UK & World News
Has Probe Detected Active Volcanoes On Venus?
Scientists who have been monitoring the European Space Agency's Venus Express probe for the last six years might have found evidence of active volcanoes on the second planet from the Sun.
Data sent back by the unmanned probe has shown large changes in the sulphur dioxide content of the planet's atmosphere, and one intriguing possible explanation is volcanic eruptions.
A new report from the ESA says: "The thick atmosphere of Venus contains over a million times as much sulphur dioxide as Earth's, where almost all of the pungent, toxic gas is generated by volcanic activity.
"Most of the sulphur dioxide on Venus is hidden below the planet's dense upper cloud deck because the gas is readily destroyed by sunlight.
"That means any sulphur dioxide detected in Venus' upper atmosphere above the cloud deck must have been recently supplied from below."
There are hundreds of volcanoes on Venus and solving the mystery of whether they remain active is an important scientific goal for Venus Express.
The mission has already found clues pointing to volcanism on geologically-recent timescales, within the last few hundreds of thousands to millions of years.
An analysis of sulphur dioxide concentration in the upper atmosphere of the planet provides a further clue.
Immediately after arriving at Venus in 2006, the spacecraft recorded a significant increase in the average density of sulphur dioxide in the upper atmosphere, followed by a sharp decrease to values roughly 10 times lower by today.
A similar fall was also seen during NASA's Pioneer Venus mission, which orbited the planet from 1978 to 1992.
Dr Emmanuel Marcq of Laboratoire Atmosph?s in France, the lead author of the paper published in Nature Geoscience, said: "If you see a sulphur dioxide increase in the upper atmosphere, you know that something has brought it up recently, because individual molecules are destroyed there by sunlight after just a couple of days."
Co-author Dr Jean-Loup Bertaux, Principal Investigator for the instrument on Venus Express that made the detections, added: "A volcanic eruption could act like a piston to blast sulphur dioxide up to these levels, but peculiarities in the circulation of the planet that we don't yet fully understand could also mix the gas to reproduce the same result."
H?n Svedhem, ESA's Project Scientist for Venus Express, also pointed out: "By following clues left by trace gases in the atmosphere, we are uncovering the way Venus works, which could point us to the smoking gun of active volcanism."
Venus, slightly smaller than the Earth, was once touted as a sister planet and, in early science fiction, as a potential home from home.
But in 1970, it was found to host an atmosphere of carbon dioxide with a pressure 90 times that on Earth and a surface cooked to 457C (855F), possibly the result of runaway global warming.