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This is Kelly's fourth mission, bringing his lifetime total to 520 days in space. The year-long mission is designed to measure the impact of space travel on Kelly's body. NASA will then compare those results to his identical twin brother, retired astronaut Mark Kelly. It's expected the "Twin Study" will yield new insights that can help inform a future mission into deep space.
Here's a look at the latest on Kelly's return to Earth.
12:04 a.m. ET
Kelly is now in a medical tent where he is being assessed by doctors.
11:52 p.m. ET
A smiling Scott Kelly has been pulled from the Soyuz spacecraft after spending 340 days in space.
11:26 p.m. ET
The Russian spacecraft has landed in Kazakhstan, according to NASA TV. Search crews will locate the Soyuz capsule and help pull Kelly and his Russian counterparts out one by one.
The astronauts will then be taken to a medical tent where, under professional supervision, they can try standing -- a feat that isn't always easy after living in a micro-gravity environment.
10:32 p.m. ET
The Soyuz has conducted a deorbit burn. It will now begin the descent back to Earth.
8:02 p.m. ET
The Soyuz has undocked from the International Space Station and will begin the journey back to Earth.
The roughly 249-mile freefall back to Earth inside the Soyuz takes about 45 minutes, and the process for making sure the trio arrive at their destination will be very complex.
The Soyuz will stay with the ISS for about two revolutions of the Earth as it fires its engines to align with the landing site. The crew members on board the spacecraft will then turn their de-orbit engines in the direction of travel and fire them for four to five minutes before falling back to Earth.
"You have a lot of G-forces pushing you down. You're watching parts of your spaceship burn up outside of your window. It’s a little alarming visually," astronaut Doug Wheelock, who has traveled in the Soyuz, told ABC News last year. "And then, of course, the heat shield on the Soyuz is ablative. It melts off and chunks roll off as you're coming through the atmosphere so, consequently, [it] gets thinner and thinner."
4:43 p.m. ET
Kelly and two Russian cosmonauts are now inside the Soyuz and the hatch has been closed. The International Space Station is currently 252 miles north of Malaysia. The Soyuz is expected to undock at 8:02 ET.
4:15 p.m. ET
Kelly and the two Russian cosmonauts who will travel with him back to Earth are saying their goodbyes to colleagues at the International Space Station. Soon, they'll enter the Soyuz and the hatch will be closed.