Even when water evaporates, it doesn't really
disappear. Traces of iron oxides, clays (phyllosilicates), carbonates, sulfates and other minerals
stay behind – and planetary scientists have embarked on an international
effort to find those aqueous clues on Mars.
CRISM will be a valuable tool in their quest. Onboard the Mars Reconnaissance Orbiter, CRISM will map the mineral signatures of water on the Martian surface, revealing Mars' past wet environments and mapping the geology, composition and layering of surface features. Some of CRISM's chief targets will be hydrothermal deposits – formed in hot waters like at Yellowstone National Park (above, right) or deep sea hydrothermal vents – where some scientists think life might have begun.
Mineral mapping spectrometers have previously flown on Mars missions. These include TES on the Mars Global Surveyor, THEMIS on Mars Odyssey, and OMEGA on Mars Express. These missions have discovered at least two kinds of mineral indicators of past water. Some regions (right) are rich in sulfate minerals and iron oxides, the fingerprint of wet, acidic environments. Other regions, mostly where Mars' oldest rocks are exposed at the surface (below), have been altered to phyllosilicates, commonly called clay – hinting at a different kind of past wet, and perhaps warm, environment.
CRISM will map these and other regions at up to 20 times the resolution
of past Mars mineral mappers, providing the first detailed
compositional maps of environments where life might have existed in
Mars' distant past.
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Hot spring at Yellowstone National Park (Image credit National Park Service)
Sulfate deposits surrounding the north polar residual cap (color code: red = most abundant, violet = least abundant)
(Image credit Mars Express/OMEGA team) |
