July 12, 2006 — Two spacewalking astronauts squeezed a putty-like sealant from a caulk gun Wednesday to test new repair techniques that might some day be necessary to save a damaged space shuttle.
"Easy motion on the trigger," astronaut Piers Sellers told his colleague, Mike Fossum, as they floated in Discovery's cargo bay and prepared for the tests on 12 deliberately damaged pieces of shuttle material.
"Good goo?" Sellers asked.
"Good goo!" Fossum responded.
More than an hour into the 6 1/2-hour spacewalk, the astronauts ran into a brief delay when one of the safety tethers on Fossum became unlocked. There was no danger of the astronaut floating away since he is attached to the complex by more than one tether, and he was able to relock it.
NASA spokesman Rob Navias said problems like that happen on occasion. During Monday's spacewalk, Seller's safety-jet backpack almost came loose while he worked on repairs.
"They are double and in some cases, triple tethered at all times depending on where they are," Navias said. "Their chances of ever floating away are zero."
Wednesday's was the third and final spacewalk planned while Discovery is docked at the space station.
Using a caulk gun, the two squirted sealant onto 12 deliberately damaged reinforced carbon-carbon samples stored on a pallet in Discovery's open payload bay.
Reinforced carbon-carbon is used to protect the shuttle's wing leading edges and nose cap from searing heat that can reach 2,300° Fahrenheit during re-entry into Earth's atmosphere. A crack in Columbia's wing in 2003 allowed fiery gases to penetrate the shuttle, destroying Columbia high over Texas and killing its seven astronauts.
The repair technique was devised by NASA to make sure such a disaster never happens again.
Wearing bulky spacesuit gloves, Sellers and Fossum massaged the sealant with a putty knife to keep it from bubbling in zero gravity.
