During the test, the external tank will be filled with liquid hydrogen and liquid oxygen, just as it is before launch. A hydrogen gas leak at the Ground Umbilical Carrier Plate, or GUCP, postponed Endeavour's launch attempts June 13 and 17. The GUCP is attached to the venting system used to carry excess hydrogen safely away from the launch pad. Engineers determined the most likely cause of the leak is a slight misalignment in the External Tank Carrier Assembly. The assembly was fastened to the tank during manufacturing. The misalignment likely is putting uneven pressure on a Teflon seal, causing a small leak when extremely low temperatures occur during fueling. Technicians replaced the old seal with a two-piece seal and added small washers to counter any movement of the external tank carrier assembly as the tank is fueled. Endeavour's launch on the STS-127 mission is targeted for 7:39 p.m. on Saturday, July 11. The 16-day mission to the International Space Station will feature five spacewalks and complete construction of the Japan Aerospace Exploration Agency's Kibo laboratory. Astronauts will attach a platform to the outside of the Japanese module that will allow experiments to be exposed to space.
Satnews Daily
June 30th, 2009
NASA Tanking On July 1st @ Kennedy Space Center
During the test, the external tank will be filled with liquid hydrogen and liquid oxygen, just as it is before launch. A hydrogen gas leak at the Ground Umbilical Carrier Plate, or GUCP, postponed Endeavour's launch attempts June 13 and 17. The GUCP is attached to the venting system used to carry excess hydrogen safely away from the launch pad. Engineers determined the most likely cause of the leak is a slight misalignment in the External Tank Carrier Assembly. The assembly was fastened to the tank during manufacturing. The misalignment likely is putting uneven pressure on a Teflon seal, causing a small leak when extremely low temperatures occur during fueling. Technicians replaced the old seal with a two-piece seal and added small washers to counter any movement of the external tank carrier assembly as the tank is fueled. Endeavour's launch on the STS-127 mission is targeted for 7:39 p.m. on Saturday, July 11. The 16-day mission to the International Space Station will feature five spacewalks and complete construction of the Japan Aerospace Exploration Agency's Kibo laboratory. Astronauts will attach a platform to the outside of the Japanese module that will allow experiments to be exposed to space.