NASA's Mars Reconnaissance Orbiter shows extensive ice on ancient Mars, researchers said.
Volcanoes erupted beneath an ice sheet on Mars billions of years ago, according to new research that indicates an environment combining heat and moisture, which could have been favourable for microbial life.
New evidence from NASA's Mars Reconnaissance Orbiter suggests there was extensive ice on ancient Mars, researchers said.
Sheridan Ackiss from Purdue University in the US and colleagues used the orbiter's mineral-mapping spectrometer to study surface composition in an oddly textured region of southern Mars called "Sisyphi Montes."
The region is studded with flat-topped mountains. Other researchers previously noted these domes' similarity in shape to volcanoes on Earth that erupted underneath ice.
The research adds information about an environment combining heat and moisture, which could have provided favourable conditions for microbial life.
"Studying the rocks can show how the volcano formed or how it was changed over time," Ackiss said.
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.
For example, the 2010 eruption of ice-covered Eyjafjallajokull volcano in Iceland lofted ash that disrupted air travel across Europe for about a week.
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 18 meters per pixel.
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 1,600 kilometres from the current south polar ice cap of Mars. The cap now has a diameter of about 350 kilometres.
The Mars Reconnaissance Orbiter Project has been using CRISM and five other instruments on the spacecraft to investigate Mars since 2006.
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