Venus: Mass, Gravity Field, Atmosphere, and Ionosphere as Measured by the Mariner 10 DualFrequency Radio System
Abstract
Analysis of the Doppler tracking data near encounter yields a value for the ratio of the mass of the sun to that of Venus of 408,523.9 ± 1.2, which is in good agreement with prior determinations based on data from Mariner 2 and Mariner 5. Preliminary analysis indicates that the magnitudes of the fractional differences in the principal moments of inertia of Venus are no larger than 10^{4}, given that the effects of gravityfield harmonics higher than the second are negligible. Additional analysis is needed to determine the influence of the higher order harmonics on this bound. Four distinct temperature inversions exist at altitudes of 56, 58, 61, and 63 kilometers. The Xband signal was much more rapidly attenuated than the Sband signal and disappeared completely at 52kilometer altitude. The nightside ionosphere consists of two layers having a peak density of 10^{4} electrons per cubic centimeter at altitudes of 140 and 120 kilometers. The dayside ionosphere has a peak density of 3 × 10^{5} electrons per cubic centimeter at an altitude of 145 kilometers. The electron number density observed at higher altitudes was ten times less than that observed by Mariner 5, and no strong evidence for a welldefined plasmapause was found.
 Publication:

Science
 Pub Date:
 March 1974
 DOI:
 10.1126/science.183.4131.1297
 Bibcode:
 1974Sci...183.1297H