Venus is the Earth's nearest planetary neighbour. It draws twice as close to our planet as Mars ever does. In terms of size and mass, Venus is Earth's twin and yet it has evolved in a radically different manner, with a surface temperature hotter than a kitchen oven and a choking mixture of noxious gases for an atmosphere. Venus Express will make unique studies of this atmosphere.

In the past, both the Russians and Americans have sent spacecraft to Venus. Being the closest planet to the Earth, it was a natural target. These studies revealed details about the surface of the planet, mainly from NASA's Magellan radar mapper. However, Venus was out of the limelight during the last decade, despite several scientific puzzles. For example, how does the atmosphere 'work'? To find the answer, scientists break down the big question into smaller questions:

"What are the global characteristics of the atmosphere?"
"How does it circulate?"
"How does the composition of the atmosphere change with depth?"
"How does the atmosphere interact with the surface?"
"How does the upper atmosphere interact with the solar wind?"
Experts have designed Venus Express to be the first spaceprobe to perform a global investigation of the Venusian atmosphere, of the plasma environment.