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Warwick, J. W.

Publications and source records attributed to Warwick, J. W..

At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Voyager 1 planetary radio astronomy observations near Jupiter

Results from the first low-frequency radio receiver to be transported into the Jupiter magnetosphere are reported. Dramatic new information was obtained, both because Voyager was near or in Jupiter's radio emission sources and because it was outside the relatively dense solar wind plasma of the inner solar system. Extensive radio spectral arcs, from above 30 to about 1 MHz, occurred in patterns correlated with planetary longitude. A newly discovered kilometric wavelength radio source may relate to the plasma torus near Io's orbit. In situ wave resonances near closest approach define an electron density profile along the Voyager trajectory and form the basis for a map of the torus. Detailed studies are in progress and are outlined briefly.

Warwick, J. W.↗
NASA NTRS1979

Voyager spacecraft radio observations of Jupiter - Initial cruise results

Low frequency (below 1326 kHz) observations of Jupiter obtained from November, 1977 through June, 1978 by the radio astronomy receivers carried by the two Voyager spacecraft are reported and compared with a large body of higher-frequency ground-based observations. Although the morphology of hectometric wavelength (HOM) emissions strongly resembles that of decametric (DAM) wavelength radio noise, they display opposite polarization. DAM emissions are strongly modulated by Io, whereas HOM emissions exhibit little or no influence from any satellite and appear to be modulated by the rotation phase of the planet. Several single-source models could possibly account for these results, including a model assuming emission at two well-separated frequencies above and below the local electron plasma frequency and the model proposed by Barbosa (1976) in which electrostatic waves at twice the upper hybrid frequency couple to both the ordinary and extraordinary electromagnetic modes. However, neither of these is entirely satisfactory.

Kaiser, M. L.↗
NASA NTRS1979

Voyager 1 Planetary Radio Astronomy Observations Near Jupiter

Results are reported from the first low frequency radio receiver to be transported into the Jupiter magnetosphere. Dramatic new information was obtained both because Voyager was near or in Jupiter's radio emission sources and also because it was outside the relatively dense solar wind plasma of the inner solar system. Extensive radio arcs, from above 30 MHz to about 1 MHz, occurred in patterns correlated with planetary longitude. A newly discovered kilometric wavelength radio source may relate to the plasma torus near Io's orbit. In situ wave resonances near closest approach define an electron density profile along the Voyager trajectory and form the basis for a map of the torus. Studies in progress are outlined briefly.

Warwick, J. W.↗
NASA NTRS1979

Voyager spacecraft radio observations of Jupiter: Initial cruise results

Jupiter's low-frequency radio emission were detected by the planetary radio astronomy instruments onboard the two Voyager spacecraft. The emission is surprisingly similar in morphology but opposite in polarization to the high-frequency Jovian radio noise that were observed with ground-based telescopes for more than two decades. Several possible explanations for the behavior of the low-frequency emission are examined, but none of them is completely satisfactory.

Kaiser, M. L.↗
NASA NTRS1978

Non-thermal radio emission from Saturn

Direct, strong evidence for non-thermal radio emission from Saturn exists in the hectometric data observed by Imp 6. The planet has been tentatively identified as a decametric source, but the most sensitive and most recent data fail to confirm this. At metric or decimetric wavelengths Saturn has no non-thermal emission like Jupiter's synchrotron sources. Finally, a comparative study of Earth and Jupiter radio emissions suggests lightning discharges.

Warwick, J. W.↗
NASA NTRS1978

Direct measurements by Voyagers 1 and 2 of the polarization of terrestrial kilometric radiation

Measurements of the polarization of intense terrestrial kilometric radiation obtained with planetary radio astronomy experiments on Voyager-1 and 2 during the early portions of each flight show the signals to be predominantly left-hand circularly polarized. Since these emissions were most probably generated above the Northern Hemisphere auroral zone, we conclude that the radiation is emitted primarily in the extraordinary mode.

Kaiser, M. L.↗
NASA NTRS1978

Direct measurements of the polarization of terrestrial kilometric radiation from Voyagers 1 and 2

Terrestrial radiation measurements obtained with planetary radio astronomy experiments on Voyager-1 and 2 during the early portions of each flight show the signals to be predominantly left-hand circularly polarized. Since these emissions were most probably generated above the Northern Hemisphere auroral zone, it is concluded that the radiation is emitted primarily in the extraordinary mode.

Kaiser, M. L.↗
NASA NTRS1978

On the observation of a flare-generated shock wave at 9.7 AU by Pioneer 10

An apparent solar-flare-generated shock wave detected by Pioneer-10 at 9.7 AU on April 9, 1976 is discussed. The shock wave may be correlated with a radio emission burst from Jupiter not associated with Io (March 30). The fact that solar flares observed on March 20 were at the central meridian with respect to Jupiter and Pioneer-10 and the fact that solar activity was very low before March 20 contribute to the argument that a shock wave had propagated to the region of the spacecraft.

Dryer, M.↗
NASA NTRS1972

Outer planets grand tours: Planetary radio astronomy team report

Requirements related to scientific observations of planetary radio emissions during outer planets grand tours are discussed. Observations at low frequencies where non-thermal cooperative plasma phenomena play a major role are considered for determining dynamical processes and magnetic fields near a planet. Magnetic field measurements by spacecraft magnetometers, and by radio receivers in their harmonic modes are proposed for interpretation of planetary radio emission.

Warwick, J. W.↗
NASA NTRS1965

Random microscopic magnetic fields in a plasma.

Random plasma magnetic fields caused by electrons coming closer to plasma atom than mean interelectron distance and by electrons that pass at or beyond this distance

PLASMA-PARTICLE INTERACTION↗