Astronauts depart International Space Station after medical emergency 

A SpaceX capsule transporting four astronauts from the International Space Station (ISS) is due to splash down off the coast of California after ending their mission early due to a medical emergency.

The SpaceX Dragon spacecraft, known as the “Endeavour”, began its 10-and-a-half-hour descent from orbit at 22:30 GMT on Wednesday and is due to land on Thursday morning in the Pacific Ocean, according to the United States space agency NASA.

On board the Endeavour are NASA astronauts Zena Cardman and Mike Fincke, Japanese astronaut Kimiya Yui, and Russian astronaut Oleg Platonov.

The group spent 167 days on board the space station conducting a long-duration science mission as part of SpaceX’s 11th crewed mission. They were also part of NASA’s Expedition 74, which began on December 8.

NASA announced on January 8 that the SpaceX-Crew 11’s mission would be ending earlier than planned due to a serious medical condition among one of the crew members. The mission was originally due to end in late February.

The agency did not disclose further details, citing crew privacy, but NASA Chief Health and Medical Officer James Polk later said it was not related to space station operations. The medical incident is the first of its kind in NASA’s history.

“Always we err on the side of the astronaut’s health and welfare and in this particular case we are doing the same,” Polk said.

Fincke, a retired US Air Force colonel who led Expedition 74, wrote on Instagram that it was the right decision to end the SpaceX mission early, according to the Reuters news agency.

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

NASA on Wednesday livestreamed the Endeavour closing its hatch, undocking from the space station, and slowly drifting away late on Wednesday, more than 400 kilometres (248 miles) above Australia.

Photos of the event shared by the ISS on social media show the four astronauts checking their black- and-white Dragon pressure suits as they prepared for departure.

Livestreaming by NASA will resume as the Endeavour fires up its engines as it returns to the Earth’s atmosphere and then opens its parachute to splash down into the Pacific Ocean.

Following the departure of SpaceX Crew-11, two Russian and one NASA astronaut will remain at the space station to carry on Expedition 74.

The next SpaceX Crew-12 mission is preparing to depart in February to bring more crew back to the space station.