Early Mars was covered in ice rather than warm, free-flowing rivers, new study shows

Mars may have been icier and colder than previously thought, a new study suggests.

Researchers analyzed more than 10,000 Martian valleys and found that most on Mars’ surface were carved by water melting beneath glacial ice sheets, rather than free-flowing rivers.

The joint study was conducted by Western University and the University of British Columbia and was published in the scientific journal Nature Geoscience on Monday.

The study’s findings go against earlier research, which suggested rivers, rainfall and oceans once existed on Mars and drew theories that the red planet may at one point have vaguely resembled Earth.

“For the last 40 years, since Mars’ valleys were first discovered, the assumption was that rivers once flowed on Mars, eroding and forming all of these valleys,” said Anna Grau Galofre, lead author of the study and former PhD student in UBC’s Department of Earth, Ocean and Atmospheric Sciences in a release.

“But there are hundreds of valleys on Mars and they look very different from each other. If you look at Earth from a satellite you see a lot of valleys: some of them made by rivers, some made by glaciers, some made by other processes, and each type has a distinctive shape. Mars is similar, in that valleys look very different from each other, suggesting that many processes were at play to carve them.”

Gordon Osinski, director of Western’s Institute for Earth and Space Exploration, said similarities between Devon Island’s “finger-like” subglacial channels located in the Canadian Arctic and Mars’ many Martian valleys motivated the study.

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At first glance, Devon Islands appears to have a river network with tributaries downstream and channels that grow larger and clearer, he said. But at a more in-depth level, Osinski said there is no evidence of streams — similar to Mars.

According to the study, these sheets of ice would have better protected the red planet from solar radiation while keeping the planet’s supply of underlying water stable — which spells good news for those still hoping to find life on Mars.

“On Earth, we know that life flows in these extreme environments underneath glaciers,” said Osinski.

A colder, icier Mars also provides an answer to a key question of how the planet’s valleys formed 3.8 billion years ago, despite the sun being weaker and Mars being at a greater distance from the sun than Earth.

Osinski said the study’s findings implicated a possibility that life on the red planet was formed differently than it was on Earth — with warmth and sunlight — but rather through meteorite impacts which created a “hot springs” effect, allowing life to survive in cold conditions.

“We need to think about Mars in a different way,” he said.