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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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NASA NTRS1992

Advanced Communications Technology Satellite (ACTS). Phase 1: Industrial/academic experimenters

This report presents the work done at Arizona State University under the ACTS Experimenters Program. The main thrust of the Program was to develop experiments to test, evaluate, and prove the commercial worthiness of the ACTS satellite which is scheduled for launch in 1993. To accomplish this goal, meetings were held with various governmental, industrial, and academic units to discuss the ACTS satellite and its technology and possible experiments that would generate industrial interest and support for ASU's efforts. Several local industries generated several experiments of their own. The investigators submitted several experiments of educational, medical, commercial, and technical value and interest. The disposition of these experimental proposals is discussed in this report.

Maisel, James E.↗
NASA NTRS1991

Interpretation of Voyager UVS observations of occultations by the atmosphere of Neptune

We propose to continue our investigation of the upper atmosphere of Neptune based primarily on the solar occultation measurements made by the Voyager Ultraviolet Spectrometer (UVS). The ultimate goal of this research is to understand the structure and composition of Neptune's upper atmosphere as encoded in the data base obtained by the UVS during the Voyager 2 encounter with Neptune. The UVS occultations provide information essential to studies of atmospheric composition and structure, energy balance, photochemistry, global transport, ionospheric structure, and airglow production mechanisms. In conjunction with other research in progress at the University of Arizona and by our colleagues at other institutions, we not only analyze and interpret individual measurements or observations by the UVS, but also construct models of the upper atmosphere which are consistent with all available data obtained by the UVS. We derive constraints from measurements of the atmospheric emissions and we combine these with constraints derived from the occultation measurements. Principal sources for the atmospheric emissions include dayglow, resonance scattering and, at long wavelengths, the reflected solar spectrum. On the dark side of the planet, a weak H Ly alpha emission is due to resonance scattering of the sky background and perhaps another source. Thus a wide range of physical processes are at work, and each provides its own constraints on the atmosphere.

Sandel, Bill R.↗
NASA NTRS1992

Crossflow Stability and Transition Experiments in a Swept-Wing Flow

An experimental examination of crossflow instability and transition on a 45 degree swept wing is conducted in the Arizona State University Unsteady Wind Tunnel. The stationary-vortex pattern and transition location are visualized using both sublimating-chemical and liquid-crystal coatings. Extensive hot-wire measurements are conducted at several measurement stations across a single vortex track. The mean and travelling-wave disturbances are measured simultaneously. Stationary-crossflow disturbance profiles are determined by subtracting either a reference or a span-averaged velocity profile from the mean-velocity data. Mean, stationary-crossflow, and travelling-wave velocity data are presented as local boundary-layer profiles and as contour plots across a single stationary-crossflow vortex track. Disturbance-mode profiles and growth rates are determined. The experimental data are compared to predictions from linear stability theory.

Dagenhart, John Ray↗
NASA NTRS1993

An extended supersonic combustion model for the dynamic analysis of hypersonic vehicles

The development of an advanced dynamic model for aeroelastic hypersonic vehicles powered by air breathing engines requires an adequate engine model. This report provides a discussion of some of the more important features of supersonic combustion and their relevance to the analysis and design of supersonic ramjet engines. Of particular interest are those aspects of combustion that impact the control of the process. Furthermore, the report summarizes efforts to enhance the aeropropulsive/aeroelastic dynamic model developed at the Aerospace Research Center of Arizona State University by focusing on combustion and improved modeling of this flow. The expanded supersonic combustor model described here has the capability to model the effects of friction, area change, and mass addition, in addition to the heat addition process. A comparison is made of the results from four cases: (1) heat addition only; (2) heat addition plus friction; (3) heat addition, friction, and area reduction, and (4) heat addition, friction, area reduction, and mass addition. The relative impact of these effects on the Mach number, static temperature, and static pressure distributions within the combustor are then shown. Finally, the effects of frozen versus equilibrium flow conditions within the exhaust plume is discussed.

Bossard, J. A.↗
NASA NTRS1993

Advanced electromagnetic methods for aerospace vehicles

The Advanced Helicopter Electromagnetics (AHE) Industrial Associates Program has continuously progressed with its research effort focused on subjects identified and recommended by the Advisory Task Force of the program. The research activities in this reporting period have been steered toward practical helicopter electromagnetic problems, such as HF antenna problems and antenna efficiencies, recommended by the AHE members at the annual conference held at Arizona State University on 28-29 Oct. 1992 and the last biannual meeting held at the Boeing Helicopter on 19-20 May 1993. The main topics addressed include the following: Composite Materials and Antenna Technology. The research work on each topic is closely tied with the AHE Consortium members' interests. Significant progress in each subject is reported. Special attention in the area of Composite Materials has been given to the following: modeling of material discontinuity and their effects on towel-bar antenna patterns; guidelines for composite material modeling by using the Green's function approach in the NEC code; measurements of towel-bar antennas grounded with a partially material-coated plate; development of 3-D volume mesh generator for modeling thick and volumetric dielectrics by using FD-TD method; FDTD modeling of horn antennas with composite E-plane walls; and antenna efficiency analysis for a horn antenna loaded with composite dielectric materials.

