NASA and SpaceX postponed the launch of the next long-duration crew to the International Space Station early on Monday, minutes before the rocket was due to lift off, citing a problem with ground systems used to monitor the flow of an engine-ignition fluid.
Members of the four-man crew - two U.S. astronauts, a Russian cosmonaut and an astronaut from the United Arab Emirates - have since exited the spacecraft and returned to their quarters to await word on when the next launch attempt will be made, the U.S. space agency said.
