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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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All sourcesNASA NTRSDOE OSTI
NASA NTRS1985

Mesospheric Winds and Tides at Arecibo/puerto Rico (18 Deg N, 67 Deg W) November 20-23, 1981

The SOUSY-VHF-Radar was operated in the period November 20 to 23, 1981 during a continuous run at the Arecibo Observatory. The data used for this analysis were recorded from 06 AST on November 20 until 06 AST on November 23. Meridional winds were measured at odd hours and zonal winds at even hours. The occurrence of mesospheric VHF radar echoes was limited as usual to the daylight hours between 06 and 18 AST. The height limits, were variable from day to day, they were roughly 62 to 90 km. The intermittency of echoes in time and height, as well as radio interference, made it fairly difficult to deduce tidal information for this time period. About 10 to 45 single velocity estimates could be used to calculate an hourly mean. The variance of the displayed resulting in data, obtained by weighted averaging over the 3 day period, is about similar to the mean. The winds were extremely low during the observation period. Velocities of the prevailing wind, observed during an earlier campaign were 5 to 10 times larger than in the period of November 20 to 23, 1981. The amplitudes of the diurnal tide are comparable.

Rottger, J.↗
NASA NTRS2004

Participation in the Mars Orbiting Laser Altimeter Experiment

The Mars Orbiting Laser Altimeter (MOLA) instrument [1,2] carried aboard the Mars Global Surveyor (MGS) spacecraft, has observed strong echoes from cloud tops at 1.064 microns on 61% of its orbital passes over the winter north pole (235deg L(sub S), < 315deg) and on 58% of the passes over the winter south pole (45deg < L(sub S), < 135deg). The clouds are unlikely to be composed of water ice since the vapor pressure of H2O is very low at the Martian nighttime polar temperatures measured by the Thermal Emission Spectrometer (TES) [3], and by an analysis of MGS radio occultations [4]. Dust clouds can also be ruled out since no correlation is seen between clouds and global dust storms. The virtually certain composition for the winter polar clouds is CO2 ice.

Pettengil, Gordon H.↗
NASA NTRS1978

Observations of auroral fading before breakup

The onset of auroral breakup was studied by using a variety of instruments with time resolution of some tens of second. Rapid sequences of all-sky photographs, and fast meridian scans by photometers, show that breakup is usually preceded by moderate brightening, followed by fading of the auroral brightness lasting one or two minutes, before the actual breakup itself. This optical activity is closely correlated with the development of auroral radar echoes. Data from a magnetometer network provide some indication of a correlated response by the local auroral and ionospheric currents. Riometer recordings show a slow decrease in ionspheric radio wave absorption over a period of about ten minutes prior to breakup, with the largest decrease essentially to quiet-time values in the region of auroral fading and subsequent breakup.

Pellinen, R. J.↗
NASA NTRS2004

Advances in Inner Magnetosphere Passive and Active Wave Research

This review identifies a number of the principal research advancements that have occurred over the last five years in the study of electromagnetic (EM) waves in the Earth's inner magnetosphere. The observations used in this study are from the plasma wave instruments and radio sounders on Cluster, IMAGE, Geotail, Wind, Polar, Interball, and others. The data from passive plasma wave instruments have led to a number of advances such as: determining the origin and importance of whistler mode waves in the plasmasphere, discovery of the source of kilometric continuum radiation, mapping AKR source regions with "pinpoint" accuracy, and correlating the AKR source location with dipole tilt angle. Active magnetospheric wave experiments have shown that long range ducted and direct echoes can be used to obtain the density distribution of electrons in the polar cap and along plasmaspheric field lines, providing key information on plasmaspheric filling rates and polar cap outflows.

Green, James L.↗
NASA NTRS1987

Circumstellar matter and the nature of the SN1987A progenitor star

It is argued that radio observations of the supernova 1987A can be interpreted in terms of its interaction with circumstellar matter. The early turn-on of the radio emission implies a relatively low density circumstellar medium. The optical properties of the supernova imply that the progenitor star had a smaller radius than that of a typical type II supernova progenitor. The mass loss properties are consistent with this hypothesis. The thermal X-ray luminosity of the supernova is predicted and noted to be below the current upper limit. A bright infrared dust echo is not expected, although a weak echo from an earlier mass loss phase is possible. Weak ultraviolet emission lines from cicumstellar gas may be visible. Although the circumstellar density is low, it is possible that the progenitor star did lose a substantial fraction of its mass prior to the supernova explosion.