Balanis, Constantine A.↗
NASA NTRS1993

Effect of sound on boundary layer stability

Experiments are conducted in the Arizona State University Unsteady Wind Tunnel with a zero-pressure-gradient flat-plate model that has a 67:1 elliptical leading edge. Boundary-layer measurements are made of the streamwise fluctuating-velocity component in order to identify the amplified T-S waves that are forced by downstream-traveling sound waves. Measurements are taken with circular 3-D roughness elements placed at the Branch 1 neutral stability point for the frequency under consideration, and then with the roughness element downstream of Branch 1. These roughness elements have a principal chord dimension equal to 2 lambda(sub TS)/pi of the T-S waves under study and are 'stacked' in order to resemble a Gaussian height distribution. Measurements taken just downstream of the roughness (with leading-edge T-S waves, surface roughness T-S waves, instrumentation sting vibrations, and the Stokes wave subtracted) show the generation of 3-D T-S waves, but not in the characteristic heart-shaped disturbance field predicted by 3-D asymptotic theory. Maximum disturbance amplitudes are found on the roughness centerline. However, some near-field characteristics predicted by numerical modeling are observed.

Saric, William S.↗
NASA NTRS1991

A high-frequency, secondary instability of crossflow vortices that leads to transition

Three-dimensional boundary-layer transition experiments are currently being conducted on a 45 deg swept wing in the Arizona State University Unsteady Wind Tunnel. Crossflow-dominated transition is produced via a model with contoured end liners to simulate infinite swept-wing flow. Fixed-wavelength, stationary and travelling crossflow vortices are observed. The frequencies of the most amplified travelling waves are in agreement with linear-stability theory; however travelling waves at frequencies an order of magnitude higher than predicted are also observed near transition. Near the transition location, the distorted boundary layer is due to the stationary crossflow vortex and is subject to a Rayleigh-type instability in the stream direction. As a result, a high-frequency secondary instability is detected in the transition region and spatial relations of the process are well documented by coupled use of flow visualization and hot-wire measurements.

Kohama, Yasuaki↗
NASA NTRS1993

Effect of micron-sized roughness on transition in swept-wing flows

Boundary-layer transition-to-turbulence studies are conducted in the Arizona State University Unsteady Wind Tunnel on a 45-degree swept airfoil. The pressure gradient is designed so that the initial stability characteristics are purely crossflow-dominated. Flow visualization and hot-wire measurements show that the development of the crossflow vortices is influenced by roughness near the attachment-line. Comparisons of transition location are made between a painted surface, a machine-polished surface, and a hand-polished surface. Then, isolated 6 micron roughness elements are placed near the attachment line on the airfoil surface under conditions of the final polish (0.25 micron rms). These elements amplify a centered stationary crossflow vortex and its neighbors, resulting in localized early transition. The diameter, height, and location of these roughness elements are varied in a systematic manner. Spanwise hot-wire measurements are taken behind the roughness element to document the enhanced vortices. These scans are made at several different chord locations to examine vortex growth.

Radeztsky, Ronald H., Jr.↗
NASA NTRS1983

Si:Bi array detectors and astronomical applications of the Goddard 10 micron camera

An improved 4 to 18 micron array camera system was developed at NASA Goddard SFC for astronomical photometry, using an Aerojet Electro Systems Corp. 16 x 16 Si:Bi accumulation mode charge injection device (AMCID) which could be suitable for eventual low-background spaceflight applications. An astronomical observing program using this device was carried out as a collaboration between NASA Goddard (Infrared and Radio Astronomy Branch and Micro Electronics Branch), the Harvard/Smithsonian Center for Astrophysics, and Steward Observatory of the University of Arizona. In 1983 the camera system was revised, and a new Aeroject Si:Bi array with 16 x 16 active pixels was obtained from NASA/Ames Research Center as part of a new scientific collaboration between the Ames and Goddard infrared array research groups. The 16 x 16 device had sufficiently good sensitivity, uniformity and noise characteristics to be used for successful observations at the Mt. Lemmon 60 and 61 inch telescopes in May 1983. Complete laboratory characterization of the 16 x 16 array was carried out in summer of 1983. Initial results indicate that this detector has sensitivity and noise characteristics comparable to other devices from the same generation of Aerojet arrays.

