NASA Inspecting Leaky Fueling Hardware
Jefferson Morris jeff_morris@AviationWeek.com 
NASA technicians are performing a detailed inspection of shuttle Discovery's leaky hydrogen fueling hardware, and while they have noticed a "slight nick" in one seal, they can't yet say for sure that was the culprit that caused a March 11 launch scrub, according to Shuttle Launch Director Mike Leinbach.
The leak was discovered near a fuel line in which excess hydrogen is vented from the orbiter's external tank back to the pad to be burned off (Aerospace DAILY, March 12). Regardless of whether or not the team finds the source of the leak, all the seals in the line will be replaced in preparation for the next launch attempt, scheduled for 7:43:44 p.m. March 15.
Tanking of Discovery would start at 10:18 a.m. that morning and the crew would enter the orbiter at about 4 p.m. If the leak re-occurs, it would be expected to happen near the end of the tanking process, as it did on March 11. If tanking is normal, launch will proceed as normal and the leak will be filed away as an unexplained anomaly, Leinbach said during a press briefing at Kennedy Space Center March 13.
Weather looks good for launch, with only a 20 percent chance of a weather-related scrub. If the shuttle launches on time, it will embark on a 13-day mission to deliver the International Space Station's (ISS) fourth and final solar array, as well as a replacement urine processor.
STS-119 originally was scheduled to include four spacewalks, but one will have to be dropped as a result of the launch delay, so that Discovery can depart the ISS before the next station crew arrives separately on a Russian Soyuz. The reason for the so-called "Soyuz cutout" is because the ISS can't handle two extra crews visiting at once.
If the launch slips to Monday, March 16, the mission will be shortened to 12 days and will only include two spacewalks. If it slips to Tuesday, the mission will lose yet another day and there will be only one spacewalk. Deferred spacewalks will have to be carried out by the station crew.
The weather forecast gets progressively worse past Sunday, with a 30 percent chance of a scrub Monday, and 60 percent on Tuesday as a front moves into the area. If Discovery can't launch Tuesday, it must wait until April to try again.
The U.S. Air Force has agreed to put the launch of the second Wideband Global Satcom (WGS) military communications satellite on hold while the shuttle tries to launch. The WGS flight on an Atlas V had been scheduled for March 14 from Cape Canaveral Air Force Station.
Photo: NASA TV
