Venus Express: ASPERA-4

The Venus Express spacecraft
(Credit: ESA)

Venus is the Earth's nearest neighbour, and it is Earth's twin in terms of size and mass. However there are many differences; on Venus a year lasts 224.70 Earth days and a day lasts 243 Earth days, the surface pressure is 92 times greater than Earth's, and the temperature on the surface of Venus is around 460ºC - making it the hottest planet in the Solar System. This high temperature has melted every man-made spacecraft to land on Venus so far.

The Venusian atmosphere consists of a noxious mixture of carbon dioxide (about 96%), nitrogen (about 3%), and a little water vapour. Above an altitude of 50km lies a very thick cloud layer largely composed of sulphuric acid droplets, giving Venus its yellowish appearance. The sulphuric acid droplets can be highly electrically charged, so offer the potential for lightening. Winds of over 220 mph keep the clouds in constant vigorous motion; the clouds circle the planet every four Earth days.

Venus Express was ESA's first mission to Venus and was launched on 9th November 2005 from the Baikonur Cosmodrome, Kazakhstan.

Image of Venus
(Credit: NASA/Magellan Project)

The satellite is based on the Mars Express design, and instruments on Venus Express have a heritage from both Mars Express and Rosetta. The main aim of the Venus Express mission is to study the Venusian atmosphere and clouds in unprecedented detail and accuracy.

RAL Space was involved in the Analyser of Space Plasma and Energetic Atoms (ASPERA-4) on board the spacecraft. ASPERA investigates the interaction between the solar wind and the atmosphere of Venus by measuring out-flowing particles from the planet's atmosphere and the particles making up the solar wind.

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Other RAL Space Planetary Science Projects

Soyuz-Fregat carrying Venus Express
(Credit: ESA/STARSEM-S. CORVAJA)

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