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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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At least 127 records · Page 7

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NASA NTRS1982

Feasibility study of solid surface subreflector production techniques

The principal effort was to study technical feasibility and cost aspects of the production technique of spin forming a subreflector reflective surface to a desired surface of revolution, back the surface with fiberglass to stabilize it sufficiently so that it may be machined to the target surface tolerance of .008 inches Root Mean Square (RMS) with a goal of .003 inches RMS. To verify this production technique, analyses was performed to define the production procedure. A price estimate for a 150 inch diameter subreflector for a 34 meter cassegrain antenna. During this feasibility study, numerous production processes were evaluated theoretically as production approaches for single surface, non-welded subreflectors. The first successful was the principal process of spin forming the reflective surface, backing with fiberglass and machining to a final contour. The second successful process was spin forming or bump forming a thicker reflective surface, with an integral (welded in) structure as a backing and machining the mounting pads and reflector to a final configuration.

Source record↗

NASA NTRS1982

A preliminary study of environmental parameters associated with the feasibility of a polygeneration plant at Kennedy Space Center

The feasibility of a polygeneration plant at Kennedy Space Center was studied. Liquid hydrogen and gaseous nitrogen are the two principal products in consideration. Environmental parameters (air quality, water quality, biological diversity and hazardous waste disposal) necessary for the feasibility study were investigated. A National Environmental Policy Act (NEPA) project flow sheet was to be formulated for the environmental impact statement. Water quality criteria for Florida waters were to be established.

Barnes, G. D.↗

NASA NTRS1983

A feasibility study: Forest Fire Advanced System Technology (FFAST)

The National Aeronautics and Space Administration/Jet Propulsion Laboratory and the United States Department of Agriculture Forest Service completed a feasibility study that examined the potential uses of advanced technology in forest fires mapping and detection. The current and future (1990's) information needs in forest fire management were determined through interviews. Analysis shows that integrated information gathering and processing is needed. The emerging technologies that were surveyed and identified as possible candidates for use in an end to end system include ""push broom'' sensor arrays, automatic georeferencing, satellite communication links, near real or real time image processing, and data integration. Matching the user requirements and the technologies yielded a ""strawman'' system configuration. The feasibility study recommends and outlines the implementation of the next phase for this project, a two year, conceptual design phase to define a system that warrants continued development.

Mcleod, R. G.↗

NASA NTRS1983

A robust Feasible Directions algorithm for design synthesis

A nonlinear optimization algorithm is developed which combines the best features of the Method of Feasible Directions and the Generalized Reduced Gradient Method. This algorithm utilizes the direction-finding sub-problem from the Method of Feasible Directions to find a search direction which is equivalent to that of the Generalized Reduced Gradient Method, but does not require the addition of a large number of slack variables associated with inequality constraints. This method provides a core-efficient algorithm for the solution of optimization problems with a large number of inequality constraints. Further optimization efficiency is derived by introducing the concept of infrequent gradient calculations. In addition, it is found that the sensitivity of the optimum design to changes in the problem parameters can be obtained using this method without the need for second derivatives or Lagrange multipliers. A numerical example is given in order to demonstrate the efficiency of the algorithm and the sensitivity analysis.

Vanderplaats, G. N.↗

NASA NTRS1983

Polarized-interferometer feasibility study

The feasibility of using a polarized-interferometer system as a rendezvous and docking sensor for two cooperating spacecraft was studied. The polarized interferometer is a radio frequency system for long range, real time determination of relative position and attitude. Range is determined by round trip signal timing. Direction is determined by radio interferometry. Relative roll is determined from signal polarization. Each spacecraft is equipped with a transponder and an antenna array. The antenna arrays consist of four crossed dipoles that can transmit or receive either circularly or linearly polarized signals. The active spacecraft is equipped with a sophisticated transponder and makes all measurements. The transponder on the passive spacecraft is a relatively simple repeater. An initialization algorithm is developed to estimate position and attitude without any a priori information. A tracking algorithm based upon minimum variance linear estimators is also developed. Techniques to simplify the transponder on the passive spacecraft are investigated and a suitable configuration is determined. A multiple carrier CW signal format is selected. The dependence of range accuracy and ambiguity resolution error probability are derived and used to design a candidate system. The validity of the design and the feasibility of the polarized interferometer concept are verified by simulation.

Raab, F. H.↗

NASA NTRS1983

Feasibility study to conduct windblown sediment experiments aboard a space station

A feasibility study was undertaken to determine if a suitable apparatus could be designed to analyze aeolian processes for operation in space and to assess the feasibility of conducting meaningful experiments to address key aspects of aeolian processes. To meet this objective a prototype apparatus was fabricated and some limited experiments were run to determine its suitability for this application. At least three general types of experiments were devised that could be carried out aboard a space station: threshold studies, swirl (dust devil) experiments, and analyses of windblown particle trajectories. How experiments in a zero-g environment could advance knowledge of aeolian processes was studied.

