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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 271 records · Page 15

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NASA NTRS1987

Nitrogen recombination on high-temperature reusable surface insulation and the analysis of its effect on surface catalysis

The energy transfer catalytic recombination coefficients for nitrogen and oxygen on a borosilicate glass are determined in nitrogen and air hypersonic arc jet streams. These data, obtained from a reacting boundary-layer analysis with first-order surface reaction kinetics, compare well with earlier results from a Goulard frozen boundary-layer model up to 1600 K. The apparent surface recombination rates increase up to 1600 K, then begin to decrease. To illustrate the effects of temperature and nitrogen dissociation on energy transfer to the glass, a diffusional heat-flux is calculated using the present results from 1450 K up to 1850 K. This diffusional heat-flux is the contribution to the total heating rate by atom recombination, and is used to compare the present results with coefficients from three previous studies.

Kolodziej, Paul↗

NASA NTRS1988

Generation of a crowned pinion tooth surface by a surface of revolution

A method of generating crowned pinion tooth surfaces using a surface of revolution is developed. The crowned pinion meshes with a regular involute gear and has a prescribed parabolic type of transmission errors when the gears operate in the aligned mode. When the gears are misaligned the transmission error remains parabolic with the maximum level still remaining very small (less than 0.34 arc sec for the numerical examples). Tooth contact analysis (TCA) is used to simulate the conditions of meshing, determine the transmission error, and determine the bearing contact.

Litvin, F. L.↗

NASA NTRS1988

Relationships between near-surface plankton concentrations, hydrography, and satellite-measured sea surface temperature

Sea surface temperatures (SSTs) mapped by IR satellite images and in situ hydrographic measurements off the west coast of British Columbia for early-winter and midsummer periods were correlated with in situ measurements of surface chlorophyll and zooplankton concentration. Correlations between winter log(e) transformed zooplankton concentrations and SSTs demonstrated that IR satellite imagery could explain 49 percent of the sampled zooplankton concentration variance. A least-squares-fit nonlinear equation showed that satellite-measured SST patterns explained 72 percent of the log(e) transformed chlorophyll variance. However, summer zooplankton concentrations were not consistently related to satellite temperature patterns.

Thomas, A. C.↗

NASA NTRS1988

Crowned spur gears - Methods for generation and Tooth Contact Analysis. II - Generation of the pinion tooth surface by a surface of revolution

A method for generation of crowned pinion tooth surfaces using a surface of revolution is developed. The crowned pinion meshes with a regular involute gear and has a prescribed parabolic type of transmission errors when the gears operate in the aligned mode. When the gears are misaligned the transmission error remains parabolic with the maximum level still remaining very small (less than 0.34 arc second for the numerical examples). Tooth Contact Analysis (TCA) is used to simulate the conditions of meshing, determine the transmission error, and the bearing contact.

Litvin, F. L.↗

NASA NTRS1991

Theoretical characterization of the potential energy surface for the reversible reaction H + O2 yields HO2(asterisk) yields OH + O. III - Computed points to define a global potential energy surface

Computed energies and geometries are reported which, combined with previously published calculations, permit a global representation of the potential energy surface for the reaction H + O2 yields HO2(asterisk) yields OH + O. These new calculations characterize the potential energy surface (PES) for all H atom angles of approach to O2 and for the region of the inner repulsive wall. The region of the T-shaped H-O2 exchange saddle point is connected with the constrained energy minimum (CEM) path, and a new collinear H-O2 exchange saddle point is characterized which lies only 9 kcal/mol above the H + O2 asymptote. A vibrational analysis which utilizes local cubic and quartic polynomial representations of the PES along the CEM path has been carried out. Optimal geometries, energies, and harmonic frequencies are reported along with anharmonic analyses for the O2 and OH asymptotes and for the HO2 minimum region of the PES.

