Although the detailed design and development of Sortie Lab is planned to start in Europe in calendar year 1974, CVT will continue to be used for breadboarding low-cost approaches to experiments and for conducting mission simulations for the development of operational procedures. Initially, these simulations will be conducted using breadboards of actual subsystems included in the European design. Later, ESRO will furnish NASA with a functional mockup or engineering model of the Sortie Lab for such simulations and integrated testing. It is anticipated that CVT and the results obtained from the integrated testing of Sortie Lab will be adaptable to the evaluation of more advanced payload carriers with the primary focus being on the conduct of low-cost Earth orbital space research. ADVANCED DEVELOPMENT INTRODUCTION The advanced development program supports the application of research and advanced technology to the study and development of experimental systems, procedures and operational techniques which form the basis for specifying the elements of new manned space flight projects. Data developed by the program are applied to the process of component selection and integration, to an understanding of overall capabilities and cost; and is effective in providing support and answers to problems within ongoing programs. This work represents an essential bridge between the results of research and advanced technology on the one side and the incorporation of these new concepts in system hardware and operations on the other. Present efforts related to the Space Shuttle include the evaluation of rocket exhaust products on environmental quality, sonic boom, pyrotechnic systems, avionics onboard checkout, vacuum-jacketed ducting technology, internal insulation materials, water impact studies, analysis of bond joint edge stress, crack growth behavior, weld bond tank construction, heat pipe application, seal material, actuator technology and multipurpose optical sensors. Ongoing effort of particular interest is the water impact study (figure 180) a SHUTTLE NASA HO MT73-5291 FIGURE 180 portion of which is being conducted by the Navy Ordnance Lab here in Washington. Shuttle first-stage recovery is studied to permit reuse of the costly hardware. Scale models of the first-stage solid rocket motors are dropped into a tank of water to determine scaling effects and to gather data on penetration depth, flotation attitude, and loads. Circumferential and longitudinal stripes have been placed on the body to aid in photographic coverage and film analysis. The tank is 35 x 100 x 75 feet tall and is part of the Hydroballistics Facility at NOL. Current fiscal year 1973 efforts in other areas are devoted to radiator development, on-line checkout of life support systems, autonomous navigation systems, energy storage systems, development of short pulse laser, onboard consumables management functions, airframe cost technology study and flame resistant fiberous materials. The fiscal year 1974 program provides for the continuation of many of these efforts as well as the initiation of a number of projects in support of the Space Tug. Following is a more detailed description of some of the more significant activities and a detailed description of the effort on the Space Tug. ELECTRICAL POWER Electrical cabling in spacecraft and launch vehicles represents a significant segment of total system weight. A promising concept for weight reduction is the flat conductor cable (FCC) system. Although progress has been made, principally in the advanced development program, in the development of these new cables, connector technology is required to complete and integrate a total system. Investigations will be conducted for the development of FCC connector bodies and FCC connector spring contacts. Additional efforts will include development of corona-proof FCC connectors, distribution boxes, and aluminum conductors. DISPLAYS The increasing complexity of spacecraft systems requires the use of multifunction alphanumeric and graphic displays. The development of suitable lightemitting diode arrays will be undertaken to replace the only media applicable for the presentation of this information, cathode ray tubes, which are usable, but not optimum for spacecraft applications because of size, high voltage requirements and fragility. The light-emitting diodes, similar to the ones now being used in miniature commercial calculator applications, are small, require low voltage, and are extremely rugged. MATERIALS In the enclosed environment of manned space vehicles, the possibility and consequences of fire can never be overlooked. Consequently, efforts are being continued to develop materials that are not only nonflammable but which will also withstand the rigors of longer mission times. In this environment other charac teristics come into play such as durability, flexibility, abrasion resistance, and even physiological compatibility with respect to the crew members. In the relatively short manned missions up to and through Apollo, these characteristics were considered as secondary to the basic requirement of nonflammability. This approach is not acceptable for the longer missions of the future. The new approach will be to develop a new composition of halogenated compounds and incorporate them into aromatic polymers which will render fibers nonflammable. THERMAL CONTROL Large, long life, spacecraft will increase the requirement for the transport and control of high thermal loads. Analytical studies and component tests have demonstrated the feasibility of heat pipe systems for thermal control. Heat pipe systems offer the advantages of a high heat transfer capability, near isothermal operating characteristics and passive thermal control features with resulting long life potential. Because these systems require no moving parts, they also present greatly increased reliability and meteoroid invulnerability and reduced weight, power and pumping requirements. Controllable high capacity pipes have already been developed. The development of components and the integration and demonstration of a complete system is the logical continuation of this effort. TUG TECHNOLOGY Weight is critical for the Space Tug to perform its design mission within the Shuttle payload limit. The propulsion system is a major weight item and is therefore a good target for weight savings. Investigations are planned for the optimization of feedline thermal conditioning and the reduction or elimination of main tank pressurization requirements. Small high pressure main engine technology studies will begin to examine low cycle fatigue, light weight reusable thrust chamber materials, small pumps and turbines, and high speed bearings and seals. Thruster design, multiple cycling, propellant conditioning equipment and integration with the main propulsion system will be considered for the attitude control system. In support of studies being conducted for a reusable interim Space Tug, the possible use of a modified RL-10 engine (figure 181) is being investigated. This engine with extensive experience has been flown very successfully on the Centaur and early Saturn programs. If this engine's performance is satisfactory with feasible modifications, it could provide the interim Tug with a low development cost propulsion system and could be available for early Shuttle operational flights. Cryogenic components must be developed for long life and must be suitable for cyclic vacuum/atmospheric exposure for multiple reuse. Various multilayer insulations for cryogenic vessels must be analyzed and tested to satisfy the weight and reusability requirements. Techniques for nondestructive evaluation of the resuable insulation after each mission must be developed. The elimination or minimization of thermal acoustic oscillations in cryogenic feedlines is another area proposed for investigations. In addition to the foregoing efforts, new tasks which respond to the challenging technology requirements of the Space Tug are required. Examples of the work which must be successfully accomplished in order to achieve an effective Space Tug system are: development and demonstration of the effective use of composite structures, thin metal structures, advanced meteoroid shields and cryogenic tankage; definition and demonstration of critical fabrication and inspection techniques; and expansion of the cryogenic technology base for providing the performance, life and operational versatility required. SPACE TUG INTRODUCTION An examination of the total projected space traffic during the next 20 years indicates that approximately 50 percent of the payloads require a velocity increment above that nominally provided by the Space Shuttle (figure 182). The Space Transportation System (STS) therefore includes both the Shuttle and a propulsive stage that is carried to a low Earth orbit by the Shuttle. The primary purpose of this propulsive stage, termed Space Tug, is to expand the operating regime of the Space Transportation System to high energy orbits extending to geosynchronous positions; and to Earth escape. The Reusable Space Tug (figure 183) will be a major factor in maximizing overall STS effectiveness. |