Endeavour’s Tank Test Complete: No Leaks Detected

Space shuttle Endeavour’s tanking test officially began at 6:52 a.m. EDT at NASA’s Kennedy Space Center in Florida. No abnormal gaseous hydrogen leaks were detected during the test, which involved filling Endeavour’s external fuel tank with liquid hydrogen and liquid oxygen just as it is on launch day.

At about 9 a.m., the liquid hydrogen tank was 98 percent full and the “topping” mode began. A vent valve at the top of the hydrogen tank began cycling, as planned, to disperse excess gaseous Hydrogen through a vent system that carries it safely away from the launch pad. At that point during two June launch attempts, a gaseous hydrogen leak was detected outside the Ground Umbilical Carrier Plate, or GUCP, where the vent line is attached.

STS-127 Mission Overview

Endeavour is targeted to launch July 11 at 7:39 p.m. EDT.

The 16-day mission 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.

The STS-127 crew members are Commander Mark Polansky, Pilot Doug Hurley and Mission Specialists Dave Wolf, Christopher Cassidy, Tom Marshburn, Tim Kopra and Canadian Space Agency astronaut Julie Payette. Kopra will join the space station crew and replace Japanese astronaut Koichi Wakata. Wakata will return to Earth on Endeavour to conclude a three-month stay at the station.

NASA Holds Test to Verify Endeavour Tank Repairs

NASA will conduct a tanking test at the agency’s Kennedy Space Center in Florida on Wednesday, July 1, to ensure repairs to space shuttle Endeavour’s external fuel tank were successful.

The test will be shown live on NASA Television beginning at 7 a.m. EDT. It will be followed by a news conference at approximately 1 p.m. Briefing participants will be shuttle program Launch Integration Manager Mike Moses and STS-127 Launch Director Pete Nickolenko.

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.

Ground Umbilical Carrier Plate Realigned, Seals Reinstalled

At NASA’s Kennedy Space Center in Florida, crews continue work to repair a plate that attaches a gaseous hydrogen vent line to space shuttle Endeavour’s external fuel tank. Hydrogen leaks in the area of the Ground Umbilical Carrier Plate, or GUCP, postponed Endeavour’s launch attempts June 13 and 17, delaying its 16-day flight to the International Space Station. The carrier plate has been realigned and seals have been installed.

On Wednesday, July 1, starting at 7 a.m. EDT, a tanking test will be conducted to ensure repairs were successful. Endeavour’s external tank will be filled with liquid hydrogen and liquid oxygen, just as it is before launch. NASA managers will hold a news conference following the test to discuss the results at approximately 1 p.m. The test and news conference will be shown live on NASA television.

Endeavour’s next launch attempt is targeted for July 11 at 7:39 p.m.
At NASA’s Johnson Space Center in Houston, the STS-127 mission astronauts will resume training Monday, June 29.