Walch, Stephen P.↗

NASA NTRS1991

A new surface impedance function for the aperture surface of a conducting body with a dielectric-filled cavity

A surface impedance function (SIF) appropriate for use on the aperture surface of a conducting body with a dielectric-filled cavity, is presented. Unlike the usual SIFs that might be used on an aperture, this SIF takes into account not only the wave transmitted through the aperture but also the wave reflected from the inside of the cavity the shape of the aperture and cavity, and the polarization and direction of the incident wave. The SIF is derived heuristically from the series-reflection solution for a plane wave normally incident on an infinite flat conducting plate with a flat dielectric coating. The SIF was developed and used in a combined method of moments (MM) solution for the scattered fields due to an incident plane wave. This combined technique greatly reduces the number of current expansion coefficients to be determined using the method of moments and hence also reduces the number of impedance elements required for calculation in the method of moments. Application of the SIF in a combined method is illustrated for a two-dimensional object.

Goggans, Paul M.↗

NASA NTRS1990

Robotic lunar surface operations: Engineering analysis for the design, emplacement, checkout and performance of robotic lunar surface systems

The assembly, emplacement, checkout, operation, and maintenance of equipment on planetary surfaces are all part of expanding human presence out into the solar system. A single point design, a reference scenario, is presented for lunar base operations. An initial base, barely more than an output, which starts from nothing but then quickly grows to sustain people and produce rocket propellant. The study blended three efforts: conceptual design of all required surface systems; assessments of contemporary developments in robotics; and quantitative analyses of machine and human tasks, delivery and work schedules, and equipment reliability. What emerged was a new, integrated understanding of hot to make a lunar base happen. The overall goal of the concept developed was to maximize return, while minimizing cost and risk. The base concept uses solar power. Its primary industry is the production of liquid oxygen for propellant, which it extracts from native lunar regolith. Production supports four lander flights per year, and shuts down during the lunar nighttime while maintenance is performed.

Woodcock, Gordon R.↗

NASA NTRS1990

Comparison of Surface Radiation Budget Satellite algorithms for downwelled shortwave irradiance with Wisconsin Fire/SRB surface-truth data

Surface radiation instruments were operated at various locations during the Wisconsin First ISSCP (International Satellite Cloud Climatology Project) Regional Experiment (FIRE) and Surface Radiation Budget (SRB) experiment in October 1986. Satellite data were distributed to scientists who had previously developed satellite algorithms to estimate downwelled shortwave irradiance. Results of intercomparison of ground-truth values with the satellite-derived estimates are described.

Whitlock, C. H.↗

NASA NTRS1993

Thermal-infrared emission spectroscopy of natural surfaces: Application to coated surfaces

Thermal-infrared vibrational spectroscopy has great potential for remotely determining the composition of planetary surface materials by taking advantage of fundamental molecular vibrational modes that produce spectral features in the range from approximately 3 to greater than 50 microns. Much of the current interest in the thermal infrared wavelength region stems from the deployment of multispectral scanners, such as the Thermal Infrared Multispectral Scanner (TIMS) and the Mars Observer Thermal Emission Spectrometer (TES). In order to support these missions, it is necessary to develop an appropriate library of laboratory measurements. The purpose of this work was to develop a technique which, with a very limited set of assumptions, can be used to determine the emissivity of natural surfaces directly by using emitted energy.

Christensen, Philip R.↗

NASA NTRS1994

Experimental measurements and analytical analysis related to gas turbine heat transfer. Part 1: Time-averaged heat-flux and surface-pressure measurements on the vanes and blades of the SSME fuel-side turbine and comparison with prediction. Part 2: Phase-resolved surface-pressure and heat-flux measurements on the first blade of the SSME fuel-side turbine

