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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 109 records · Page 6
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NASA NTRS1975

Development of a laser Doppler system for the detection and monitoring of atmospheric disturbances

A Scanning Laser Doppler Velocimeter System (SLDVS) capable of detecting and monitoring atmospheric disturbances, including wake vortices of landing aircraft and vertical wind profiles in the atmosphere was developed. The SLDVS is a focused, continuous wave, CO2 system that determines the line-of-sight velocities of particles in the focal volume by measuring the Doppler shift created by these particles. At present, the SLDVS is designed to have a range coverage of approximately 2000 ft with a vertical angle coverage of approximately 60 deg. It is also designed to detect Doppler velocities of up to 200 ft/sec with a velocity resolution of approximately 1.8 ft/sec. A complete velocity spectrum is provided by the SLDVS at each point in space at which it is focused. The overall operation and performance of the system and the description of its individual components and data handling capabilities were given.

Jeffreys, H. B.↗
NASA NTRS1976

DSS 14 operating noise temperature during Helios 1 near-sun tracking

When spacecraft are tracked near the line-of-sight of the sun, the ground antenna sidelobes see the solar noise. The solar noise increases the ground system operating noise temperature and degrades the downlink RF reception performance. At specific antenna azimuthal angles relative to the sun, noise peaks and nulls occur periodically throughout a day's tracking pass due to the quadripod support leg-generated sidelobes. This article documents this effect while tracking Helios 1, illustrates the time of the peaks, and compares the predicted time of the noise temperature peaks with the measured data.

Stelzried, C. T.↗
NASA NTRS1975

Molecular hydrogen in the Galaxy and galactic gamma rays

Recent surveys of 2.6-cm CO emission and 100-MeV gamma-radiation in the galactic plane reveal a striking correlation suggesting that both emissions may be primarily proportional to the line-of-sight column density of H2 in the inner Galaxy. Both the gamma-ray and CO data suggest a prominent ring or arm consisting of cool clouds of H2 at a galactocentric distance of about 5 kpc with a mean total hydrogen density equivalent to approximately 5 atoms per cu cm. Estimates are made of column densities of H2 at 0 deg galactic longitude and are compared with estimates from infrared and X-ray absorption measurements. These estimates are all consistent, indicating that H2 is far more abundant than H I in the inner Galaxy and is the key to a more satisfactory explanation of the gamma-ray observations than previous suggestions. The importance of H2 in understanding galactic gamma-ray observations is also reflected in the correlation of galactic-latitude distribution of gamma-rays and dense dust clouds. The deduced cosmic-ray distribution inferred from the calculations is similar to that of galactic supernova remnants, suggesting a galactic origin for most cosmic rays.

Stecker, F. W.↗
NASA NTRS1975

Multifrequency techniques for studying interplanetary scintillations

Rytov's approximation, or the method of smooth perturbations, is utilized to derive the temporal frequency spectra of the amplitude and phase fluctuations of multifrequency plane and spherical waves propagating in the interplanetary medium and solar corona. It is shown that multifrequency observations of interplanetary scintillations using either compact radio stars of spacecraft radio signals are desirable because the correlation of the multifrequency waves yields additional independent measurements of the solar wind and turbulence. Measurements of phase fluctuations are also desirable because, unlike amplitude fluctuations, they provide information on the full range of scale sizes for the electron-density fluctuations. It is also shown that a coherent dual-frequency radio system is particularly useful in making such measurements. In addition to providing a means for interpreting observations of multifrequency interplanetary scintillations, the present analysis is essential for estimating the effects of solar corona turbulence on the communications and navigation of a spacecraft whose line-of-sight path passes close to the sun.

Woo, R.↗
NASA NTRS1975

Velocity dispersions in galaxies. IV - The nucleus of NGC 1068

A high-resolution spectrum of the Seyfert galaxy NGC 1068, obtained with an integrating television system, is compared with the spectrum of a KO III star (delta Tau) to derive the line-of-sight velocity dispersion of the stars in the galactic nucleus. An Fe I absorption line observed at 4059.7 A yields a velocity dispersion of 150 (plus or minus 50) km/sec. An upper limit for the nuclear mass is derived in terms of this velocity dispersion, an estimated nuclear radius of 136 pc, and a Hubble constant of 50 km/sec per Mpc. The results, 14 (+10, -8) by 10 to the 8th power solar masses, is shown to be consistent with a number of quasar models scaled down in luminosity to provide the energy source for a Seyfert nucleus. Strong H and K interstellar absorption lines superposed on the spectrum of NGC 1068 are analyzed.-

