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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 505 records · Page 28
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

The energetics and mass structure of regions of star formation - S201

Theoretical predictions about dust and gas in star-forming regions are tested by observing a 4-arcmin region surrounding the radio continuum source in S201. The object was mapped in two far-infrared wavelengths and found to show significant extended emission. Under the assumption that the molecular gas is heated solely via thermal coupling with the dust, the volume density was mapped in S201. The ratios of infrared optical depth to CO column density were calculated for a number of positions in the source. Near the center of the cloud the values are found to be in good agreement with other determinations for regions with lower column density. In addition, the observations suggest significant molecular destruction in the outer parts of the object. Current models of gas heating were used to calculate a strong limit for the radius of the far-infrared emitting grains, a equal to or less than 0.15 micron. Grains of about this size are required by the observation of high temperature (T equal to or greater than 20 K) gas in many sources.

Thronson, H. A., Jr.↗
NASA NTRS1984

NGC 2024 - Far-infrared and radio molecular observations

New far-infrared continuum and millimeter-wave molecular observations of NGC 2024 are presented. The measurements were obtained at relatively high angular resolution making it possible to describe the source energetics and mass distribution in greater detail than previously reported. The object appears to be dominated by a dense ridge of material, extended in the north-south direction and centered on the dark lane that is seen in visual photographs. The maps of the source using the 'high-density' molecules CS and HCN confirm this picture and makes it possible to describe the core structure and molecular abundances. The radio molecular and infrared observations support the idea that an important exciting star in NGC 2024 has yet to be identified and is centered on the dense ridge about 1 arcmin south of the bright mid-infrared source IRS 2. The data presented here, along with other observations, make it possible to describe a model for the source.

Thronson, H. A., Jr.↗
NASA NTRS1985

Statistical magnetic anomalies from satellite measurements for geologic analysis

The errors of numerically averaging satellite magnetic anomaly data for geologic analysis are investigated using orbital anomaly simulations of crustal magnetic sources by Gauss-Legendre quadrature integration. These simulations suggest that numerical averaging errors constitute small and relatively minor contributions to the total error-budget of higher orbital estimates (approx. 400 km), whereas for lower orbital estimates the error of averaging may increase substantially. Least-squares collocation is also investigated as an alternative to numerical averaging and found to produce substantially more accurate anomaly estimates as the elevation of prediction is decreased towards the crustal sources.

Goyal, H. K.↗
NASA NTRS1988

Feasibility studies of the growth of 3-5 compounds of boron by MOCVD

Boron-arsenic and boron-phosphorus films have been grown on Si sapphire and silicon-on-sapphire (SOS) by pyrolyzing Group 3 alkyls of boron, i.e., trimethylborane (TMB) and triethylborane (TEB), in the presence of AsH3 and PH3, respectively, in an H2 atmosphere. No evidence for reaction between the alkyls and the hydrides on mixing at room temperature was found. However, the films were predominantly amorphous. The film growth rate was found to depend on the concentration of alkyl boron compound and was essentially constant when TEB and AsH3 were pyrolyzed over the temperature range 550 C to 900 C. The films were found to contain mainly carbon impurities (the amount varying with growth temperature), some oxygen, and were highly stressed and bowed on Si substrates, with some crazing evident in thin (2 micron) B-P and thick (5 micron) B-As films. The carbon level was generally higher in films grown using TEB as the boron source. Films grown from PH3 and TMB showed a higher carbon content than those grown from AsH3 and TMB. Based on their B/As and B/P ratios, films with nominal compositions B sub12-16 As2 and B sub1.1-1.3 P were grown using TMB as the boron source.

Manasevit, H. M.↗
NASA NTRS1988

Space station neutral external environment

Molecular contamination levels arising from the external induced neutral environment of the Space Station (Phase 1 configuration) were calculated using the MOLFLUX model. Predicted molecular column densities and deposition rates generally meet the Space Station contamination requirements. In the doubtful cases of deposition due to materials outgassing, proper material selection, generally excluding organic products exposed to the external environment, must be considered to meet contamination requirements. It is important that the Space Station configuration, once defined, is not significantly modified to avoid introducing new unacceptable contamination sources.

