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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 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

Measurement of H2O and other trace gases in the stratosphere using a high resolution far-infrared spectrometer at 28 km

Data analysis results from the 1983 BIC 1 and 2 balloon flights are presented, with emphasis on H2O2, OH, HCL, O3, O2, and H2O. A 2 sigma limit on H2O2 abundance was set, as a function of altitude. This is comparable to or less than the theoretically predicted winter abundances from the 2-D models of Dupont, with a large enough summer maximum to facilitate concentration profile measurements. There is a definite drop in OH concentration from day to night following two model profiles. There was general agreement between HF measurements. The dominant role of the far wings of H2O lines in low altitude spectra was recognized. The strength of these wings exceeds that of many molecular line cores, including O3 and O2, especially near the long wavelength end of the spectra (100 cm (-1)). Newly measured positions for O3 and H2O were obtained.

Traub, W. A.↗
NASA NTRS1984

Incoherent scatter observations of an artificially modified ionosphere

The 'experiment of opportunity' to test incoherent scatter radar techniques for the diagnostic study of a chemically induced modification of the ionosphere occasioned by the launch of the HEAO-C satellite is described. The optimal utilization of a steerable incoherent scatter radar for a short duration event is examined. The choice of keeping the antenna fixed to obtain good control data and excellent time resolution along a given direction versus scanning the antenna to obtain mixed spatial and temporal morphologies is discussed. Results for fixed position measurements, elevation scans, ion-drift, and total electron content are presented. The first unambiguous observations of a gas expansion 'snowplow effect' is reported along with the derivation of local and height-integrated plasma recombination rates and the full spatial, temporal, and dynamical morphologies of a large-scale ionospheric hole.

Wand, R. H.↗
NASA NTRS1985

Detecting Cracks in Rough Metal Surfaces

Test based on eddy-current probe technique identifies cracks in swaged metals. Hinged collar with spring-loaded latch holds probe in place on part tested. For repeated measurements on same or similar parts, collar loosened and moved to various measuring positions. Method suitable for many kinds of metal parts, including swaged fittings, tubing, and pipes. Used for rapid crack/no-crack determinations in suspect parts already installed.

Zuver, N. T.↗
NASA NTRS1985

Multiple Scattering Effects in de/dx-E Instruments for Isotopic Composition Studies

The development of cosmic ray telescopes to separate individual isotopes of heavy elements using the dE/dx-vs.-E technique depends on the incorporation of precise trajectory sensing elements into these systems. In typical implementations the particle trajectory is derived from a set of position measurements made prior to a particle's entering the first energy loss detector. The use of the trajectory obtained in this way to correct energy loss signals for the actual pathlengths through the detectors depends on the assumption that the particle trajectory is a straight line. In order to resolve iron isotopes the angles of incidence, theta the particle track must be known rather accurately.

Wiedenbeck, M. E.↗
NASA NTRS1983

An imaging gas scintillation proportional counter for use in X-ray astronomy

An imaging gas scintillation proportional counter (GSPC) has been constructed for use in X-ray astronomy. The IGSPC consists of a gas scintillation proportional counter (GSPC) with a 1 micron polypropylene window coupled to a multiwire proportional counter (MWPC) via a calcium fluoride window. The MWPC, filled with a mixture of argon, methane, and tetrakis (dimethylamino) ethylene, detects the UV photons emitted by the xenon gas in the GSPC. The measured energy resolution is 17.0 percent (fwhm) and 8.0 percent (fwhm) at 1.5 keV and 5.9 keV, respectively. The measured position resolution is 1.9 mm (fwhm) and 0.9 mm (fwhm) at 1.5 and 5.9 keV, respectively. Possible astrophysical observations which can be performed with an IGSPC at the focal plane of a grazing incidence telescope are also discussed.

Hailey, C. J.↗
NASA NTRS1985

Images in the rocket ultraviolet - The initial helium abundance and distance modulus of the globular cluster M5 from photometry of horizontal-branch stars

A natural laboratory for the study of postmain-sequence evolution of low-mass (less than one solar mass) metal-poor stars is provided by globular clusters. These clusters are, therefore, a critical aid for developing an understanding of advanced stages of stellar evolution and of the chemical evolution of the Galaxy. Bohlin et al. (1983) have described a study of the postasymptotic branch star near the center of M5. The present investigation is concerned with the fainter horizontal-branch stars. The observations were made with the aid of a rocket-borne 38 cm f/9.0 Ritchey-Chretien telescope. Attention is given to payload and flight data, preflight bandpass calibration, the reduction of flight data, star selection, position measurement, photometry, the minimum observed horizontal-branch mass and inferences on mass loss, and individual UV-bright stars.