Time averaged Stanton number and surface-pressure distributions are reported for the first-stage vane row, the first stage blade row, and the second stage vane row of the Rocketdyne Space Shuttle Main Engine two-stage fuel-side turbine. Unsteady pressure envelope measurements for the first blade are also reported. These measurements were made at 10 percent, 50 percent, and 90 percent span on both the pressure and suction surfaces of the first stage components. Additional Stanton number measurements were made on the first stage blade platform blade tip, and shroud, and at 50 percent span on the second vane. A shock tube was used as a short duration source of heated and pressurized air to which the turbine was subjected. Platinum thin-film heat flux gages were used to obtain the heat flux measurements, while miniature silicon-diaphragm flush-mounted pressure transducers were used to obtain the pressure measurements. The first stage vane Stanton number distributions are compared with predictions obtained using a version of STAN5 and a quasi-3D Navier-Stokes solution. This same quasi-3D N-S code was also used to obtain predictions for the first blade and the second vane.

Source record↗

NASA NTRS1994

Modelling of Surfaces. Part 1: Monatomic Metallic Surfaces Using Equivalent Crystal Theory

We present a detailed description of equivalent crystal theory focusing on its application to the study of surface structure. While the emphasis is in the structure of the algorithm and its computational aspects, we also present a comprehensive discussion on the calculation of surface energies of metallic systems with equivalent crystal theory and other approaches. Our results are compared to experiment and other semiempirical as well as first-principles calculations for a variety of fcc and bcc metals.

Bozzolo, Guillermo↗

NASA NTRS1993

Lunar surface operations. Volume 3: Robotic arm for lunar surface vehicle

A robotic arm for a lunar surface vehicle that can help in handling cargo and equipment, and remove obstacles from the path of the vehicle is defined as a support to NASA's intention to establish a lunar based colony by the year 2010. Its mission would include, but not limited to the following: exploration, lunar sampling, replace and remove equipment, and setup equipment (e.g. microwave repeater stations). Performance objectives for the robotic arm include a reach of 3 m, accuracy of 1 cm, arm mass of 100 kg, and lifting capability of 50 kg. The end effectors must grip various sizes and shapes of cargo; push, pull, turn, lift, or lower various types of equipment; and clear a path on the lunar surface by shoveling, sweeping aside, or gripping the obstacle present in the desired path. The arm can safely complete a task within a reasonable amount of time; the actual time is dependent upon the task to be performed. The positioning of the arm includes a manual backup system such that the arm can be safely stored in case of failure. Remote viewing and proximity and positioning sensors are incorporated in the design of the arm. The following specific topic are addressed in this report: mission and requirements, system design and integration, mechanical structure, modified wrist, structure-to-end-effector interface, end-effectors, and system controls.

Shields, William↗

NASA NTRS1994

Observations, models, and mechanisms of failure of surface rocks surrounding planetary surface loads

Geophysical models of flexural stresses in an elastic lithosphere due to an axisymmetric surface load typically predict a transition with increased distance from the center of the load of radial thrust faults to strike-slip faults to concentric normal faults. These model predictions are in conflict with the absence of annular zones of strike-slip faults around prominent loads such as lunar maria, Martian volcanoes, and the Martian Tharsis rise. We suggest that this paradox arises from difficulties in relating failure criteria for brittle rocks to the stress models. Indications that model stresses are inappropriate for use in fault-type prediction include (1) tensile principal stresses larger than realistic values of rock tensile strength, and/or (2) stress differences significantly larger than those allowed by rock-strength criteria. Predictions of surface faulting that are consistent with observations can be obtained instead by using tensile and shear failure criteria, along with calculated stress differences and trajectories, with model stress states not greatly in excess of the maximum allowed by rock fracture criteria.

Schultz, R. A.↗

NASA NTRS1959

Tire-to-Surface Friction-Coefficient Measurements with a C-123B Airplane on Various Runway Surfaces

An investigation was conducted to obtain information on the tire-to-surface friction coefficients available in aircraft braking during the landing run. The tests were made with a C-123B airplane on both wet and dry concrete and bituminous pavements and on snow-covered and ice surfaces at speeds from 12 to 115 knots. Measurements were made of the maximum (incipient skidding) friction coefficient, the full-skidding (locked wheel) friction coefficient, and the wheel slip ratio during braking.

