14 DAY TRIAL // Just seven hours before the space shuttle Discovery was scheduled to take off from Launch Pad 39A at the Kennedy Space Center (KSC), in Cape Canaveral, Florida, a broken fill-and-drain valve, which operated the hydrogen propellant system, malfunctioned and forced mission controllers to scrub the launch. This is the second day in a row when the STS-128 mission is aborted, after yesterday's thunderstorms breached the ten-mile safety limit around the space center.
Initially scheduled to take off at 1:10 am EDT (0510 GMT) Wednesday morning, the shuttle has now been delayed until Friday, as engineers at the space agency are getting on with troubleshooting the error. “This particular valve did not open and close the way it was supposed to,” Allart Beutel, who is NASA's launch commentator, explains. The problems started popping up shortly after Discovery's fueling sequence began, at around 5:52 pm EDT (2152 GMT), Space reports.
Experts at NASA explain that the valve needs to be closed during lift-off. When engineers gave the command for it to close, they received no clear signs that it had done so. Therefore, the entire operation was called off, as engineers investigated the problem. The valve is currently in its “open” position, which means that the 526,000 gallons of super-cold liquid hydrogen and liquid oxygen propellants that are used in the shuttle and its external tank can be safely drained away.
In addition to the valve, engineers also discovered a small hydrogen leak on the main tank. Although it is well under the agency's safety limits, mission controllers opted to investigate it as well, especially given the fact that it is located fairly close to the defective valve. It remains to be seen whether Discovery will launch on Friday, officials at the agency say. If the valve error was simply a glitch, then chances are high. But, if there's something more to it, and the instrument needs to be replaced, then NASA may have to cancel its plans of launching the flight before August 30th, when the launch window closes.