According to NASA, Venus could have contributed to life billions of years ago

Today, Venus and Earth have little in common, except for being of the same size and orbiting the same star. Venus has an atmospheric pressure and a surface temperature high enough to melt the lead. However, Venus could have been more similar to Earth in the past. New simulations from NASA's Goddard Institute for Space Studies show how this change could have happened.

Venus is potentially in the habitable zone of the sun (opinions differ), so could have liquid water on the surface. This is not the case. Scientists speculated that Venus's water would have evaporated as it warmed through an uncontrolled greenhouse effect. The current surface temperature is above 450 degrees Celsius (700 degrees Fahrenheit) and the atmospheric pressure is almost 100 times higher than the Earth's. The surface of the planet is obscured by clouds of sulfuric acid rather than by water vapor. Even robotic undercarriages do not last long under these conditions, and life as we know it has no chance.

Michael Way and Anthony Del Genio of Goddard produced five simulations of Venus, all of which show that the planet could be habitable for 2 to 3 billion years. This has changed from about 700 to 750 million years ago. At that time, massive resurfacing released huge amounts of carbon dioxide that was previously blocked below the surface. Three of the scenarios assumed that the ancient Venus had a topographic map similar to the one we see today, including an ocean of 310 meters deep water and another deeper 10 meters deep. The pair also performed a simulation with the topography of the Earth and an ocean of 310 meters and a version of Venus with a stretch of water of 158 meters covering the entire surface.

The surface of Venus captured by a Soviet probe Venera.

According to the simulations, Venus should have been able to accommodate liquid water and therefore life. From what we know of the Earth, the first Venus would have had high levels of carbon dioxide that gradually became enclosed in silicate rocks. The simulations indicate temperatures ranging from 20 to 50 degrees Celsius (68 to 18 degrees Fahrenheit). To get to its current state, something had to change on Venus about 700 million years ago. Way and Del Genio assume that large flows of magma released carbon dioxide from the silicates, but cooled down before reaching the surface. This could have created a barrier preventing reabsorption of the gas.

We need more data on Venus to know the accuracy of these models. It is possible for the planet to cool rapidly and, like the Earth, condensed water very early. However, it is possible that larger amounts of carbon dioxide have been released into the atmosphere for billions of years, preventing it from harboring water even before the major resurfacing event. Scientists may need to develop a more robust breed of robots that can spend more than a few minutes on the infernal surface of the planet.

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