Richstone, D. O.↗
NASA NTRS1975

Preliminary Shuttle payload contamination assessment

The paper discusses the molecular induced atmosphere of the Shuttle Orbiter and a payload carrier (Spacelab) configuration - long module and a 3-m pallet) in the Shuttle Orbiter payload bay and compares it to the ambient atmosphere at various orbital altitudes. The density and flux of the contaminants are expressed as a function of distance out of the payload bay for a line-of-sight perpendicular to the payload bay and payload carrier. Isodensity plots about the Shuttle Orbiter for a side and end view for each major source are presented. The major sources considered are the external surface materials mass loss, pressurized habitation area leakage, attitude control engines, and supplemental flash evaporator venting. The resulting plots provide an insight into the extent and spatial variation of the on-orbit contaminant-induced environment.

Ress, E. B.↗
NASA NTRS1976

Velocity dispersions in galaxies. V - The nuclei of M31 and M32

Stigmatic spectra between 4160 and 4385 A of the central regions of M31 and M32 as well as the K0 III star 51 Ori are presented which were obtained using a SEC-vidicon integrating television tube and the coude spectrograph of the Hale telescope. Line-of-sight velocity dispersions of approximately 130 and 55 km/s are determined for the nuclei of M31 and M32, respectively, by directly comparing their spectra with Gaussian-broadened spectra of 51 Ori. The analytical techniques are outlined, and alternative methods for estimating velocity dispersions are evaluated, including least-squares fitting of intensities and division of Fourier transforms. It is noted that the broadened spectrum of 51 Ori fits the nucleus of M32 and the bulge of M31 much better than the nucleus of M31 in the region between 4180 and 4370 A.

Morton, D. C.↗
NASA NTRS1976

Inverse atmospheric radiative transfer problems - A nonlinear minimization search method of solution

The paper studies the inversion of the radiative transfer equation describing the interaction of electromagnetic radiation with atmospheric aerosols. The interaction can be considered as the propagation in the aerosol medium of two light beams: the direct beam in the line-of-sight attenuated by absorption and scattering, and the diffuse beam arising from scattering into the viewing direction, which propagates more or less in random fashion. The latter beam has single scattering and multiple scattering contributions. In the former case and for single scattering, the problem is reducible to first-kind Fredholm equations, while for multiple scattering it is necessary to invert partial integrodifferential equations. A nonlinear minimization search method, applicable to the solution of both types of problems has been developed, and is applied here to the problem of monitoring aerosol pollution, namely the complex refractive index and size distribution of aerosol particles.

Fymat, A. L.↗
NASA NTRS1977

A solar plasma stream measured by DRVID and dual-frequency range and Doppler radio metric data

S- and X-band DRVID, S- and X-band dual-frequency range (SX(p)), and Doppler (SX(p)) measured a 15-fold increase in the line-of-sight electron content of the solar plasma above the normal plasma background. A general increase in the plasma electron content continued for nearly 50 hours: it started about 12:00 (GMT) on 12 March 1976 and continued to grow until 17:00 (GMT) on 14 March. For the next 55 hours, between 17:00 (GMT) on 14 March to 00:54 (GMT) on 17 March, the plasma level diminished as the background level was approached. Not only were the temporal changes and absolute level of the plasma content measured but the measurements were also used to ascertain the mean-plasma-concentration location: it was estimated to be 4.1 light minutes from earth.

Winn, F. B.↗
NASA NTRS1976

Measurements of rain effects on an 18-GHz dual-polarized propagation link

The paper presents highlights of rain attenuation and depolarization data collected between August 1972 and March 1974 in an experimental setup consisting of a 1.43-km line-of-sight path with 1.22-m diam dual-polarized parabolic reflector antennas at each end. The antennas used question-mark mounted scalar feeds oriented to transmit or receive linearly polarized 17.65-GHz signals having electric field vectors at +45 deg and -45 deg from the vertical. Rain data were collected and analyzed for 24 individual storms in which the rain rate exceeded 10 mm/hr. Received signal levels were sampled once each second and stored by a small digital computer which controlled the experiment and performed preliminary data processing. The results are compared with a theoretical model presented by Wiley et al. (1974). Experimental cross-polarization isolation data are found to agree well with theoretical values, especially at high rain rates where the antenna effects are the least significant.