Chevalier, R. A.↗
NASA NTRS1988

Supernova 1987A in the Large Magellanic Cloud; Proceedings of the Fourth George Mason Astrophysics Workshop, George Mason University, Fairfax, VA, Oct. 12-14, 1987

Papers concerning SN 1987A are presented, covering topics such as images and spectrograms of the SN 1987A progenitor, a linear polarimetric study of SN 1987A, the energetics, nature, and uniqueness of the supernova, comparison of the SN 1987A light curve with other type II supernovae, P-Cygni features and photospheric velocities, the neutrino burst from SN 1987A, mass determination of neutrinos, neutrino transport, energetics, and oscillations. Additional papers discuss supernovae light echoes, the UV interstellar spectrum of SN 1987A, theoretical models of SN 1987A, circumstellar and interstellar interaction, the supernova as a stripped asymptotic-branch giant in a binary system, pulsar formation and the fall back mass fraction, the signals of particle acceleration at SN 1987A, the effects of the mixing of the ejecta on the hard X-ray emissions from the supernova, possible s-process gamma-ray lines in supernovae, detectability of early thermal radiation from a neutron star in SN 1987A, NASA studies of the supernova, and information exchange for SN 1987A. Observational studies presented include optical, IR, radio, and UV observations, IR speckle-interferometry, coded mask X-ray observations, broad band X-ray imaging spectrophotometry, gamma-ray and thermal X-ray observations, and reports from several observatories.

Kafatos, Minas↗
NASA NTRS2014

A Multi-Wavelength Investigation of the Radio-Loud Supernova PTF11qcj and its Circumstellar Environment

We present the discovery, classification, and extensive panchromatic (from radio to X-ray) follow-up observations of PTF11qcj, a supernova (SN) discovered by the Palomar Transient Factory (PTF). Our observations with the Karl G. Jansky Very Large Array show that this event is radio-loud: PTF11qcj reached a radio peak luminosity comparable to that of the famous gamma-ray-burst-associated SN 1998bw (L (sub 5 gigahertz) approximates 10 (sup 29) ergs per second per hertz). PTF11qcj is also detected in X-rays with the Chandra Observatory, and in the infrared band with Spitzer. Our multi-wavelength analysis probes the SN interaction with circumstellar material. The radio observations suggest a progenitor mass-loss rate of approximately 10 (sup -4) the mass of the sun per year times (v (sub omega) divided by 1000 kilometers per second), and a velocity of approximately 0.3-0.5 c (the speed of light in a vacuum) for the fastest moving ejecta (at around 10 days after explosion). However, these estimates are derived assuming the simplest model of SN ejecta interacting with a smooth circumstellar wind, and do not account for possible inhomogeneities in the medium and asphericity of the explosion. The radio data show deviations from such a simple model, as well as a late-time re-brightening. The X-ray flux from PTF11qcj is compatible with the high-frequency extrapolation of the radio synchrotron emission (within the large uncertainties). A light echo from pre-existing dust is in agreement with our infrared data. Our pre-explosion data from the PTF suggest that a precursor eruption of absolute magnitude M (sub r) approximately equal to -13 mag may have occurred approximately 2.5 years prior to the SN explosion. Overall, PTF11qcj fits the expectations from the explosion of a Wolf-Rayet star. Precursor eruptions may be a feature characterizing the final pre-explosion evolution of such stars.

