Mars Gullies Mystery Solved: Gullies Not Carved By Flowing Water, NASA Study Finds

Gullies that sit on the surface of Mars are similar to gullies found on the exterior parts of the Earth. The gullies found on Earth are carved out by flowing water. A new look was taken at the Red Planet — what were the findings? There was no evidence of water being the cause of gullies found on the surface of Mars.

In NASA’s Mars Reconnaissance Orbiter (MRO), the gullies on Mars appear to light up in shades of pastel purple, green, blue, and pink. These gullies streak across Mars’ surface like veins in the human body. These colors are detailing a chemical composition of a region of gullies, according to the website SPACE.

NASA issued a statement that the 100 gully sites provide no evidence of “abundant liquid water or its byproducts.” Formerly, many scientists theorized the gullies form in the same fashion to gullies on Earth. Scientist have managed to piece together a few clues in an attempt to figure out how these gullies were formed. Once this mystery is solved, scientists can then learn more about the geologic activity on Mars.

These Martian gullies are a “widespread and common feature” on Mars. The features usually appear in both hemispheres, and generally occur “on slopes that face toward the poles,” according to the NASA statement.

Observations have been done by MRO’s powerful High Resolution Imaging Science Experiment (HiRISE) camera which show the seasonal activity in gullies. Jorge Núñez of the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, and lead author of the new study discusses the behavior of gullies in a statement.

The fact that there are seasonal variations in the surface of Mars (made by gullies), suggest these changes are associated with the ups and downs in temperature (such as melting water or freezing water). SPACE gives an example of dark streaks on the slopes of some Martian hills are caused by the flow of very salty water. These Martian hillsides are known as a recurring slope line (RSL).

Now, Mars’ gullies are different from the RSL-type gullies. Previously, researchers and scientists thought liquid water may be the cause of the gullies forming. Núñez notes the “main mechanism” researchers suspected was the freezing and subsequent thawing of carbon dioxide frost. Evidence of the cause of Martian gullies have been studied more and more in the recent years. Two studies done in 2010 and 2014 have built strong cases against liquid water being the cause of Martian gullies.

gullies on mars

Scientist were not 100 percent certain which mechanism caused the gullies on Mars, so researchers took a deeper look into the minerals present within the gullies. In a statement, Núñez discusses the various minerals present in Mars’ gullies.

“On Earth and on Mars, we know that the presence of phyllosilicates — clays — or other hydrated minerals indicates formation in liquid water.”

Since different chemical elements absorb light in different ways, you can in fact read light coming from an object to see the different elements presented within it. To do this, you must use an instrument called a spectrometer. So, NASA scientists aimed an instrument called a Compact Reconnaissance Imaging Spectrometer for Mars (or, CRISM) at the gullies.

“In our study, we found no evidence for clays or other hydrated minerals in most of the gullies we studied…rather than altered in more recent flowing water.”

Núñez mentioned the clays they did see seemed to be ancient deposits which were exposed during the formation of the gullies.

“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.”

[Photos by NASA/ESA/Getty Images]