Venus Gravity: A Harmonic Analysis

Bruce G. Bills (1), Walter S. Kiefer (2), and Robert L. Jones (1)

(1) Lunar and Planetary Institute
(2) Division of Geological and Planetary Sciences, Caltech

J. Geophysical Research, 92, 10,335-10,351, 1987.

Abstract: An improved model of Venusian global gravity has been obtained by fitting an eighteenth-degree and eighteenth-order spherical harmonic series to 78 orbital arcs of high altitude (950-1350 km at periapsis) tracking data and 351 orbital arcs of lower-altitude (150-200 km at periapsis) data from the Pioneer Venus Orbiter. Compared to a recently published tenth degree model (Mottinger et al., 1985), which is based on the 78 high-altitude arcs only, the current model provides a significant improvement in resolution and fidelity. As a measure of this improvement, we note that for the low-altitude arcs alone, the variance of the residuals for the present model is reduced to 19% of the data variance, compared to 51% for the tenth-degree model. Venus differs significantly from the Earth in that it exhibits a significant correlation between long-wavelength topography and gravity. The gravity/topography spectral admittances are inconsistent with either Airy or Pratt isostasy, but they are consistent with dynamic support by mantle convection.

Text of article (on AGU website)

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Walter S. Kiefer,   kiefer@lpi.usra.edu