BUILD THE SPACECRAFT

Eight different “vehicles" were designed and built: three stages of the giant Saturn V launch vehicle: four spacecraft modules (command module [CM], service module [SM], together forming the CSM; and the lunar module (LM) with its descent stage

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and ascent stage); and on the lunar surface, the lunar roving vehicle (LRV). the spaccsuit, and its backpack with oxygen, cooling and communications. They were all required to perform an advanced Apollo lunar surface mission.

To provide operations, support, and supply, each of the four spacecraft modules required several major systems, including specific combinations of guidance and navigation, electrical, communications, control (rockets), environmental, sequential (pyrotechnics), and consumables (propellant, water, cooling). Of course each system itself consisted of several subsystems and a myriad of components. These essential systems had twenty-five modes of operation (automatic, semi-automatic, and manual for both prime and backup systems).

Additionally, Apollo was the first flight vehicle to be controlled through a digital computer (a “digital autopilot’-, or DAP). ‘I’his remarkable advance in computers would soon propagate through both government and industry as an essential element of both spacecraft and aircraft. At the time of Apollo, of course, the capability of the DAP was relatively meagre because each of the identical computers in the CM and the LM had only 38,000 words of memory (a mobile phone today can have over two billion words!) and what happened was that the spacecraft would be flown by the astronauts using the DAP as their main interface with operating systems.

And simultaneously with the spacecraft, the ground “systems– were designed and built, including a worldwide network of tracking and communications and especially the Mission Control Center (MCC) in Houston. In its broader sense the very complex and capable MCC was like a spider web in that it consisted of a central hub with ever expanding sequential “rings– and connected through nodes like spokes on a wheel. Each node was. in its own way. a “mission control center’’, and was manned by the true experts in that particular discipline.