High Resolution and Low Risk

CRISM is a visible-infrared imaging spectrometer with a scannable field of view. CRISM can cover wavelengths from 370 to 3,920 nanometers (nm) at 6.55 nm/channel - meaning the CRISM team will be able to identify a broad range of minerals on the Martian surface.

CRISM's high spatial resolution (18 meters/pixel at 300 kilometers altitude) will reveal deposits as small as house-sized outcrops. CRISM will make thousands of targeted observations at geometries needed for analysts to separate and characterize Mars' surface and atmosphere.

To control cost and reduce risk, CRISM draws extensively upon the electronics and design of imaging technology developed for the CONTOUR comet-study spacecraft and MESSENGER Mercury orbiter.

'Seeing' the Surface

Once in orbit, CRISM's investigations begin with sunlight reflected off the Martian surface. CRISM breaks this light into a spectrum, from which it measures 544 colors. The wide range of colors helps CRISM determine the mineralogy of the surface.

CRISM's thin rectangular field of view measures a region about 18 meters (60 feet) wide and 10.8 kilometers (6.7 miles) long, if Mars Reconnaissance Orbiter is about 300 kilometers (186 miles) above the planet. As the orbiter flies over a given area, CRISM's scanning mechanism tracks a region on the surface and slowly sweeps the field of view across it. CRISM only needs 3 minutes to map several hundred kilometers.

The instrument's capability to measure so many colors of light makes it possible to identify most common minerals by their habits of preferentially absorbing light of different wavelengths. This powerful technique has been used for decades to study the Red Planet. For example, the map at right was made from only three colors (green, red and infrared) in Mars Pathfinder images and shows iron oxide coatings crusted on rocks.

CRISM's key investigation sites include smooth interiors of ancient craters that may have been filled in by lakes, volcanic regions and crustal sections exposed in steep cliffs.

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