If leak fixed, shuttle flies tonight
NASA confident after faulty valve replaced
NASA aims to launch shuttle Discovery and seven astronauts tonight after a
fuel-loading operation that will prove conclusively whether the agency has fixed the gaseous hydrogen leak that forced a launch scrub Wednesday.
Discovery and its crew are scheduled to blast off from Kennedy Space Center at 7:43 p.m. — the middle of a 10-minute opportunity to put the spaceship on course for a rendezvous with the International Space Station.
The weather outlook is good. Forecasters say there is an 80 percent chance conditions will be acceptable for an on-time launch.
NASA officials are confident that the replacement of a suspect quick-disconnect valve and associated seals will fix a gaseous hydrogen leak in an area where a critical vent line connects to the shuttle’s 15-story external tank.
“If it doesn’t leak, we’re going to be perfectly safe to fly,” said NASA Shuttle Launch Director Mike Leinbach. “We should be good to go.”
NASA is facing a launch deadline Tuesday. After that, the Discovery mission would be pushed back to at least April 7 so Russia can launch an already-scheduled station crew rotation mission that will involve a weeklong change-of-command at the outpost.
Tuesday is the last day NASA could launch Discovery and complete mission objectives before departing the station a day before the planned March 26 launch of the Expedition 19 crew and space tourist Charles Simonyi, who will be making a return trip to the outpost.
Simonyi, a billionaire who led the development of Microsoft Word and Excel software, flew a round trip to the station in April 2007 and is paying the Russian Federal Space Agency a reported $35 million to visit the outpost again.
NASA’s prime mission objective for the Discovery flight is the delivery and installation of a fourth and final set of massive American solar wings. A new distillation assembly for a system that turns urine into potable water also will be hauled up. Both are key to plans to double the size of resident crews to six in May.
NASA scrubbed a launch attempt Wednesday when a dangerous leak of gaseous hydrogen was detected at the end of a three-hour external tank propellant-loading operation.
The leak was traced to a 7-inch valve designed to vent excess gaseous hydrogen from the external tank. The excess is routed down a launch-pad line to a flare stack, where it is burned off.
NASA contractor technicians replaced the valve and two associated seals, but they ran into trouble reconnecting the gaseous hydrogen vent line to the tank. That put NASA about three to four hours behind schedule Saturday.
Leinbach said he expected the agency would be back on schedule early today. Engineers are scheduled to start filling Discovery’s external tank with a half-million gallons of liquid hydrogen and liquid oxygen at 10:28 a.m. today.
A launch today would lead to a docking at the station around 5 p.m. Tuesday. The shuttle crew would depart the outpost on March 25 and land at KSC on March 28.