Astronauts test repair methods during final spacewalk

Two astronauts are preparing to test whether a puttylike sealant can be used to repair a damaged space shuttle during the third and final spacewalk of Discovery’s mission at the international space station today.

Using a caulk gun, astronauts Piers Sellers and Mike Fossum plan to squirt the sealant onto 12 deliberately-damaged reinforced carbon-carbon samples stored on a pallet in Discovery’s open payload bay.