A close-up view of the eroded terrain in Nili Fossae using a CRISM infrared image to colorize a high-resolution HiRISE camera image. Beneath a rough-textured capping rock unit (purple) are banded olivine-bearing layers (yellow) which in some places have been partially altered to carbonate (bright green).Evidence of a key mineral on Mars has been found at several locations on the planet’s surface, suggesting that any microbial life that might have been there back when the planet was wetter could have lived comfortably.