Radio↗
NASA NTRS2002

Intercontinental Bistatic Radar Test Observation of Asteroid 1998 WT24

We describe the first intercontinental planetary radar test performed in Italy observing the near Earth asteroid (NEA) 33342 (1998 WT24) in December 2001 by means of the bistatic configurations Goldstone (California, USA)-Medicina (Italy) and Evpatoria (Ukraine)-Medicina. The experiment goal was to characterize the system for realtime radar follow-up observations of NEAs and artificial orbiting debris, in the framework of a feasibility study which aims at using the Sardinia Radio Telescope, at present under construction, also as a planetary radar facility. We report the preliminary results of the radar observations carried out by the IRA-CNR (Instituto di Radioastronomia - Consiglio Nazionale delle Ricerche) and the OATo (Osservatorio Astronomico di Torino) groups, aimed at exploring the scientific potentials of a new space radar program, using the existing facilities in Italy. The planetary radar technique is uniquely capable of investigating geometry and surface properties of various solar system objects, demonstrating advantages over the optical methods in its high spatial resolution and ability to obtain three-dimensional images. A single radar detection allows to obtain extremely accurate orbital elements, improving the instantaneous positional uncertainties by orders of magnitude with respect to an optically determined orbit. Radar is a powerful means to spatially resolve NEAs by measuring the distribution of the echo power in time delay (range) and Doppler frequency (line-of-sight velocity) with extreme precision in each coordinate, as it provides detailed information about the target physical properties like size, shape, rotation, near-surface bulk density and roughness and internal density distribution. The Medicina 32m antenna had been successfully used for the first time as the receiving part of a bistatic configuration during a test experiment (September 2001) held to check the capabilities of the entire data acquisition system. This test was possible thanks to the collaboration undertaken with the Evpatoria radar station, and consisted in the observation of the ETALON-1 low orbit satellite

Righini, S.↗
NASA NTRS2002

Estimation of High-Frequency Earth-Space Radio Wave Signals via Ground-Based Polarimetric Radar Observations

Expanding human presence in space, and enabling the commercialization of this frontier, is part of the strategic goals for NASA's Human Exploration and Development of Space (HEDS) enterprise. Future near-Earth and planetary missions will support the use of high-frequency Earth-space communication systems. Additionally, increased commercial demand on low-frequency Earth-space links in the S- and C-band spectra have led to increased interest in the use of higher frequencies in regions like Ku and Ka-band. Attenuation of high-frequency signals, due to a precipitating medium, can be quite severe and can cause considerable disruptions in a communications link that traverses such a medium. Previously, ground radar measurements were made along the Earth-space path and compared to satellite beacon data that was transmitted to a ground station. In this paper, quantitative estimation of the attenuation along the propagation path is made via inter-comparisons of radar data taken from the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) and ground-based polarimetric radar observations. Theoretical relationships between the expected specific attenuation (k) of spaceborne measurements with ground-based measurements of reflectivity (Zh) and differential propagation phase shift (Kdp) are developed for various hydrometeors that could be present along the propagation path, which are used to estimate the two-way path-integrated attenuation (PIA) on the PR return echo. Resolution volume matching and alignment of the radar systems is performed, and a direct comparison of PR return echo with ground radar attenuation estimates is made directly on a beam-by-beam basis. The technique is validated using data collected from the TExas and Florida UNderflights (TEFLUN-B) experiment and the TRMM large Biosphere-Atmosphere experiment in Amazonia (LBA) campaign. Attenuation estimation derived from this method can be used for strategiC planning of communication systems for future HEDS missions.

Bolen, Steve↗
DOE OSTI2024

Spin-energy entanglement of a time-focused neutron

Intraparticle entanglement of individual particles such as neutrons could enable another class of scattering probes that are sensitive to entanglement in quantum systems and materials. Here, in this work, we present experimental results demonstrating quantum contextuality as a result of entanglement between the spin and energy modes (i.e., degrees of freedom) of single neutrons in a beam using a pair of resonant radio-frequency neutron spin flippers in the modulated intensity with zero effort configuration. We verified the mode entanglement by measuring a Clauser-Horne-Shimony-Holt contextuality witness S defined in the spin and energy subsystems, observing a clear breach of the classical bound of |S| ≤ 2, obtaining S = 2.40 ± 0.02. These entangled beams could enable alternative approaches for directly probing dynamics and entanglement in quantum materials whose low-energy excitation scales match those of the incident entangled neutron.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
NASA NTRS2005

Deep Interior Mission: Imaging the Interior of Near-Earth Asteroids Using Radio Reflection Tomography

