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were determined to be crystallized water vapor venting from the air-conditioning system. Near the end of Glenn%u2019s first orbit, the spacecraft%u2019s automatic control system began to malfunction, resulting in erratic movements. Switching to manual control, he was able to regain its equilibrium.In total, John Glenn spent 4 hours and 56 minutes circling the Earth, made three complete orbits, and reached speeds of more than 17,000 miles-per-hour. He%u2019d been scheduled for seven orbits, but the potential of a heat-shield problem was discovered, so his trip was shortened to three. He carried with him three drugs (morphine, for pain; wyamine, a stimulant; and tigan, an antimotion-sickness drug), but used none.During reentry, the straps holding Glenn%u2019s retrorockets in place began flapping violently, with flaming chunks of debris flying past his spacecraft%u2019s window. There was also a loss of radio contact with the ground for four minutes. But the capsule splashed down safely in the Atlantic Ocean, 800 miles southeast of Bermuda, and he was soon brought aboard the destroyer U.S.S. Noa, one of six ships in the recovery fleet. %u201cIt was hot in there,%u201d were his first words after stepping onto the ship%u2019s deck. Glenn was acclaimed as a national hero. President John Kennedy awarded him the NASA Distinguished Service Medal, and he was honored in a ticker tape parade in New York City. Schools and streets across the country were named after him. It wasn%u2019t until decades after Project Mercury that powerful electronic computers were commonplace. In the 1950s and 1960s, %u201chuman computers%u201d were used for many of the complicated computational tasks. For Glenn%u2019s flight, primitive (by today%u2019s standards) electronic computers were used for the first time to calculate his trajectory, launch window, and emergency return path, but Glenn didn%u2019t trust the machines. In fact, he refused to fly until one human computer in particular%u2014Katherine Johnson, a bril-