STS-127 (ISS assembly flight 2J/A) was a NASA Space Shuttle mission to the International Space Station (ISS). It was the twenty-third flight of Space Shuttle Endeavour. The primary purpose of the STS-127 mission was to deliver and install the final two components of the Japanese Experiment Module: the Exposed Facility (JEM EF), and the Exposed Section of the Experiment Logistics Module (ELM-ES). When Endeavour docked with the ISS on this mission in July 2009, it set a record for the most humans in space at the same time in the same vehicle, the first time thirteen people have been at the station at the same time. It also tied the record of thirteen people in space at any one time.
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 Space Shuttle Discovery 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.
The second launch attempt on 17 June 2009 was also scrubbed due to hydrogen leak issues seen from the Ground Umbilical Carrier Plate. Due to conflicts with the launch of the LRO, and due to a beta angle constraint, the next available launch opportunity was scheduled for 11 July 2009. A successful tanking test for leak checks was performed on 1 July 2009, with modified GUCP seals allowing launch preparations to proceed as scheduled. Because of lightning strikes near the launch pad during the evening of 10 July 2009, NASA scrubbed the launch for the third time and rescheduled for 12 July 2009. Due to a Return To Launch Site (RTLS) weather violation, NASA scrubbed the launch for the fourth time on the evening of 12 July 2009.
STS-127’s fifth launch attempt, on 13 July 2009, was also scrubbed due to anvil clouds and lightning within 10 nautical miles (19 km) of the launch site, which violated launch safety rules. STS-127 finally launched successfully on its sixth launch attempt, on 15 July 2009 at 18:03 EDT. Pieces of foam were observed falling off of the External Tank during the ascent, the same occurrence that had led to the loss of Columbia in 2003. However, Endeavour only received minor scuffs to its heat shield, the damage not enough to cause concern over reentry. The shuttle landed at Kennedy Space Center 16 days later at 10:48 EDT on 31 July 2009.