Two years of Columbia accident, NASA is still undecided about procedures for in-flight repair on the heat shield. Columbia broke apart over Texas during re-entry on Feb. 1, 2003. All seven astronauts were killed. A loose piece of foam from the giant external fuel tank struck the left wing 81 seconds after liftoff.
NASA engineers are debating three procedures for in-flight repairs of the shuttle's protective tiles and two methods of patching carbon panels on the leading edges of the wings, both critical to keeping the shuttle intact during its fiery re-entry into Earth.
Mission commander Eileen Collins, who was at the Kennedy Space Center, said NASA had not yet decided on which repair techniques to test.