British astronaut Tim Peake has successfully completed the London Marathon whilst orbiting 400 km (248 miles) above the Earth aboard the International Space Station. Peake is only the second astronaut to complete a Marathon in space, alongside NASA Astronaut Sunita Williams, who took part in the Boston Marathon from the ISS back in 2007.

Peake set out at 10:00 GMT on Apr. 24 just as 33,000 participants began their run below. The astronaut had previously completed the Marathon back in 1999, finishing with an impressive time of 3:18:50. In order to compete in the marathon, Tim was strapped into the T2 Colbert Treadmill located in Node-3 of the station's Tranquility module.

The treadmill is designed in such a way as to operate without shaking the rest of the space station, while providing enough downforce to the user so as to provide an adequate facsimile of running on Earth.

Tim ran the marathon despite suffering from the detrimental effects of over 18 weeks worth of muscle and bone loss sustained due to the microgravity environment prevailing on the ISS. Having evolved under the nurturing force of Earth's gravity, our bodies are ill-equipped to deal with the microgravity conditions prevailing in low-Earth orbit. Astronauts suffer significant bone and muscle loss while in space, owing to the decreased gravitational pressure of the space station environment.

Peake and other residents aboard the station adhere to a strict exercise regime designed to combat the wasting effects of microgravity. However, even with these precautions, astronauts engaged in a future long haul journey to Mars and back will be forced to contend with severe performance degradation due to muscle and bone atrophy.

Originally, Tim had planned to complete the marathon by sticking to a steady pace of 7.5 mph (12 km/h), but as the straps of the rig began to dig into the astronaut's shoulders, he decided to up the rate, punishing his legs in the hope of saving his shoulders.

All the while Peake watched live coverage of the event, and observing the streets of London via the RunSocial app, thus adding a sense of connection to the vast crowd of runners back on Earth.

In the end, Tim finished the 42-km (26-mile) marathon with an impressive time of 3:35:21, well inside the 3:30 - 4:00 timeframe he had set for himself prior to the event.

Source: ESA