Bohlin, R. C.↗
NASA NTRS1986

Non-dynamic decimeter tracking of earth satellites using the Global Positioning System

A technique is described for employing the Global Positioning System (GPS) to determine the position of a low earth orbiter with decimeter accuracy without the need for user dynamic models. A differential observing strategy is used requiring a GPS receiver on the user vehicle and a network of six ground receivers. The technique uses the continuous record of position change obtained from GPS carrier phase to smooth position measurements made with pseudo-range. The result is a computationally efficient technique that can deliver decimeter accuracy down to the lowest altitude orbits.

Yunck, T. P.↗
NASA NTRS1986

Transonic airfoil calculations including wind tunnel wall-interference effects

The results of Reynolds-averaged time-dependent inviscid and turbulent compressible Navier-Stokes computations using the implicit finite-difference approach of Steger (1978), modified by incorporating a pressure boundary condition, (PBC) to account for wall interference are compared with experimental data on a NACA 64A010 airfoil (Johnson and Bachalo, 1980) in graphs and briefly characterized. The computational approach is the same as that used by King and Johnson (1980), but a 137 x 50 mesh is used instead of a 97 x 35 mesh, and special care is taken in resolving the nose, shock, and trailing-edge regions. Imposition of PBC is shown to improve significantly the accuracy of the computations for the flowfield on the upper surface of the airfoil, shifting the shock forward to its experimentally measured position in the case of turbulent flow. The failure of the method, even with PBC, to match the experimental shock location in the case of a flow with a separation bubble is attributed to inadequacies in the algebraic turbulence model employed (Baldwin and Lomax, 1978).

King, L. S.↗
NASA NTRS1987

Measuring and Plotting Surface-Contour Deviations

Hand-held device measures deviation of contour of surface from desired contour and provides output to x-y plotter. Carriage on device rolled along track representing desired contour, while spring-loaded stylus on device deflects perpendicularly to track to follow surface. Operator moves carriage of contour-measuring device on beamlike track. Stylus on carriage traces contour of surface above it. Carriage of measuring device holds transducer measuring cross-track displacement of surface from desired contour, and multiple-turn potentiometer measuring position along track.

Aragon, Lino A.↗
NASA NTRS1986

Long-term changes in reflectivity and larger scale motions in the atmospheres of Jupiter and Saturn

A multi-color, broad-band photographic program for monitoring atmospheric variability of Jupiter and Saturn with the 61-cm, f/75 telescope was continued. The archivial product consists of approximately 20 sequential images on 3 1/4 x 4 1/4 glass plates with a plate scale of 4.53 arc sec/mm. An eleven-step sensitometric wedge, recorded times of acquisition, and fiducial marks which determine the orientation of the plate, are recorded on each individual plate. This allows accurate positional measurements, as well as detailed relative surface brightness determinations. Detailed measurements of the Red Spot are being utilized in a study of zonal velocity variation and the ability to predict the longitude of the Red Spot during the Galileo mission. An ongoing 5-color series of Saturn has been maintained to map the seasonal changes in the belt-zone reflectivity. Digitization of a series of blue images containing the Red Spot and a series of red and blue images excluding the Red Spot are being processed and reduced to normalized surface brightness maps. This data is being utilized to map time-dependent brightness variations of selected features, belts, and ones.

Beebe, R. F.↗
NASA NTRS1987

Observational studies of Saturn's rings

Several noteworthy phenomena in Saturn's rings were investigated which have until now received an inadequate amount of attention. Among these are the periodic variation of the spokes in the B ring and eccentric features throughout the rings. One of the major discoveries by Voyager was the existence of eccentric features within the predominantly circular rings of Saturn. Several of these nonaxisymmetric features are narrow elliptical rings which share many characteristics with the rings of Uranus. In recent work, two narrow ringlets were added to the list of eccentric features in the rings of Saturn. Voyager imaging and occultation data are now in hand, as well as image-processing software which allows accurate absolute positional measurements to be made in Voyager imaging data. Work is in progress to re-examine this region of Saturn's rings and to study the possibility of a dynamical interaction between the outer B ring edge, the Huygens ringlet and the nearby Mimas 2:1 resonance. An understanding of the kinematics and dynamics of this region promises to yield important clues to a matter of great interest in both theoretical and observation ring studies.

