A former Navy SEAL who completed an illustrious career as a NASA astronaut and engineer over the last decade is returning to active-duty military service, according to NASA.

Jonny Kim will continue serving as a lieutenant commander in the U.S. Navy and work in naval aviation training once he leaves the government agency Thursday.

“Contributing to space exploration and serving NASA has been the honor of a lifetime,” said Kim. “Throughout my career, I’ve learned that beyond the missions, the training, and the hardware, success always comes down to the people. They are our greatest asset, and leading with love and empathy is how we achieve the impossible.”

Kim conducted scientific research aboard the International Space Station for eight months in 2025, orbiting the Earth 3,920 miles and traveling over 104 million miles, NASA said.

He became a NASA astronaut in 2017, served as a capsule communicator in the Mission Control Center at Johnson Space Center in Texas, helped develop the Artemis program that is working toward launching U.S. astronauts back to the moon by 2028 and served as an increment lead for Expedition 65.

Born in Los Angeles, California, Kim enlisted in the Navy in 2002 and joined SEAL Team Three, completing over 100 combat missions as a combat medic, sniper, navigator and point man during two deployments to the Middle East.

Kim has earned the Silver Star, the nation’s third-highest award for valor, and the Bronze Star with Combat “V,” among other awards.

He was eventually commissioned into the medical corps through the Naval Reserve Officers Training Corps.

He graduated summa cum laude with a bachelor’s degree in mathematics from the University of San Diego and a doctor of medicine from Harvard Medical School.

Kim also became a naval aviator and flight surgeon simultaneously.

He accomplished this feat after finishing flight training at Naval Air Stations Corpus Christi in Texas and Whiting Field in Florida and completing aerospace medical training at the Naval Aerospace Medical Institute at Naval Air Station Pensacola.

Despite his momentous achievements, Kim previously told Military Times that when he joined the Navy, he had no lofty plans beyond becoming a SEAL.

But his time as a naval special warfare operator made an indelible impression on him.

“[Being a SEAL] was certainly a memorable experience because it redefined new limits, gave me new benchmarks on how to judge the rest of my life,” Kim told Military Times.

When he deployed to Ramadi in 2006 as a corpsman, Kim said that he felt helpless while trying to save the lives of civilians and other SEALs because he couldn’t do more than stabilize the patient before handing them off to a surgeon.

This sparked his interest in medicine.

But even as he worked toward becoming a doctor, his ambition still could not be satiated.

While he was at medical school, thoughts of becoming an astronaut first crept into Kim’s head.

Kim said the ambition came from a desire to push past human limits, a desire he will undoubtedly bring with him as he returns to the sea after traversing the stars.

“I look forward to carrying my commitment to service, my enduring love for space and technology, and the hard-earned lessons of this past decade into my next chapter to make a meaningful impact on humanity’s future,” Kim concluded.