Space shuttle Discovery grounded for weeks by fuel leak, foam crack
Earliest launch for space shuttle Discovery, poised to undertake its last mission, is now Nov. 30, NASA says. Friday's launch was scrubbed after engineers detected a fuel leak that allowed dangerous levels of hydrogen gas to build up around the orbiter.
The space shuttle Discovery, poised on the launch pad for its final mission, is acting like the little engine that didn't want to.
A leak allowing dangerous levels of hydrogen gas to build up around the orbiter has prompted mission managers to shift Discovery's launch from Friday to no earlier than Nov. 30.
The leak appeared about 7 a.m. Eastern Daylight Time as controllers were pumping fuel into the shuttle's external fuel tanks.
Engineers quickly spotted the problem and traced it to a fitting on the outside of the tank that bleeds excess hydrogen into a line that sends it to a flare stack roughly 0.2 miles from the pad, where the hydrogen is burned.
The same problem cropped up on two missions last year. This time around, the leak was worse, occurring when fuel was coursing into the tank at its highest rate. The concentration of hydrogen gas at the offending fitting was so high it exceeded the upper limit the leak sensors could measure.
As if to add insult to injury, when workers returned to the pad after controllers drained the fuel tanks, they discovered a seven-inch crack in foam insulation on the outside of the tank facing the shuttle, near the orbiter's nose. It looked as though the piece of foam involved had shifted slightly, which would have given ice a chance to build up in the area prior to lift-off.
The Columbia accident in 2003, in which seven astronauts were killed as the orbiter broke up on re-entry, was traced to foam and ice striking the orbiter's left wing during its ascent and damaging the tiles and carbon-composite materials designed to protect the underside of the shuttle from the heat of re-entry.