Is it mold on a bathroom wall? A close-up of a Dalmatian? The results of a tragic toner-cartridge accident?
—Image courtesy NASA/JPL/University of Arizona
In fact, it’s a Martian volcano in the process of defrosting. The ancient cauldron is part of a group of volcanoes that rings the Hellas impact basin on the red planet’s southern hemisphere.
The imaging team with the recently reactivated Mars Reconnaissance Orbiter released the picture this week. Taken in January, the shot shows the volcano covered in frost, except for a few dark patches where the icy sheath is starting to melt away.
Researchers aren’t sure why the patchy areas are so special, although they suggest that the spots could be dark sand dunes that soak up the sun’s heat better than the surrounding soil.
This particular volcano is a patera, a type of volcanic crater where lava once erupted from vents inside the depression. Research has suggested that some of Mars’s paterae could be the tops of shield volcanoes—gently sloping peaks like Hawaii’s Mauna Loa—that got buried by later lava flows.
Others could have formed when groundwater mixed with magma, triggering an explosion that created the signature scalloped bowl shape.
Today Mars’s volcanoes are no longer active, so it’s hard to get a clear picture of how they formed. Some of the youngest known lava flows are anywhere from 20 million to 200 million years old.
Olympus Mons, the solar system’s biggest volcano, appears to be a shield volcano, but it has an odd asymmetrical shape that geologists can’t quite account for.
In a new study released this week, geophysicists used a computer model to see how Olympus might have formed.
What they found is that a bed of clay sediments would have been needed to reduce friction as the lava spread out, creating the lopsided shield. And those clays needed water to form.
—Image courtesy NASA
Evidence for water-requiring minerals on Mars is kinda old news at this point. But the new study is making waves because it also offers the tantalizing hint that liquid water—a key ingredient for life—could still be lurking underneath the massive volcano.
“This deep reservoir, warmed by geothermal gradients and magmatic heat and protected from adverse surface conditions, would be a favored environment for the development and maintenance of thermophilic organisms,” the study authors conclude in last month’s issue of the journal Geology.
In other words, if there’s still heat under the mountain’s skirts, Martian life could be hiding in its belly.