A newly discovered depression may breathe new life into the pursuit to find life on Mars.
A strangely shaped depression—likely formed by a volcano beneath a glacier—could be a warm, chemical-rich environment suited for microbial life, according to a study from the University of Texas at Austin.
“We were drawn to this site because it looked like it could host some of the key ingredients for habitability — water, heat and nutrients,” lead author Joseph Levy, a research associate at the University of Texas Institute for Geophysics, a research unit of the Jackson School of Geosciences, said in a statement.
The depression is located inside a crater perched on the rim of the Hellas basin and is surrounded by ancient glacial deposits.
The depression first came to light in 2009 when Levy noticed crack-like features on pictures of depressions taken by the Mars Reconnaissance Orbiter looked similar to ice cauldrons formations found in Iceland and Greenland, which were made by volcanos erupting under an ice sheet. Levy and others also discovered another depression in the Galaxias Fossae region of Mars that had a similar appearance.
“These landforms caught our eye because they’re weird looking,” Levy said. “They’re concentrically fractured so they look like a bulls-eye. That can be a very diagnostic pattern you see in Earth materials.”
Earlier this year, Levy and his research team were able to more thoroughly analyze the depressions using stereoscopic images to investigate whether the depressions were made by underground volcanic activity that melted away surface ice or by an impact from an asteroid.
Timothy Goudge, a postdoctoral fellow at the University of Texas- Austin, used pairs of high-resolution images to create digital elevation models of the depressions that enabled in-depth analysis of their shape and structure in 3D.
“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,” Levy added. “That 3D view lets us test this idea of volcanic or impact.”
A closer analysis showed that both depressions shared an unusual funnel shape with a broad perimeter that gradually narrowed with depth.
“That surprised us and led to a lot of thinking about whether it meant there was melting concentrated in the center that removed ice and allowed stuff to pour in from the sides,” Levy said. “Or if you had an impact crater, did you start with a much smaller crater in the past and by sublimating away ice, you’ve expanded the apparent size of the crater.”
After running formation scenarios for the two depressions, researchers concluded that the debris spread around the Galaxias Fossae depression suggests that it was the result of an impact with the possibility it could be formed by a volcano due to the volcanic history of the area. However, the Hellas depression has many signs of volcanic origins, lacks the surrounding debris of an impact and has a fracture pattern associated with concentrated removal of ice by melting or sublimation.
According to Levy, the interaction of lava and ice to form a depression would show that it could create an environment with liquid water and chemical nutrients.
The study, which was published in Icarus, the International Journal of Solar System Studies, can be viewed here.