New evidence finds Mars may have had conditions that could have supported life

A new study led by a University of Calgary scientist has found evidence that suggests Mars once had a carbon cycle, giving further support for the past habitability of the red planet.

Using data collected from the Mars rover Curiosity, a team of scientists found an iron carbonate mineral called siderite in the planet's Gale Crater.

It's believed that this mineral formed through the process of water evaporating, and then being deposited in pores on the Martian surface. 

These findings around the sequestration of CO2 suggest that 3½ billion years ago, Mars had a very thick atmosphere and flowing water, making it a habitable environment.

The finding of sederite was surprising, the scientists said, particularly because orbital measurements taken by satellites hadn't been able to detect any siderite.

"[The samples] contain CO2, which we've been predicting for decades that should be there, but they weren't necessarily forthcoming in most of the missions to date," said Ben Tutolo, the paper's lead author and an associate professor at the University of Calgary's faculty of science.

Earlier orbital data had found magnesium sulfates, Tutolo said, more commonly known as epsom salts here on Earth.

"Then when we get there on the ground with the drill, we find that it contains more siderite than any deposit that's ever really been investigated on Mars," Tutolo said. "So that's a surprise, right?

"And then we have to go back: Did all of those [scientists] that were doing all this very careful work, looking at this data, miss something?"

The answer was no: It was simply that the siderite was masked by the magnesium sulfate salts.

These new findings are a testament to the value of the Curiosity rover, said Chris Herd, a planetary geologist and professor at the University of Calgary who was not involved in the study. Since landing in 2012, the car-sized has travelled more than 33 kilometres across the red planet's surface, collecting rock, soil and air samples.

"The rover has been going for over 12 years now and still going strong," he said. 

"It's a testament to the team itself, to the science team, that they're able to continue to get such great data. And not just get the data, but actually make use of it, interpreting it in a very meaningful way."

Though conditions were right for a habitable environment on Mars, it doesn't mean it was steadily habitable.