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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 613 records · Page 34
All sourcesNASA NTRSDOE OSTI
NASA NTRS1994

The EMSS catalog of X-ray-selected clusters of galaxies. 1: An atlas of CCD images of 41 distant clusters

An atlas of deep, wide-field R-band charge coupled device (CCD) images of a complete sample of distant, X-ray-selected clusters of galaxies is presented. These clusters are the 41 most distant (z is greater than or equal to 0.15) and most X-ray-luminous (L(sub x) is greater than or equal to 2 x 10(exp 44) ergs/s) clusters in the Einstein Observatory Extended Medium Sensitivity Survey (EMSS) catalog that are observable from Mauna Kea (delta is greater than -40 deg). The sample spans a redshift range of 0.15 is less than or equal to z is less than or equal to 0.81 and includes at least two and possibly as many as six rich clusters with z is greater than 0.5. For the most part, the data are of superior quality, with a median seeing of 0.8 sec full width half-maximum (FWHM) and coverage of at least 1 Mpc x 1 Mpc in the cluster frame (H(sub 0) = 50; q(sub 0) = 1/2). In addition, we update the available optical, X-ray, and radio data on the entire EMSS sample of 104 clusters. We outline the cluster selection criteria in detail and emphasize that X-ray-selected cluster samples may prove to be more useful for cosmological studies than optically selected samples. The EMSS cluster sample in particular can be exploited for diverse cosmological investigations, as demonstrated by the detection of evolution in the X-ray luminosity function previously reported, and more recently by the discovery of a large number of gravitationally lensed images in these clusters.

Gioia, I. M.↗
NASA NTRS1987

Ion-molecule calculation of the abundance ratio of CCD to CCH in dense interstellar clouds

Laboratory measurements and calculations have been performed to determine the abundance ratio of the deuterated ethynyl radical (CCD) to the normal radical (CCH) which can be achieved in dense interstellar clouds via isotopic fractionation in the C2H2(+) (HD)=C2HD(+)(H2) system of reactions. According to this limited treatment, the CCD/CCH abundance ratio which can be attained is in the range 0.02-0.03 for the Orion molecular cloud and 0.0l-0.02 for TMC-1. These ranges of numbers are in reasonable agreement with the observed values in Orion and TMC-1. However, the analysis of the CCD/CCH abundance ratio is complicated via the presence of competing fractionation mechanisms, especially in the low-temperature source TMC-1.

Herbst, Eric↗
NASA NTRS1988

The flight test of a grazing incidence relay optics telescope for solar X-ray astronomy utilizing a thinned, back-illuminated CCD detector

The new AS&E Ultrahigh Resolution Soft X-ray Solar Research Rocket Payload has been successfully flown twice on Black Brant IX Sounding Rockets from White Sands Missile Range. These flights, conducted on 15 August 1987 and 11 December 1987, provided the first test of the new payload which consists of 3.8X magnifying hyperboloid-hyperboloid grazing incidence relay optic used in conjunction with an existing Wolter-I primary mirror. An RCA SID 500 series CCD detector was utilized in a thinned, back-illuminated configuration for recording the images. The 5.4 m effective focal length of the compound optics system resulted in a plate scale of 1 arc second per pixel which is comparable to the inherent resolution of the primary mirror. These flights represent the first use in X-ray astronomy of either of these two new technologies. These observations are presented with comparison to laboratory measurements and theoretical expectations of the instrument performance.

Moses, J. Daniel↗
NASA NTRS1989

Autonomous star referenced attitude determination

A general star pattern recognition algorithm has been used to develop JPL's redundant, microcomputer-equipped ASTROS II CCD star tracker into a full-sky autonomous star tracker (FAST), capable of determining its attitude about all three axes without requiring any a priori attitude knowledge. A large field of view allows the number of guide stars in the all-sky data-base of the tracker to be limited to a manageable number, while high accuracy ensures that the pattern formed by the observed guide stars is unique. The recognition algorithm can also be used for automating the acquisition of celestial targets by astronomy telescopes, for autonomously updating the attitude of gyro-based attitude control systems, and for automating ground-based attitude recognition. Using both Monte Carlo simulations and a quasi-analytical method, it is shown that the general recognition algorithm and a less software-intensive special algorithm can be used to reliably automate the acquisition of celestial targets by astronomy telescopes.

