The planet Venus today is today one of the least hospitable planets in the solar system. The second planet from the Sun features a crushing carbon dioxide atmosphere 90 times as thick as Earth’s and surface temperatures reaching 462C (864F). But now NASA has calculated Venus may have once been home to alien life for billions of years.
New NASA computer models of Venus’ climate history, show that until around 700 million years ago temperatures ranged from 20C (68F) to 50C (122F), cool enough for liquid water on the surface.
NASA Pioneer Venus mission found in the 1980s hints the planet once had a shallow ocean.
However, because it receives far more sunlight than Earth, scientists believe it had quickly evaporated before life could become established.
With no water vanishing from the surface, CO2 levels rose in the atmosphere, triggering a runaway greenhouse effect creating its current hellish conditions.
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Now the latest computer modelling by the NASA Goddard Institute for Space Science suggests the ocean on Venus may have survived for up to three billion years.
And this not only suggests life could have once evolved on Venus.
It also opens-up new possibilities about where aliens may exist outside of our Solar System.
Dr Michael Way, the NASA study’s lead researcher, said: “Our hypothesis is that Venus may have had a stable climate for billions of years.”
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“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.
“Our models show that there is a real possibility that Venus could have been habitable and radically different from the Venus we see today.
“This 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.”
Soon after its formation, at approximately 4.2 billion years ago, Venus would have completed a period of rapid cooling and carbon-dioxide would have prevailed in its atmosphere.
If Venus evolved in an Earth-like way over the next 3 billion years, the carbon dioxide would have been drawn down by rocks, locking it into the surface.
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By around 715 million years ago, its atmosphere would have been dominated by nitrogen with trace amounts of carbon dioxide and methane – similar to the Earth’s today.
And these conditions could have remained stable up until present times.
However Dr Way believes that intense volcanic activity around 700 million years ago transformed Venus.
One theory is large amounts of magma bubbled up, releasing carbon dioxide from molten rocks into the atmosphere.
The magma solidified before reaching the surface, creating a barrier that meant the gas could not be reabsorbed, triggering runaway global warming.