Nasa has ordered its first medical evacuation from the International Space Station in its 25-year history after an astronaut in the orbital laboratory fell ill with a “serious” but undisclosed issue.
The US space agency said in a press conference that the crew of four led by the US commander Zena Cardman would return to Earth in the coming days, earlier than planned.
Officials did not identify the astronaut or the issue, citing patient privacy. “This was a serious medical condition,” Nasa’s administrator, Jared Isaacman, said. “That is why we’re pursuing this path.”
The decision to evacuate the team in a space capsule comes after a series of hurried Nasa statements about a medical situation that arose on Wednesday. The development later forced the agency to cancel its first spacewalk of the year.
Isaacman said Nasa expected to provide updates in the next 48 hours on the astronauts’ undocking and atmospheric reentry timeline.
The crew of four arrived on a SpaceX capsule in August for a stay of at least six months. Cardman is accompanied by the US astronaut Mike Fincke, Japan’s Kimiya Yui and Russia’s Oleg Platonov.
The sick crew member was now stable but there was a “lingering risk”, said Nasa’s chief health and medical officer, Dr James Polk, adding that the issue has not been properly diagnosed.
What the medical issue might be is a matter of speculation, but it is clear that it was not properly treatable on the ISS. Isaacman said that even if a doctor had been aboard, the agency would still have wanted to bring the astronaut home.
He said there was some time to play with and that if there had been an emergency, the crew would have been able to escape in a matter of hours.
Serious medical issues have been dealt with in the past on the station, which has been continuously inhabited since 2000. They include one astronaut suffering a blood clot in their jugular vein, suggesting that the current situation is particularly serious.
The only other time a space agency has ended a space station mission early because of health concerns was in 1985, when the cosmonaut Vladimir Vasyutin returned from the Soviet station with an infection and high fever.
Only one person on the current Nasa mission is sick, but all four need to return because the agency aims to make sure the ISS never has more crew on board than there are available seats in docked space capsules. Those capsules need to serve as lifeboats or rescue vehicles.
Cardman and Fincke were supposed to carry out the spacewalk to make preparations for a future rollout of solar panels to provide additional power for the space station.
It was Fincke’s fourth visit to the ISS and Yui’s second, according to Nasa. It was the first spaceflight for Cardman and Platonov.
“I’m proud of the swift effort across the agency thus far to ensure the safety of our astronauts,” Isaacman said.
The ISS will not be left empty. Three other people are living and working aboard. The US astronaut Chris Williams and Russia’s Sergei Mikayev and Sergei Kud-Sverchkov, arrived in November on board a Soyuz rocket for an eight-month stay.
Nasa plans to bring the ageing space station, which is expensive to operate, out of orbit by late 2030 or early 2031. The idea is to do so slowly so the metal laboratory will burn up, with some debris falling into the ocean.
