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Could anything have ever lived on Venus?

By Elizabeth Rayne
NASA image of volcano on Venus

There is no amount of sunblock or air conditioning that could keep Earth creatures alive on Venus (even spacecraft have had a tough time with that), but could it be possible that this hostile planet ironically named for the Greco-Roman goddess of love was once livable for some kind of life-form?

Earth’s “twisted sister,” as Venus is sometimes called, might have had air very similar to what we breathe billions of years ago. Michael Way of NASA’s Goddard Institute for Space Studies believes the Venusian atmosphere once made the planet habitable. Way recently presented a study at this year’s EPSC-DPS Joint Meeting that suggests something could have been crawling around Venus before it literally became too hot to handle.

“Venus may have had a stable climate for billions of years,” Way told the EuroPlanet society. “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.”

Way and colleague Anthony Del Genio virtually went back in time by creating a series of simulations that supported evidence from NASA’s 1978 Pioneer Venus mission that hinted at Venus once having had liquid water on the surface. Every simulation the scientists ran showed the planet should have been able to stay at temperatures that were low enough for liquid water to exist, and that there there must have even about three billion years of stable temperatures.

Backtrack to when Venus first came into being about 4.2 billion years ago. Venus is thought to have cooled rapidly, with an atmosphere that was mostly carbon dioxide. If it evolved like Earth, silicate rocks would have drawn it downwards and locked it into the surface. Its atmosphere would have been extremely similar to Earth’s — nitrogen-dominant with traces of CO2 and methane. It would have stayed that way if there wasn’t a major disruption 750 million years ago.

What exactly happened to turn the heat up is unclear, but Way is convinced it was a massive outgassing (release) of CO2.

“Something happened on Venus where a huge amount of gas was released into the atmosphere and couldn’t be re-absorbed by the rocks,” he said. “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.”

We can’t collect samples from Venus (yet), but until we can, Way and Del Geno believe that it is highly possible liquid magma erupted from volcanoes like Sapas Mons (pictured above) and cooled too rapidly to reabsorb the gas, which then accumulated in the atmosphere and triggered a greenhouse effect. We still need to find out how Venus shot up to an average temp of 462 degrees, how fast it cooled after formation, whether liquid water could even condense on its surface, and if it was just one event that changed it forever.

Way and Del Geno’s study “opens up all kinds of implications for exoplanets found in what is called the ‘Venus Zone’, which may in fact host liquid water and temperate climates,” as they said

Does this mean aliens? Fossilized aliens? It depends on whether you’re considering Earth standards for life or imagining a totally different type of biology, but future missions to Venus could give us more insight.

(via the EuroPlanet Society)