NASA announces the retirement of astronaut Peggy Whitson

Peggy Whitson, 58, announced her retirement on her last day on the job. She spent more time off the planet than any American: 665 days in three missions. Whitson was the first woman to command the International Space Station, holding the position twice, and the oldest woman ever to fly in space. She was also the only woman to have served as chief of NASA's male-dominated astronaut corps.