NASA Chief Betting on Safe Shuttle Liftoff

Amid lingering concerns over insulating foam flaking off the space shuttle’s external fuel tank, NASA Administrator Michael D. Griffin said Friday that today’s scheduled launch of Discovery is a risk, but 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 press briefing near the launch pad, “but we are playing the odds.”

He said balancing the danger of another catastrophic accident like the ones that destroyed Challenger in 1986 and Columbia in 2003 against the pressure to keep to a schedule that calls for shutting down the shuttle program in 2010 “is what you pay us for as taxpayers.”

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 both recommended “no go” at a Flight Readiness Review two weeks ago.

They were concerned that while 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 the foam-covered ice frost ramps.

That foam shields 34 brackets holding the super-cooled liquid fuel lines in place.

Studies showed there could be a 1-in-75 chance that enough foam could flake off the ice frost ramps to seriously damage the orbiter on liftoff.

Griffin offered two reasons for overruling his advisors. First, the biggest piece of foam that has ever come off the ice frost ramps weighed 0.2 pound, far less than the amount that would damage the shuttle. Second, even if the craft is damaged, the crew could stay in the International Space Station and wait for rescue.

In e-mail messages obtained by the Orlando Sentinel, some officials in the inspector general’s office suggested Griffin might be bowing to scheduling pressures.

To finish construction of the International Space Station by the 2010 deadline, the shuttle must launch 16 more times, about four missions per year. That is roughly the rate at which NASA has launched shuttles throughout the program’s 25-year history, although in the last three years it has managed only one mission.

Griffin admitted to being 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.”

Discovery crew members have consistently said they are happy with the work NASA has done to fix the shuttle and consider danger from the ice frost ramp minimal.

John Logsdon of the Space Policy Institute in Washington said the dissenters in NASA “were doing their jobs” by raising concerns. But he said it’s impossible to reduce the threat to zero.

He called Griffin’s decision “rather courageous” when it would have been easy to err on the side of caution.

NASA officials said Discovery appears to be in good shape and ready to take off, but the weather may not cooperate. Kathy Winters, the agency weather expert, said Friday that there was a 60% chance that thunderstorms would prevent a launch not only today but Sunday and Monday as well.

NASA rules prevent launching if there is a weather problem within 20 nautical miles.

The launch window is open 10 minutes each day until July 19. The next window is from Aug. 28 to Sept. 14.

Discovery will carry two tons of cargo for the space station. Besides food and water, it will haul replacement equipment and a backup oxygen system, which will allow the station crew to expand to six. Currently, there are two astronauts aboard the station, but Discovery will leave a third, the European Space Agency’s Thomas Reiter.

Two spacewalks are scheduled, on the fifth and seventh days of the 12-day mission.