NASA and SpaceX early on Monday postponed the launch of a capsule containing two US astronauts, a Russian cosmonaut and a United Arab Emirates crewmate minutes before scheduled lift-off from Florida on a flight to the International Space Station. The US space agency and SpaceX, the private rocket company founded by billionaire Elon Musk, cited a technical glitch concerning the ignition fluid used to start the spacecraft’s engines.

The countdown had seemed to be progressing smoothly until about two-and-a-half minutes before blastoff, when NASA announced on its live webcast that the launch of the four crew members on a six-month science mission would be postponed. The SpaceX Falcon 9 rocket topped with a Crew Dragon capsule had been scheduled for liftoff at 1:45 a.m. EST (0645 GMT) from NASA’s Kennedy Space Center in Cape Canaveral, Florida.