rockingham, as he flashes over australia and across the pacific to contact waiting ground stations in wymass friendship 7 streaks home to the land of its origin. an unseen comet lining across the united states in eight lightning minutes of flight. completing three history-making circuits of the globe, john glenn fires retro rockets to slow the spacecraft. john glenn fires retro rockets to slow the spacecraft, to direct it back to earth. >> five, four, three, two, one. fire. >> roger. firing. are they ever. it feels like i'm going back to hawaii. >> then the first ominous note. the first warning of possible disaster. a chilling signal flashes an indication that the capsule's heat shield may be loose. the astronaut might perish like an earthbound meteor in 3,000 degrees of re-entry heat without the heat shield. strapped over it, the metro pack might hold it in place. cape canaveral makes the decision. >> we are recommending that you leave the package on through the entire re-entry. >> as all the world listens and stands hope, cape control shows the way. using fly by wire control for re-entry,