Running the London Marathon is hard enough. Running it in space? That's another challenge entirely. British astronaut Tim Peake is headed to the International Space Station (ISS) on December 15th and wants to complete the race at the same time as everyone down on Earth. He won't be running the actual route though -- instead, he'll be on a treadmill with a harness system that includes a waist-belt and shoulder straps. These will apply some much-needed downforce to counter Peake's weightlessness and recreate his natural running style in space. He'll also have a video feed of the route which will speed up and slow down to reflect his pace.