Greeley, R.↗

NASA NTRS1984

A preliminary study of the feasibility of detecting the floating macrophytes by means of digital processing of MSS/LANDSAT data

The feasibility of mapping the floating macrophytes (mostly water hyacinth: (Eichornia crassipes) in the Salto Grande reservoir in Americana, SP, by means of digital processing of MSS/LANDSAT data is described. The area occupied by the macrophytes was extracted by exclusion after the merging of two thematic masks representing the area of vegetation free water surface. One of the masks was obtained from a date when the vegetal cover is insignificant, while the other represents a large infestation episode. The utilization of digital processing of MSS/LANDSAT data techniques for the documentation of macrophytes infestation is feasible only when the phenomenon occurs in large areas.

Valeriano, D. D.↗

NASA NTRS1984

Chemical feasibility of lithium as a matrix for structural composites

The chemical compatibility of lithium with tows of carbon and aramid fibers and silicon carbide and boron monofilaments was investigated by encapsulating the fibers in liquid lithium and also by sintering. The lithium did not readily wet the various fibers. In particular, very little lithium infiltration into the carbon and aramid tows was achieved and the strength of the tows was seriously degraded. The strength of the boron and silicon carbide monofilaments, however, was not affected by the liquid lithium. Therefore lithium is not feasible as a matrix for carbon and aramid fibers, but a composite containing boron or silicon carbide fibers in a lithium matrix may be feasible for specialized applications.

Swann, R. T.↗

NASA NTRS1984

Interpretation of the lunar microwave brightness temperature spectrum - Feasibility of orbital heat flow mapping

The feasibility of an orbital mapping of heat flow by means of microwave radiometers is examined on the basis of a detailed model of the lunar regolith. The results obtained are discussed in terms of contributions of physical properties and regolith structure to the spectral signature of lunation-averaged brightness temperatures. Even for regions for which remote heat flow detection is not feasible, detailed interpretations of remote measurements in terms of physical properties and regolith structure could be made by means of the model presented. Surface and subsurface scattering effects are considered in evaluating possible wavelength dependencies of the microwave emissivity.

Keihm, S. J.↗

NASA NTRS1984

Long term cryogen storage in space - A feasibility study

The conduction of future space missions will require the long term storage of cryogens in space. Such missions will be performed in connection with the employment of the long life version of the Shuttle Infrared Telescope Facility (SIRTF), the Large Deployable Reflector (LDR), Gravity Probe B (GPB), Orbital Transfer Vehicles (OTVs), and the Space Station. The feasibility of building a long lifetime helium Dewar for space applications has been studied. A feasible concept was to be developed for a Shuttle-launchable 3-yr lifetime Dewar. The developed concept was to be used for the identification of key technology development areas. The desired long lifetime requires the minimization of the parasitic heat loads. It has been found that the majority of the parasitic heat load can be provided by the fiberglass-epoxy tension band supports. A new type of support system, the Passive Orbital Disconnect Strut (PODS), was developed to reduce the considered contribution to the heat load.

Kittel, P.↗

NASA NTRS1985

Feasibility study of the welding of SiC

In a brief study of the feasibility of welding sintered alpha-SiC, solid-state welding and brazing were investigated. Joint quality was determined solely by microstructural examination. Hot-pressure welding was shown to be feasible at 1950 C. Diffusion welding and brazing were also successful under hot isostatic pressure at 1950 C when boride, carbide, and silicide interlayers were used. Furnace brazing was accomplished at 1750 C when a TiSi2 interlayer was introduced.

Moore, T. J.↗

NASA NTRS1985

Feasibility of using LANDSAT images of vegetation cover to estimate effective hydraulic properties of soils

Research activities conducted from February 1, 1985 to July 31, 1985 and preliminary conclusions regarding research objectives are summarized. The objective is to determine the feasibility of using LANDSAT data to estimate effective hydraulic properties of soils. The general approach is to apply the climatic-climax hypothesis (Ealgeson, 1982) to natural water-limited vegetation systems using canopy cover estimated from LANDSAT data. Natural water-limited systems typically consist of inhomogeneous vegetation canopies interspersed with bare soils. The ground resolution associated with one pixel from LANDSAT MSS (or TM) data is generally greater than the scale of the plant canopy or canopy clusters. Thus a method for resolving percent canopy cover at a subpixel level must be established before the Eagleson hypothesis can be tested. Two formulations are proposed which extend existing methods of analyzing mixed pixels to naturally vegetated landscapes. The first method involves use of the normalized vegetation index. The second approach is a physical model based on radiative transfer principles. Both methods are to be analyzed for their feasibility on selected sites.

