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 design orbital parameters, to control attitude during thrusting, correct velocity errors, maneuver, counter disturbance forces (e.g., drag), and control and correct angular momentum. The propulsion subsystem includes a propellant, tankage, distribution system, pressurant, and propellant controls. It also includes thrusters or engines. Spacecraft design The design of spacecraft covers a broad area, including the design of both robotic spacecraft (satellites and planetary probes), and spacecraft for human spaceflight (spaceships and space stations). Spacecraft design was born as a discipline in the 1950's and 60's with the advent of American and Soviet space exploration programs. Since then it has progressed, although typically