Venus as a water world. Image Credit: ESA
In Europe, scientists have found evidence that searing Venus may once have been a water world, perhaps suitable for life.
Their speculation is based on findings from the European Space Agency’s Venus Express, a spacecraft mission launched in November 2005 for studies of the cloud-shrouded planet’s atmosphere as well as temperature distributions on the surface.
The size and basic compositions of the Earth and Venus are quite similar. But there is one stark difference. The Earth’s oceans, if allowed to coat the entire planet, would form a layer of water nearly two miles thick. On Venus, a similar water layer would be a little more than an inch thick.
However, Venus may once have been more Earth-like. The Venus Express has confirmed the second planet from the sun has lost large quantities of water into space.
Scientists gathered in Aussois, France for a conference believe they have an explanation, according to the European Space Agency.
Ultraviolet radiation from the sun stream’s into the atmosphere of Venus, where it breaks up water molecules into two atoms of hydrogen and one of oxygen. The tiny atoms escape into space.
European spacecraft studies Venus. Image Credit: ESA
Scientists base their theory on measurements from the Venus Express that are finding twice as much hydrogen as oxygen is escaping from the planet. There is a second contributing finding: a heavy form of hydrogen, deuterium, is found in greater quantities in the upper atmosphere. Deuterium is less prone to escape.
“Everything points to there being large amounts of water on Venus in the past,” says Colin Wilson, an Oxford University scientist, cited by ESA.
Experts will debate whether that moisture was only resident in the atmosphere of Venus or pooled on the surface.
One computer model suggests the water was atmospheric and remained early in the formation of the solar system, when Venus was molten. Venus solidified as a planet as the atmospheric moisture streamed into space, according to the model.
That model, however, does not rule out the possibility that after Venus solidified, it was struck by comets, which delivered enough water for an ocean, creating conditions in which biological activity was possible.