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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Communications system maintains phase lock of weak telemetry signals with a minimal expenditure of power and bandwidth. An estimate of the frequency variation as a function of time is used to achieve coherent phase demodulation.
Economic and social benefits from weather forecasting developments, noting expenditures on satellites and high speed computers
Decelerating effect of atmospheric drag assures minimum fuel consumption and time expenditure during braking for soft landing.
A space vehicle in an orbit around a spherical planet is considered. It is proposed to bring the vehicle, by a series of orbital maneuvers, into a final orbit. It is sought to minimize the total characteristic velocity for the maneuver. Since for a high-thrust propulsion system the characteristic velocity provides a direct measure of the fuel consumption, the optimal trajectory considered yields the minimum fuel expenditure. It is assumed that the planet is surrounded by a spherical atmosphere.
By means of simple geometric construction compact expressions for the maximum and minimum eclipse durations of a circular orbit, whose semimajor axis and inclination are specified, can be obtained. The method outlined in this note provides the designer with the necessary envelope of eclipse durations that a spacecraft will experience throughout its lifetime, and, therefore, provides a quick method of estimating necessary thermal constraints. Moreover, the closed form method presented eliminates the need for extensive machine time expenditure previously required for this type of analysis. Some numerical data to aid in the design of the spacecraft is provided.
The oxygen system cleaning specifications drawn from 23 industrial and government sources are presented along with cleaning processes employed for meeting these specifications, and recommended postcleaning inspection procedures for establishing the cleanliness achieved. Areas of agreement and difference in the specifications, procedures, and inspection are examined. Also, the lack of clarity or specificity will be discussed. This absence of clarity represents potential safety hazards due to misinterpretation. It can result in exorbitant expenditures of time and money in satisfying unnecessary requirements.
The analyses and rationale used to develop requirements for the oxygen-hydrogen auxiliary propulsion systems to be used with the space shuttle are presented. The requirements apply to a fully reusable space shuttle vehicle system using internal, reusable main engine propellant tanks in both the orbiter and booster stages. Requirements of principal interest are engine thrust, number of engines, maximum system thrust, total impulse, and total impulse expenditure history.
An economic analysis of space tug operations is presented. The subjects discussed are: (1) cost uncertainties, (2) scenario analysis, (3) economic sensitivities, (4) mixed integer programming formulation of the space tug problem, and (5) critical parameters in the evaluation of a public expenditure.
The author has identified the following significant results. Rates of erosion and accretion of the shoreline are being calculated for two test areas along the New Jersey coast. Measurements are made on aerial photographs taken over the last 20 years and processed by computer. The rates are presented in graphic form on an ERTS-1 base map at a scale of 1:125,000. These rates are being used to determine the effectiveness of various shore protection structures at preventing sand removal and encouraging sand accumulation. Information on maintenance and construction expenditures is being used to obtain a cost effectiveness ratio for various shore protection devices. The relationship of erosion rates, property value, and project cost are all criteria for selection of site type and extent of a shore protection structure. Compilation and evaluation of historical data will identify past decision making patterns. The effectiveness of these decisions with respect to erosion rates, property value, and project cost, can be used as an added criteria for future allocation of money and the selection of site and type of structure to be built.
Simulation studies have played an increasingly important role in planning for the First GARP Global Experiment (FGGE) during the last two years by providing information on the meteorological impact of various untested or incompletely tested elements of the GARP observing system. The studies are intended to provide information to FGGE planners on the capabilities of alternature systems for meeting a specific FGGE requirement. The simulation studies also provide a valuable input to cost-effectiveness studies by indicating tradeoffs of one possible type of observing platform against another, such as constant-level balloons vs buoys. These tradeoffs can lead to major gains in research yield per dollar of expenditure on the observing system.
Investigation of the effect of hypoxia on the depletion of metabolites that occurs in helium-aided induction of hypothermia. Hypoxic slowing of the heart of a hamster while exposed to cold helox is demonstrated. An attempt is made to evaluate the relative importance of cardiac slowing and limitation of thermogenesis in determining the effect of hypoxia. In explanation of the results presented, it is suggested that hypoxia limits the energy expenditure by the heart during induction.
The life sciences experiments conducted during Skylab missions are discussed. The general categories of the experiments are as follows: (1) mineral and hormonal balance, (2) hematology and immunology, (3) cardiovascular status, (4) energy expenditure, (5) neurophysiology, and (7) biology. Each experiment within the general category is further identified with respect to the scientific objectives, equipment used, performance, and data to be obtained.
High-resolution ground-based planetary observations, visual and photographic, have, for several decades, seemed to have reached a rather firm limit. The causes for this restriction are briefly reviewed. At the time when space probes make major advances possible, at incomparably higher levels of expenditure, the need arises to re-examine the limiting factors of earth-based planetary resolution. In addition to familiar refinements (of which seven are listed) carried somewhat further, a specific approach, yet insufficiently developed, is the study of the atmospheric boundary layer over the observatory site and the use of an appropriately elevated station.
The classical problem of determination of the rocket trajectory which minimizes mass expenditure during motion between two points in the field of a single gravitating body is analyzed. The known integrals of the system are incorporated into the adjoint equations resulting in a reduction from a seventh-order adjoint system to a third-order adjoint system. The first case which is treated in that of planar motion under specific end conditions. In this case a regularization of the recently derived equations is achieved. The general three-dimensional case is also reduced from a seventh-order adjoint system to a third-order adjoint system. In this case a regularization has not been found.
GSFC contractors with cost-plus contracts provide cost estimates for each of the next four quarters on a quarterly basis. Actual expenditures over a two-year period were compared to the estimates, and the data were sorted in different ways to answer several questions and give quantification to observations, such as how much does the accuracy of estimates degrade as they are made further into the future? Are estimates made for small dollar amounts more accurate than for large dollar estimates? Other government agencies and private companies with cost-plus contracts may be interested in this analysis as potential methods of contract management for their organizations. It provides them with the different methods one organization is beginning to use to control costs.
The BRAVO User's Manual is presented which describes the BRAVO methodology in terms of step-by-step procedures, so that it may be used as a tool for a team of analysts performing cost effectiveness analyses on potential future space applications. BRAVO requires a relatively general set of input information and a relatively small expenditure of resources. For Vol. 1, see N74-12493; for Vol. 2, see N74-14530.
The goal of reduction of space system costs is pursued in the areas of standardization of subsystem test requirements as well as overall subsystem test program resource requirements. A number of standard components are being developed by NASA. The rationale for the various environmental tests applicable to future missions and launch vehicles is discussed. The need for and approach to developing standard component specifications is presented. In addition, a method for reduction of test expenditures utilizing indexes of mission effect and hardware history as indicators of test requirements is proposed.
Maximum permissible concentrations of oxygen and carbon dioxide in a controlled atmosphere were determined by evaluating their effects on human gas exchange, blood coagulation, and tolerances to acute hypoxia, acceleration, and physical loads. It was found that functional disturbances depend on the concentration of respiratory gases and the length of stay in an altered atmosphere. By changing the atmospheric composition and by bringing the gaseous environment into accordance with the work and rest regimen and energy expenditures, the general reactivity of the body changes favorably.