Porco, Carolyn C.↗
NASA NTRS1986

NASA star simulator

A star simulator is described which is capable of simulating a field of three or more stars in response to signals from a computer interface. Star magnitude and spectral output can be manipulated and absolute position measurements can be obtained with the system. The simulator is a single axis system which consists of two assemblies: a light source and filter wheel assembly, and a translation stage assembly. The assemblies are self contained on 60.96 x 60.96 cm breadboards and are connected via three fiber optic cables. A summary of operational modes is provided.

Source record↗
NASA NTRS1986

Cosmic Background Explorer (COBE) transfer orbit attitude control system

The Cosmic Background Explorer (COBE) spacecraft will be launched by the Shuttle from Vandenberg AFB into a 300 km altitude, 99 deg inclination, 6 a.m. or 6 p.m. ascending node orbit. After release from the Remote Manipulator System (RMS) arm, an on-board monopropellant hydrazine propulsion system will raise the orbit altitude to 900 km. The spacecraft continuously spins during transfer orbit operations with the spin axis nominally horizontal and in or near the orbit plane. The blowdown propulsion system consists of twelve 5 lb thrusters (3 'spin', 3 'despin', and 6 'axial') with the latter providing initially 30 lb of force parallel to the spin axis for orbit raising. The spin/despin jets provide a constant roll rate during the transfer orbit phase of the mission and the axials control pitch and yaw. The axial thrusters are pulsed on for attitude control during coast periods and are normally on- and off-modulated for control during orbit raising. Attitude sensors employed in the control loops include an array of two-axis digital sun sensors and three planar earth scanners for position measurements, as well as six gyroscopes for rate information. System redundancy is achieved by means of unique three-axes-in-a-plane geometry. This triaxial concept results in a fail-safe operational system with no performance degradation for many different component failure modes.

Placanica, Samuel J.↗
NASA NTRS1982

Pilot selection and training

Personality and situational factors relevant to individual and group performance in highly demanding environments, such as those faced by astronauts or by jet transport crew, are discussed. It is emphasized that although technical competence and proficiency in pilot selection are prerequisites for safety, operating a modern jet transport is a group endeavor that requires the effective coordination of the entire crew. A self-report test battery for measuring positive and negative personality traits of pilot candidates, termed the Personal Characteristics Inventory, is described.

Helmreich, Robert L.↗
NASA NTRS1987

Interdiffusion in Ni-rich, Ni-Cr-Al alloys at 1100 and 1200 C. I - Diffusion paths and microstructures. II - Diffusion coefficients and predicted concentration profiles

Interdiffusion in Ni-rich Ni-Cr-Al alloys is investigated experimentally after annealing at 1100 and 1200 C using gamma/gamma, gamma/gamma+beta, gamma/gamma+gamma prime, and gamma/gamma+alpha diffusion couples. The amount and location of Kirkendall porosity suggests that Al diffuses more rapidly than Cr which diffuses more rapidly than Ni in the gamma phase of Ni-Cr-Al alloys. The location and extent of maxima and minima in the concentration profiles of the diffusion couples indicate that both cross-term diffusion coefficients are positive. Measurements are also presented of the ternary interdiffusion coefficients of the gamma phase in the Ni-Cr-Al system. It is shown that the interdiffusion coefficients can be accurately predicted by using a ternary finite-difference interdiffusion model.

Nesbitt, J. A.↗
NASA NTRS1987

The exploration of Halley's comet - An example of international cooperation

The history of international cooperation in studies of comets started with observations in 1577 and 1680, when Tycho Brahe and Newton, respectively, collected position measurements made in different countries to determine the paths of the comets observed. In the fall of 1979, a worldwide Comet Halley watch was proposed. As a result of international cooperation, Comet Halley was explored during its recent appearance from the ground, earth orbit, Venus orbit, interplanetary space, and from within the comet itself. The various activities in space were coordinated by the ESA, the USSR Intercosmos, the Japanese ISAS, and NASA, through the Inter-Agency Consultative Group. The activities of the ground-based observers were coordinated by the International Halley Watch.

Rahe, Jurgen H.↗
NASA NTRS1988

The polarization of the far-infrared radiation from the Galactic center

The first detection of linear polarization of the far-infrared (100-micron) radiation from the about 3-pc-diameter dust ring surrounding the galactic nucleus is reported. The percentage of polarization is between 1 and 2 percent at the three measured positions. It is argued that the polarized radiation is produced by thermal emission from elongated interstellar grains oriented by the local magnetic field. The dust ring is optically thin at 100 microns; therefore the observations sample dust through the entire depth of the cloud and are free of confusing effects due to embedded sources, scattering, or selective absorption. These data provide the first information about the configuration of the magnetic field in the dust ring.

Werner, M. W.↗