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Posted by bio_man   September 25, 2019   721 views

Here's what Venus would look with water, and without its thick CO2 atmosphere

When we think of Venus, we envision a planet that'd make a great place for hell - fiery red, extremely hot, and toxic. However, a new study makes an argument that Venus may have once been able to support life, until a mysterious resurfacing event took all that away about 700 million years ago.

According to planetary scientist Michael Way from NASA's Goddard Institute for Space Studies, Venus may have had a stable climate for billions of years.

"It is possible that the near-global resurfacing event is responsible for its transformation from an Earth-like climate to the hellish hot-house we see today."

The research – presented last week at the EPSC-DPS Joint Meeting 2019 in Geneva, Switzerland – builds upon two previously published studies by Way and his team, and related papers modelling virtualized Venus-like worlds and topographies.

The upshot, the team says, is that 3D GCM (general circulation model) supports the 'optimistic' view that Venus "spent most of its history with surface liquid water, plate tectonics, and subsequently a stable temperate climate akin to that of Earth through much of its own [history]".

This period of Earth-like climatic stability with liquid water in Venusian oceans may have lasted for up to 3 billion years, the researchers think, based on a number of simulations of what the ancient planet's climate conditions may have been like.

Across a number of hypothetical scenarios run at different points in history – contemplating both deep (310-metre deep) and shallow (10-metre deep) simulated oceans, and a water-world scenario where an imaginary ocean covered all of an 'aquaplanet' Venus – the results suggest ancient Venus could have supported liquid water, with moderate surface temperatures on the planet of 20 to 40 degrees Celsius (68 to 104 Fahrenheit).

At least, this would have been the case as far back as 4.2 billion years ago, right up until about 700 million years ago. Somewhere around that time, something happened on Venus, and ever since the planet has been incredibly hot, with a toxic, heat-trapping 'greenhouse effect' atmosphere dominated by carbon dioxide and nitrogen.

Way mentions that Venus likely inherited its extraordinarily high temperatures and atmospheric pressure due to large-scale outgassing. "Something happened on Venus where a huge amount of gas was released into the atmosphere and couldn't be re-absorbed by the rocks," Way says. "On Earth ... for instance the creation of the Siberian Traps 500 million years ago is linked to a mass extinction", but nothing on this scale of what transformed Venus.

In the researchers' version of events, an Earth-like carbonate-silicate cycle (where CO2 is naturally removed from the atmosphere by being absorbed into rocks) got interrupted on Venus, possibly by a period of intense volcanic activity, with magma solidifying on the planet's surface, suspending the cycle, and preventing the gas from being reabsorbed.

Planets Astronomy Venus Earth
Posted in Research
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