A major finding on Mars could indicate that the surface of what we now know as the Red Planet may not have been red and dusty and forbidding at all, but rather a lush, blue landscape not dissimilar to Earth in many ways. Scientists using NASA’s MAVEN spacecraft have found that Mars once had a thick atmosphere, but it was stripped away gradually by radiation and solar wind, turning it from a planet that may have once had flowing liquid water and possibly even life to the massive desert that it is today.

Scientists from the University of Colorado at Boulder based that on new test results that show 65 percent of the argon that once likely existed on the planet appear to be completely gone, and many other gases that may have once existed in the Martian atmosphere probably left as well when the atmosphere did, according to the study, which was published in the journal Science.

The loss of the atmosphere meant that liquid water wouldn’t have been able to survive the thin and cold atmosphere, but we know it was once there because of riverbeds and minerals formed by water that are present on the planet’s surface. It shows that at one point in the past, Mars was a very different place, and perhaps one that could have supported life.

“We’ve determined that most of the gas ever present in the Mars atmosphere has been lost to space,” said Bruce Jakosky, principal investigator for MAVEN and a professor at the Laboratory for Atmospheric and Space Physics (LASP). “The team made this determination from the latest result, which reveals that about 65 percent of the argon that was ever in the atmosphere has been lost to space.”

“We determined that the majority of the planet’s CO2 also has been lost to space by sputtering,” said Jakosky. “There are other processes that can remove CO2, so this gives the minimum amount of CO2 that’s been lost to space.”