July 3, 2006 — NASA managers weren't ruling out a Fourth of July launch for space shuttle Discovery on Monday, even after inspectors found a five-inch-long crack in the foam insulation on its external fuel tank.
Officials said they needed more time to evaluate the problem and planned to meet again Monday evening to decide whether to go ahead with the launch.
The space agency's engineers believe the crack was caused by the expanding and shrinking of the tank as it was fueled with supercold propellant, which also caused a three-inch-long triangle-shaped piece of foam to fall off the area and land on a platform below.
The chunk of foam was too small to have caused damage if it had fallen during the launch, said John Shannon, deputy manager of the shuttle program.
"What we think happened yesterday, when we had all of that rain, we had condensation," Shannon said. "It's very cold. It froze."
NASA technicians planned to continue loading fuel into Discovery's power system.
"We want to make sure we understand all the considerations that caused this," said John Chapman, shuttle tank manager.
If NASA decides to go ahead with the launch Tuesday, it would be the first manned launch by the United States on the nation's birthday, and only the second liftoff of a space shuttle since the 2003 Columbia disaster.
Concerns about cracks in the fuel tank's foam insulation have dogged the program since Columbia broke apart over Texas on Feb. 1, 2003. A chunk of flyaway foam had damaged Columbia's wing during liftoff, allowing superheated gas to penetrate the shuttle when it re-entered the atmosphere.
NASA tried to fix the problem before attempting another launch, but more foam broke off Discovery's redesigned tank last July, barely missing the shuttle.
Inspectors this time spotted the 5-inch-long crack in the foam insulation during an overnight check of the shuttle. NASA had scrubbed launch plans Saturday and Sunday because of poor weather and had removed fuel from the tank.
That crack, an eighth- to quarter-inch wide, was in the foam on a bracket about two-thirds of the way up on the side of the external fuel tank facing the orbiter. The location would make it easy to hit the shuttle if a piece of foam came off.
One option for NASA would be to sand down the area of foam where the crack occurred, which would take a couple of hours and could be done on the launch pad. Another would be to cut out the area of foam and replace it, which could take several days, said Marion LaNasa Jr., a spokesman for Lockheed Martin Space Systems Co., which makes the tank.
NASA Administrator Michael Griffin decided last week that the shuttle should go into orbit as planned, despite the concerns of two top agency managers who wanted additional repairs to the foam insulation.
The mission for Discovery's crew this time is to test shuttle-inspection techniques, deliver supplies to the international space station and drop off German astronaut Thomas Reiter for a six-month stay.
The weather forecast for a Tuesday liftoff was better than it was on Sunday or Monday, with a 40 percent chance that storms at launch time would prevent liftoff, said U.S. Air Force 1st Lt. Kaleb Nordgren, a shuttle weather forecaster. NASA planned to make launch attempts on Tuesday and on Wednesday if necessary.
