John Glenn was not popular with the other astronauts. Glenn was the backup pilot for Shepard and Grissom on the first two manned Project Mercury flights, the sub-orbital missions Mercury-Redstone 3 and Mercury-Redstone 4. Glenn was selected for Mercury-Atlas 6, NASA's first manned orbital flight, with Carpenter as his backup. Putting a man in orbit would achieve one of Project Mercury's most important goals. Shepard and Grissom had named their spacecraft "Freedom 7" and "Liberty Bell 7". The numeral 7 had originally been the production number of Shepard's spacecraft, but had come to represent the Mercury 7. Glenn named his spacecraft, number
Spacecraft Propulsion Research Facility altitude to launch their payloads out of Earth orbit. More than ten tests of Centaur rockets here enabled the later successful launches in the Pioneer, Voyager, and Viking programs. Spacecraft Propulsion Research Facility The Spacecraft Propulsion Research Facility, now known as the In-Space Propulsion Facility, is (according to NASA), the "world’s only facility capable of testing full-scale upper-stage launch vehicles and rocket engines under simulated high-altitude conditions." The facility, located at NASA's Plum Brook Station of the Glenn Research Center near Sandusky, Ohio, was built in 1968. Its first major use was for testing stages of the Centaur Rocket, which