Veteran Astronaut Scott Kelly Retires From NASA

American astronaut, Scott Kelly, 52, officially retired from NASA after a two-decade-long service that saw him setting new records in space.

Kelly, who took his retirement on April 1, had already announced it in early March after having come back from his last journey in to space. The astronaut's 20-year old space career remained constantly highlighted by many milestones and achievements. He set a new record of spending 522 days in space.

The veteran embarked on his last space journey on March 27, 2015 along with Mikhail Kornienko, a Russian cosmonaut. The one-year long mission that completed with their return to Earth on March 1, 2016 is considered to be one of the most successful and ambitious ones in the history of space explorations, which also marked the advent of a new era.

The duration of the mission saw nearly 400 experiments that will carve the way for future explorations by NASA. The research included experiments that studied the reaction of the human body to isolation, radiation, weightlessness and stress associated with long duration spaceflights.

It should be noted that though Kelly has officially retired, his involvement with NASA is far from over. The astronaut is and will be undergoing various tests that will analyze the effects of the long term space mission on his body. Kelly's twin brother Mark Kelly, also a former astronaut, is part of the ongoing research. He was observed in parallel studies to throw light on genetic changes that result from a long duration spent in space. Scott's body was tested in space and Mark underwent similar testing on earth simultaneously.

#ThankYou, @NASA! It's been an incredible 20 years! #YearInSpace https://t.co/BR7xP2AoAm pic.twitter.com/wKUVbWA3Fe

— Scott Kelly (@StationCDRKelly) March 31, 2016

"#ThankYou, @NASA! It's been an incredible 20 years!" Scott Kelly tweeted on March 31, along with a YouTube video link called Speed of Sound. The link is a collection of clips that have captured various moments of Kelly's recent stint in space.