SUSSEX astronaut Tim Peake is aiming to become the first man to run a marathon in space.

The 43-year-old will become the first person to run a marathon in space on the International Space Station (ISS) when he takes on the 26.2 miles on a treadmill at the same time as the London Marathon in April.

Mr Peake, from Chichester, is due to blast off from the Baikonur Cosmodrome in Kazakhstan on December 15 and will stay in space for 173 days until June 5 next year.

When he takes on the marathon, he will be attached to the treadmill by a harness in order to combat weightlessness and will be watching a video of the London course on a big screen.

Mr Peake, who went to Chichester High School for Boys, said: "The London Marathon is a worldwide event. Let's take it out of this world.

"The thing I'm most looking forward to is that I can still interact with everybody down on Earth. I'll be running it with the iPad and watching myself running through the streets of London whilst orbiting the Earth at 400km above the surface and going 27,000km per hour.

"One of the biggest challenges I'll be facing is the harness system. In microgravity I would float if I didn't strap myself down to the treadmill so I have to wear a harness system that's a bit similar to a rucksack.

A seasoned runner back on planet Earth, Major Peake completed the London Marathon in 1999, finishing in three hours and 18 minutes - but he does not expect to beat that time.

"I don't think I'll be setting any personal bests," he said. "I've set myself a goal of anywhere between 3 hours 30 minutes to 4 hours."

Major Peake, who is running to raise awareness for The Prince's Trust, is the first Briton to be selected by the European Space Agency (ESA) for a mission to the ISS.

Because of the effects of weightlessness in space, maintaining fitness is crucial for an astronaut's bone density and muscle.

Hugh Brasher, event director of the London Marathon, said: "Tim's mission will undoubtedly inspire a generation of children to explore science and space. We hope that this extraordinary marathon run in space will also inspire that generation to run."