Van Bezooijen, R. W. H.↗
NASA NTRS1991

Laboratory investigation of visible shuttle glow mechanisms

Laboratory experiments designed to uncover mechanistic information about the spectral and spatial characteristics of shuttle glow were conducted. The luminescence was created when a pulse of O atoms traveling at orbital velocities was directed toward NO molecules previously adsorbed to aluminum, nickel, and Z306 Chemglaz (a common baffle black) coated surfaces held at various temperatures. Spectral and spatial measurements were made using a CCD imaging spectrometer. Corroborative spectral information was recorded in separate measurements using a scanning monochromator and gated photomultiplier arrangement. The e-folding distance at several temperatures was calculated from images of the surface glow using the photometrics image processing capability of the imaging spectrometer. The e-folding distance was not altered as a function of incoming O beam velocity. The results are presented and the observations provide direct evidence that the visible shuttle glow results from recombination of oxygen atoms and surface bound NO.

Leone, A.↗
NASA NTRS1997

High Speed CCD Photometry of the P/Shoemaker-Levy 9-Jupiter Collision

Using the National Solar Observatory 64-inch Vacuum Tower Telescope at Sacramento Peak, we have obtained high spatial and time resolution images of Jupiter in the visible continuum at 5000 A, in the 7250 A and 8900 A methane bands, plus their adjacent continuum bands (at 7500 A and 9500 A), before, during, and after the times of the collisions. In addition, with the use of a beam splitter, near-IR images (J-band) were also obtained simultaneously with a 256 x 256 NICMOS chip. The observations spanned the time period 14 - 25 July 1994, at intervals of several hours each day, depending on the weather and the visibility of Jupiter. The original proposal was to use the data to track the evolution of the impact clouds produced by impacts from comet Shoemaker-Levy 9. We are still refining the automated data analysis software and finalizing the calibration of the images. The latter is an arduous problem since many of the images were made in daylight. We expect to finish these two tasks in early 1998, whereupon the analysis will proceed very quickly. Our goals remain unchanged. We will use lightcurves of the impact sites for the following goals: (1) to monitor and understand the time variability of the optical depths of the impact clouds; (2) to monitor and understand the time variability of the masses of the impact clouds; (3) to monitor the wind speeds in the upper atmosphere of Jupiter.

Source record↗
NASA NTRS1999

Science Observations of Deep Space One

During the Deep Space One (DS1) primary mission, the spacecraft will fly by asteroid 1992 KD and possibly comet Borrelly. There are two technologies being validated on DS1 that will provide science observations of these targets, the Miniature Integrated Camera Spectrometer (MICAS) and the Plasma Experiment for Planetary Exploration (PEPE). MICAS encompasses a camera, an ultraviolet imaging spectrometer and an infrared imaging spectrometer. PEPE combines an ion and electron analyzer designed to determine the three-dimensional distribution of plasma over its field of view. MICAS includes two visible wavelength imaging channels, an ultraviolet imaging spectrometer, and an infrared imaging spectrometer all of which share a single 10-cm diameter telescope. Two types of visible wavelength detectors, both operating between about 500 and 1000 nm are used: a CCD with 13-microrad pixels and an 18-microrad-per-pixel, metal-on-silicon active pixel sensor (APS). Unlike the CCD the APS includes the timing and control electronics on the chip along with the detector. The UV spectrometer spans 80 to 185 nm with 0.64-nm spectral resolution and 316-microrad pixels. The IR spectrometer covers the range from 1200 to 2400 nm with 6.6-nm resolution and 54-microrad pixels PEPE includes a very low-power, low-mass micro-calorimeter to help understand plasma-surface interactions and a plasma analyzer to identify de individual molecules and atoms in the immediate vicinity of the spacecraft that have been eroded off the surface of asteroid 1992 KD. It employs common apertures with separate electrostatic energy analyzers. It measures electron and ion energies spanning a range of 3 eV to 30 keV, with a resolution of five percent. and measures ion mass from one to 135 atomic mass units with 5 percent resolution. It electrostatically sweeps its field of view both in elevation and azimuth. Both MICAS and PEPE represent a new direction for the evolution of science instruments for interplanetary spacecraft. These two instruments incorporate a large fraction of the capability of five instruments that had typically flown on NASA's deep space missions The Deep Space One science team acknowledges the support of Philip Varghese, David H. Lehman, Leslie Livesay, and Marc Rayman for providing invaluable assistance in making the science observations possible.

