John GlennThe third manned Mercury flight, Friendship 7, puts John Glenn in orbit for nearly five hours, the first American astronaut to circle the Earth. The retro-rocket package on Glenn’s vehicle, Friendship 7, becomes an issue when a sensor indicates that the heat shield protecting the capsule’s interior from the intense heat of reentry has slipped. Intended to be cast off before reentry, the retro package is left on at the insistence of ground controllers, resulting in an unusually rough ride home after only three orbits.