Venus Gravity: Global Field Results

The Pioneer Venus Orbiter has provided a vast amount of gravity data, since March 1979. High resolution results have revealed the high correlation between topography and gravity. These data were acquired at relatively low spacecraft altitudes (150 km) where atmospheric effects and high frequency variations were significant and modelling with global spherical harmonics was difficult. During 1982 data were acquired over a complete Venus rotation where the lowest altitudes were 1000 km or more, thus removing atmospherics and high frequency gravity effects. These data that have been reduced to produce a tenth degree and order spherical harmonic model of the global gravity field of Venus. The reduction technique used a least squares where 78 independent arcs of data were combined in a simultaneous inversion. The tenth degree and order gravity field solution has 117 parameters describing the spherical harmonic coefficients. This provides approximately 1800 km feature resolution. These coefficients are presented as a geoid map.