Ehlers, H.↗
NASA NTRS1987

Engima of a thermal anomaly - A TM/AVHRR study of the volcanic Arabian highlands

Discovery of a large thermal anomaly in the western Arabian highlands on Landsat TM imagery is reported. The anomaly, 15 C warmer than surroundings, forms a 2-km-wide arc around the southern flank of Jebel Chada, a volcano active in 1256 AD. It is recorded by AVHRR imagery as well, despite the 1.1-km spatial resolution of this sensor. Air photos and geologic maps show no bedrock unit that corresponds to the anomaly. Digital techniques were applied to the TM and AVHRR data, including contrast enhancement, density slicing, principal components analysis, and construction of multiband composite images. It is concluded that the anomaly results from a thin cover of volcanic ash or cinder that is optically indistinguishable from underlying basalt, rather than from internal (volcanic or hydrologic) heat sources.

Blodget, H. W.↗
NASA NTRS1991

Second-epoch VLA observations of compact radio sources in NGC 253

Results are presented of second-epoch 6-cm VLA observations of the starburst galaxy NGC 253 in early 1989, approximately 18 months after the first observations identified more than 30 compact radio sources in the galaxy. The galaxy was also mapped at 3.6 cm. No new radio sources were found at 6 cm after the 18-month interval. Assuming that at least two-thirds of new type II supernovae would have been detectable radio emitters stronger than 3 mJy, the 95-percent confidence upper limit to the SN rate is 3.0/yr. None of the 13 sources with flux densities above 1 mJy showed significant decreases in strength over 18 months; the strongest source showed an apparent increase of 6.5 percent in flux density, which differs from that of Kronberg and Sramek (1985) for M82. The 3.6 map identified a number of new sources because of the reduction of confusion. The available spectral data show that a few of the resolved sources may be H II regions.

Ulvestad, James S.↗
NASA NTRS1991

Development of a shock noise prediction code for high-speed helicopters - The subsonically moving shock

A previously defined airfoil subsonic shock-noise prediction formula whose result depends on a mapping of the time-dependent shock surface to a time-independent computational domain is presently coded and incorporated in the NASA-Langley rotor-noise prediction code, WOPWOP. The structure and algorithms used in the shock-noise prediction code are presented; special care has been taken to reduce computation time while maintaining accuracy. Numerical examples of shock-noise prediction are presented for hover and forward flight. It is confirmed that shock noise is an important component of the quadrupole source.

Tadghighi, H.↗
NASA NTRS2003

Modeling Study of Mesospheric Planetary Waves: Genesis and Characteristics

In preparation for the measurements from the TIMED mission and coordinated ground based observations, we discuss results for the planetary waves (PWs) that appear in our Numerical Spectral Model (NSM). The present model accounts for a tropospheric heat source in the zonal mean (m = 0), which reproduces qualitatively the observed zonal jets near the tropopause and the accompanying reversal in the latitudinal temperature variations. We discuss the PWs that are solely generated internally, i.e., without the explicit excitation sources related to tropospheric convection or topography. Our analysis shows that PWs are not produced when the zonally averaged heat source into the atmosphere is artificially suppressed, and that the PWs generally are significantly weaker when the tropospheric source is not applied. Instabilities associated with the zonal mean temperature, pressure and wind fields, which still need to be explored, are exciting PWs that have amplitudes in the mesosphere comparable to those observed. Three classes of PWs are generated in the NSM. (1) Rossby waves, (2) Rossby gravity waves propagating westward at low latitudes, and (3) Eastward propagating equatorial Kelvin waves. A survey of the PWs reveals that the largest wind amplitudes tend to occur below 80 km in the winter hemisphere, but above that altitude they occur in the summer hemisphere where the amplitudes can approach 50 meters per second. It is shown that the non-migrating tides in the mesosphere, generated by non-linear coupling between migrating tides and PWs, are significantly larger for the model with the tropospheric heat source.

Mayr, H. G.↗
NASA NTRS2006

Swift: Results from the first year of the mission

The Swift gamma-ray burst explorer was launched on Nov. 20,2004 from Cape Canaveral, Florida. The first instrument onboard became fully operational less than a month later. Since that time the Burst Alert Telescope (BAT) on Swift has detected more than one hundred gamma-ray bursts (GRBs), most of which have also been observed within two minutes by the Swift narrow-field instruments: the X-Ray Telescope (XRT) and the Ultra-Violet and Optical Telescope (UVOT). Swift trigger notices are distributed worldwide within seconds of the trigger through the Gamma-ray burst Coordinates Network (GCN) and a substantial fraction of GRBs have been followed up by ground and space-based telescopes, ranging in wavelength from radio to TeV. Results have included the first rapid localization of a short GRB and further validation of the theory that short and long bursts have different origins; detailed observations of the short-term power-law decay of burst afterglows leading to an improved understanding of the fireball model; and detection of the most distant GRB ever found. Swift is also a sensitive X-ray observatory with capabilities to monitor galactic and extragalactic transients on a daily basis, carry out the first all-sky hard X-ray survey since HEAO-1, and study in detail the spectra of X-ray transients. significant results, both in GRB science and in the search for and study of hard X-ray sources. In this talk I will provide a broad overview of the Swift mission and its most significant results, both in GRB science and in the search for and study of hard X-ray sources.

