NASA has postponed Friday's scheduled launch of the space shuttle Discovery after a hydrogen leak was found in the craft's external fuel tank.
NASA space shuttle managers are meeting to determine when the next launch attempt will be. The agency says Monday is the earliest possible date. Officials will hold a news conference later Friday.
In a statement, NASA said the leak was discovered as the shuttle's external tanks were being filled in preparation for launch later in the day.
Discovery was originally scheduled to lift-off earlier this week. It has been delayed by technical problems and severe weather at the Florida launch site.
Discovery's six-member crew will deliver a final module for the U.S. portion of the orbiting laboratory during the 11-day mission. The shuttle will also carry the world's first humanoid robot, Robonaut 2, into space.
This will be Discovery's 39th and final flight in its 26-year history. NASA's shuttle fleet will be retired next year, bringing an end to the 30-year-old space shuttle program.
Some information for this report was provided by AP, AFP and Reuters.