IOWA -- NASA astronaut and Iowa native Peggy Whitson has announced she is retiring.
Whitson has completed three long-duration missions to the International Space Station and set records each time. In 2002, she become NASA's first Space Station science officer, and in 2008 become the first female commander of the Space Station.
Last year, Whitson became the first woman to command the Space Station twice, claimed the title for most spacewalks as a woman, and set the record for the most time in space by a US astronaut with 665 days.
In a tweet on Friday, Whitson said being a NASA astronaut was her greatest honor.