Krimm, H. A.↗
NASA NTRS1996

Three Weak-Lined T Tauri Stars in Orion

We have identified three new weak lined T Tauri stars in Orion using the Double Spectrograph and 5-m telescope at Palomar Observatory. One of these is a candidate for the X-ray source RX0535-0633. H(alpha) and H(beta) line emisison are detected and equivalent widths measured in all three stars, and in V942 Ori. We also searched without success for H(alpha) line variability in V942 Ari.

stars emission line be stars flare stars V942 Ori ↗
NASA NTRS2004

Rest-Frame Mid-Infrared Detection of an Extremely Luminous Lyman Break Galaxy with the Spitzer Infrared Spectrograph (IRS)

We present the first rest-frame of approximately 4 microns detection of a Lyman break galaxy. The data were obtained using the 16 microns imaging capability of the Spitzer Infrared Spectrograph. The target object, J134026.44+634433.2, is an extremely luminous Lyman break galaxy at z=2.79, first identified in Sloan Digital Sky Survey (SDSS) spectra (as reported by Bentz et al.). The source is strongly detected with a flux of 0.94 +/- 0.02 mJy. Combining Spitzer and SDSS photometry with supporting ground-based J- and K-band data, we show that the spectral energy distribution is consistent with an actively star-forming galaxy. We also detect other objects in the Spitzer field of view, including a very red mid-infrared source. We find no evidence of a strong lens among the mid-infrared sources.

cosmology↗
NASA NTRS2009

NEOCAM: Near Earth Object Chemical Analysis Mission: Bridging the Gulf between Telescopic Observations and the Chemical and Mineralogical Compositions of Asteroids or Diogenes A: Diagnostic Observation of the Geology of Near Earth Spectrally-Classified Asteroids

Studies of meteorites have yielded a wealth of scientific information based on highly detailed chemical and isotopic studies possible only in sophisticated terrestrial laboratories. Telescopic studies have revealed an enormous (greater than 10(exp 5)) number of physical objects ranging in size from a few tens of meters to several hundred kilometers, orbiting not only in the traditional asteroid belt between Mars and Jupiter but also throughout the inner solar system. Many of the largest asteroids are classed into taxonomic groups based on their observed spectral properties and are designated as C, D. X, S or V types (as well as a wide range in sub-types). These objects are certainly the sources far the meteorites in our laboratories, but which asteroids are the sources for which meteorites? Spectral classes are nominally correlated to the chemical composition and physical characteristics of the asteroid itself based on studies of the spectral changes induced in meteorites due to exposure to a simulated space environment. While laboratory studies have produced some notable successes (e.g. the identification of the asteroid Vesta as the source of the H, E and D meteorite classes), it is unlikely that we have samples of each asteroidal spectral type in our meteorite collection. The correlation of spectral type and composition for many objects will therefore remain uncertain until we can return samples of specific asteroid types to Earth for analyses. The best candidates for sample return are asteroids that already come close to the Earth. Asteroids in orbit near 1 A.U. have been classified into three groups (Aten, Apollo & Amor) based on their orbital characteristics. These Near Earth Objects (NEOs) contain representatives of virtually all spectral types and sub-types of the asteroid population identified to date. Because of their close proximity to Earth, NEOs are prime targets for asteroid missions such as the NEAR-Shoemaker NASA Discovery Mission to Eros and the Japanese Hyabusa Mission to Itokawa. Also due to their close proximity to Earth, NEOs constitute the most likely set of celestial objects that will impact us in the relatively near future.

