Shuttle Tiles Perforated, But Repair Poses Dangers

Because of where the damage is located, any in-flight repair of the shuttle would involve significant risk to the astronauts doing the spacewalk, NASA spokesman Kelly Humphries said yesterday. Astronauts have simulated such a repair spacewalk before on Earth but never in space, he added.

NASA has never confronted this kind of issue before. Before the 2003 Columbia disaster, mission officials could not check for damage incurred to shuttles as they lifted off. But Columbia was doomed, investigators concluded, when a one-pound piece of foam insulation came loose and hit the shuttle, damaging heat tiles.

The agency subsequently developed an extensive camera system, capable of better examining a shuttle once it arrives at the international space station, and three remedies for repairing the heat shield while in orbit.

To patch the gouge, astronauts would have to spacewalk to the end of the shuttle's 100-foot robotic arm and extension boom, which would carry them under the spacecraft. They would then either apply to the damaged area a high-tech black paint or squirt an adhesive that NASA calls "goo."

The paint, which is intended to help dissipate heat, was tested on a previous shuttle flight. The "goo" has never been tested in space.