The first launch attempt, on 13 June 2009, was scrubbed due to a gaseous hydrogen leak observed during tanking. The Ground Umbilical Carrier Plate (GUCP) on the external fuel tank experienced a potentially hazardous hydrogen gas leak similar to the fault that delayed the mission STS-119 in March 2009. Since a launch date of 18 June 2009 would have conflicted with the launch of the Lunar Reconnaissance Orbiter (LRO)/Lunar Crater Observation and Sensing Satellite (LCROSS), NASA managers discussed the scheduling conflict with both the Lunar Reconnaissance Orbiter project and the Air Force Eastern Range, which provides tracking support for rockets launched from Florida. A decision was made to allow the shuttle to attempt a second launch on 17 June 2009, allowing LRO to launch on 18 June 2009.