Venus Express arrives in orbit
At 8:17 (GMT) this morning, ESA's Venus Express space probe fired its main engine for 50 minutes, which brought it safely into orbit around Venus. Venus. The manouevre marked the end of a 153 day and 400 million km cruise into the inner Solar System.
Artist's impression of Venus Express arriving safely in orbit - 08.17 GMT on 11/04/06. © ESA
The main engine burn reduced the probe's relative velocity toward the planet from 29,000 to 25,000 km/h and allowed it to be captured by the planet's gravity field. During the next four weeks, Venus Express will perform a series of adjustments to move from its current highly elongated 9 day orbit to a 24 hour polar orbit at 66,000 kilometres. From this vantage point, the orbiter will conduct detailed observations of the structure, chemistry and flow of the atmosphere of Venus for at least two Venusian days (486 Earth days).
Venus is the nearest planet to Earth and passes twice as close to our planet than Mars. In terms of its size and mass, Venus is very similar to Earth and yet it has evolved in a very different way. Being closer to the Sun, its atmosphere should be a little warmer than the Earth, but past missions have found that a runaway greenhouse effect has resulted in surface temperatures of around 450°C, which is 400°C hotter than they would otherwise be. Combine this with the mixture of poisonous gases and sulphuric acid rain that has been discovered, and you have a scary vision of an atmosphere that has gone terriibly wrong.
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