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Finding Evidence of Mars鈥 Ancient Water

The Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) was a high-tech detective that uncovered the compositional clues to the Red Planet鈥檚 geologic history.

About the Instrument

Instrument Type
Optical

Where ancient water existed on Mars, what mineral record did it leave? How did it shape the surface, and could it have sustained life? How did Mars鈥 crust form? These are some of the questions that CRISM was built to answer.

A detailed, 3D rendering of the CRISM instrument.
A detailed, 3D rendering of the CRISM instrument.

CRISM launched aboard NASA鈥檚 Mars Reconnaissance Orbiter in August 2005, becoming operational at Mars about a year later. From an orbit that took it 160 to 200 miles (255 to 320 kilometers) above Mars鈥 dusty surface, this workhorse of an instrument scanned the Red Planet in search of the chemical fingerprints of past water.

Offering greater capability to map spectral variations than any similar instrument sent to another planet, CRISM could read 544 visible and near-infrared 鈥渃olors鈥 in reflected sunlight to distinguish different minerals in the surface and atmosphere. The images allowed researchers to study Mars鈥 rock compositions, track changes in the planet鈥檚 atmosphere, and examine how volatile ices move between the atmosphere and polar caps.

The instrument鈥檚 observations played a large part in confirming the presence of large amounts of water on Mars in the past. It revealed Mars鈥 complex geologic history and informed decisions on where to land rovers on the surface. CRISM鈥檚 detection of clay and carbonate minerals that indicate a past benign water environment, plus the types of sediments good for fossilizing signs of life, for example, was a significant factor in Jezero crater鈥檚 selection as the Perseverance rover鈥檚 landing site.

CRISM was turned off on April 4, 2023, closing out 16 years of operation.

Mission

Mars Reconnaissance Orbiter

Blasting off in 2005, NASA鈥檚 Mars Reconnaissance Orbiter left in search of evidence that water persisted on the Martian surface for long periods of time, helping to answer the outstanding question of whether water was ever around long enough on Mars to provide a habitat for life.
 

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