On this day in 1962, United States Marine Lieutenant Colonel John Glenn became the first American to orbit the Earth aboard his Mercury spacecraft, Friendship 7. It was the third flight of Project Mercury following two sub-orbital flights, and the first to use the more powerful Atlas ICBM booster rocket. The flight plan called for between three and seven orbits. However, Glenn made only three orbits, as a sensor indicated that his vital heat shield might have been coming loose. He was forced to make an unorthodox reentry into Earth’s atmosphere while leaving the retro-rocket package, a device strapped over the heat shield used to slow the spacecraft for the return home, in place instead of being jettisoned. It was hoped that the straps would hold the shield in place. After reporting “a real fireball outside”, there were a few tense minutes as Glenn flew through an expected communications blackout. Soon after, John Glenn radioed that his parachutes were deployed and he made a safe splashdown in the Atlantic Ocean. The flight lasted just under five hours. It was later determined that the heat shield sensor was faulty.