NASA's Mars Reconnaissance Orbiter (MRO) has discovered evidence of ancient volcanoes on the surface of the Red Planet. They are believed to have erupted under a sheet of ice, despite the fact that they were discovered around 1,000 miles (1,609 km) away from the vast southern Martian ice cap.
The MRO's Compact Reconnaissance Imaging Spectrometer (CRISM) detected zeolites, sulfates and clays at a number of the potential eruption sites in the Sisyphi Montes region of Mars. These minerals, as well as the distinctive flat-top shape of the features, bear a striking resemblance to the aftermath of subglacial volcanic events observed back on Earth.
As recently as 2010, the vast and difficult to pronounce Eyjafjallajökull subglacial volcano erupted in spectacular fashion, spewing ash miles into the air above Iceland, wreaking havoc with air travel.
Whilst they may be a majestic hazard back on Earth, the presence of the distinctive subglacial volcanoes on Mars hints at a very different environment to the arid landscape we see today. It is possible that the ice sheets covering the poles of the Red Planet extended over a far greater area, and that volcanic eruptions under the sheets could have generated vast quantities of heat and moisture, two conditions that are extremely favorable to microbial life.