17 July 2008
The evidence for a warmer, wetter ancient Mars just keeps piling up! In 2 new papers, the team for the CRISM spectrometer onboard NASA’s Mars Reconnaissance Orbiter has reported new evidence for water on the surface of ancient Mars, based on the ubiquitous presence of water-bearing minerals.
Universe Today has a great post up on the findings, so I won’t repeat too much of Nancy’s explanation.
In brief, the CRISM team has identified a whole new suite of minerals on Mars, in addition to a few already observed, that only form with copious amounts of water. While some of these minerals are associated with local deposits that look like sedimentary layers set down by surface water, others seem to be present across vast regions of the ancient southern highlands. In particular, the minerals tend to be associated with the ejecta, floors, and central peaks of craters in the ancient terrains. Because the impacts probably dug up the minerals from several kilometers down in the crust, the crust must have been altered by water to at least that depth. For example, the image below shows where CRISM has detected phyllosilicates (a hydrated clay mineral) in one region of the highlands. Because almost every crater has a phyllosilicate detection, the basement material has probably interacted with water throughout this region.
We tend to think of “Mars” as one place with a history that can be described by one storyline, even though Mars is a whole planet with as much surface area as dry land on Earth. What’s really great about these findings is that they really bring home that the surface of Mars probably had just as many different environments as Earth does now. Mars scientists have used the composition of minerals and their geologic context to identify ancient hydrothermal springs, shallow seas, lakes, and floods on Mars. With all of these different environments, life very well may have been able to eke out an existence in one of them…