But the deeper story unfolded days later.

The crack was not a "mission failure." It was a warning. It said: You cannot inspect your way to infinite safety. Every weld, every seam, every cycle of heating and cooling brings entropy closer. The Shuttle was a miracle of engineering, but miracles don’t scale to 135 missions without accumulating ghosts in the machine.

Every reentry burn of the left OMS engine—used for the deorbit sequence—carried a small but non-zero chance of catastrophic failure. They performed the deorbit burn with the right OMS only, a contingency never before flown. Endeavour landed safely at Kennedy Space Center on August 21, 2007. Post-flight inspection showed the crack had grown by 0.05 inches—just enough to confirm the models were right, but not enough to fail. The tile repair held.

The decision: , but with a modified reentry profile—a shallower angle of attack to reduce thermal and aerodynamic loads on the left OMS pod. They also added a 4-hour thermal soak at 160,000 feet to allow gradual heating.

STS-118 was no exception. Launched on August 8, 2007, Endeavour carried the SPACEHAB module and the S5 truss to the International Space Station (ISS). Commander Scott Kelly led a crew of seven. At T+58 seconds into ascent, a 0.25-pound piece of foam insulation—precisely the kind that doomed Columbia —broke away from the external tank’s (ET) "bipod ramp" region and struck the underside of Endeavour near the landing gear door. High-resolution post-launch imagery revealed a gouge in tile number V6 (a reinforced carbon-carbon tile near the nose landing gear door). The gouge measured approximately 3.5 inches by 2 inches, with a depth of nearly 1 inch.