NASA's space ninja Peggy Whitson retires at 58

NASA's renowned astronaut Peggy Whitson retired on Friday. The astronaut retired within a year after returning from her last and the longest spaceflight.

Whitson has also spent the highest amount of time in space more than any other US astronaut. She had spent 665 days in space throughout three space missions. Peggy Whitson, the oldest woman ever to go to space, is also widely known for being the world's most experienced female spacewalker.

She was the first female commander of the ISS with Expedition 16 and she held this position not once but twice. Remarkably, she was the one and the only woman to serve as the chief of NASA's astronaut corps.

"It's been the greatest honour to live out my lifelong dream of being a @NASA Astronaut. Thank you to the #NASAVillage and all who have supported me along the way. As I reminisce on my many treasured memories, it's safe to say my journey at NASA has been out of this world," tweeted the astronaut, whom the fellow astronauts call, a "space ninja."

Whitson had joined the American space agency in 1986 as a researcher and became an astronaut in 1996.

"She set the highest standards for human spaceflight operations as well as being an outstanding role model for women and men in America and across the globe," the director of flight operations at Johnson Space Center in Houston, Brian Kelly, said in a statement.