Debate is always on whether Mars was a wet planet a long time ago or not. Now, scientists studied data collected by Mars Reconnaissance Orbiter of NASA and found that liquid water isn’t responsible for the creation of Martian gullies.

A study on Martian gullies published in Geophysical Research Letters has shown how complex the Red Planet is. Findings have described some Martian features that may have formed in the past in ways not to similar to anything on our planet.

Researchers have a hunch that earth’s neighbor planet was different a long time ago. The prehistoric Mars had thick atmosphere that supported liquid water and clouds. There’re huge possibilities that the planet was once-inhabitable, as per some scientists. It was the planet’s past, but researchers on earth are still looking for signs that could prove that Mars was really a habitable planet. They have even found clues indicating that the Red Planet once had liquid water that flowed on the planet’s surface.

NASA’s Mars rovers—Spirit, Opportunity and Curiosity—have collected data suggesting ancient Mars had water. Curiosity, NASA’s car-sized robotic rover which has been active on the Red Planet since 2012, collected data on chemical and mineral evidence suggesting possibility of lakes in the past. The data even suggested that the planet had right chemical ingredients to support life.

But Martian gullies were also a matter of debate. Their structure suggests that flowing water has carved them, but some think dry ice is responsible for their formation. “It could be water snow or it could be CO2 snow; we just don’t know. So we felt that there could be some information that composition could provide to maybe help add a piece to the puzzle”, said Jorge Nuñez, a researcher from Johns Hopkins University Applied Physics Laboratory and lead author of the study.

A report published in Seeker revealed, "The hunt for what carved channels into polar-facing slopes on Mars -- a process that is ongoing today -- took a new twist on Friday with the release a study showing no chemical fingerprints of flowing water at more than 100 gully sites."

Nevertheless, telltale signs of water, in the form of hydrated salts, has been tied to another seasonal feature on Mars known as recurring slope lineae, or RSL. Scientists are beginning to take test images of potential RSL sites in Gale Crater with NASA's Mars rover Curiosity, project scientist Ashwin Vasavada told DNews.

In the new study, planetary scientist Jorge Nunez with Johns Hopkins University Applied Physics Laboratory, and colleagues correlated high-resolution images of more than 100 gullies taken by Mars Reconnaissance Orbiter with chemical data obtained by the spacecraft's Compact Reconnaissance Imaging Spectrometer for Mars, or CRISM, instrument.

According to a report in Astronomy by Jordan Rice, "Using data from NASA’s Mars Reconnaissance Orbiter (MRO), researchers found that Martian gullies were likely not formed by flowing liquid water like those on Earth. These findings allow researchers to narrow down the theories on how they formed in the first place and reveal more information on Mars’ geological processes."

The term “gully” is used to describe features with three distinct characteristics: a channel, deposited material at the bottom, and an alcove at the top. Gullies are different from other similar features on Martian slopes, streaks called by the researchers “recurring slope lineae” (RSL). They can be distinguished by their seasonal darkening and fading,

They are a very widespread feature on the surface of Mars and occur mostly between 30 and 50 degrees latitude in both hemispheres. Similar gullies on Earth are formed by the flow of liquid water, but currently Mars is devoid of liquid water, with occasional traces of brine in RSL streaks. This lack of water to create the gullies, as resulted in many theories to explain their creation, ranging from carbon dioxide frost to the evaporation of water.