Volume: 04, Issue: 06 11/16/2005 
Artist's impression of Venus Express in orbit. Image copyright ESA.
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Artist's impression of Venus Express in orbit around Venus. Image copyright ESA.
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The launch of Venus Express from Baikonur at 3:33 UT Nov. 9, 2005. Image copyright ESA/Starsem.
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Other Articles in This Issue:
Spitzer Harvests Dozens of New Stars
Mountains of Creation Captured by Spitzer
Paul McCartney Performs for ISS Crew
Space Education In and Out of the Classroom

Venus Express Blasts Off for Earth’s Neighbor

The European Space Agency (ESA) embarked on its first mission to Earth’s nearest neighbor when Venus Express launched successfully from the Baikonur Cosmodrome in Kazakhstan on Nov. 9, 2005. The mission’s science objectives are to study the atmosphere, the plasma environment, and the surface of Venus in great detail.

A Soyuz-Fregat rocket carried Venus Express into space and placed the spacecraft in its transfer orbit to Venus. The interplanetary cruise will last 153 days. Once it is captured by Venusian gravity, Venus Express will take 5 days to maneuver into its operational orbit: a 24-hour elliptical, quasi-polar orbit. At its closest, it will reach an altitude of 250 kilometers, and at its furthest, it will be 66,000 kilometers away from the planet.

Venus Express is a follow on from ESA’s Mars Express mission. Many of the instruments on the mission are simply upgraded versions of those on the Mars Express platform. After a 153-day cruise to Venus the spacecraft will enter Venusian orbit in April 2006.

Venus is Earth's nearest planetary neighbor. It draws twice as close to our planet as Mars ever does. In terms of size and mass, Venus is Earth's twin, 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.

One cannot understand the Venusian weather and atmosphere by comparing them to Earth's. Scientists are unable to explain some of the more extreme atmospheric phenomena that take place on Venus. For example, the planet only rotates once every 243 Earth days. However, in the upper atmosphere, hurricane-force winds sweep around the planet, taking just four Earth days to circumnavigate the planet.

The surface of Venus also baffles scientists. The oldest craters seem to be only 500 million years old, which may indicate that the planet behaves like a volcanic pressure cooker. On Earth, the constant, steady eruption of volcanoes and shifting of Earth's surface (in turn causing earthquakes) ensures that the energy released in Earth is dissipated gradually. This probably does not happen on Venus. Instead, pressure builds up inside the planet until the whole world is engulfed in a global eruption, resurfacing the planet and destroying any craters that have formed. This probably happened last ~500 million years ago, accounting for the lack of older craters.

Today, there is a strong relationship between the surface and the atmosphere. Is there any similarity between the ocean-atmosphere relationship on Earth and the surface-atmosphere relationship on Venus? Venus Express will supply scientific data that could shed light on both these mysteries.

For more information, visit the Venus Express homepage: http://www.esa.int/SPECIALS/Venus_Express/.

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