Mars Gullies Not Formed By Liquid Water, NASA Concludes

New information from NASA's Mars Reconnaissance Orbiter reveal that gullies on modern Mars were most likely not formed by flowing liquid water. The new evidence found will enable researchers to further investigate on the theories about how Martian gullies were formed, and show more details about the recent geologic processes in Mars.

The National Aeronautics and Space Administration (NASA) said that experts use the term "gully" for feature on Mars that have three characteristics in their shape: an alcove at the top, a channel, and an apron of deposited material at the bottom. Gullies are unique from another type of feature in Martian slopes, streaks known as "recurring slope lineae," or RSL which are usually identified by seasonal darkening and fading than the characteristics of how the ground is shaped.

There was water in the form of hydrated salt that had been identified at the RSL site. The new study focuses on gullies and how they were formed by adding composition information to the images that were acquired in the past.

Phys.org reported that researchers from the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland, analyzed high-resolution compositional data from over 100 gully sites around Mars. The data collected by the orbiter's Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) were later correlated with the images from the same spacecraft's High Resolution Imaging Science Experiment (HiRISE) camera and Context Camera (CTX).

Findings showed that there was no mineralogical evidence to prove the abundance of water or even its by-products. This showed the mechanisms other than the flow of water, like the freeze and thaw of carbon dioxide frost, as being the major drivers of recent gully evolution, space.com reported.

"In our study, we found no evidence for clays or other hydrated minerals in most of the gullies we studied," Jorge Núñez, lead author of the new study said. He noted that the clays they did see appeared to be ancient deposits that were exposed in the formation of the gullies, "rather than altered in more recent flowing water."

"These gullies are carving into the terrain and exposing clays that likely formed billions of years ago when liquid water was more stable on the Martian surface," he added. Meanwhile, reports said that the new study doesn't say exactly that carbon dioxide frost is the culprit in forming the gullies. However, it adds support to models that demonstrate that hypothesis.