Venus may have been habitable

Dramatic changes happened 700 million years ago

VENUS may have had a stable climate for billions of years.

NEAR-GLOBAL resurfacing made it the hellish hot-house of today.

Washington, Sept 23: Venus may have hosted liquid water for 2-3 billion years, until a dramatic transformation starting over 700 million years ago resurfaced around 80 per cent of the planet, according to a NASA study. The research gives a new view of Venus’s climatic history and may have implications for the habitability of exoplanets in similar orbits.

Forty years ago, NASA's Pioneer Venus mission found tantalising hints that Earth’s ‘twisted sister’ planet may once have had a shallow ocean's worth of water.

To see if Venus might ever have had a stable climate capable of supporting liquid water, researchers from NASA Goddard Institute for Space Studies (GISS) in the US created a series of five simulations assuming different levels of water coverage.

In all five scenarios, they found that Venus was able to maintain stable temperatures between a maximum of about 50 degrees Celsius and a minimum of about 20 degrees Celsius for around three billion years.

A temperate climate might even have been maintained on Venus today had there not been a series of events that caused a release, or 'outgassing', of carbon dioxide stored in the rocks of the planet about 700-750 million years ago. “Our hypothesis is that Venus may have had a stable climate for billions of years. 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,” said Way.