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 The first plateau, pre-launch, terminates at launch from the Complex 39 facility at Merritt Island. The launch to earth orbit is performed with the first two stages and a partial burn of the third stage of the Saturn V launch vehicle. As shown in Figure 2, the earth ascent phase represents the major expenditure of propellant for the lunar landing mission, approx­ imately 5½ million pounds of propellant has been expended to place the approximately 300,000 pound payload in earth orbit.

Referring to Figure 3, the earth ascent phase is shown schemati­ cally as it might be seen from some distant point in space looking down on the earth-moon plane. The moon's position at launch is shown in the lower right hand corner, and its daily movement, as as the mission continues, is shown at successive points. Following the ascent, the spacecraft reaches the second mission plateau, earth parking orbit. During each parking orbit, which can last up to 4½ hours, spacecraft systems are checked out and made ready for the next major maneuver, translunar injection. As shown in Figure 2, translunar injection represents a consider­ able change in spacecraft energy; the velocity is increased by some 10,000 ft/sec with a propellant expenditure of about 150,000 lbs. from the second burn of the launch vehicle's third stage.

Following translunar injection, the spacecraft is on the next plateau, translunar coast. An initial period of ground tracking is performed to confirm that the spacecraft is on a satisfactory trajectory, and following this confirmation, the transposition and docking operation is performed. This operation involves the Command and Service Modules (CSM) separating from the rest of the configuration, turning around and docking on the Lunar Module (LM), which is still attached to the S-IVB, and continuing the translunar coast. Sufficient separation velocity is applied by the Service Module Reaction Control System (RCS) to assure that there is no possibility of subsequent recontact with the S-IVB.

The spacecraft continues to coast on the translunar leg of the trip for approximately the next three days. Two or three mid­ course corrections will be made by the Service Propulsion System (SPS) during the translunar coast phase to assure that the spacecraft arrives at the correct location for its next major burn, lunar orbit insertion.

The lunar orbit insertion maneuver occurs be11ind the moon after the spacecraft has passed out of line of sight to earth. The maneuver is performed with the SPS and requires approximately