Venus Express launch on a Russian Soyuz rocket from Baikonur

Venus Express will launch on a Russian Soyuz rocket from Baikonur Cosmodrome in Kazakhstan at 0333 GMT on Wednesday. The robotic craft will orbit the planet for about 500 Earth days to study its atmosphere, which has experienced runaway greenhouse warming.

Scientists hope the mission will shed further light on the mechanisms of climate change on our own world. &to=http://english.pravda.ru/science/19/94/377/16208_continent.html' target=_blank>Venus is almost identical in size to Earth, and is thought to have a similar composition. But there the resemblance ends, reports BBC News.

According to Seattle Post Intelligencer, Europe's first mission to Venus is aimed at exploring the hot and dense atmosphere around the planet, concentrating on its greenhouse effect and the permanent hurricane- force winds that encircle it.

Instruments on the probe will try to discover whether Venus' many volcanoes are active, and look at how a planet so similar to Earth could have evolved so differently.

"Venus is still a big mystery," said Gerhard Schwehm, head of the planetary missions at ESA. Not only is Venus the nearest planet to Earth within the solar system, but the two share also roughly the same mass and density. Both have inner cores of rock and are believed to have been formed at roughly the same time.

But the two have vastly different atmospheres, with Venus' composed almost entirely of carbon dioxide with very little water vapor. It is also the hottest surface of all the planets and lacks atmospheric pressure.