Lamb, Gerald↗
NASA NTRS1988

Autonomous space processor for orbital debris removal and flame augmentation additives in scramjets for the National Aerospace Plane

This is a brief description of the USRA-sponsored design project at the University of Arizona. Approximately eighty-percent of this effort was spent pursuing a novel engineering concept for the in-situ processing of orbital debris utilizing resources available in low Earth orbit (LEO); the other twenty-percent was devoted to discovering innovative additives for the anchoring of supersonic combustion zones that find direct use in the Aerospace Plane that is expected to use scramjets. The seriousness of the orbital debris problem is briefly described. Available 'solutions' are outlined from the literature. The engineering design is briefly mentioned, with an emphasis on the positive aspects of the space environment that should be used in an economical approach. The aspects of operating in microgravity, vacuum, and in utilizing solar energy are mentioned. A quantitative computer animation was developed to provide design data. Three specific dead spacecraft were identified for an initial cleanup mission. The design concept, which includes a solar processor, remote arm manipulators, and the gradual processing of the debris, is also described. This is followed by a description of hardware construction. Operation and actual processing of simulated debris parts (aluminum, for now) are demonstrated in the NASP task, construction of the new design for measuring the radiation from the key free radicals (as enhanced by the additives) is described. Immediate (1988) and long-range (through 1992) future plans are shown to clearly indicate the full engineering design strategy in the light of the national space program thrusts.

Source record↗
NASA NTRS1990

Planetary astronomy of Mars. Mars data reduction

Grant #NAGW-1408 was specifically awarded to obtain telescopic visible and near-IR spectral imaging of Mars during the 1988 apparition (9/28/88). The observing program was highly successful producing approximately 2 Gbytes of data, but was only funded for one year and virtually all of the funds were spent in data acquisition. The follow-up grant was funded the following year for reduction of these data into a scientifically productive form, which because of the size and nature of our observations, was a non-trivial task. A more detailed scientific analysis of these data (fully reduced) is in progress now and will take a number of years. Extended geologic analyses of the astronomical data are being funded by the NASA Planetary Geology and Geophysics program. The objective was to produce detailed reflectance spectra for contiguous, spatially resolved surface elements covering most of the planet (about +50 degrees to -90 degrees latitude, all longitudes). A total of 6 observing runs, of 3-4 days duration each, were conducted on the University of Arizona's 1.5m telescope on Mt. Bigelow. We present a sketch map showing the approximate total extent of our spectral image coverage. Nearly all of Mars south of 40 degrees N was observed at least once. About half of the area shown was observed multiple times. South of 65 degrees S, including the south polar cap, our coverage is heavily redundant. The first run was conducted June 29 - July 1, 1988 (all dates are UT) to serve as a baseline prior to possible dust storm activity on Mars. The other observing runs were closer to opposition: Sept. 3-6, 13-15, 24-26, and Oct. 5-7 and 16-18. The September and October observations were scheduled to provide maximum longitudinal coverage. This was also intended to provide a balance between surface observations and observations of predicted dust storm activity. No global dust storm developed in 1988, so we have a large volume of data for the surface of Mars.

Singer, Robert B.↗
NASA NTRS1993

High speed transition prediction

The main objective of this work period was to develop, maintain and exercise state-of-the-art methods for transition prediction in supersonic flow fields. Basic state and stability codes, acquired during the last work period, were exercised and applied to calculate the properties of various flowfields. The development of a code for the prediction of transition location using a currently novel method (the PSE or Parabolized Stability Equation method), initiated during the last work period and continued during the present work period, was cancelled at mid-year for budgetary reasons. Other activities during this period included the presentation of a paper at the APS meeting in Tallahassee, Florida entitled 'Stability of Two-Dimensional Compressible Boundary Layers', as well as the initiation of a paper co-authored with H. Reed of the Arizona State University entitled 'Stability of Boundary Layers'.

Gasperas, Gediminis↗
NASA NTRS1992

Autonomous space processor for orbital debris advanced design project in support of solar system exploration

This paper is regarding a project in the Advanced Design Program at the University of Arizona. The project is named the Autonomous Space Processor for Orbital Debris (ASPOD) and is a NASA/Universities Space Research Association (USRA) sponsored design project. The development of ASPOD and the students' abilities in designing and building a prototype spacecraft are the ultimate goals of this project. This year's focus entailed the development of a secondary robotic arm and end-effector to work in tandem with an existent arm in the removal of orbital debris. The new arm features the introduction of composite materials and a linear drive system, thus producing a light-weight and more accurate prototype. The main characteristic of the end-effector design is that it incorporates all of the motors and gearing internally, thus not subjecting them to the harsh space environment. Furthermore, the arm and the end-effector are automated by a control system with positional feedback. This system is composed of magnetic and optical encoders connected to a 486 PC via two servo-motor controller cards. Programming a series of basic routines and sub-routines has allowed the ASPOD prototype to become more autonomous. The new system is expected to perform specified tasks with a positional accuracy of 0.5 cm.

