The Latest from nasa.gov:

Engineers Narrow In on Cause of Endeavour Hydrogen Leak

Sun, 21 Jun 2009 10:40:29 AM EDT

Space Shuttle Program Manager John Shannon says engineers believe they now understand why a hydrogen gas vent line has been leaking, causing shuttle Endeavour's STS-127 mission to be postponed twice. He says a plate that attaches the vent line to Endeavour's external fuel tank is slightly misaligned and that's allowing a small leak to happen during the fueling process.

Teams at NASA Kennedy Space Center's Launch Pad 39A are taking precise measurements of the attaching plate during

the weekend before crews disassemble it, realign the plate and install a new set of seals to fix the leak. Shannon also says technicians are preparing to test the repair plan by filling Endeavour's external tank with liquid hydrogen and liquid oxygen in the next week and a half, just as they would for a launch. This "tanking test" will confirm whether the repairs will work before another launch attempt is made. Hydrogen leaks in the vent line postponed Endeavour's launch attempts June 13 and 17, delaying its 16-day flight to the International Space Station. If the repairs are successful, Endeavour's next launch attempt is targeted for July 11 at 7:39 p.m. EDT.