CAPE CANAVERAL, Fla. -- Amid lingering concerns that insulating foam might flake off the space shuttle's external fuel tank, NASA Administrator Michael D. Griffin said yesterday that today's scheduled launch of Discovery is a risk worth taking.
"You're not going to like this, and I'm sure I'm not going to like the way it sounds in print," Griffin said at a media briefing near the shuttle's launch pad. "But we are playing the odds."
Balancing the danger of a catastrophe like the ones that destroyed Challenger in 1986 and Columbia in 2003 against the pressure to adhere to a schedule that calls for shutting down the shuttle program in 2010 "is what you pay us for as taxpayers," he said.
Griffin has taken heat in recent weeks for deciding to go ahead with the launch, the second since Columbia was brought down by a piece of insulating foam that tore a hole in the orbiter's left wing. The agency's top safety officer and chief engineer recommended against the launch at a flight readiness review two weeks ago.
They were concerned that although NASA had addressed the problem that destroyed Columbia by removing more than 30 pounds of insulating foam from the side of the fuel tank, there was still a potential problem with foam shielding the 35 brackets that hold in place the lines carrying the shuttle's super-cooled liquid fuel.
Probability studies found as high as a 1-in-75 chance that enough foam could flake off to seriously damage the orbiter on liftoff.
Griffin said he overruled his advisers because the biggest piece of foam that has ever come off the ice frost ramps weighed a little more than 3 ounces, far less than the amount it would take to damage the shuttle, and because the crew could safely stay aboard the International Space Station and wait for rescue even if the craft were damaged.
In e-mail messages obtained by the Orlando Sentinel, officials in the inspector general's office raised concerns about Griffin's decision, suggesting that he might be bowing to scheduling pressures. To finish construction of the International Space Station by the 2010 deadline, 16 more shuttle launches are required, about four missions a year.
Griffin acknowledged that he is concerned about schedules. "There are no activities humans undertake that don't have schedule" pressures, he said. "I can't accept that as a criticism."
NASA officials said Discovery appears to be ready to take off as scheduled at 3:49 p.m. The only problem is the weather. Kathy Winters, the agency weather expert, said yesterday that there is a 60 percent chance that the weather will prevent a launch today, tomorrow or Monday.
John Johnson Jr. writes for the Los Angeles Times.