Shuttle Discovery crew on board for 3rd launch try
CAPE CANAVERAL, Fla, July 4: NASA today counted down to a third attempt to launch space shuttle Discovery on a mission vital to the program's future after easing worries over a crack in foam insulation on the ship's fuel tank.
Bad weather canceled planned launches on Saturday and Sunday, but NASA forecasters said there was an 80 per cent chance of favorable weather on this US Independence Day, the best prediction so far in this launch window.
The flight, set to lift off at 1438 hrs from the Kennedy Space Center in Florida, is critical to NASA's plan to finish the half-built International Space Station before the fleet is retired in 2010. An accident or serious problem likely would ground the shuttles permanently.
The crew of five men and two women waved small flags as they headed from their quarters to the launch pad -- US flags for the six Americans marking the Fourth of July holiday and a German flag for Thomas Reiter of Germany.
A small crack in the foam that insulates Discovery's massive external tank raised concerns yesterday, and NASA experts inspected the area early today to see if any potentially damaging ice had formed in the area of the crack.
None had, according to NASA flight commentator George Diller.
''That is good news, that there has not been any ice buildup in that area where the insulation was lost,'' Diller said.
A circuit breaker problem relating to the shuttle's booster joint heaters prompted NASA to assemble a repair team to send to the launch pad, but in the end no team was sent and the system was judged functional and capable of flying ''as is.'' Problems with falling foam insulation have been a key concern for NASA since the fatal disintegration of shuttle Columbia on February. 1, 2003. That accident was caused by a briefcase-sized chunk of foam that hit Columbia's left wing on launch, opening a hole that let in superheated gas during re-entry, killing all seven crew.
Despite extensive investigation, trouble-shooting and new design features, the problem recurred a year ago during a launch of Discovery. It forced NASA to ground the shuttle fleet while engineers worked on more modifications. Even before this latest problem with foam, NASA administrator Michael Griffin had decided to proceed with the current launch over objections of his chief engineer and head of safety.
But there was no dissent over the immediate problem of the cracked foam insulation.
''I think the teams have done a very good job of avoiding ... launch fever,'' NASA's associate administrator for spaceflight, Bill Gerstenmaier, said late yesterday after managers decided the small foam crack along an oxygen fuel line was not a launch hazard.
Inspectors discovered the 5-inch long, 1/2-inch wide crack in the fuel tank foam following the second launch attempt on Sunday. A small wedge of foam broke away and was found on the launch platform.
The crack was probably caused by condensation trailing down the shuttle's liquid oxygen fuel line and then freezing due to the extreme cold of the fuel flowing through the pipe. When the fuel tank was emptied after Sunday's delay, the ice melted and the foam cracked as the line expanded in the warm air.
Kennedy Space Center technicians used a tiny camera encased in flexible plastic to get detailed, close-up pictures of the crack and surrounding area, and those images showed the rest of the foam was in good shape.
The shuttle will head toward the space station to deliver equipment and supplies, make repairs to a mobile rail cart, and deliver a new crewmember. Since the Columbia accident, the station has been operated by two crew to save on supplies.
The primary goal of NASA's 115th shuttle mission, however, is to test the new tank design and other safety upgrades.