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  • 1
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    Modeling and investigative studies of Jovian low frequency emissions (1986)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The Voyager data in a newly produced noise-reduced and recalibrated format has been received. New color spectrograms were developed on high resolution color terminals which display this data. The production of these new spectrograms utilizing the new format data is quite important, because it eliminates a serious problem of noise contamination and miscalibration in the old data set. In addition, a new Jovian plasma model was introduced, which includes the Io torus and accounts for 7 ionic species. The new plasma model is important in the ray tracing of hectometric (HOM) and kilometric (KOM) radiation which may be influenced by the Io torus.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA, Washington Reports of Planetary Astronomy, 1985; p 44-45
    Format: text
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  • 2
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    First detection of HDO in the atmosphere of Venus at radio wavelengths - An estimate of the H2O vertical distribution (1991)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The 225.9 GHz line of HDO has been detected in absorption in the atmosphere of Venus, with the 30-m IRAM antenna. This measurement gives information regarding the vertical distributions of HDO, and thus H2O, in this planet. The observations are consistent with an H2O vertical distribution strongly depleted by saturation at an altitude of 95 km, and, assuming a D/H enrichment of 120 with respect to the terrestrial value, with a mixing ratio of 3.5 (+ or - 2.0) ppm in the range 65-95 km.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 246; 1, Ju
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  • 3
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    Uranus - Variability of the microwave spectrum (1983)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Radio astronomical observations of Uranus show that the radio emission spectrum is evolving in time. Ammonia vapor must be depleted in the Uranian atmosphere as Gulkis et al. (1978) previously suggested. Since 1965, ammonia either has been decreasing in time or is a decreasing function of latitude, or both, provided that the radio emission is atmospheric in origin. If Uranus has an observable low-emissivity 'surface', these trends may be reversed. The microwave observations made in 1965, at the time when the spin axis of Uranus was nearly perpendicular to the sun-Uranus line, are consistent with an atmospheric opacity profile that would be produced by saturated ammonia vapor in a predominantly hydrogen atmosphere. At the present time, when the spin axis of Uranus is nearly aligned with the sun-Uranus line, the measurements require an opacity that would be produced by saturated water vapor. A large thermal gradient between the pole and equator is ruled out.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science (ISSN 0036-8075); 221; July 29
    Format: text
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  • 4
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    Saturn's microwave spectrum: Implications for the atmosphere and the rings (1978)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Measurements of Saturn's disk temperature are compiled to determine the planet's microwave spectrum from 1 mm to 100 cm wavelength. The data were adjusted to conform with a common flux density scale. A model of Saturn's rings is used to remove the effects of the rings from the atmospheric component at centimeter and decimeter wavelengths. Theoretical spectra for a number of convective atmospheric models were computed and compared with the observed spectrum. Radiative-convective models with approximately solar composition and with an effective temperature of approximately 89 K are in good agreement with the observations. The agreement between the observed and theoretical spectra is a strong indication that gaseous ammonia is present in Saturn's atmosphere. A good fit to the data is obtained with an ammonia mixing ratio of approximately 5 x 10,0001. A comparison of the millimeter wavelength data with the best-fitting atmospheric spectrum indicates that the thermal component of the ring brightness temperature near 1 mm wavelength is approximately 25 k.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Its The Saturn System; p 195-216
    Format: application/pdf
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  • 5
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    Modeling and investigative studies of Jovian low frequency emissions (1986)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Jovian decametric (DAM) and hectometric (HOM) emissions were first observed over the entire spectrum by the Voyager 1 and 2 flybys of the planet. They display unusual arc-like structures on frequency-versus-time spectrograms. Software for the modeling of the Jovian plasma and magnetic field environment was performed. In addition, an extensive library of programs was developed for the retrieval of Voyager Planetary Radio Astronomy (PRA) data in both the high and low frequency bands from new noise-free, recalibrated data tapes. This software allows the option of retrieving data sorted with respect to particular sub-Io longitudes. This has proven to be invaluable in the analyses of the data. Graphics routines were also developed to display the data on color spectrograms.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-TM-89299 , NAS 1.15:89299
    Format: application/pdf
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  • 6
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    A Review of the Millimeter and Centimeter Observations of Uranus (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Millimeter and centimeter wave astronomical data of Uranus are presented and discussed. Some recent observations of the brightness distribution across the disk at 2 cm and 6 cm wavelength are reported. Data related to the variability of the microwave spectrum are reanalyzed, taking into account the strong variation of temperature with wavelength, and including up to date data. The results indicate that the brightness temperatures of Uranus have probably reached their maximum values. The evidence for the depletion of ammonia in the upper atmosphere is discussed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Uranus and Neptune; p 225-262
    Format: text
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  • 7
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    Planetary radio astronomy observations from Voyager 2 near Jupiter (1979)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: The Voyager 2 Planetary Radio Astronomy experiment to Jupiter has confirmed and extended to higher zenomagnetic latitudes results from the identical experiment carried by Voyager 1. The kilometric emissions discovered by Voyager 1 often extended to 1 megahertz or higher on Voyager 2 and often consisted of negatively, or less frequently, positively drifting narrowband bursts. On the basis of tentative identification of plasma wave emissions similar to those detected by Voyager 1, the plasma torus associated with Io appeared somewhat denser to Voyager 2 than it did to Voyager 1. The paper reports on quasi-periodic sinusoidal or impulsive bursts in the broadcast band range of wavelengths (800 to 1800 kHz). A Faraday effect appears at decametric frequencies, which probably results from propagation of the radiation near its sources on Jupiter. Finally, the occurrence of decametric emission in homologous arc families is discussed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science; 206; Nov. 23
    Format: text
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  • 8
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    Jovian decametric arcs - An estimate of the required wave normal angles from three-dimensional ray tracing. (1984)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Three-dimensional ray tracing is applied to an analysis of variable radio wave normal angle effects on the associated decametric (DAM) arc structures in the Jovian magnetosphere. The analysis is bed on 1-40 MHz radio signature recorded during Voyage 1 and 2 passages. The frequencies considered are above the R-X cut-off, and several ratios of the emission frequency/source frequency. The ray tracing code is based on a cold plasma formula and integration of the Hasselgrove (1955) equations. It is assumed that the emission is in the R-X mode, the source lies at the foot of an Io flux tube, and the emission cone is hollow. Attention is focused on data for two intense, vertex-late, high curvature DAM arc. A possible source for the arcs is found to be doppler-shifted gyroemission from a beam of electrons with an energy of 10 keV. A value of 1.1 is set as the limit of the doppler shift of the DAM emissions.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 89; 9089-909
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  • 9
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    The magnetic field of Jupiter - A comparison of radio astronomy and spacecraft observations (1979)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: The inner magnetic field of Jupiter is characterized on the basis of Pioneer 10 and 11 measurements and earth-based decimetric radio observations. The dipole parameters derived from the two data sets are in good agreement. Problems in reconciling asymmetries observed in the earth-based data and the spacecraft data are discussed. Models of synchrotron emission from arbitrary magnetic field configurations and high-resolution maps of the Jovian radiation belts in all polarizations are needed to further understanding of Jupiter's magnetic field
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 10
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    Planets and satellites of the outer solar system, asteroids, and comets (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The cosmogenic significance of outer solar system objects is evaluated with emphasis on planets and larger satellites of greatest biological interest; comets, asteroids, and the smaller satellites are also discussed. Principal physical and rudimentary photometric data for the five outer planets are presented in tables. Sufficient information on planetary motions is included for most calculations in physical planetology.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Found. of Space Biol. and Med., Vol. 1; p 197-268
    Format: text
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