Managers to set Endeavour launch plan today

Editor's note: today's news conference is expected to start at 5 p.m. EDT.

NASA mission managers will meet at 2 p.m. today to decide when to try to launch Endeavour again.

A planned 7:17 a.m. Saturday attempt was scrubbed when a potentially dangerous gaseous hydrogen leak was discovered during fueling of the external tank.

You'll be able to watch a press conference following the meeting at Kennedy Space Center right here - just click on the NASA TV still image on the right side of the page to launch a viewer.

Technicians this morning (shown above) reached the area of launch pad 39A where repairs will be needed - the same vent line that caused trouble during the first attempt to launch Discovery in March. Click here to see a graphic showing the area in question.

The line vents hydrogen gas from the external tank to a flare stack. Seals within the Ground Umbilical Carrier Plate, or GUCP, could start to be replaced this afternoon.

Even if the repair proceeds smoothly - Discovery's was a success, even though the exact cause of the leak wasn't determined - managers face obstacles to launching.

Wednesday is the earliest possible time Endeavour could be ready to liftoff on a 16-day mission to the International Space Station.

But an unmanned a United Launch Alliance Atlas V rocket carrying two moon-bound satellites is already scheduled to launch that afternoon from Cape Canaveral Air Force Station.

If that launch holds its place, Endeavour's next and only opportunity before July would be June 20.

Then, the sun's angle to the space station would put Endeavour's mission on hold for several weeks, because it would not generate enough power or dispel enough heat to support a docked shuttle.

A delay until July would push back the remaining seven other shuttle missions, which are supposed to be completed by the end of next year according to NASA's current budget plan.

Managers are expected to discuss their plans after the 2 p.m. meeting.

Endeavour mission commander Mark Polansky and his crew remain in quarantine and are also waiting for the news.

Polansky wrote as follows in an 11:15 p.m. Saturday "tweet", which was approximately noon according to the crew's sleep schedule" "Waiting 4 Sun meeting at 2pm to tell us when r next launch attempt is. Taking the day off, but still in quarantine."

IMAGE NOTE: Above, a Kennedy Space Center closed-circuit camera shows technicians at launch pad 39A working on a vent line that leaked hydrogen gas during fueling of the external tank Saturday. Below, visible after rollback of the rotating service structure on Friday and looming like giants against the sky are the solid rocket boosters, external tank and space shuttle Endeavour, poised for launch on Launch Pad 39A at NASA's Kennedy Space Center. The launch will be Endeavour's 23rd flight. The shuttle will carry the Japanese Experiment Module's Exposed Facility, or JEM-EF, and the Experiment Logistics Module-Exposed Section, or ELM-ES, on STS-127. Photo credit: NASA/Jim Grossmann.