Ramohalli, Kumar↗
NASA NTRS1994

Thermal emission measurements (5-25 microns) of Hawaiian palagonitic soils with implications for Mars

Careful laboratory studies have shown that the coloring agent in Mars analog Hawaiian palagonitic soils is nanophase iron oxide. We have measured the emissivity of two Mauna Kea palagonitic soils whose transmission spectra exhibit different spectral features and of a thermally-altered volcanic tephra sample that exhibits a wide range of crystallinity and degree of alteration (from black cinders to fully hematitic). Both of these samples may represent analogs for formation mechanisms involving the production of highly-altered secondary weathering products on Mars. The emission spectra of all samples were measured at the TES spectroscopy laboratory at Arizona State University. The data were converted to emissivity using blackbody measurements combined with measurements of each sample at different temperatures.

Roush, Ted L.↗
NASA NTRS1994

Thermal emission measurements (5-25 microns) of palagonite/Fe-substituted montmorillonite intimate mixtures: Applications to Mars

The emissivity of a Mauna Kea palagonitic soil mixed with an Fe-substituted montmorillonite (FeM) was measured. The emission spectra of all samples were measured at the TES spectroscopy laboratory at Arizona State University. The data were converted to emissivity using blackbody measurements combined with measurements of each sample at different temperatures. This preliminary study has demonstrated that both naturally-occurring palagonites, thought to be good visible to near-IR spectral analogs for Mars, and FeM exhibit complex emissivity spectra at thermal wavelengths. FeM exhibits greater emissivity variations than palagonite, and emissivity peaks observed in the FeM spectrum allows its identification for abundances greater than or equal to 15 percent when mixed with palagonite. Smaller abundances of FeM are potentially identifiable when mixed with palagonite, but this remains to be determined.

Roush, Ted L.↗
NASA NTRS1994

The future of large format HgCdTe arrays for astronomy

Rockwell has developed the 256 x 256 Near Infrared Camera and Multi-Object Spectrometer 3 (NICMOS3) FPA for the Hubble Space Telescope under funding from NASA through the University of Arizona. Since 1989, dozens of science grade devices have been delivered to astronomers throughout the world for ground based infrared observations. These devices have excellent sensitivity at 77 K with mean dark currents of 0.1 e(-)/s, noise of 25 e(-), and quantum efficiency of 55-70%. Pixel yields as high as 99.9% have been achieved. Our present plans are to develop a 1024 x 1024 focal plane array (FPA) with 2.5 micron cutoff and make it available to astronomers. Such large arrays are made possible by the advances in detector material size (3 in. diameter producible alternative to CdTe for epitaxy (PACE-I) wafers), multiplexer advances (ability to verify the design in detail and availability of advanced foundries), and novel hybridization and reliability approaches.

Vural, K.↗
NASA NTRS1994

The size and shape of the near-Earth asteroid belt

Evidence was recently reported for the existence of a near-Earth belt of small, Earth-approaching asteroids (SEAs) with diameters less than approximately 50 m. This result was based upon observations made with the Spacewatch Telescope of the University of Arizona during the course of an ongoing search for Earth-approaching asteroids. Using a model to describe the effects of observational bias, it was shown that the orbits observed for SEAs are inconsistent with the orbits of Earth approaches larger than approximately 1 km, and imply a relatively high fraction of Earth-like orbits among the SEAs. In this paper, new observations are included and the bias model is extended in order to quantify the number of SEAs within the near-Earth belt and to further constrain their orbital distribution. The calculation shows that relative to larger Earth approachers. SEAs are deficient in Aten-type orbits for which the semimajor axis is less than 1.0 AU. Instead, nearly all SEAs with aphelia less than 1.4 AU (5 +/- 3% of the total population) have perihelia between 0.9 and 1.1 AU, thus defining a near-Earth belt. Those SEAs with aphelia greater than 1.4 AU, however, have a distribution of orbits that are indistinguishable from the orbits of larger Earth approachers. Taking the near-Earth belt into account does not significantly alter the previously determined enhancement in the number of SEAs the previously determined enhancement in the number of SEAs compared to an extrapolation of the number of larger Earth approachers. At approximately 10 m, the enhancement factor is 40 to within a factor of 2. Also, the RMS impact velocity of SEAs with Earth (17 km/sec) is nearly the same as for larger Earth approachers (18 km/sec).

Rabinowitz, David L.↗