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Venus Express is ESA's first mission to Earth's nearest planetary neighbour, Venus. The mission was born after ESA asked for proposals, in March 2001, suggesting how to reuse the design of the Mars Express spacecraft.

The guidelines were extremely strict. The mission would have to run to a tight timeframe because it had to reuse the same design as Mars Express, and the same industrial teams that worked on that mission. It would have to be ready to fly in 2005. Out of a number of promising proposals, ESA selected Venus Express.

What made the mission especially attractive was that many of the spare instruments developed for ESA's Mars Express and Rosetta missions could be used to achieve Venus Express's science objectives, which were to study the atmosphere in great detail.

Scientific objectives

Venus is the Earth's nearest planetary neighbour. 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.

Venus Express studied the complex dynamics and chemistry of Venus, and the interactions between the atmosphere and the surface, providing clues about the surface’s characteristics of the planet. It also studied the interactions between the atmosphere and the interplanetary environment (solar wind) to better understand the evolution of the planet.

Venus Express research questions

In the most comprehensive study of the Venusian atmosphere ever, Venus Express addressed many open questions, in particular:

  • How do the complex global dynamics of the planet work?
    - What causes the super-fast atmospheric rotation and the hurricane-force winds?
    - What maintains the double atmospheric vortex at the poles?
  • How does the cloud system work?
    - How do clouds and haze form and evolve at different altitudes?
    - What is at the origin of mysterious ultraviolet marks at the clouds tops?

Atmosphere of Venus related science

  • What processes govern the chemical state of the atmosphere?
  • What role does the ‘green-house effect’ play in the global evolution of the Venusian climate?
  • What governs the escape processes of the atmosphere?
  • Are there water, carbon dioxide or sulphuric acid cycles on Venus?

Surface of Venus related science

  • What caused the global volcanic resurfacing of Venus 500 million years ago?
  • Why are some areas on the surface so reflective to radar?
  • Is there present volcanic or seismic activity on the planet?
Venus Express in orbit around Venus. Copyright: ESA.
Artist's impression of Venus Express orbiting Venus. Credits ESA.
Visualisation of Venus Express during aerobraking manoeuvre. Credits ESA–C. Carreau.