Nelson, Robert M.↗
NASA NTRS1991

Analysis and interpretation of CCD data on P/Halley and physical parameters and activity status of cometary nuclei at large heliocentric distance

The scientific objectives were as follows: (1) to construct a well sampled photometric time series of comet Halley extending to large heliocentric distances both post and pre-perihelion passage and derive a precise ephemeris for the nuclear spin so that the physical and chemical characteristics of individual regions of activity on the nucleus can be determined; and (2) to extend the techniques in the study of Comet Halley to the study of other cometary nuclei and to obtain new observational data.

Belton, Michael J. S.↗
DOE OSTI2020

An Extreme-precision Radial-velocity Pipeline: First Radial Velocities from EXPRES

The EXtreme-PREcision Spectrograph (EXPRES) is an environmentally stabilized, fiber-fed, R = 137,500, optical spectrograph. It was recently commissioned at the 4.3 m Lowell Discovery Telescope near Flagstaff, Arizona. The spectrograph was designed with a target radial-velocity (RV) precision of 30 cm s{sup −1}. In addition to instrumental innovations, the EXPRES pipeline, presented here, is the first on-sky, optical, fiber-fed spectrograph to employ many novel techniques—including an “extended flat” fiber used for wavelength-dependent quantum efficiency characterization of the CCD, a flat-relative optimal extraction algorithm, chromatic barycentric corrections, chromatic calibration offsets, and an ultra-precise laser frequency comb for wavelength calibration. We describe the reduction, calibration, and RV analysis pipeline used for EXPRES and present an example of our current sub-meter-per-second RV measurement precision, which reaches a formal, single-measurement error of 0.3 m s{sup −1} for an observation with a per-pixel signal-to-noise ratio of 250. These velocities yield an orbital solution on the known exoplanet host 51 Peg that matches literature values with a residual rms of 0.895 m s{sup −1}.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1986

First optical candidate for a recovered classical nova in a globular cluster - Nova 1938 in M14

U, B, V, R, and H-alpha CCD frames of the field of the nova which appeared in the globular cluster M14 in 1938 have been compared with the nova discovery images. On the basis of positional coincidence, brightness, and blue color, a candidate nova was identified and its right ascension and declination to within 1 arcsec each. Confirmation of the candidate and detailed study of the quiescent nova will probably require Hubble Space Telescope observations.

Shara, Michael M.↗
NASA NTRS1997

New Research by CCD Scanning for Comets and Asteroids

The purpose of Spacewatch is to explore the various populations of small objects within the solar system. Spacewatch provides data for studies of comets and asteroids, finds potential targets for space missions, and provides information on the environmental problem of possible impacts. Moving objects are discovered by scanning the sky with charge-coupled devices (CCDs) on the 0.9-meter Spacewatch Telescope of the University of Arizona on Kitt Peak. Each Spacewatch scan consists of three drift scan passes over an area of sky using a CCD filtered to a bandpass of 0.5-1.0 microns (approximately V+R+I with peak sensitivity at 0.7 micron). The effective exposure time for each pass is 143 seconds multiplied by the secant of the declination. We have been finding some 30,000 new asteroids per year and applying their statistics to the study of the collisional history of the solar system. As of the end of the observing run of Nov. 1997, Spacewatch had found a total of 153 Near-Earth Asteroids (NEAs) and 8 new comets since the project began in the 1980s, and had recovered one lost comet. The total number of NEAs found by Spacewatch big enough to be hazardous if they were to impact the Earth is 36. Spacewatch is also efficient in recovery of known comets and has detected and reported positions for more than 137,000 asteroids, mostly new ones in the main belt, including more than 16,000 asteroids designated by the Minor Planet Center (MPC).

