New evidence suggests that supervolcanoes may have erupted on the surface of ancient Mars.
The discovery of a new form of volcano on Mars, similar to the one in Yellowstone National Park in Wyoming in the US, could alter the way we think about climate evolution on the planet.
Museum Mars researcher Dr Joseph Michalski, who led the study, was originally studying impact craters by re-analysing data and satellite photos generated from spacecraft orbiting Mars over the past 15 years.
He realised that some of what were considered craters could have been a form of ancient volcano, different to those typically seen on Mars. He then brought in colleague Jacob Bleacher, who specialises in Martian volcanoes, to further study the area.
Dr Michalski said that although we already know about the volcanoes on Mars spanning 3.5 billion years, the mystery of Martian science has been what happened in the first billion years.
One possible theory has been that any volcanoes from this very early period were eroded away.
Typical Mars volcanoes are mountain-shaped shields created from layers of lava and most closely resemble mountains in Hawaii.The newly discovered supervolcanoes are much older and, rather than forming mountains, have collapsed inwardly.
These recently discovered giant volcanoes, which look like irregularly shaped craters, are in an area in the northern highlands of Mars known as Arabia Terra. Until now, volcanoes have not been identified in this region.
Supervolcano is the term given to a large explosive volcano that produces more than 1,000 cubic kilometres of ash and lava during one eruption.
Dr Michalski's discovery could affect our understanding of the atmosphere on Mars since all atmospheres, including Earth's, are made up of gases originally emitted from volcanoes that eventually bind with other compounds and settle.
Curiosity-eye-view of Mars from the rover's arm-mounted camera, angled for driving. Curiosity, which landed on Mars in August 2012, will continue to investigate the possibility of an environment benign enough to support simple life © NASA.
The atmosphere on Mars consists predominantly of carbon dioxide, carbon monoxide and argon, which originated through volcanic emissions.
Dr Michalski said that because gases released by these supervolcanoes would have disturbed the early Martian climate, the more we discover about them, the better we will understand the timing of the planet's evolution and how habitable the surface might have been.
Dr Michalski said, 'Volcanism is the thread binding nearly every aspect of Mars' geological evolution. The better we understand it, the better we understand the planet.'