Scott Kelly returns to earth after a year in space

After living for nearly a year aboard the International Space Station, NASA astronaut Scott Kelly is two inches taller than his identical twin brother Mark.

One of the main goals of his groundbreaking mission is to study how well humans can endure — mind, body and spirit — on a long-duration spaceflight.

Kelly is the first American astronaut to spend close to a year in space, and he says he "feels pretty good" and now begins what may be a year-long project to monitor his health.

(Photo:Russian cosmonauts Mikhail Kornienko (L), Sergey Volkov of Roscosmos (C), and Expedition 46 Commander Scott Kelly of NASA (R) rest in chairs outside the Soyuz TMA-18M spacecraft just minutes after they landed in a remote area near the town of Zhezkazgan, Kazakhstan on Wednesday, March 2, 2016. BILL INGALLS / NASA via AFP - Getty Images file)

Fun facts on what a year in space can do in your body:

1. Brittle bones

2. Weak muscles

3. Puffy face and legs

4. Smaller heart

5. Balance issues

6. Increases chances of getting cancer

7. Messed up body clock

8. Astronauts get taller in space - On Earth, the disks of the spinal column are slightly compressed due to gravity. In space, that compression is no longer present causing the disks to expand. The result: the spine lengthens, and the astronaut is taller.