Gehrels, Tom↗
NASA NTRS1999

Interannual Variabilities in Tropical Tropospheric Ozone

This paper presents the first detailed characterization of interannual variability in tropical tropospheric column ozone (TCO) to delineate the relative importance of biomass burning and large-scale transport. TCO time series are derived from 20 years (1979-1998) of total ozone mapping spectrometer (TOMS) data using the convective cloud differential (CCD) method. Our study identifies three regions in the tropics with distinctly different characteristics related to interannual variability. These three regions are the eastern Pacific, Atlantic, and western Pacific. The Atlantic region indicates a quasi-biennial oscillation (QBO) in TCO which is out of phase with the QBO in stratospheric ozone. This is consistent with the photochemical control of this region by ozone-producing precursors. The observed pattern however does not seem to be related to interannual variability in ozone precursors related to biomass burning. Instead it appears to be a manifestation of the UV modulation of upper tropospheric chemistry on a QBO time scale caused by stratospheric ozone. During El Nino events there is anomalously low TCO in the eastern Pacific and high values in the western Pacific, indicating the effects of convectively-driven transport. The observed increase of 10-20 DU in TCO in the Indonesian region in the western Pacific during the recent 1997-1998 El Nino was associated with large-scale fires which may have contributed 5-10 DU of the total increase.

Ziemke, Jerry R.↗
DOE OSTI2021

Validation of the HyRAM+ physics models for use with propane

The Hydrogen Risk Assessment Model Plus (HyRAM+) toolkit combines quantitative risk assessment with simulations of unignited dispersion, ignited turbulent diffusion flames, and indoor accumulation with delayed ignition of fuels. HyRAM+ is differentiated from HyRAM in that it includes models and leak data for other alternate fuels. The models of the physical phenomena need to be validated for each of the fuels in the toolkit. This report shows the validation for propane which is being used as a surrogate for autogas, which is a mixture of propane and butane and used in internal combustion engines in vehicles. For flame length comparisons, five previously published experiments from peer reviewed journals were used to validate our models. The validation looked at flame lengths and flame widths with respect to different leak diameters, mass flow rates, and source pressures. Most of the sources included more than one set of experimental data, which were collected using different methods (CCD cameras, IR visualization etc.). In general, HyRAM+ overpredicts the flame lengths by around 65%. For heat and radiation models, we compared the heat flux and radiation data reported from two different sources to the values calculated by HyRAM+. For higher mass flow rates, the HyRAM+ calculated flame length results gave a better estimate of what is found in the experiments (65% error), but a higher error (85%) is observed between the HyRAM+ calculated lengths and the experimental flame lengthsfor lower mass flows. Some differences can be attributed to outdoor environmental effects (i.e. wind speed) and uncertainties in jet flame shapes. The propane flame trajectory is predicted for a high Reynolds number case with Re = 12,500 and a low Reynolds number case where Re = 2,000. The Re=12,500 case which is momentum dominated matches well with the experimental flame trajectory, but the agreement for the bouancy driven low Reynolds number case is not as good. Dispersion modeling for unignited propane was also analyzed. We compared the mole fraction, mixture fraction, mean velocity, concentration half width, and inverse mass concentration over an axial distance from different credible journals to the values calculated by HyRAM+. The results display good agreement but generally, HyRAM+ predicts a wider profile for mole fraction and mixture fraction experiments. Overall, HyRAM+’s results are reasonable for predicting the flame length, heat flux, flame trajectory, and dispersion for propane and can be used in risk analyses

08 HYDROGEN↗
NASA NTRS1985

Soft X-Ray Telescope (SXRT)

The soft X-ray telescope (SXRT) will provide direct images of the solar corona with spatial resolution of about 1 arcsecond. These images will show the global structure of the corona, the location and area of coronal holes, and the presence of even the smallest active regions and flares. The good spatial resolution will show the fine scale magnetic structure and changes in these phenomena. These observations are essential for monitoring, predicting, and understanding the solar magnetic cycle, coronal heating, solar flares, coronal mass ejections, and the solar wind. These observations complement those of the White Light Coronagraph and Ultra-Violet Coronal Spectrometer; the SXRT will detect active regions and coronal holes near the east limb, thereby giving a week or more of advanced warning for disturbed geomagnetic conditions at Earth. The instrument consists of a grazing incidence collecting mirror with a full disk film camera at the primary focus, and a secondary relay optic that feeds a CCD camera with a field of view about the size of an average active region.

