Scott Kelly Retires from NASA after 20 Years

Scott Kelly Retires from NASA after 20 Years

[1]Astronaut Scott Kelly retired today after 20 years with NASA and spending a year in space.

[2] During his career, Kelly completed four separate mission 1999, 2007, 2010, 2015, accruing 520 days in space.

Scott Kelly 

✔‎@StationCDRKelly

#ThankYou, @NASA! It's been an incredible 20 years!#YearInSpace https://youtu.be/53mBaj7ElM8 

4:50 AM - 1 Apr 2016

 
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Kelly's final excursion included participating in NASA’s twin study.

Kelly spent 340 consecutive days floating in the International Space Station, while his identical twin brother, Mark Kelly, remained on Earth. Since Scott’s return on March 1, he and his brother have been the subjects of extensive medical testing.

NASA is comparing them to see how the human body responds to extended time in space.

ABC News' Erin Dooley contributed to this report.