Images: When Mars was a wetland

These are four renderings of an image of an area south of Mawrth Vallis that was taken by another instrument aboard the Mars orbiter. The image was compared to measurements of various minerals, and the bottom two renderings at left show clay deposits rich in iron and aluminum.

The type of clay formed is determined by the composition of the rock in the area, as well as the temperature, acidity and salt content of the water. The mission of the CRISM (Compact Reconnaissance Imaging Spectrometer for Mars) spectrometer that created these images is to find identifying characteristics of aqueous and hydrothermal deposits on the planet and then map the geography and composition of the planet's surface.

In this exercise, for example, scientists were able to spot locations where clay and rocks rich in the same mineral exist.

Photo by NASA/JPL/JHUAPL/Brown University