DESTINATION MOON: A History of the Lunar Orbiter Program
Preparations for the First Launch
[225] NASA launched five Lunar Orbiter spacecraft to the Moon between August 1966 and August 1967, and all five successfully performed their missions. This record set a precedent in the Office of Space Science and Applications in lunar exploration. Not every Orbiter proved an unqualified success, but each one obtained valuable photographic data that subsequently aided the Apollo Program in site selection for the manned lunar landings of Astronauts Neil A. Armstrong and Edwin E. Aldrin, Jr. (Apollo 11, July 20, 1969); Charles Conrad, Jr., and Alan L. Bean (Apollo 12, November 19, 1969); and later missions. Moreover, Lunar Orbiter photos enabled Surveyor Program personnel to verify landing sites and to place Surveyors in highly significant areas on the Moon's surface to perform their missions.
One major reason for the impressive record of five successful missions was the philosophy motivating the many individuals in the program. The men who had spent long months of preparation and training for the Lunar Orbiter flights had developed emergency procedures for many nonstandard situations which might arise. It was, however, obviously impossible to anticipate or simulate all possible failure modes in these training exercises, and only a [226] limited set of contingencies were practiced. The experience gained from these sessions proved invaluable in detecting and eliminating "bugs" in the operational systems, improving detection and correction of potential catastrophes during a mission and the probability of squelching problems in their embryonic stages.1
NASA and Boeing had designed Lunar Orbiter to be "tweaked." It was not launched and sent on its way to the Moon and then left alone to perform its mission automatically and expire. On the contrary, it was designed to operate with the assistance of ground controllers to overcome risks in each mission, potential failures in subsystems, and the external hazards of space. Built to function for a thirty-day minimum lifetime and an extended period of operation after the termination of the photographic mission, each of the five Lunar Orbiters proved successful in fulfilling its mission assignments.
The missions, in addition, proved the usefulness of the orbiter concept in unmanned lunar and planetary exploration. Lunar Orbiter-unlike Ranger, which was designed to send back television pictures of the Moon as it raced toward a terminal impact point on its surface-had the greater [227] advantage of orbiting its target for an extended period. Ground control operators thus had time to analyze any problems which arose and to prepare commands to the spacecraft to solve each problem.2 Although risk was a constant companion, the Lunar Orbiters had a new dimension of flexibility once they were in orbit around the Moon. The greatly extended time of an orbiting mission over an impact mission allowed flight operations personnel the luxury of compensation if a command was wrong or sent at the wrong time.
Twenty-eight months of industrious work and planning since the time when NASA Administrator James E. Webb had officially approved the program brought all activities to the eve of the first launch. During the months from April to August 1966 Langley and Boeing completed the final tasks which preceded the launch. On July 25 program officials conducted the Flight Readiness Review at Cape Kennedy, and on July 26 Langley accepted the spacecraft from Boeing, certified ready for launch.3