Image copyright LONDON MARATHON Image caption Tim Peake has run the London Marathon before, in 1999

Tim Peake is going to run the London Marathon in space.

The British astronaut, who is about to blast off to the orbiting platform, will complete 26.2 miles on a treadmill - at the same time as athletes are pounding the streets of the UK capital.

Running is routine on the station, as the astronauts look to maintain body condition in the weightless environment 250 miles above Earth.

Nasa's Sunita Williams ran the Boston Marathon on the ISS in 2007.

Mr Peake has run the London event before - in 1999, finishing with a time of 3 hours and 18 minutes.

Fighting the float

But the exertion is not his main concern this time. Rather, it is the contraption he must wear to hold him down.

"One of the biggest challenges I'll be facing is the harness system," he said.

"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.

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

"I am running in space to raise awareness of The Prince's Trust, which has a team running on the ground - Team Astronaut - while I'm running on the ISS."

Image copyright NASA Image caption Sunita Williams completed the Boston Marathon in 4 hours and 23 minutes

Tim Peake goes to the space station on a Soyuz rocket on 15 December. He is due currently to stay on the platform until June.

The Digital Virgin Money London Marathon takes place on Sunday 24 April.

The former British Army helicopter pilot will start his run at 10:00 GMT, the same time that 37,000-plus runners set off from Greenwich to cover the famous Earth-bound course.

Mr Peake will have a digital video of London's streets in front of him, so he can get a better feel for what is happening down below.

"The London Marathon is a worldwide event. Let's take it out of this world," he said.

"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."