Bostian, C. W.↗
NASA NTRS1977

On the physical conditions in the 'high-velocity' cloud near Zeta Ori

The problem of the 'high-velocity' clouds is rediscussed. Recent OAO-C Copernicus observations of lines of four atoms and ions have been used to estimate the density and temperature in both the 'high-velocity' and 'normal' interstellar clouds in the line-of-sight to Zeta Ori. The temperature and densities in the normal cloud are similar to previous results for interstellar clouds, yielding temperatures of the order of 100 K and compositions underabundant relative to the sun by factors of 3 or more. The high-velocity cloud, however, is warmer (at least 1000 K) and appears to have a normal solar abundance.

Drake, J. F.↗
NASA NTRS1977

Abundance variations in high-velocity interstellar gas

Based on line-of-sight models and profile fitting, abundance variations of Ca, Si, Fe, and Na in high-velocity interstellar clouds toward Mu Columbae, HD 28497, and HD 50896 are discussed. The correlation of larger ratios N(Ca II)/N(Na I) with increasing radial velocity in clouds with absolute values of radial velocity from 20 to 100 km/s, is shown to quite likely be due to abundance variations in Ca rather than an ionization effect. Copernicus UV data show that the ratios N(Fe II)/N(S II) and N(Si II)/N(S II) have the same velocity correlation as Ca II, and the ambiguity concerning the relative abundance of Na I to hydrogen is removed. Theories of grain disruption are discussed as they relate to the observed Ca, Si, and Fe enhancements and their correlation with cloud velocity.

Shull, J. M.↗
NASA NTRS1977

Lunar gravity - A mass point model

A point-mass representation of a quasi-global lunar gravity field is developed by processing Apollo 15 and 16 subsatellite and Lunar Orbiter 5 Doppler tracking data. The model is generated by reducing the long-period variations in the mean orbital elements. The model consists of 117 point masses distributed over the region of + or - 30 deg in latitude about the lunar equator and resolves all the previously known 'mascons' on the near side as broad positive-gravity regions. The near-side acceleration map evaluated at 100 km above the lunar surface shows good agreement with line-of-sight acceleration results. The lunar far-side gravity map shows strong broad positive-gravity regions for the highland areas. However, all the major ringed basins are resolved as localized negative anomalies in contrast with the near-side basins. This model does not indicate any evidence for the existence of any mascon-type feature on the lunar far-side.

Ananda, M. P.↗
NASA NTRS1977

Lunar gravity - A harmonic analysis

A sixteenth-degree and sixteenth-order spherical harmonic lunar gravity field has been derived from the long-term Keplerian variations in the orbits of the Apollo subsatellites and Lunar Orbiter 5. This model resolves the major mascon gravity anomalies of the lunar near side and is in very good agreement with line-of-sight acceleration results. The far-side map shows the major ringed basins to be strong localized negative anomalies located in broad regions of positive gravity which correspond closely to the highlands. The rms pressure levels calculated from equivalent-surface height variations show that the moon and earth support nearly equal pressures, whereas Mars is appreciably stronger. The moon appears to support larger loads than earth owing to its weaker central gravity field and perhaps a colder upper lithosphere. Significant differences between the low-degree gravity and topography spectra indicate that the longer-wavelength topographic features are isostatically compensated.

Ferrari, A. J.↗
NASA NTRS1961

Analog Simulation of a Pilot-Controlled Rendezvous

The rendezvous of a pilot-controlled space ferry vehicle with an orbiting space station was simulated in six degrees of freedom. A fixed-base simulator and an analog computer were used. The ferry vehicle was assumed to have a single main thrusting rocket and to be provided with attitude control. Control of the thrust was provided by a rocket throttle quadrant which could provide either proportional or on-off control. The attitude of the vehicle was controlled during the rendezvous with a two-axis, pencil-type side-arm controller and rudder pedals. For the most part rendezvous maneuvers were made with the target satellite in a circular orbit. In addition, an elliptical station orbit was investigated. Tolerable initial conditions, as well as adequate data presentations, were determined. Results of the investigation indicate that a human pilot can rendezvous successfully with the vehicle and instrumentation considered over a wide band of initial conditions. Coplanar conditions are not necessary. Retro-rocket fuel used is not greatly increased by imposing perturbing influences such as rocket-misalignment torques on the rendezvous vehicle. When excessive attitude-control torques are required to maintain the necessary trim attitudes under misalignment influences, the reaction fuel used for this control increases. The time required for a specific rendezvous varies somewhat between pilots. If control of the time for completing the rendezvous is desired, requirements for retrorocket fuel are affected, and an energy-management schedule is required. Continuous variation of the thrust is not necessary. The pilot positions the throttle to obtain a desired level of thrust, and applies bursts of thrust as required. All data were presented on dialed instruments. The quantities required are range and range rate and line-of-sight rates between the vehicle and the station, vehicle attitudes and angular rates, and the angles subtended by the line of sight. For the equipment assumed herein, satellite rendezvous presented no great problem to the pilot.

