New Delhi: New evidence from NASA's Mars Reconnaissance Orbiter (MRO) suggests that volcanoes erupted beneath an ice sheet on Mars billions of years ago, far from any ice sheet on the Red Planet today.
The data also reveals that a massive ice sheet once covered Mars.
The new findings could help reveal if the Martian environment had flowing water and was once habitable.
Sheridan Ackiss of Purdue University, West Lafayette, Indiana, and collaborators used the orbiter's mineral-mapping spectrometer to investigate surface composition.
The focused on an oddly textured region of southern Mars called "Sisyphi Montes", which is studded with flat-topped mountains. Other researchers previously noted these domes' similarity in shape to volcanoes on Earth that erupted underneath ice.
"Rocks tell stories. Studying the rocks can show how the volcano formed or how it was changed over time," Ackiss said. "I wanted to learn what story the rocks on these volcanoes were telling."
When a volcano begins erupting beneath a sheet of ice on Earth, the rapidly generated steam typically leads to explosions that punch through the ice and propel ash high into the sky.
Characteristic minerals resulting from such subglacial volcanism on Earth include zeolites, sulfates and clays.
Those are just what the new research has detected at some flat-topped mountains in the Sisyphi Montes region examined with the spacecraft's Compact Reconnaissance Imaging Spectrometer for Mars (CRISM), providing resolution of about 60 feet (18 meters) per pixel.
"We wouldn't have been able to do this without the high resolution of CRISM," Ackiss said.
The Sisyphi Montes region extends from about 55 degrees to 75 degrees south latitude. Some of the sites that have shapes and compositions consistent with volcanic eruptions beneath an ice sheet are about 1,000 miles (about 1,600 kilometers) from the current south polar ice cap of Mars. The cap now has a diameter of about 220 miles (about 350 kilometers).
The Mars Reconnaissance Orbiter Project has been using CRISM and five other instruments on the spacecraft to investigate Mars since 2006