British astronaut Tim Peake is preparing to return home after a triumphant six months in space which saw him take part in more than 250 experiments, perform a spacewalk, run the London Marathon on a treadmill, and receive an honour from the Queen.
Former helicopter test pilot Major Peake, 44, became the first Briton to join the crew of the International Space Station (ISS) as a European Space Agency (Esa) astronaut on December 15 last year.
On Saturday, he journeys back to Earth with American colleague Colonel Tim Kopra and Russian cosmonaut Yuri Malenchenko.
Together they will make the potentially hazardous trip crammed into the tiny Soyuz TMA descent capsule. Hitting the atmosphere at more than 17,000mph, the three men will rely on friction, parachutes and retro-rockets to ensure a safe landing.
If all goes according to plan, their spacecraft will bump down on a remote spot in the vast, flat scrubland of the Kazakhstan steppe at 10.15 UK time.
Rescue teams will be on hand to come to their assistance. The weakened space travellers, suddenly having to readjust to Earth gravity, will be lifted one-by-one from the capsule and placed in the care of medical experts.
Major Peake's mission was named Principia after Sir Isaac Newton's landmark work describing the laws of motion and gravity.
Its primary purpose was to contribute to scientific knowledge by conducting experiments in zero gravity, but Major Peake did much more than that as he constantly kept in touch with the world by Twitter, took part in video-linked Q&A sessions, and engaged in educational activities that reached more than a million schoolchildren.
His success in putting Britain on the space-faring map earned him a unique place in the Queen's Birthday Honours list.
Becoming the first person to be honoured while in space, he was made a Companion of the Order of St Michael and St George for "extraordinary service beyond our planet".
Read more: In Pictures - Tim Peake's most amazing photos from space
Speaking from the ISS last week, he said his spacewalk, conducted with Col Kopra in January to repair electrical components, was the highlight of his mission.
He added that he was looking forward to "private time" with his family, fresh air, and the feeling of raindrops on his face.
During his time in space Major Peake worked up to 14 hours a day, participating in more than 250 experiments devised by scientists from around the world.
Read more: Tim Peake shares photograph of Edinburgh taken from International Space Station
They included numerous studies of his own body's responses to the space environment involving his brain, lungs, stomach, muscles, bones, skin, immune system and body clock.
The tests will continue as he begins a lengthy process of rehabilitation back on Earth.
While weakened muscles recover quickly after a long spell in space, it can take up to three years for bones to return to normal. Despite their strict exercise regime, astronauts on average lose up to 1.5% of their bone mass for each month spent in space.
Major Peake was originally scheduled to return at the beginning of June, but his homecoming was delayed when the launch of the replacement crew was pushed back.
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