Despite concerns raised by some engineers, NASA said Friday that it plans to put off any further design changes to the shuttle's external fuel tank until after Discovery's flight in July.
The space agency had been considering changing the design of the tank's so-called ice frost ramps to stop insulating foam from falling off. The ice frost ramps are wedge-shaped brackets that hold in place the tank's pressurization lines.
NASA already has removed 37 pounds (16 1/2 kilograms) of foam from two other areas on the tank — a modification that space shuttle program manager Wayne Hale described as "the largest aerodynamic change we have made to the space shuttle launch system since it first flew."
NASA's top leaders decided to see how those changes hold up during the next launch before making any further alterations, Hale said.
The decision was not unanimous. NASA chief safety officer Bryan O'Connor, for one, initially preferred modifying the ice frost ramps before the shuttle flew. But Hale said O'Connor ultimately concurred with the final decision.
"There was a strong, concerted opinion from several folks that we should wait until we have a good design on these pieces of foam and then change them before we go flying," Hale said. "But at the end of the day, it is appropriate to make one change at a time with the biggest problem we have, and then work our way to the next situation."
Foam breaking off from the external tank at liftoff doomed Columbia and its seven astronauts in 2003. Despite extensive modifications to the tank, foam still fell off during last July's launch of Discovery.