Astronauts pose for a group photo before they board the Crew Dragon spacecraft at NASA's Kennedy Space Center in Cape Canaveral of Florida, the United States, April 23, 2021.Photo:Xinhua

NASA and SpaceX on Monday delayed for the second time a mission to send four astronauts to the International Space Station due to a "minor medical issue" with a crew member.

"The issue is not a medical emergency and not related to COVID-19," NASA said in a statement, without giving further details.

The members of "Crew-3" - US astronauts Raja Chari, Kayla Barron and Tom Marshburn, as well as German astronaut Matthias Maurer - will remain in quarantine at the Kennedy Space Center until their launch, the statement said.

The crew were originally due to launch aboard a Crew Dragon spacecraft named Endurance fixed atop a Falcon 9 rocket from the Kennedy Space Center in Florida on Sunday.

But the day before, the flight was postponed to Wednesday to avoid "a large storm system."

The launch is now scheduled for Saturday at 11:36 pm from Cape Canaveral in Florida.

Crew-3 is part of NASA's multibillion dollar partnership with SpaceX that it signed after ending the Space Shuttle program in 2011 and aims to restore US capacity to carry out human spaceflight.

The team will replace four Crew-2 astronauts, including Frenchman Thomas Pesquet, who have been stationed on the International Space Station since April.

AFP