Symposium on Radar and Radiometric Observations of Venus during the 1962 Conjunction: Mariner 2 microwave radiometer experiment and results

On 14 December 1962 the Mariner 2 spacecraft passed within 34 350 km of the surface of Venus after a flight of 109.5 days from earth. During the passage, a microwave radiometer experiment abroad the spacecraft successfully measured emission from the planet at wavelengths of 13.5 and 19 mm on three scans of the planetary disk. The areal resolution was high, the half-power beamwidths of the antennas being approximately 1/6 of the angle subtended by the Venusian disk. The purpose of this paper is to: (1) Review the background and objectives of the experiment and the design constraints imposed by spacecraft tech- nology. (2) Provide an engineering description of the experiment. (3) Describe the in-flight performance of the equipment and its effect on the planetary results. (4) Present the microwave data acquired. (5) Pre- sent an analysis and interpretation of the data and the conclusions drawn therefrom. The results provide quantitative data for microwave limb darkening of Venus and thus give strong support to that class of model atmospheres which have high temperatures originating at, or near, the surface of the planet.