Eagleson, P. S.↗

NASA NTRS1985

Feasibility study for convertible engine torque converter

The feasibility study has shown that a dump/fill type torque converter has excellent potential for the convertible fan/shaft engine. The torque converter space requirement permits internal housing within the normal flow path of a turbofan engine at acceptable engine weight. The unit permits operating the engine in the turboshaft mode by decoupling the fan. To convert to turbofan mode, the torque converter overdrive capability bring the fan speed up to the power turbine speed to permit engagement of a mechanical lockup device when the shaft speed are synchronized. The conversion to turbofan mode can be made without drop of power turbine speed in less than 10 sec. Total thrust delivered to the aircraft by the proprotor, fan, and engine during tansient can be controlled to prevent loss of air speed or altitude. Heat rejection to the oil is low, and additional oil cooling capacity is not required. The turbofan engine aerodynamic design is basically uncompromised by convertibility and allows proper fan design for quiet and efficient cruise operation. Although the results of the feasibility study are exceedingly encouraging, it must be noted that they are based on extrapolation of limited existing data on torque converters. A component test program with three trial torque converter designs and concurrent computer modeling for fluid flow, stress, and dynamics, updated with test results from each unit, is recommended.

Source record↗

NASA NTRS1985

Long life feasibility study for SIRTF

The Phase A baseline for the Shuttle Infrared Telescope Facility (SIRTF) consists of an 85-cm diameter Cassegrain telescope, cooled to temperatures in the range from 10 to 20 K to provide background limited imaging for up to six instruments contained within a multiple instrument chamber (MIC). Colder temperature zones are also provided. A cryogenics system for a 15-day mission lifetime was first considered. In another study, the feasibility was assessed to extend the lifetime of the baseline SIRTF concept to at least six months, taking into account a mission involving the use of a space platform or a free-flyer configuration. According to the considered requirements, the optics temperature is to be kept below 10 K for at least 30 days. The temperatures are not to exceed 20 K at the end of the six months mission. It is shown that by using solid hydrogen, long-life operation is feasible with present technology.

Naes, L. G.↗

NASA NTRS1986

A feasibility assessment of nuclear reactor power system concepts for the NASA Growth Space Station

A preliminary feasibility assessment of the integration of reactor power system concepts with a projected growth Space Station architecture was conducted to address a variety of installation, operational, disposition and safety issues. A previous NASA sponsored study, which showed the advantages of Space Station - attached concepts, served as the basis for this study. A study methodology was defined and implemented to assess compatible combinations of reactor power installation concepts, disposal destinations, and propulsion methods. Three installation concepts that met a set of integration criteria were characterized from a configuration and operational viewpoint, with end-of-life disposal mass identified. Disposal destinations that met current aerospace nuclear safety criteria were identified and characterized from an operational and energy requirements viewpoint, with delta-V energy requirement as a key parameter. Chemical propulsion methods that met current and near-term application criteria were identified and payload mass and delta-V capabilities were characterized. These capabilities were matched against concept disposal mass and destination delta-V requirements to provide a feasibility of each combination.

Bloomfield, H. S.↗

NASA NTRS1987

A feasibility study of a hypersonic real-gas facility

A four month feasibility study of a hypersonic real-gas free flight test facility for NASA Langley Research Center (LARC) was performed. The feasibility of using a high-energy electromagnetic launcher (EML) to accelerate complex models (lifting and nonlifting) in the hypersonic, real-gas facility was examined. Issues addressed include: design and performance of the accelerator; design and performance of the power supply; design and operation of the sabot and payload during acceleration and separation; effects of high current, magnetic fields, temperature, and stress on the sabot and payload; and survivability of payload instrumentation during acceleration, flight, and soft catch.

Gully, J. H.↗

NASA NTRS1986

SRB/SLEEC (Solid Rocket Booster/Shingle Lap Extendible Exit Cone) feasibility study, volume 1

A preliminary design and analysis was completed for a SLEEC (Shingle Lap Extendible Exit Cone) which could be incorporated on the Space Transportation System (STS) Solid Rocket Booster (SRB). Studies were completed which predicted weights and performance increases and development plans were prepared for the full-scale bench and static test of SLEEC. In conjunction with the design studies, a series of supporting analyses were performed to assure the validity and feasibility of performance, fabrication, cost, and reliability for the selected design. The feasibility and required amounts of bench, static firing, and flight tests considered necessary for the successful incorporation of SLEEC on the Shuttle SRBs were determined. Preliminary plans were completed which define both a follow on study effort and a development program.

Baker, William H., Jr.↗

NASA NTRS1988

The optical field angle distortion calibration feasibility study for the Hubble Space Telescope fine guidance sensors

The results of an analytical study to investigate the feasibility of calibrating the Hubble Space Telescope's (HST's) fine guidance sensors (FGSs) within HST mission accuracy limits are presented. The study has two purposes: (1) to determine the mathematical feasibility of the optical field angle distortion (OFAD) calibration algorithm and (2) to confirm that the OFAD, plate scale, and FGS-to-FGS alignment calibration algorithms produced a calibration of the FGSs that satisfied mission requirements. The study concluded that the mathematical specification of the OFAD algorithm is adequate and permits a determination of the FGS calibration parameters (accurate to better than 0.003 arc-second) sufficient to meet the mission requirements. The algorithms implemented, the characteristics of the simulated data and procedures for data analysis, and the study's results are discussed. In addition, several useful techniques for improving the stability and accuracy of the OFAD solution are outlined.

Luchetti, K.↗