Near-Earth asteroids are important exploration targets since they provide clues to the evolution of the solar system. They are also of interest since they present a clear danger to Earth. Our mission objective is to image the internal structure of two NEOs using radio reflection tomography (RRT) in order to explore the record of asteroid origin and impact evolution, and to test the fundamental hypothesis that some NEOs are rubble piles rather than consolidated bodies. Our mission s RRT technique is analogous to doing a CAT scan of the asteroid from orbit. Closely sampled radar echoes are processed to yield volumetric maps of mechanical and compositional boundaries, and to measure interior material dielectric properties. The RRT instrument is a radar that operates at 5 and 15 MHz with two 30-m (tip-to-tip) dipole antennas that are used in a cross-dipole configuration. The radar transmitter and receiver electronics have heritage from JPL's MARSIS contribution to Mars Express, and the antenna is similar to systems used in IMAGE and LACE missions. The 5-MHz channel is designed to penetrate greater than 1 km of basaltic rock, and 15-MHz penetrates a few hundred meters or more. In addition to RRT volumetric imaging, we use redundant color cameras to explore the surface expressions of unit boundaries, in order to relate interior radar imaging to what is observable from spacecraft imaging and from Earth. The camera also yields stereo color imaging for geology and RRT-related compositional analysis. Gravity and high fidelity geodesy are used to explore how interior structure is expressed in shape, density, mass distribution and spin. Ion thruster propulsion is utilized by Deep Interior to enable tomographic radar mapping of multiple asteroids. Within the Discovery AO scheduling parameters we identify two targets, S-type 1999 ND43 (approximately 500 m diameter) and V-type 3908 Nyx (approximately 1 km), asteroids whose compositions bracket the diversity of solar system materials that we are likely to encounter, from undifferentiated to highly evolved. The 5-15 MHz radar is capable of probing more primitive bodies (e.g. comets or C-types) that may be available given other launch schedules. 5 MHz radar easily penetrates, with the required SNR , greater than 1 km of basalt (a good analog for Nyx). Basalt has a greater loss tangent than expected for most asteroids, although iron-rich M-types are probably not appropriate targets. 15 MHz radar penetrates the outer approximately 100 m of rocky 1 km asteroids and the deep interiors of comets. Laboratory studies of the most common NE0 materials expected (S-, C- and V-type meteorite analogs) will commence in 2005.

Safaeinili, A.↗
NASA NTRS1995

Instrument technology for magnetosphere plasma imaging from high Earth orbit. Design of a radio plasma sounder

The use of radio sounding techniques for the study of the ionospheric plasma dates back to G. Briet and M. A. Tuve in 1926. Ground based swept frequency sounders can monitor the electron number density (N(sub e)) as a function of height (the N(sub e) profile). These early instruments evolved into a global network that produced high-resolution displays of echo time delay vs frequency on 35-mm film. These instruments provided the foundation for the success of the International Geophysical Year (1958). The Alouette and International Satellites for Ionospheric Studies (ISIS) programs pioneered the used of spaceborne, swept frequency sounders to obtain N(sub e) profiles of the topside of the ionosphere, from a position above the electron density maximum. Repeated measurements during the orbit produced an orbital plane contour which routinely provided density measurements to within 10%. The Alouette/ISIS experience also showed that even with a high powered transmitter (compared to the low power sounder possible today) a radio sounder can be compatible with other imaging instruments on the same satellite. Digital technology was used on later spacecraft developed by the Japanese (the EXOS C and D) and the Soviets (Intercosmos 19 and Cosmos 1809). However, a full coherent pulse compression and spectral integrating capability, such as exist today for ground-based sounders (Reinisch et al., 1992), has never been put into space. NASA's 1990 Space Physics Strategy Implementation Study "The NASA Space Physics Program from 1995 to 2010" suggested using radio sounders to study the plasmasphere and the magnetopause and its boundary layers (Green and Fung, 1993). Both the magnetopause and plasmasphere, as well as the cusp and boundary layers, can be observed by a radio sounder in a high-inclination polar orbit with an apogee greater than 6 R(sub e) (Reiff et al., 1994; Calvert et al., 1995). Magnetospheric radio sounding from space will provide remote density measurements of unprecedented precision and coverage in the plasmasphere, inner magnetosphere and magnetopause, from which the structure, inter-relationship, and variations of different plasma regions can be determined (Armstrong Johnson, 1995). A space-borne Radio Plasma Imager (RPI) could provide a unique global view of the magnetosphere revealing the underlying structure of remote plasma regions, thereby providing a framework for the interpretation of images obtained by other techniques as identified in the technical areas TA1 to TA4 in the MSFC NRA8-8.

Haines, D. Mark↗