The crater is perched on the rim of the Hellas basin, in the southern hemisphere of the Red Planet, and was probably formed by a volcano beneath a glacier. It could have been a warm, chemical-rich environment well suited for microbial life, says Joseph Levy, a researcher at the University of Texas say.
“These landforms caught our eye because they’re weird-looking. They’re concentrically fractured so they look like a bull’s eye. We were drawn to this site because it looked like it could host some of the key ingredients for habitability – water, heat and nutrients.”
It first caught the researchers’ attention in photos taken by the Mars Reconnaissance Orbiter, thanks to its similarity to ‘ice cauldrons’– formations made by volcanoes erupting beneath an ice sheet – found in Iceland. They then used pairs of high-resolution images to create detailed 3D models of the depressions that enabled in-depth analysis of their shape and structure.
“The big contribution of the study was that we were able to measure not just their shape and appearance, but also how much material was lost to form the depressions. That 3D view lets us test this idea of volcanic or impact,” Levy said.
The analysis revealed the crater has an unusual funnel shape, and features a fracture pattern that suggests the ice has been melted away by volcanic activity. It also lacks the surrounding debris that would have been left by an asteroid impact. This means it may once have been host to liquid water and nutrients – elements thought to be required for the existence of life.