exposed very ancient surface crust that would have been in contact with water. This means that water was widespread on the Martian surface sometime in the past. This is great news for scientists who are working to understand the role that water played on Mars early in its history. The presence of water means that conditions could have been favorable for life. It doesn’t prove that life existed on Mars — that takes other studies and will very likely require us to visit the planet to prove it for sure. But, the existence of water is a big thing.  There are hints of it all over Mars, not just in the hydrated silicates, but in the landforms that seem to be carved by the action of water.  This is a fascinating story that is still unfolding for planetary scientists. I, for one, think that we’ll find substantial reservoirs of water (probably locked away in subsurface aquifers and permafrost) on Mars when our first explorers set foot on that dry and dusty desert surface.