Hydrogen Leak Discovered During Fueling

ANN REALTIME UPDATE 03.12.09 0001 EDT: No sooner than Sunday. That's the word from NASA regarding the launch of the space shuttle Discovery, after crews discovered a potentially catastrophic hydrogen leak while fueling the orbiter Wednesday.

Shuttle Launch Director Mike Leinbach says workers will take their first up-close look Thursday afternoon at the gaseous hydrogen vent line that began leaking during the countdown to Wednesday night's scheduled launch attempt. The leak prompted a postponement of the STS-119 launch to the International Space Station.

If all goes well during that inspection -- and the problem is relatively easy to fix -- NASA could make another launch attempt as soon as Sunday.

Leinbach said the leak developed on the piping that runs from the fixed service structure to a valve at the intertank section of the shuttle’s external tank (shown below). The pipe moves hydrogen gas away from the shuttle and to a flare stack near the launch pad that burns it away safely.

There was never any danger to the shuttle while it was being fueled... but as the leak allowed too much gaseous hydrogen to escape the vent line, it could have been dangerous had the shuttle launched with the leak undetected.

Leinbach told Bloomberg he's "99.9 percent sure" the leak is in the piping from the launch gantry, and not on the shuttle tank.

Originally scheduled to liftoff February 12, Discovery was grounded for a month as NASA examined hydrogen flow control valves linking the external tank to the orbiter. One of those valves was found cracked after Endeavour returned from its mission in November; NASA opted to swap the valves originally installed on Discovery, with lower-time parts.

It does not appear the latest issue is related to that problem.

Earlier Reports

1455 EDT: Well, rats! NASA has once again pushed off the launch of the space shuttle Discovery on the STS-119 mission, after a hydrogen leak was discovered in a Liquid Hydrogen vent line between the orbiter and the external fuel tank. Engineers found the problem during fueling operations for tonight's scheduled launch.

NASA hopes to try again to launch Discovery at 8:54 pm EDT Thursday evening.

The agency has not said whether the leak may be related to the problematic hydrogen flow control valves that have delayed Discovery's launch for nearly a month. Those valves control hydrogen pressure inside the external tank during liftoff, and are also located on the hardpoints between the orbiter and external tank.

1230 EDT: It looks to be a beautiful evening Wednesday night at Kennedy Space Center, as NASA attempts to launch the shuttle Discovery on the latest mission to the International Space Station.

Commander Lee Archambault will lead Discovery's crew of seven, along with Pilot Tony Antonelli, and Mission Specialists Joseph Acaba, John Phillips, Steve Swanson, Richard Arnold and Japan Aerospace Exploration Agency astronaut Koichi Wakata on mission STS-119 to the International Space Station, targeted for liftoff at 9:20 pm EDT.

The Discovery crew members are set to fly the S6 truss segment and install the final set of power-generating solar arrays to the International Space Station. The S6 truss will complete the backbone of the station and provide one-fourth of the total power needed to support a crew of six.

An updated weather forecast shows a 95 percent chance weather will NOT be a factor for the launch, with the only possible snag being a very slight chance of a low cloud ceiling. Weather also looks favorable should NASA need to delay the launch by 24 hours for technical issues; it also looks good at 48 hours out.

As ANN has reported, NASA delayed Discovery's launch by nearly one month, as the agency investigated broken hydrogen flow valves found after the shuttle Endeavour returned from its STS-126 mission last November.

NASA eventually opted to replace the valves, that had been installed between Discovery and its external fuel tank, with parts with less time on them... resulting in the delay from the original February 12 launch date.

FMI: www.nasa.gov/shuttle