“The crew member of concern is doing fine,” NASA said after their return early Thursday, the first time in the space station’s 25-year history that a crew returned home early because of a medical concern.

Four astronauts safely returned to Earth early Thursday, capping a dramatic and unusual week in space that required the crew to leave the International Space Station about a month earlier than planned because of a medical issue that arose in orbit.

NASA astronauts Zena Cardman and Mike Fincke, Japanese astronaut Kimiya Yui and Russian cosmonaut Oleg Platonov splashed down in the Pacific Ocean, off the coast of San Diego, at 3:41 a.m. ET after a nearly 11-hour journey.

“On behalf of SpaceX and NASA, welcome home, Crew-11,” mission controllers radioed to the astronauts moments after their Dragon capsule hit the water.

Their return was the first time in the space station’s 25-year history that a mission was cut short because of a medical issue.

The SpaceX Crew Dragon Endeavour spacecraft splashes down in the Pacific Ocean off San Diego on Thursday.NASA

In a post-landing news briefing, NASA Administrator Jared Isaacman said all four astronauts were “safe and in good spirits.”

“All crew members are currently undergoing the routine post-splashdown medical evaluation,” he said. “The crew member of concern is doing fine. We will share updates on their health as soon as it’s appropriate to do so.”

Because of medical privacy concerns, NASA has not disclosed the identity of the affected crew member or given any details about the medical incident.

Isaacman called it a “serious situation” in orbit, prompting the space agency to make the rare decision to bring the astronauts home early. He said, however, that the crew member in question has been safe and stable ever since.

At a news briefing last week, Isaacman said the decision to bring the crew members back was made out of an abundance of caution.

The medical issue forced NASA to call off a planned spacewalk on Jan. 8, which was to have Cardman and Fincke perform upgrades to the exterior of the ISS. A second spacewalk, originally scheduled to take place Thursday morning, has also been postponed.

Recovery teams approach the Dragon capsule.NASA

Before he left the orbiting outpost, Fincke said he and his colleagues were “stable, safe and well cared for.”

“This was a deliberate decision to allow the right medical evaluations to happen on the ground, where the full range of diagnostic capability exists,” Fincke wrote in a statement on LinkedIn. “It’s the right call, even if it’s a bit bittersweet.”

The astronauts returned to Earth in the same SpaceX Dragon capsule that they flew to the space station in.

The journey home was a smooth one, with mission controllers reporting “pristine weather conditions” at the splashdown site off the coast of California. The capsule’s drogue and main parachutes successfully deployed minutes before landing, slowing the spacecraft before it hit the water.

Recovery operations for NASA’s Crew-11 Dragon Endeavour spacecraft and its four crew members.NASA

SpaceX personnel quickly arrived at the scene to examine the capsule before it was hoisted onto the deck of the recovery vessel. Dolphins could be seen playfully swimming around as it bobbed in the ocean.

Fincke was the first to be helped out of the capsule, roughly 50 minutes after splashdown, followed by Cardman, Yui and Platonov. The crew members were all smiles as they emerged, flashing thumbs-up and waving to the cameras.

The crew members, known as Crew-11, spent 165 days aboard the space station. It was the first spaceflight for Cardman and Platonov, while Yui finished his second trip into orbit. Fincke, meanwhile, now has four spaceflights under his belt.

The crew arrived at the ISS in August and was scheduled to stay until late February. With Crew-11’s early departure, only three people are aboard the space station: NASA astronaut Chris Williams and Russian cosmonauts Sergey Kud-Sverchkov and Sergei Mikaev.

From left, astronauts Zena Cardman, Mike Fincke, Kimiya Yui and Oleg Platonov disembark the Dragon Endeavour spacecraft Thursday.NASA

The next rotation of space station crew members was scheduled to lift off no earlier than Feb. 15, but NASA said it is looking into options to bump up that flight. Still, Williams is likely to be the only NASA astronaut overseeing U.S. science experiments and operations on the station for at least a few weeks.

Joel Montalbano, deputy associate administrator for NASA’s Space Operations Mission Directorate, said in Thursday’s news briefing that agency officials will weigh the best timing for the next space station flight, known as Crew-12, with the needs of the space station and other upcoming launches in February, including NASA’s Artemis II mission.

That mission is a key test flight that will send four astronauts on a roughly 10-day journey around the moon.

“This is what we’re going to spend the next few days on,” Montalbano said.