Britain is to build a space probe that will go into orbit around Mercury, the closest planet to the sun. The order to construct the spacecraft has been won by the aerospace team at Astrium in Stevenage, Herts.

Stevenage scientists will also design and build fuel systems that will power the probe’s mothership on the BepiColombo mission, due for launch in 2013.

Colleagues at Astrium’s Portsmouth base will work on the orbiter’s 11 scientific instruments that will put the planet under intense scrutiny.

The European Space Agency awarded the overall £220 million contract for the mission to aerospace giant Astrium, based in Germany. Astrium immediately revealed that its UK centre in Stevenage, Herts, will be entirely responsible for building the Mercury Planetary Orbiter.

The craft will spend at least a year flying from pole to pole, photographing Mercury’s mountainous and heavily cratered surface. Astrium’s second major UK base in Portsmouth will be responsible for building the spacecraft’s instruments.

BepiColombo is a joint project with Japan and will also carry their own orbiter probe to measure Mercury’s magnetic field. The two probes and their mothership, or transfer module, will be about 15ft tall and weigh around three tons, including fuel.

BepiColombo will be launched by a Soyuz rocket from Korou in French Guyana, South America. Conventional fuel thrusters will lift it clear of Earth and then a scifi-style ion engine built in Portsmouth will propel it by “light drive” on its long journey to Mercury. Finally, rockets will again fire to slow it so that it can go into orbit around Mercury.

Astrium spokesman Jeremy Close told Skymania News: “It sounds like a long route but it is the most efficient way to get to its target. As the probe flies towards Mercury, it will be pulled by the sun’s gravity. We have to make sure it is moving slowly enough when it reaches Mercury to be captured into its orbit.”

He added: “The fully assembled mission will be about the size of two Transit vans which is quite a fitting analogy. The craft will act like a van by delivering the Japanese probe into orbit and then dropping off the UK orbiter.”

Little is known about Mercury, a Moon-like planet that lies just 36 million miles from the sun and has a year 88 days long. Nasa’s Mariner 10 probe flew past Mercury three times in the Seventies and took photos revealing that it was covered in craters. A UK researcher believes Mercury was formed when an asteroid struck another bigger planet.

One of the biggest challenges facing Astrium’s engineers will be preparing the probe for the extreme heat it will encounter from solar radiation that will be ten times greater than on Earth. Temperatures reach 470 Celsius on Mercury’s surface.

BepiColombo will take six years to reach Mercury because engineers will bounce it around the solar system in a game of planetary snooker, just as they are doing with the Rosetta comet probe. The manoeuvres will allow the spacecraft to use the gravity fields of the Moon, Earth and Venus to propel it to its final destination.

Picture: An Astrium artist’s impression of the European Mercury orbiter.

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