Nuth, Joseph A.↗
NASA NTRS2012

Optical Signature Analysis of Tumbling Rocket Bodies via Laboratory Measurements

The NASA Orbital Debris Program Office has acquired telescopic lightcurve data on massive intact objects, specifically spent rocket bodies, in order to ascertain tumble rates in support of the Active Debris Removal (ADR) task to help remediate the LEO environment. Rotation rates are needed to plan and develop proximity operations for potential future ADR operations. To better characterize and model optical data acquired from ground-based telescopes, the Optical Measurements Center (OMC) at NASA/JSC emulates illumination conditions in space using equipment and techniques that parallel telescopic observations and source-target-sensor orientations. The OMC employs a 75-watt Xenon arc lamp as a solar simulator, an SBIG CCD camera with standard Johnson/Bessel filters, and a robotic arm to simulate an object's position and rotation. The light source is mounted on a rotary arm, allowing access any phase angle between 0 -- 360 degrees. The OMC does not attempt to replicate the rotation rates, but focuses on how an object is rotating as seen from multiple phase angles. The two targets studied are scaled (1:48), SL-8 Cosmos 3M second stages. The first target is painted in the standard government "gray" scheme and the second target is primary white, as used for commercial missions. This paper summarizes results of the two scaled rocket bodies, each rotated about two primary axes: (a) a spin-stabilized rotation and (b) an end-over-end rotation. The two rotation states are being investigated as a basis for possible spin states of rocket bodies, beginning with simple spin states about the two primary axes. The data will be used to create a database of potential spin states for future works to convolve with more complex spin states. The optical signatures will be presented for specific phase angles for each rocket body and shown in conjunction with acquired optical data from multiple telescope sources.

Cowardin, H.↗
NASA NTRS1998

Dust Morphology of Comet Hale-Bopp (C/1995 01). II. Introduction of a Working Model

A Monte Carlo image simulation code for dust features in comets is applied to comet Hale-Bopp in order to model the object's persistent porcupine-like appearance on high-resolution images taken between May 11 and November 2, 1996. In this scenario, the dust-emission profile is dominated by several brief flare-ups, or puffs in the production of dust from one of the sources.

comet↗
DOE OSTI2012

PXIE: Project X Injector Experiment

A multi-MW proton facility, Project X, has been proposed and is currently under development at Fermilab. We are planning a program of research and development aimed at integrated systems testing of critical components comprising the front end of the Project X. This program is being undertaken as a key component of the larger Project X R&D program. The successful completion of this program will validate the concept for the Project X front end, thereby minimizing a primary technical risk element within Project X. Integrated systems testing, known as the Project X Injector Experiment (PXIE), will be accomplished with a new test facility under construction at Fermilab and will be completed over the period FY12-16. PXIE will include an H{sup -} ion source, a CW 2.1-MeV RFQ and two superconductive RF (SRF) cryomodules providing up to 25 MeV energy gain at an average beam current of 1 mA (upgradable to 2 mA). Successful systems testing will also demonstrate the viability of novel front end technologies that are expected find applications beyond Project X.

43 PARTICLE ACCELERATORS↗
DOE OSTI2022

High temperature thermochemical energy storage system

A thermochemical energy storage system and method of storing thermal energy are described. The energy storing system described herein comprises a reactor comprising: a) a reactor with a CO 2 sorbent including MgO; and b) a supercritical CO 2 source with supercritical CO 2 and H 2 O, wherein the supercritical CO 2 source is in fluid communication with the reactor and the CO 2 sorbent including MgO to allow flow of the supercritical CO 2 and H 2 O between the supercritical CO 2 source and the reactor, thereby allowing contact of CO 2 with the CO 2 sorbent comprising MgO.

Muto, Andrew Jerome↗
DOE OSTI2024

Performance of the Fermilab Linac Injector

The Fermilab Linac injection line consists of a 35 keV magnetron-type H\textsuperscript{-} ion source, two-solenoid Low Energy Beam Transport (LEBT), 201 MHz 4-rod 750 keV Radio Frequency Quadrupole (RFQ), and a Medium Energy Transport (MEBT) containing 4 quadrupoles and a bunching cavity. The injector delivers 25 mA, 48 µs pulses to the drift-tube Linac at a repetition rate of 15Hz. The transmission efficiency of the injector has been lower than expected since commissioning. Recent beam current measurements suggest that the beam is primarily lost upstream of the RFQ exit. Numerical simulations indicate that ions passing through the non-linear field region of the solenoids could produce a beam with an increased emittance resulting in up to 50\% of the LEBT beam current failing to meet the RFQ acceptance. An aperture restriction was installed upstream of the first solenoid to remove these ions. This report describes the results of measurements and simulations as well as the LEBT tuning.

43 PARTICLE ACCELERATORS↗