Scientists to examine Venus for clues on greenhouse effect

The planet Venus. Picture / Nasa

Europe's first space mission to the planet Venus will shed new light on the greenhouse effect here on Earth, scientists said yesterday.

The Venus Express spacecraft is scheduled for launch a week today and one is of its primary goals is to understand the nature of the intense greenhouse effect heating Venus.

Scientists involved in the £140m mission said that studying the extreme environment of Venus will help climate researchers to make better predictions about global warming caused by changes to our own atmosphere.

"With the Earth evolving to become much warmer and polluted, our sister planet Venus has much to offer us in terms of understanding our own climate," said Professor Keith Mason, head of the Particle Physics and Astronomy Research Council.

"The science data set to return next year will have a huge impact on the way in which we deal with conditions on Earth demonstrating how the exploration of the Solar System has real impact on our daily lives," Professor Mason said.

Venus, the second planet from the Sun and the closest neighbour to Earth, is one of the least understood bodies in the Solar System primarily because it is shrouded in dense, impenetrable clouds of sulphuric acid.

Venus was formed at the same time as the Earth and from the same sort of material.

It is also about the same size, mass and density, which is why astronomers have dubbed it the Earth's twin sister.

However, unlike Earth, Venus is a searing hot place with average temperatures hovering around 464C, about 400C higher than they should be because of an intense Venusian greenhouse effect traps the Sun's energy before can be reflected from the planet's surface back into space.

Professor Fred Taylor of Oxford University, who first proposed the mission to Venus, said that Venus had been an object of fascination and mythology for millennia.

"The human race has been studying Venus since the beginning of time because it's far the brightest object in the sky," Professor Taylor said.

Yet despite the many reasons for believing that Venus is the twin planet of Earth, scientists are still not sure about the precise reasons why the two planets differ so widely in their respective greenhouse effects.

One reason could be the extremely dense atmosphere on Venus - which is about 90 times the pressure of Earth's - another could have something to do with the planet's volcanoes, which are large and numerous.

"There are a lot of subtleties in how the greenhouse effect on Venus works that we still don't understand," Professor Taylor said.

One question the Venus Express probe may be able to answer is whether the many volcanoes on Venus are still active.

"We want not just to see whether there is active volcanism, but to say how much," Professor Taylor said.

The Venus Express probe, which is due to be launched from the Russian cosmodrome of Baikonaur on 26 October, will take nearly six months to travel the 26 million miles to its final destination.

Professor David Southwood, director of science at the European Space Agency, said that the probe is based on the previous Mars Express and Rosetta missions and has been built within three years to a tight budget.

"It is one of the least expensive missions that the European Space Agency has made but it is nevertheless a jewel in the crown," Professor Southwood said.

British instruments on board the probe have been designed to explore the outer atmosphere of Venus, which is being constantly degraded by the solar wind blowing at a million miles per hour, said Andrew Coates, a planetary scientist at University College London.

"Venus had developed in quite a different way to Earth and in many respects can be regarded as an evil twin," Dr Coates said.

Unlike the Earth, which is protected by its own magnetic field, Venus has no magnetosphere to act as a shield against the solar wind, which is why its atmosphere is being constantly degraded, he said.

"We're going to be looking at the escape of material from the top of the atmosphere of Venus," Dr Coates said.

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