A recently-discovered depression on the surface of Mars could be conducive to the existence of microbial life, making it a good target for future habitability research, scientists at the University of Texas at Austin and their colleagues reported in this month issue of the journal Icarus.
“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 UT Institute for Geophysics explained in a statement. Described as an oddly-shaped depression, the location was likely formed by a sub-glacial volcano, Levy and his colleagues noted.
The depression is located inside a crater on the edge of the Hellas basin region of the Red Planet and may have contained the right chemicals and the right amount of warmth to be well suited for the development of microbes, they explained. Surrounded by ancient glacial deposits, this region was found by Levy while he studied images from the Mars Reconnaissance Orbiter in 2009.
During his analysis, the UT researcher noticed crack-like features similar to “ice cauldrons” on Earth. These “ice cauldrons,” the authors explained, formed in Greenland and Iceland following the eruption of volcanoes located beneath ice sheets. The features are “concentrically fractured” and their appearances resemble “a bulls-eye,” Levy said in a statement.
Could This Depression Contain Life?
Levy was a postdoctoral researcher at Portland State University when he first saw the photos, and it wasn’t until this year that he and his new colleagues at UT were able to take a closer look at the Hellas depression using stereoscopic images to investigate whether or not it was actually the result of sub-glacial volcanic activity, or were created by an asteroid impact.
They used high-resolution images to create digital elevation models of the depression, as well as a second, similar one in the Galaxias Fossae region of Mars. This made it possible to measure the shape and appearance of the depressions in 3D, which also allowed them to determine how much material was lost to form the depression. They discovered that the depressions possessed strange funnel-like shapes that were wide at the perimeter, but narrowed as they deepened.
“That surprised us,” Levy said, “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. 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.”
He and his colleagues tested multiple scenarios and found evidence that while the debris that surrounds the Galaxias Fossae depression suggests that it was caused by an impact, the Hellas depression may have been the result of volcanic origin. In fact, Levy said, the absence of debris surrounding it and its fracture pattern is consistent with the removal of ice through sublimation or melting – which could create an environment with liquid water and the chemicals needed for the formation of simple biological organisms.
Image credit: Sigurðsson/Icelandic Meteorological Office