Planet Venus may have been habitable for billions of years, says Nasa

Venus may have been warm and wet for billions of years, long enough for life to become established

The planet Venus may have been habitable for billions of years, Nasa scientists have calculated.

New computer models of the climate history of the second planet from the Sun, show that until around 700 million years ago temperatures ranged from 68F (20C) to 122F (50C), cool enough for liquid water.

In the 1980s, Nasa’s Pioneer Venus mission found hints that the planet once had a shallow ocean, but because it receives far more sunlight than Earth, scientists believed it had quickly evaporated before life could become established.

In the late 1950s and early 1960s, many thought that America’s next space project would be the establishment of a crewed space station. It was believed at the time, that space flights to other destinations would originate from this station. Langley researchers worked with Goodyear Aircraft Corporation on a 24-foot diameter inflatable ring or torus. Langley built several models of this configuration, including a full-sized version that was displayed for a December 1961 visit by then NASA Administrator James Webb

With no water left on the surface, carbon dioxide rose in the atmosphere, triggering a runaway greenhouse effect that created current conditions.

Today Venus has a crushing carbon dioxide atmosphere 90 times as thick as Earth’s and temperatures at the surface reach 864 degrees Fahrenheit (462C), making life impossible.

But new computer modelling by Nasa Goddard Institute for Space Science suggests that the ocean may have lasted for two to three billion years.

Not only does it suggest that life could have once evolved on Venus, but it opens up new possibilities about where aliens may exist outside of our Solar System.

“Our hypothesis is that Venus may have had a stable climate for billions of years,” said lead researcher Dr Michael Way.

After intense public support and interest in NASA's space program after the moon landing, NASA had proposed a "space station" that could house people living and working in space. In 1969, the Space Base concept (artist's conception shown here) was born. The Marshall-McDonnel Douglas approach envisioned the use of two common modules as the core configuration of a 12-man space station. But, in order to keep costs down, NASA would need to develop a reusable vehicle to go between Earth and the space station. This vehicle would become toe Space Shuttle. 

 “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.”

At around 4.2 billion years ago, soon after its formation, Venus would have completed a period of rapid cooling and its atmosphere would have been dominated by carbon-dioxide. 

Today the surface of Venus is too hot for life

If the planet evolved in an Earth-like way over the next 3 billion years, the carbon dioxide would have been drawn down by rocks and locked into the surface.

By around 715 million years ago, the 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 possibility is that large amounts of magma bubbled up, releasing carbon dioxide from molten rocks into the atmosphere. 

The magma solidified before reaching the surface and this created a barrier that meant that the gas could not be reabsorbed, causing runaway global warming.  

Images taken by Nasa's Pioneer mission hinted that Venus once had an ocean

Most researchers believe that Venus is beyond the inner boundary of our Solar System’s habitable zone and is too close to the Sun to support liquid water. But the new study suggests that this might not be the case.

“Venus currently has almost twice the solar radiation that we have at Earth. However, in all the scenarios we have modelled, we have found that Venus could still support surface temperatures amenable for liquid water,” said Dr Way.