NASA has postponed the scheduled launch of the space shuttle Discovery until Sunday or Monday.

CAPE CANAVERAL, Fla. – NASA has postponed the launch of space shuttle Discovery because of a gas leak. The leak of gaseous hydrogen occurred as the launch team was filling the external fuel tank for liftoff Wednesday night. The seven astronauts had yet to board the spaceship.

Discovery’s flight to the international space station is already a month late because of concern about hydrogen gas valves in the engine compartment. NASA officials say the leak occurred in plumbing outside of the shuttle and had nothing to do with those valves.