Will the third time be a charm for space shuttle Endeavour? NASA successfully tested a troublesome gas-venting system this morning, green-lighting the twice-delayed launch of the shuttle to the International Space Station.

The space agency filled the shuttle's external fuel tank with liquid hydrogen and liquid oxygen and found that the vent system, which carries excess hydrogen gas away from the launch pad, was no longer leaking near the shuttle.

Hydrogen leaks at the Ground Umbilical Carrier Plate, which connects the vent line to the shuttle's tanks, were detected in advance of planned launches on June 13 and June 17. Endeavour is now scheduled for a July 11 launch.

In a news conference today at Kennedy Space Center in Florida, Michael Moses, launch integration manager for the Space Shuttle Program, said the problem had been solved by tweaking the alignment of the two connecting pieces and installing a new seal where they meet.

During today's tanking test the vent connection "stayed in alignment, it was a good seal with no leakage," Moses said. "We're in really good shape and we're going to try for [a launch on] the 11th."

Still of Endeavour's Ground Umbilical Carrier Plate connecting the shuttle's external fuel tank to the hydrogen-gas vent system: NASA/KSC