UBC researchers have concluded that early Martian landscape probably looked similar to this image of ... [+]
Was the “red planet” once the “white planet?”
It’s known that the southern highlands of Mars are dissected by hundreds of valley networks, which were thought to be evidence that flowing water once sculpted the Martian surface.
There were rivers on Mars?
Probably not. New research published in Nature Geoscience suggests that most of the valleys were caused not by flowing water, but by water melting beneath glaciers.
Given what scientists know about early Mars, this makes a lot more sense than the Martian surface hosting liquid water rivers.
It may even increase the chances for ancient life on Mars.
What was ancient Mars like?
Climate simulations suggest that ancient Mars was cold and icy. After all, Mars is further away from the sun than Earth, and when its surface was forming 3.8 billion years, the Sun was less intense. Through that lens, liquid water running amok across its surface—as rivers, rainfall and oceans—does seem hopeful.
So is the “warm and wet” theory of ancient Mars as dead as the planet is today?
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Was early Mars a world of ice sheets rather than rivers?
“For the last 40 years, since Mars’ valleys were first discovered, the assumption was that rivers once flowed on Mars, eroding and originating all of these valleys,” said Anna Grau Galofre, a SESE Exploration Post-doctoral Fellow at Arizona State University and a former PhD student at the University of British Columbia (UBC).
“But there are hundreds of valleys on Mars, and they look very different from each other.”
Examining 10,000 of Martian valleys, Grau Galofre and her co-authors compared the Martian valleys to the subglacial channels in the Canadian Arctic archipelago.
The similarities were striking.
Collage showing Mars's Maumee valleys (left half) superimposed with channels on Devon Island in ... [+]
Earth and Mars from above
“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,” said Grau Galofre. “Mars is similar, in that valleys look very different from each other, suggesting that many processes were at play to carve them.”
However, she thinks that the dominant mechanisms are linked to water melting beneath glaciers, not rivers.
The case of Devon Island
The motivation behind the study came from the similarity between valleys on Mars and the subglacial channels on Devon Island in Baffin Bay in the Canadian Arctic.
It’s the largest uninhabited island in the world.
“Devon Island is one of the best analogues we have for Mars here on Earth—it is a cold, dry, polar desert, and the glaciation is largely cold-based,” said co-author Gordon Osinski, professor in Western University’s department of earth sciences and Institute for Earth and Space Exploration.
An aerial view of the CCGS Amundsen, a Canadian reasearch ice-breaker navigating near an ice floe ... [+]
Is the ‘warm and wet’ hypothesis dead?
This research provides the first-ever evidence for meltwater drainage beneath an ancient ice sheet on Mars.
“The findings demonstrate that only a fraction of valley networks match patterns typical of surface water erosion, which is in marked contrast to the conventional view,” said co-author Mark Jellinek, professor in UBC's department of earth, ocean and atmospheric sciences. “Using the geomorphology of Mars’ surface to rigorously reconstruct the character and evolution of the planet in a statistically meaningful way is, frankly, revolutionary.”
Geomorphology is the study of landforms and how they evolved.
“Climate modelling predicts that Mars’ ancient climate was much cooler during the time of valley network formation,” said 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.”
What does this mean for the possibility of ancient life on Mars?
Ice rather than liquid water means less chance of ancient life, right?
Not so, say the researchers, who point out that a sheet of ice would mean a stable body of water that was protected from solar radiation. In short, such pools of water under glaciers could possibly have hosted ancient life.
As well as uncovering more about ancient Mars, it’s thought that the analytical tools developed for this research could be used to help reconstruct the history of glaciation on Earth. Currently researchers can look back to a maximum of five million years; these new tools could extend that to at least 35 million years ago.
Wishing you clear skies and wide eyes.
#News | https://sciencespies.com/news/was-mars-once-the-white-planet-ice-sheets-not-rivers-created-martian-valleys-say-scientists/
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