Study results indicated that no major state-of- the-art advances would be required for a rotating space station program. If the program was to be implemented, maximum utilization could be made of the technologies, equipment, and facilities developed for the Mercury, Gemini, and Apollo programs. Significant reductions in cost, development time, and technological risk for a large rotating space station program would thereby be obtained. Four principal objectives were established for the study: study of alternate configurations, conceptual design of a rotating station, selection of station systems, and a program plan for the rotating station. Ground rules and guidelines were established to limit, define, and focus the studies. A summary of these follows. The launch vehicle was to be a two-stage Saturn V. Launch was to be from Cape Canaveral, Florida, in July 1968; the period from 1967 to 1970 was to be considered. The station was to be fully operational for one to five years. The space station was to be launched unmanned. Crew size was to be 24 men. The space station would be capable of remaining in the unmanned condition for a minimum period of one month. Meteoroid and radiation environment was as specified by NASA-MSC. Cabin pressure was to be variable from 24 to 101 kilonewtons per sq m (3.5 to 14.7 psia) within any one module or the zero-gravity laboratory, with the normal value being 48 kilonewtons per sq m (7.0 psia). Design criteria for the life support system were those specified by NASA. The space station was to be designed to accommodate emergencies, and rapid egress would not be a primary design constraint. Crew duty cycles would vary between three months and one year. The basic resupply period would be 90 days; however, variations to this period would be considered. Logistic spacecraft to be considered would include the 12-man ballistic or lifting body designs or a 6-man modified Apollo. Maximum use would be made of already available or planned equipment and technology or modest extensions thereof. If the Gemini and Apollo programs were continued at the current pace, research requirements for implementing a large rotating space station were few. These requirements were Aeronautics No aeronautics problems, as such, were anticipated; however, continuing research on the properties of the atmosphere at the orbital altitude would allow more accurate prediction of orbit decay rates. Biotechnology and Human Research Research to define more precisely the radiation environment and its effects on man should be continued. In connection with this work, better methods of measuring radiation dosage to man and of prognosis of potential damage were required. Continuing research on the long-term effects of reduced gravity and methods of counteracting such effects were necessary. Major contributions would be made in the Gemini and Apollo programs. Analysis and experimentation in the area of crew performance under reduced or zero gravity would aid in the design of equipment for both operations and maintenance. Environmental and Stabilization Controls Active systems had been proposed for stabilizing the rotating space station. Research in the area of passive stabilization devices would provide both increased reliability and decreased power consumption. Environmental control on the space station would use currently available hardware, with the exception of the oxygen regeneration unit. The proposed arrangement would make use of the Bosch process, which requires a large amount of electrical power for the electrolysis of water. Research would be required on the electrolysis process and on alternative means of reclaiming oxygen. Materials and Structures Continuing research on the meteoroid environment and on penetration mechanics and hazards of penetration, based on representative space station structures and operating pressures, would be required to permit more accurate evaluation of station and crew survival. The effect of long-term exposure of materials to the space environment would aid in reducing the space station development span. Of primary interest were sealing, materials, lubricants, repair techniques, and surface coatings for preserving thermal properties and for preventing or facilitating vacuum welding. Current toxicity data on materials dealt only in terms of industrial exposure times. The toxicity of the various materials that would be used in the space station should be evaluated for long-term human exposure in a representative environment. Nuclear Systems Nuclear power devices offered many attractive advantages for space station use; however, at that time, their development status, shielding requirements, and cost had prevented their use. Further research in both nuclear and radioisotope systems appeared justified in view of the potential benefits that could be realized. Propulsion and Power Generation One of the major logistic requirements for the space station would be propellants. The possibility of reducing propellant resupply requirements existing in the use of high-specific-impulse devices was now under development. Further research would be required to make the weight, size, thrust, and power consumption more compatible with space station requirements. In the existing space station design, the primary power source, solar cells, needed to be complemented with power storage devices in the form of silvercadmium batteries. Research, aimed at increasing battery life as a function of depth of discharge, would result in a marked reduction of power system weight and logistic requirements. The study recommended that effort in the following areas would provide critically needed technology: Development of a flight-rated oxygen regeneration system. Development of water reclamation components. Construction of a full-scale mockup. Design and testing of candidate wall constructions. Determination of the effect on materials of long-term exposure to the s environment. Increased battery life to minimize logistics.