Considerable analytical and experimental work was underway on engineering problems associated with landing the LEM on the Moon. Landing loads and stability were studied by dropping dynamically scaled models on simulated lunar soil and by computer runs which utilized mathematical models of both the LEM and the lunar surface. At the same time an effort was underway to deduce in engineering terms the surface characteristics and soil mechanics of the lunar surface, Only the sparse photographic information from Ranger was available to the engineers, yet later data from Surveyor and Orbiter led to no significant change in the LEM design. In addition to lack of definition of the lunar surface, uncertainty about the cislunar space environment also handicapped design progress. The intensity of the radiation flux during solar flares was not fully understood. In addition to worry about radiation sickness, a particular concern was possible damage to the eyes in the form of cataracts of the astronauts. Thick transparent plastic eye shields were proposed. A program was instituted to learn more about predicting solar events and a network of H-alpha telescopes and radio frequency detectors was planned for this purpose. At the same time much effort was expended to assure that neither the spacecraft nor the astronauts' space suits would be damaged by micrometeors. In this regard help came from the data obtained by the Pegasus micrometeor detection satellites orbited by the last two Saturn I launch vehicles.
During this same period the Gemini program entered into its operational phase with a launch rate averaging once every two months. Significant to the Apollo mission were the development of operational procedures for orbital rendezvous, "shirtsleeve" operation by the crew in orbit, and exposure to fourteen days of weightlessness with only incidental physiological effects.
Finally, important scientific aspects of the mission were defined. Studies of lunar sample return and back contamination had progressed to the point that the essential features of the Lunar Receiving Laboratory were established. Further definition of the lunar geological surveys was achieved. With a goal of better precision in selection of Apollo landing sites, a coordinated activity was instituted with the Orbiter project. The Apollo Lunar Science Experiment Package (ALSEP) design progressed to the point of commitment to a 56-watt radioisotope power generator. Thus these small automated science stations would be assured an extended lifetime of operation after departure of the astronauts. It was also during this period that NASA recruited its first group of scientist astronauts.
In summary, during this period the Apollo program settled into the substance and routine of making the lunar landing a reality. The tremendous challenge in scope and depth of the venture was unmistakably clear to the government-industry team mobilized to do the job.
Maxime A. Faget
Director of Engineering and Development
Johnson Space Center