On April 3, NASA turned off CRISM, one of its oldest instruments used to study Mars. The instrument was aboard NASA’s Mars Reconnaissance Orbiter and had been providing high-resolution mineral maps for 17 years. CRISM, or the Compact Reconnaissance Imaging Spectrometer for Mars, detected minerals such as clays, hematite, and sulfates on the Red Planet’s surface, which helped scientists understand how water shaped the planet billions of years ago.
CRISM’s two detectors could see in visible and infrared light, identifying the chemical fingerprints of minerals that form in the presence of water. These maps were crucial in identifying scientifically interesting landing sites, such as Gale Crater, where Curiosity has been exploring since 2012, and Jezero Crater, where NASA’s Perseverance rover recently collected its 19th sample.
To study infrared light, which is invisible to the human eye, CRISM used cryocoolers to isolate one of its spectrometers from the warmth of the spacecraft. However, the last of these cryocoolers completed its lifecycle in 2017, so the CRISM team had to find a new way to produce data. They created two new maps, the first of which relied on previously collected data and viewed a limited range of minerals in visible and near-infrared light. This map covered 86% of Mars and had a spatial resolution of 600 feet per pixel.
The second map, with a spatial resolution of 300 feet per pixel, was gathered by CRISM’s remaining spectrometer and is set to be released in September. Despite the formal end of the CRISM investigation, the data products it produced will be used by scientists for years to come.