Iron-rich rocks from Minnesota could hold key to explaining liquid water on Mars

Scientists have been thinking a lot about the history of water on Mars and whether the fourth rock from the sun was ever habitable.

There are many signs of liquid water on its surface but for some reason, it all dried up 3.5 billion years ago.

Mars is known as the red planet and that’s because its surface contains a lot of iron.

Benjamin Tutolo is an associate professor at the University of Calgary who is looking at rocks on Earth with a similar iron content.

"It turns out, you can't just go to your normal rocks here on Earth," he said.

"You have to go to very special places, like this 1.1-billion-year-old Duluth Complex in Minnesota, which is a very iron-rich igneous intrusion, so lava flows or magma has been placed into the earth that crystallized over geologic time about a billion years ago."

When these iron-rich rocks come in contact with water, they undergo a chemical reaction called serpentinization, producing unique minerals and hydrogen.

"Whenever hydrogen gas is in tandem with other greenhouse gases like carbon dioxide, it can be a very potent greenhouse gas and a very effective way of warming early Mars," said Tutolo.

Tutolo and his co-author, Dr. Nicholas Tosca from the University of Cambridge, discovered the serpentinization process in the ancient iron-rich rocks from Minnesota generated around five times more hydrogen than regular Earth rocks and that could have helped create habitable conditions under similar conditions on Mars.

"So there was carbon dioxide (on Mars), potentially making the planet a little bit warm," said Tutolo.

"But really, to drive sustained warmth and to maintain habitable conditions for a long time, you need an extra kick, and that hydrogen provides an extra kick."

Their findings were published as "Observational Constraints on the Process and Products of Martian Serpentinization" by the journal Science Advances.

Mars is a smaller planet than Earth and has no tectonic plates, so all the rocks found today on its surface are the same age. Now, scientists have to figure out why the red planet cooled.

"Hydrogen is a slippery gas," said Tutolo.

"It likes to leak out into space, so the fact that it had less gravity and less magnetic field means that hydrogen just slipped out into space and the neat thing about this story is it explains why it was once warm and is now no longer warm."

For the past year, Tutolo has been part of NASA's Curiosity Rover team and takes part in regular weekly meetings.

His opinion is this is the most exciting time in the decade-long mission that the rover has been on Mars.

"As you can imagine, there are many people that work at NASA – many experts in very different parts of the system," he said.

"So I happen to be somebody that can combine expertise in understanding serpentinization reactions and also expertise in understanding the history of Mars, and so the kind of feedback I get from that is exciting, to be part of the team, because you sort of can have your feet in both ponds at the same time."

Tutolo hopes soon he'll be able to work with data collected by Curiosity on the Martian surface, so he can study the iron-rich rock samples to support his findings.