A funnel-shaped depression on
Mars could be a new place to look for signs of life on the Red Planet, a study
The depression was probably formed by a volcano beneath a glacier and could
have been a warm, chemical-rich environment well suited for microbial life.
“We were drawn to this site because it looked like it could host some of
the key ingredients for habitability — water, heat and nutrients,” said
lead author Joseph Levy from University of Texas at Austin.
The depression is inside a crater perched on the rim of the Hellas basin on
Mars and surrounded by ancient glacial deposits.
It first caught Levy’s attention in 2009, when he noticed crack-like features
on pictures of depressions taken by the Mars Reconnaissance Orbiter that looked
similar to “ice cauldrons” on Earth, formations found in Iceland and
Greenland made by volcanos erupting under an ice sheet.
“These landforms caught our eye because they’re weird looking. They’re
concentrically fractured so they look like a bulls-eye. That can be a very
diagnostic pattern you see in Earth materials,” said Levy, who was a
postdoctoral researcher at Portland State University when he first saw the
photos of the depressions.
But it was not until this year that he and his research team were able to more
thoroughly analyse 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.
“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 said.
The analysis, published in Icarus, the International Journal of Solar System
Studies, revealed that both depressions shared an unusual funnel shape, with a
broad perimeter that gradually narrowed with depth.
After testing formation scenarios for the two depressions, researchers found
that they probably formed in different ways.
The Hellas depression and, to a lesser extent, the Galaxias Fossae depression,
should be kept in mind when looking for habitats on Mars, Levy said.