NASA has released a new image from NASA's Mars Reconnaissance Orbiter (MRO), the $720 million multipurpose spacecraft launched in 2005 to find evidence that water persisted on the surface of planet Mars for a long period of time.
Gullies Running Through Martian Sand Dunes
The High Resolution Imaging Science Experiment camera (HiRISE) onboard NASA's MRO captured stunning images of the Red Planet's Matara Crater featuring gullies running through sand dunes.
NASA said that these gullies have been very active with many flows over the past decade.
"In this image from NASA's Mars Reconnaissance Orbiter we see frost in and around two gullies, which have both been active before," NASA described the image. "There are no fresh flows so far this year, but HiRISE will keep watching."
Common Feature On Mars
Gullies are a common feature on the surface of the Red Planet. They often occur between 30 and 50 degrees latitude in the northern and southern hemispheres, usually on slopes facing toward the poles.
Analysis of the Martian gullies, which were published in the journal Geophysical Research Letters in 2016 suggests that unlike the gullies on Earth that are carved by liquid water, the gullies on Mars may have formed due to other mechanisms other than the flow of water.
Jorge Núñez, from the Johns Hopkins University Applied Physics Laboratory, the lead author of this study, and colleagues suspect that the gullies were formed because of the freezing and thawing of carbon dioxide frost.
"On Earth and on Mars, we know that the presence of phyllosilicates -- clays -- or other hydrated minerals indicates formation in liquid water," Núñez said. "We found no evidence for clays or other hydrated minerals in most of the gullies we studied.
How Gullies On Planet Mars Form
The Martian atmosphere is more than 95 percent carbon dioxide. Mars has seasons and during winter, the temperature condenses atmospheric carbon dioxide from gas to solid, which is then deposited into the surface in the latter form. These solid carbon dioxide blocks then form the gullies and furrows on the surface of the Red Planet.
The 2016 study did not provide conclusive proof that carbon dioxide frost is behind the formation of gullies on Mars, but it provided additional evidence to support models that demonstrate this hypothesis. It is possible that liquid water may also be the mechanism that form the gullies albeit a mounting number of evidence suggests otherwise.