Pioneer Venus - Evolving coverage of the near-Venus environment

The manner in which secular changes in the orbit of the Pioneer Venus Orbiter (PVO) research satellite influence its data collecting capabilities is discussed. A brief description of the propulsion system and sensor arrays of the satellite is presented, and the susceptibility of these systems to changes in power supply due to the decline in solar activity is considered. It is pointed out that the PVO should have enough fuel to continue to transmit data until after the arrival of Comet Halley in 1986, and that, during the 1991 to 1992 period, more moderate levels of solar activity will permit more accurate measurements of thermospheric and ionospheric parameters.