Mars covered in ice sheets, not flowing rivers, Western study shows
The findings go against the general belief that rainfall and oceans once existed on Mars
A new study out of Western University suggests Mars may have been colder than previously thought.
The findings, published in Monday's Nature Geoscience, show ice sheets, not rivers, sculpted the surface of the red planet.
"Our study challenges the widely held view that most valley networks on Mars were formed by rivers fed by precipitation. While we found evidence consistent with a small handful of valley networks having formed in this way, our observations suggest that the majority formed beneath ice sheets," said Gordon Osinski, director of Western's Institute for Earth and Space Exploration.
The study was inspired when researchers noted the similarities between valleys on Mars and subglacial channels on Devon Island in the Canadian Arctic.
"Devon Island is one of the best analogues we have for Mars here on Earth," said Osinski, a co-author on the study. "It is a cold, dry polar desert and we know the glaciation is largely cold-based."
Research doesn't rule out signs of life
But the research doesn't necessarily mean there was never life on Mars.
Researchers said an ice sheet would have given more protection and stability, as well as providing shelter from solar radiation in the absence of a magnetic field, something Mars once had, but which disappeared billions of years ago.
Anna Grau Galofre, lead author on the study and current Postdoctoral Fellow at Arizona State University, analyzed more than 10,000 valleys on Mars.
"For the last 40 years, since Mars's valleys were first discovered, the assumption was that rivers once flowed on Mars, eroding and forming all of these valleys," said Grau Galofre.
"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."
Grau Galofre's theory also explains how valleys formed 3.8 billion years ago on Mars, during a time when the sun was less intense.
"Climate modelling predicts that Mars' ancient climate was much cooler during the time of valley network formation."