Navy SEAL-turned-astronaut Jonny Kim leaves NASA

Jonny Kim has already lived a few careers. He was a Navy SEAL with more than 100 combat missions. He became a doctor. Then, in 2017, NASA picked him to be an astronaut. On Thursday, Kim left NASA for good. He's returning to active duty in the Navy, training as a naval aviator instead.

Kim's resume reads like fiction. A Silver Star. A Bronze Star with Combat 'V.' A medical degree from Harvard. A spot in NASA's 2017 astronaut class, nicknamed 'the Turtles.' Last year, he finally got his one and only spaceflight: eight months aboard the International Space Station. NASA hasn't said exactly why Kim is leaving now. Kim is going back to the Navy full time, headed into naval aviation training rather than a desk job.

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Will this departure leave a real gap at the agency? Kim combined military discipline, medical training, and one real spaceflight, a rare mix even among astronauts. He's leaving right as NASA gears up for a packed stretch of moon missions under the Artemis program. NASA didn't name a replacement for whatever work Kim was doing, and it likely won't need to. The bigger point is simpler: even NASA's most decorated astronauts don't have to stay if another calling pulls them home.