Simulations Suggest Venus may have once been able to Support Life

Venus approaches the Sun in a 2012 transit visible from Earth. Credit: NASA

A team of researchers with NASA, Uppsala University, Columbia University and the Planetary Science Institute has created several simulations of conditions on Venus billions of years ago using Earth climate models and has found some instances that suggest the planet may at one time have been capable of harboring life.

Venus is extraordinarily hot, volcanically active and has an atmosphere that is mostly carbon dioxide. But the simulations created by the research team suggest it may not have always been that way. They started with the idea that Venus and Earth were probably similar billions of years ago—a time when Earth’s atmosphere was also mostly carbon dioxide. From there, they created 4 possible scenarios for the future of Venus based on climate models developed for studying the history of Earth’s climate. The models differed only slightly, with variances in energy received from the sun, or the length of days. They also considered conditions with shallow oceans. They let the models run, creating simulations of the planet as it evolved for approximately 2 billion years.

The team found that one simulation resulted in a planet with temperatures low enough to support life—one with clouds and sometimes snowfall—and it persisted until 715 million years ago—a period during which life was already present on Earth.

Venus is the closest planet in size to Earth – the difference in diameter is only 403 miles (650 km). It’s often described as Earth’s sister planet.

But if such simulations are accurate, what caused the conditions that exist today? The simulations did not advance that far, but the researchers note that the speed at which the planet spun on its axis might have had something to do with it—they noted that speeding up the rotation slightly resulted in rapidly rising temperatures as weather patterns that tended to keep the planet cool were disrupted. Today, it takes 243 Earth days for Venus to spin just once, which is actually longer than the amount of time it takes to circle the sun—225 days. arxiv.org/abs/1608.00706 http://phys.org/news/2016-08-simulations-venus-life.html