Sawyer, Richard H.↗

NASA NTRS1997

The Planet Mercury Surface Spectroscopy and Analysis from the Kuiper Airborne Observatory and Analysis and Modeling to Determine Surface Composition

We had two successful flights to observe Mercury from the Kuiper Airborne Observatory (KAO) using High-efficiency Infrared Faint-Object Grating Spectrograph (HIFOGS). Flights were May 8, 1995 (eastern elongation) and July 6, 1995 (western elongation) For the observations one half of the primary mirror was covered to prevent sunlight from entering the telescope. All equipment and the airplane and its crew performed well. These flights were historical firsts for the KAO and for spectroscopy of Mercury in that it was the first time any spectroscopic observations of Mercury from above the Earth's atmosphere had been made. It was the first time the KAO had been used to @bserve an object less than 30 degrees from the Sun. Upon completion of the basic data reduction it became obvious that extensive modeling and analysis would be required to understand the data. It took three years of a graduate student's time and part time the PI to do the thermal modeling and the spectroscopic analysis. This resulted in a lengthy publication. A copy of this publication is attached and has all the data obtained in both KAO flights and the results clearly presented. Notable results are: (1) The observations found an as yet unexplained 5 micron emission enhancement that we think may be a real characteristic of Mercury's surface but could have an instrumental cause; (2) Ground-based measurements or an emission maximum at 7.7 microns were corroborated. The chemical composition of Mercury's surface must be feldspathic in order to explain spectra features found in the data obtained during the KAO flights.

Sprague, Ann↗

NASA NTRS2001

MSFC Surface Metrology (Surface Morphology)

NASA's Surface Metrology is presented in viewgraph form. The topics include: 1) Facilities/Major Equipment; 2) Taylor Hobson NanoStep II; 3) Topometrix; and 4) Surface Metrology Applications.

Shapiro, Alan P.↗

NASA NTRS2002

Estimating the Ocean Flow Field from Combined Sea Surface Temperature and Sea Surface Height Data

This project was part of a previous grant at MIT that was moved over to the Scripps Institution of Oceanography (SIO) together with the principal investigator. The final report provided here is concerned only with the work performed at SIO since January 2000. The primary focus of this project was the study of the three-dimensional, absolute and time-evolving general circulation of the global ocean from a combined analysis of remotely sensed fields of sea surface temperature (SST) and sea surface height (SSH). The synthesis of those two fields was performed with other relevant physical data, and appropriate dynamical ocean models with emphasis on constraining ocean general circulation models by a combination of both SST and SSH data. The central goal of the project was to improve our understanding and modeling of the relationship between the SST and its variability to internal ocean dynamics, and the overlying atmosphere, and to explore the relative roles of air-sea fluxes and internal ocean dynamics in establishing anomalies in SST on annual and longer time scales. An understanding of those problems will feed into the general discussion on how SST anomalies vary with time and the extend to which they interact with the atmosphere.

Stammer, Detlef↗

NASA NTRS2004

Analyses of IR-Stealthy and Coated Surface Materials: A Comparison of LIBS and Reflectance Spectra and Their Application to Mars Surface Exploration

Identification of non-silicate samples on Mars, such as carbonates, sulfates, nitrates, or evaporites in general, is important because of their association with aqueous processes and their potential as exobiology sites. Infrared (IR) and thermal emission (TE) spectroscopy have been considered the primary tools for remote identification of these minerals. This includes current and future orbital assets such as TES on MGS, THEMIS on Mars Odyssey, OMEGA on Mars Express, CRISM on MRO, and now the Mini-TES on the MER rovers. While reflectance and emission spectroscopy have clearly been the method of choice for these missions, the technique is not always successful in mineral identifications due to dust, surface weathering chemistry, coatings, or surface texture. Here we describe and show IR spectra of several such samples, and then report on the relative success of LIBS analyses in determining the rock type.

Wiens, R. C.↗