Kelly and crewmate Mikhail Kornienko have spent 340 days in space, the longest mission since Valeri Polyakov spent 437 days aboard Mir in 1995
He landed with a bump in the mid-morning sun, the vast Kazakh steppe his first contact with Earth after a year in space devoted to medical tests, commanding the International Space Station and chasing his crew around in a gorilla suit.
Nasas Scott Kelly gave a thumbs-up as ground crew carried him and his fellow travellers, the Russians Mikhail Kornienko and Sergey Volkov, from the Soyuz capsule and gently lowered them into chairs where they warmed themselves beneath thick, dark blankets.
The air feels great out here, Kelly said to the men in big coats and hats who had come to his assistance. I have no idea why you guys are all bundled up.
The touchdown, at 10.26am local time on Wednesday, wrapped up a 340-day mission for Kelly, who enters the record books as the first US astronaut to spend so long in space. No-one has flown a longer mission than Kelly and Kornienko in more than 20 years. It was 1995 when Valeri Polyakov spent 437 days aboard Mir and so set the all-time record.
Officially named the One Year Mission, Kellys mammoth stint on the space station had a clear and concrete purpose. Having set its sights on sending humans to Mars, Nasa must now work out how to get them there safely. Rocket science is one thing. Keeping humans fit and well while weightless, exposed to radiation and in isolation for months on end, is another.