Moore, R. L.↗
NASA NTRS1982

Extreme ultraviolet imaging spectrometer for thermospheric emissions

One of the instruments that has been developed to fly on the Space Shuttle is the Imaging Spectrometric Observatory, an array of five imaging spectrometers to cover the 300-12,000-A wavelength range. In this paper the spectrometer designed to operate in the extreme ultraviolet is described. The instrument is intended for studies of the thermosphere and magnetosphere and support of various plasma experiments to be performed from the Shuttle. The design is modular so that various components such as gratings and detectors can be changed and optimized for a range of specific studies following the first survey mission. The detector is an intensified 2-D CCD which permits simultaneous spectral and spatial imaging. The spectral multiplexing gives the spectrometer a considerable speed advantage. The instrument has a small field of view and is thus capable of obtaining much needed scale height information on the atmospheric EUV emissions. Operating from the Shuttle, global and temporal coverage will be obtained, and the EUV data will be enhanced by the simultaneously acquired UV, visible, and near-IR observations.

Torr, M. R.↗
NASA NTRS1986

Soft X-ray telescope (SXRT)

The soft X-ray telescope (SXRT) will provide direct images of the solar corona with spatial resolution of about 1 arcsecond. These images will show the global structure of the corona, the location and area of coronal holes, and the presence of even the smallest active regions and flares. The good spatial resolution will show the fine scale magnetic structure and changes in these phenomena. These observations are essential for monitoring, predicting, and understanding the solar magnetic cycle, coronal heating, solar flares, coronal mass ejections, and the solar wind. These observations complement those of the White Light Coronagraph and Ultra-Violet Coronal Spectrometer; the SXRT will detect active regions and coronal holes near the east limb, thereby giving a week or more of advanced warning for disturbed geomagnetic conditions at Earth. The instrument consists of a grazing incidence collecting mirror with a full-disk film camera at the primary focus, and a secondary relay optic that feeds a CCD camera with a field of view about the size of an average active region.

Moore, R.↗
NASA NTRS1991

Measuring the direct sky brightness on CCD images

A new method of determining the background sky brightness for stellar photometric measurements with CCDs is described. By fitting and subtracting stellar profiles from a CCD image, one can measure the sky brightness directly at the position of each star after subtraction. These sky values can then be used for the next round of profile fitting and subtraction. The 'direct sky' brightness for a star is the convergent value of the sky after a few such iterations and is the most direct measurement of the line-of-sight contribution of the background to the observed magnitude of a star. Using this method, a decrease of the random photometric errors by more than a factor of two over standard methods is possible, with the most significant improvements for stars in very crowded regions and areas of strong and highly variable nebulosity.

Parker, Joel WM.↗
NASA NTRS1999

Optical Imaging of Flow Pattern and Phantom

Time-resolved optical imaging technique has been used to image the spatial distribution of small droplets and jet sprays in a highly scattering environment. The snake and ballistic components of the transmitted pulse are less scattered, and contain direct information about the sample to facilitate image formation as opposed to the diffusive components which are due to multiple collisions as a light pulse propagates through a scattering medium. In a time-gated imaging scheme, these early-arriving, image-bearing components of the incident pulse are selected by opening a gate for an ultrashort period of time and a shadowgram image is detected. Using a single shot cooled CCD camera system, the formation of water droplets is monitored as a function of time. Picosecond time-gated image of drop in scattering cells, spray droplets as a function of let speed and gas pressure, and model calcification samples consisted of calcium carbonate particles of irregular shapes ranging in size from 0. 1 to 1.5 mm affixed to a microscope slide have been measured. Formation produced by an impinging jet will be further monitored using a CCD with 1 kHz framing illuminated with pulsed light. The desired image resolution of the fuel droplets is on the 20 pm scale using early light through a highly scattering medium. A 10(exp -6)m displacement from a jet spray with a flow speed of 100 m/sec introduced by the ns grating pulse used in the imaging is negligible. Early ballistic/snake light imaging offers nondestructive and noninvasive method to observe the spatial distribution of hidden objects inside a highly scattering environment for space, biomedical, and materials applications. In this paper, the techniques we will present are time-resolved K-F transillumination imaging and time-gated scattered light imaging. With a large dynamic range and high resolution, time-gated early light imaging has the potential for improving rocket/aircraft design by determining jets shape and particle sizes. Refinements to these techniques may enable drop size measurements in the highly scattering, optically dense region of multi-element rocket injectors. These types of measurements should greatly enhance the design of stable, and higher performing rocket engines.

Galland, Pierre A.↗