Brissenden, Roy F.↗
NASA NTRS2026

The Thermal and Kinematic Sunyaev–Zeldovich Effect in Galaxy Clusters and Filaments Using Multifrequency Temperature Maps of the Cosmic Microwave Background A399–A401 Cluster Pair Case Study

We present a multifrequency and multi-instrument methodology to study the physical properties of galaxy clusters and cosmic filaments using cosmic microwave background observations. Our approach enables simultaneous measurement of both the thermal (tSZ) and kinematic Sunyaev–Zeldovich (kSZ) effects, incorporates relativistic corrections, and models astrophysical foregrounds such as thermal dust emission. We do this by jointly fitting a single physical model across multiple maps from multiple instruments at different frequencies, rather than fitting a model to a single Compton-y map. We demonstrate the success of this method by fitting the A399–A401 galaxy cluster pair and filament system using archival data from the Planck satellite and new, targeted deep data from the Atacama Cosmology Telescope, covering 11 different frequencies over 14 maps from 30 GHz to 545 GHz. Our tSZ results are consistent with previous work using Compton-y maps. We measure the line-of-sight peculiar velocities of the cluster–filament system using the kSZ effect and find statistical uncertainties on individual cluster peculiar velocities of ≲600 km s −1 , which are competitive with current state-of-the-art measurements. Additionally, we measure the optical depth of the filament component with a signal-to-noise of 8.5σ and reveal hints of its morphology. This modular approach is well-suited for application to future instruments across a wide range of millimeter and submillimeter wavebands.

Ajay S Gill↗
DOE OSTI2025

Characterization of Flashback and Flame-Holding in a Jet-in-Crossflow Mixing Configuration with Methane-Hydrogen Fuel Blends

An approach that combines experimental and numerical analyses has been implemented to characterize the fundamentals of flashback events and flame-holding phenomena during high-hydrogen combustion in a jet-in-crossflow (JICF) configuration. Such flame dynamics are visualized experimentally using nanosecond (ns)-based hydroxyl planar laser-induced fluorescence (OH-PLIF) and chemiluminescence diagnostics techniques. The JICF burner has an optically accessible pre-mixing tube allowing the optical diagnostics. The testing was conducted for varied pre-mixer velocities (V) and equivalence ratio (ϕ) for 90%-100% (H2, by mole) H2/CH4 reactant mixtures at atmospheric temperature and pressure conditions. Two distinct flashback events were identified – conventional rich flashback and lean flashback, recorded while increasing ϕ and decreasing ϕ, respectively. The cause of lean flashback was attributed to the lower momentum flux ratio which bends the jet sharply, closer toward the injection plane. The mean OH-PLIF images characterized the flame-holding behavior where the flame was found to be stabilized on the leeward side only or on both windward and leeward sides as a lifted flame near the fuel port. A Large Eddy Simulation (LES) with detailed chemistry combustion modeling approach was implemented along an OH* sub-mechanism, and it showed qualitative agreement with the integrated line-of-sight chemiluminescence results as well as the planar OH-PLIF measurements.

flame holding↗
DOE OSTI2025

Stripline Block Sensor System

The Long Baseline Neutrino Facility requires a secondary sensor system to aid in the installation and replacement of the stripline blocks. These blocks are responsible for delivering large amounts of current to the horn and must be installed with high precision to avoid possible physical damage. There are many constraints due to the modules' surroundings, such as small clearances and a highly radioactive environment. Existing systems have already been implemented within the process; however, these systems offer limited information, leaving much risk during operations. This calls for a sufficiently accurate sensor system, which has a small space requirement and provides valuable information throughout the replacement period. A variety of methods and technologies were explored to provide an applicable approach to the issue. The proposed solution consisted of the use of retroreflective and target, however, it cannot provide positional feedback throughout the entire process. A proposed alternative utilizes a three-dimensional indoor positioning system to provide the operator with real-time positioning and rotational information. Sensors placed on the module and stripline would communicate with fixed receivers surrounding the target hall to provide precise positional feedback. However, this solution may still contain line-of-sight issues as well as installation complications due to the radioactive environment. Future work would consist of finding vendors capable of providing technology that fits our constraints, proof of concept tests for both solutions, implementation planning, and trials within the target hall itself. Due to its ability to provide continuous positional and rotational feedback, the indoor positioning system is the most suitable solution for accurately installing the stripline block.

Espinoza, David [Unlisted, US]↗