After Numerous Delays, Space Shuttle Endeavour Launches to Dock at the International Space Station

STS-127 (ISS assembly flight 2J/A) is the technical name of the current space shuttle mission to the International Space Station.

It is the twenty-third flight of Space Shuttle Endeavour. The primary purpose of the STS-127 mission is to deliver and install the final two components of the Japanese Experiment Module: the Exposed Facility, and the Exposed Section of the Experiment Logistics Module (ELM-ES).

When Endeavour docks with ISS, it will set a record for the most humans in space at the same time in the same vehicle, the first time thirteen people will have been at the station at the same time. It will also tie the record of thirteen people in space at any one time.

The first launch attempt on June 13, 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 June 18, 2009 would have conflicted with the launch of the Lunar Reconnaissance Orbiter (LRO)/Lunar Crater Observation and Sensing Satellite (LCROSS), NASA managers discussed the conflict issues with both the Lunar Reconnaissance Orbiter project, as well as the Air Force Eastern Range that provides tracking support for rockets launched from Florida, and looked at options for launching the shuttle, without affecting the LRO project significantly. A decision was made to allow the shuttle to attempt a second launch on June 17, 2009 and LRO would launch on June 18, 2009.

The second launch attempt on June 17, 2009 was also scrubbed due to hydrogen leak issues seen from the GUCP.[ Due to conflicts with the launch of the LRO, and with a solar heating in space constraint, the next available launch opportunity was scheduled for July 11, 2009. A successful tanking test for leak checks performed on July 1, 2009 with modified GUCP seals allowed launch to proceed as then scheduled. Because of lightning strikes near the launch pad during the evening of July 10, 2009, NASA scrubbed the launch for the third time and rescheduled for July 12, 2009. Due to a RTLS (Return To Launch Site) weather violation on the evening of July 12, 2009, NASA scrubbed the launch for the fourth time.

STS-127's fifth launch attempt on July 13 was also scrubbed due to anvil clouds and lightning within 10 nautical miles of the launch site, violating launch safety rules. STS-127's sixth launch attempt was successful, on Wednesday, July 15, 2009 at 6:03p.m. EDT. Pieces of foam were observed falling off of the External Tank during launch, as happened when the space shuttle Columbia was lost.