"After discussions with Chief Health and Medical Officer Dr. James Polk and leadership across the agency, I've come to the decision that it's in the best interest of our astronauts to return Crew-11 ahead of their planned departure within the coming days," Isaacman added. 

"The Dragon Endeavour spacecraft will depart the International Space Station with Commander Zena Cardman, pilot Mike Fincke, Kimia Yui from JAXA and Oleg Platonov of Roscosmos and safely return them to Earth."

Isaacman said the agency expects to provide an update within the next 48 hours on the anticipated undocking and reentry timeline.

Over the past five months, Crew-11 completed most of its mission objectives, supporting space station operations and conducting scientific research.

NASA said Crew-12 is scheduled to launch as soon as mid-February, with the agency evaluating whether an earlier launch is possible, while NASA astronaut Chris Williams will remain aboard the station to maintain an American presence and support ongoing operations.

Associate Administrator Amit Kshatriya said flight controllers and astronauts followed established procedures, calling the response a textbook example of NASA’s training for unexpected events.

"Every discussion over the last 24 hours as we’ve assessed the situation, crew safety has always remained our highest priority," Kshatriya said. "We never take shortcuts. We never compromise when it comes to protecting our astronauts."

Polk said the decision was driven by limits on conducting a full diagnostic workup aboard the space station.

Polk said the astronaut is stable but that diagnostic uncertainty in microgravity prompted NASA to err on the side of bringing the crew member back to Earth.

"Because the astronaut is absolutely stable, it’s not an emergent evacuation. We're not immediately disembarking and getting the astronaut down," Polk said. "But it leaves that lingering risk and lingering question as to what that diagnosis is. … And, so, always, we err on the side of the astronaut’s health and welfare."

The announcement comes as Crew-11 members were scheduled to conduct a 6½-hour spacewalk Thursday to install hardware outside the ISS.

Astronauts typically live aboard the ISS for stints of six to eight months and are equipped with basic medical equipment and medications in the event of an emergency.

The crew launched from Florida in August and had been scheduled to return to Earth in May.

Spacewalks are highly strenuous and involve months of training.

Last year, NASA canceled a planned spacewalk after an astronaut reportedly experienced "spacesuit discomfort." In 2021, U.S. astronaut Mark Vande Hei’s spacewalk was called off due to a pinched nerve.

Fox News Digital’s Julia Bonavita contributed to this report.