This graphic illustrates where Mars mineral-mapping from orbit has detected a few minerals -- sulfates (blue) and iron oxides (pink) -- that can indicate where a volcano erupted beneath an ice sheet.

The site is far from any ice sheet on modern Mars, in oddly textured terrain where the shapes of flat-topped mountains had previously been recognized as a possible result of ancient subglacial volcanism. Researchers used the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) to check surface composition in the area, and their findings strengthen the evidence for volcanic eruptions that burst through a cover of ice.

These mountains are in a region called Sisyphi Montes. In this graphic, the base image shows a portion of the region about 130 miles (230 kilometers) across, centered at 17.73 degrees east longitude, 63.46 degrees south latitude. Red outlines indicate possible subglacial volcanic structures. CRISM data are presented in the overlay box at upper right, with an indication of the ground area covered by this CRISM observation. The color key at upper left shows how the spectrometer data correspond to presence of sulfates and iron oxide minerals, which are characteristic of subglacial volcanism sites on Earth.

The base map uses imaging from the Thermal Imaging System (THEMIS) camera on NASA's Mars Odyssey orbiter. CRISM is one of six instruments on NASA's Mars Reconnaissance Orbiter.

Building and operating CRISM has been led by Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland. THEMIS was supplied by and is operated by Arizona State University, Tempe. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter and Mars Odyssey projects for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, built both orbiters.