Page last updated at 10:09 GMT, Monday, 31 August 2009 11:09 UK

British plan to tackle asteroids


A 3D visualisation of an asteroid before it hit the Earth as devised by Queen's Astrophysics Research Centre astronomers

A team of British scientists and engineers is developing plans for a spacecraft that could stop large asteroids from hitting the Earth.

The 10-tonne "gravity tractor" would deflect any orbiting rocks years before any potential collision could happen.

The device, which would rely on the force of gravity, is being developed by Stevenage space company EADS Astrium.

However, the idea is still in its early stages and the company says a prototype is some way off from being built.

Gravity tractory
The tractor would steer asteroids away from the Earth

The US space agency's (Nasa) Near Earth Object programme reports on its website that it has recorded 1068 known "Potentially Hazardous Asteroids", however there are thousands more estimated to be present in space.

Dr Ralph Cordey, who is EADS Astrium's head of exploration and business, told BBC News that the concept of a gravity tug was actually first mooted by two Nasa astronauts, Edward Lu and Stanley Love, a few years ago.

He said: "Frankly, I thought it was crackers. I thought it would never work."

But he said after reconsidering the idea and focusing on specific engineering issues, including the size of the spacecraft, and long-term propulsion methods, it was considered by the team to be potentially feasible.

The tractor would intercept the asteroid from just 48m away and exert a small gravitational force on it, pulling the rock towards it. The pair would then embark on a slightly different orbit, away from the Earth.

It could possibly be powered using solar panels.

However, the device would have to be launched at least 15 years before any predicted collision and would need a team to monitor it from the ground during this time.

Dr Cordey said the company had worked with a number of space authorities on other methods of protecting the Earth from asteroids but this one would be able to target a wider range.

He said: "We have done quite a lot of design work on this with the European Space Agency and we believe this would work just as well on a big solid iron asteroid as well as other types."

But the high cost implications mean that before the device could be made, it would have to be commissioned by a government or a group of governments working together.

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