Space

Ancient Mars may not have been "warm and wet" but covered in ice

Ancient Mars may not have been...
The Devon Ice Cap in Canada, which, according to the researchers on the new study, is what ancient Mars may have looked like
The Devon Ice Cap in Canada, which, according to the researchers on the new study, is what ancient Mars may have looked like
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The Devon Ice Cap in Canada, which, according to the researchers on the new study, is what ancient Mars may have looked like
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The Devon Ice Cap in Canada, which, according to the researchers on the new study, is what ancient Mars may have looked like
The top half of this image shows the Maumee valleys on Mars, while the bottom half shows glacial channels on Devon Island, Canada – similarities between the two led researchers to the conclusion that much of ancient Mars' water was glacial run-off
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The top half of this image shows the Maumee valleys on Mars, while the bottom half shows glacial channels on Devon Island, Canada – similarities between the two led researchers to the conclusion that much of ancient Mars' water was glacial run-off

Modern Mars is a barren world, drier than any desert on Earth. But geological evidence shows that this wasn’t always the case – in the distant past the Red Planet had flowing water. It’s long been thought that ancient Mars was warm and wet, but a new study has found evidence that it was instead covered in ice sheets, and much of its water was glacier run-off.

There’s no shortage of evidence that Mars was once much wetter than it is today. Between orbiters in the sky and rovers on the ground, we’ve seen signs of ancient oceans, shorelines, lakes, rivers and flood plains.

All of this has led scientists to hypothesize that Mars used to be far more Earth-like, with a warm, temperate climate and regular rainfall. But now a new study, from researchers at the University of British Columbia, has found that this story doesn’t account for all of the structures seen.

“For the last 40 years, since Mars’s valleys were first discovered, the assumption was that rivers once flowed on Mars, eroding and originating all of these valleys,” says Anna Grau Galofre, lead author of the study. “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.”

To investigate, the researchers used an algorithm that studies the shape of valleys and figures out the erosion process that most likely created them. The team put this algorithm to work analyzing over 10,000 Martian valleys.

The researchers found that only a fraction of the valley networks studied match the patterns expected of surface water erosion. Instead, many of the others resembled run-off channels that form underneath glaciers, as meltwater drains away.

The top half of this image shows the Maumee valleys on Mars, while the bottom half shows glacial channels on Devon Island, Canada – similarities between the two led researchers to the conclusion that much of ancient Mars' water was glacial run-off
The top half of this image shows the Maumee valleys on Mars, while the bottom half shows glacial channels on Devon Island, Canada – similarities between the two led researchers to the conclusion that much of ancient Mars' water was glacial run-off

This scenario also helps plug a major plot hole in the previous warm-and-wet hypothesis. At the time these channels formed – around 3.8 billion years ago – the Sun was much quieter, and Mars’ climate should have been very cold.

“Climate modeling predicts that Mars’ ancient climate was much cooler during the time of valley network formation,” says Grau Galofre. “We tried to put everything together and bring up a hypothesis that hadn’t really been considered: that channels and valleys networks can form under ice sheets, as part of the drainage system that forms naturally under an ice sheet when there’s water accumulated at the base.”

The idea that Mars was mostly icy and not a warm paradise might seem to pour cold water (so to speak) on the chances of ancient life on the Red Planet – but the team says the opposite is true. They say the ice sheet would have stabilized the water supply, and could have protected any life from solar radiation. That’s a job our magnetic field does well, but Mars is lacking such protection.

The research was published in the journal Nature Geoscience.

Source: University of British Columbia

2 comments
Chris Coles
Single thought immediately coming to mind . . . if Mars was so cold as to have it's entire surface covered in ice; then how does the ice melt to form rivers? Yes I do understand the implications of glacial melt from the base of the glacier, but they already state that there is evidence of more than glacial melt channels. Then again, having viewed many images of the surface, to me at is still, entirely, a frozen surface, but now covered in dust. So we can imagine that the ice has been under the influence of what is a very familiar process; freeze drying; where ice in a low pressure and temperature environment evaporates; dries out leaving the dusty surface from inclusions in the original ice surface. So the new research seems very logical to me; which also means we may never find any evidence of fossils from anything living on the surface. That does not preclude the potential for life within the structure creating the methane emissions being recorded. Roll on the arrival of Perseverance.
Worzel
Given that our planet emerged from its ''Snowball Earth'' event 600 million years ago, it would seem logical that if Mars had any water on its surface, given its distance from the sun, it would also be a snowball.
So any fantasies that Mars was ''warm and wet'' must be just that, combined with a good helping of wishful thinking.
Seems that its in the same class of fantasy that suggested that comets were 'slushy snowballs'!
When the Earth was a snowball, then Mars must have been cold enough so that even its CO2 atmosphere was solid. Maybe the 'glaciers' were frozen CO2?