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  • 1
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    Scintillation estimates for a Jupiter entry probe: Phase 1 (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A model of the electron density irregularities in the Jovian ionosphere is constructed based on a preliminary interpretation of the Pioneer 10 Jovian ionospheric scintillations. The ionospheric irregularities exist over an altitude range of 3000 km. The structure constant c sub n of refractive index fluctuations is constant throughout this altitude range. The spatial wavenumber spectrum of the electron density irregularities follows the Kolmogorov spectrum and the outer scale size is greater than 6 km. Estimates of scintillation for a Jovian entry probe based on this model indicate that it is small at S-band but could be substantial at 4000 MHz. The temporal frequency spectrum of the log-amplitude fluctuation is less than 1 Hz and is consequently rather narrow.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-CR-145769 , JPL-TM-33-745
    Format: application/pdf
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  • 2
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    Measurements of the magnetic field orientation in the Jovian ionosphere deduced from Pioneer 10 and 11 scintillation observations (1978)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: In this paper the S band scintillations observed during the Pioneer 10 and 11 occultation measurements of Jupiter are analyzed. It is found that while the electron density irregularities are isotropic in the collision-dominated lower ionosphere, they are anisotropic in the upper ionosphere because of alignment along the magnetic field. By using Rytov's approximation the frequency spectrum of the log-amplitude scintillations is derived for a wave propagating in an anisotropic turbulent medium. It is shown that the spectrum depends to a large extent on the direction of anisotropy and is therefore useful for measuring the orientation of the magnetic field in regions that have not yet been probed by direct measurements. This new technique is applied to the Pioneer 10 and 11 observations, and is used to deduce the first measurements of magnetic field orientation in the ionosphere of Jupiter.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 83; Nov. 1
    Format: text
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  • 3
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    Measurements of electron density irregularities in the ionosphere of Jupiter by Pioneer 10 (1976)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: It is demonstrated that when the frequency spectrum of log amplitude fluctuations is used, the radio-occultation experiment is a powerful tool for detecting, identifying, and studying ionospheric irregularities. Analysis of Pioneer 10 radio-occultation measurements reveals that the Jovian ionosphere possesses electron-density irregularities which are very similar to those found in the earth's ionosphere. This is the first time such irregularities have been found in a planetary ionosphere other than that of the earth. The Pioneer 10 results indicate that the spatial wave-number spectrum of the electron-density irregularities is close to the Kolmogorov spectrum and that the outer scale size is greater than the Fresnel size (6.15 km). This type of spectrum suggests that the irregularities are probably produced by the turbulent dissipation of irregularities larger than the outer scale size.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 81; July 1
    Format: text
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