A new NASA study based on computer based climate models has revealed that Venus was once inhabitable. In their publication in “Geophysical Research Letters”, the scientific team lead by Michael Way believe it is possible that Venus may have had a shallow liquid-water ocean and earth-like surface temperatures for up to 2 billion years of its early history.
According to way the mathematical climate models used were similar to those used for predicting Earth´s future climate. In this case the models were used to make estimations about the past rather than the future. Ancient Venus was probably very different from what it is today.
Today´s temperatures reach 462 degrees celcius (864 Fahrenheit). There is almost no water vapor and its has a carbon dioxide atmosphere 90 times thicker than Earth´s. It seems according to some scientist that Venus had a similar composition to that of Earth but for some reason followed a different evolutionary path.
Data collected from NASA´s space mission in the 80s provided some first indications that Venus may once have had an ocean. At some moment in time the water was evaporated as water-vapor molecules were broken apart by ultraviolet radiation. Without water left on the surface, carbon dioxide built up in the atmosphere creating present inhospitable conditions.
Scientists are theorising that Venus was probably the first inhabitable planet in our solar system before Earth and was inhabitable until 715 million years ago. Ancient Venus had more dry land overall than Earth, especially in the tropics but had enough water to support life.
Way and his colleagues simulated conditions of a hypothetical early Venus with an atmosphere similar to Earth’s, a day as long as Venus’ current day, and a shallow ocean consistent with early data from the Pioneer spacecraft. The researchers added information about Venus’ topography from radar measurements taken by NASA’s Magellan mission in the 1990s, and filled the lowlands with water, leaving the highlands exposed as Venusian continents. The study also factored in an ancient sun that was up to 30 percent dimmer. Even so, ancient Venus still received about 40 percent more sunlight than Earth does today.
In the simulation, Venus’ slow spin exposes its dayside to the sun for almost two months at a time,” co-author and fellow GISS scientist Anthony Del Genio said. “This warms the surface and produces rain that creates a thick layer of clouds, which acts like an umbrella to shield the surface from much of the solar heating. The result is mean climate temperatures that are actually a few degrees cooler than Earth’s today.