A cold and wet Mars could have harbored an ocean in the northern part of the Red Planet three billion years ago, a new study finds.
New 3D climate simulations of the planet’s ancient atmosphere and water suggest that a liquid ocean once existed in the basin of the northern lowlands of mars. This ocean potentially persisted even when average global surface temperatures were below the freezing point of water, the peer-reviewed work suggests.
Although present-day Mars is cold and dry, decades of evidence suggest that the ancient surface was covered with rivers, streams, ponds and lakes. Since water on Earth usually points to life, these old signs of water raise the possibility that the Red Planet was once home to life, and could still harbor it.
Earth and Mars potentially had similar climates about three billion years ago, when life was spreading on our planet. However, scientists debate whether Mars was warm enough to support an ocean of water, a question that could strongly influence whether the Red Planet was habitable enough to support life.
In fact, NASA’s Perseverance rover mission is one of many sent to Mars to assess the planet’s suitability for hosting ancient life.
The new findings in the Proceedings of the National Academy of Sciences, published on January 17, 2022, contradict previous research that suggested Mars could not have harbored such an ocean three billion years ago.
Relatively few branching river valleys date to that time on Mars, for example, suggesting a lack of widespread, heavy precipitation expected from a hot, humid climate.
But not all the evidence points to a dry world; other evidence from contemporary tsunami debris argues against a Martian climate that was too cold and dry for an ocean.
The new study suggests that a liquid northern ocean was possible because ocean circulation patterns may have warmed the surface of that region by as much as 40.1 degrees Fahrenheit (4.5 degrees Celsius), well above the freezing point of water.
There was also potentially more water in ample supply. The northern ocean could have experienced moderate rainfall within it, as well as near its shores. Another potential source was glaciers flowing from the southern highlands of the Red Planet, which harbored ice sheets.
An ocean-friendly Martian atmosphere looks a bit like the carbon dioxide-filled version we see today, but with a twist: About 10% of the atmosphere was made up of 10% hydrogen gas, which could be released. by volcanoes, cosmic impacts or chemical interactions. between the water and the rock.
This combination of carbon dioxide and hydrogen atmosphere could have trapped enough heat from the Sun to keep surface temperatures warm enough for a liquid water ocean, the study suggests.
But nevertheless, it remains uncertain whether this ocean could have supported life. “We are only studying the conditions in which life could appear,” told Space.com the lead author of the study, Frédéric Schmidt, a planetary scientist at the University of Paris-Saclay.
“A large body of long-stable stagnant water is important, probably necessary, but perhaps not enough for life to appear,” he added.
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Eddie is an Australian news reporter with over 9 years in the industry and has published on Forbes and tech crunch.