Cloud detecting nephelometer for the Pioneer-Venus probes

Design specifications of a cloud detecting nephelometer for the Pioneer-Venus probe are given. The instrument is designed to measure the presence of clouds, their vertical structure or extent, and from the multiple probe data, provide some guides as to the global variability of the cloud structure. Specifications for the instrument include the ability to operate in the near ultraviolet, visible, and near infrared wavelengths, monitor optical quality of windows and temperatures of critical components, operate at altitudes of less than or equal to 300 m.