Venus once had a habitable atmosphere

Venus
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Venus may have been habitable 700m years ago, could this be promising for Venus-like planets in other solar systems?

New research has suggested that Venus may have been habitable over 700m years ago, before a resurfacing changing 80% of the planet’s surface. This may have implications for the habitability of other similar exoplanets.

The study presented at the EPSC-DPS Joint Meeting 2019 by Dr Michael Way of The Goddard Institute for Space Science offered an insight into Venus’ climatic history. Around forty years ago, NASA discovered that Venus may have once had a shallow ocean.

Researchers, Dr Michael Way and Anthony Del Genio, began their study by creating five simulations assuming different levels of water coverage on Venus.

In each of the simulations, the researchers found that Venus was able to sustain stable temperatures. In each scenario, the temperatures didn’t exceed 50°C, nor did they drop bellow 20°C for 3bn year of the simulation.

This temperature stability could have been maintained on the Venus in our solar system, had it not been for a series of unfortunate circumstances. The events cause a release, or ‘outgasses’, of carbon dioxide stores in the rocks on Venus around 700m years ago.

“Something happened on Venus where a huge amount of gas was released into the atmosphere and couldn’t be re-absorbed by the rocks. On Earth we have some examples of large-scale outgassing, for instance the creation of the Siberian Traps 500 million years ago which is linked to a mass extinction, but nothing on this scale. It completely transformed Venus,” said Way.

“Our hypothesis is that 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 thehellishhot-house we see today,” said Way.

Three of the five simulations assumed the topography of Venus as it exists today and considered an ocean averaging around 310m deep, a shallow layer of water averaging around 10m in addition to a small amount of water locked into the soil. Dr Way and Del Genio compared this with a scenario where Venus’ topography is similar to that of earth.

“Venus currently has almost twice the solar radiation that we have at Earth. However, in all the scenarios we have modelled, we have found that Venus could still support surface temperatures amenable for liquid water,” said Way.

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