Pioneer Venus & Galileo Probe Development: Comparison/Assessment

Abstract

This paper provides a comparison and assessment of the Pioneer Venus Large Probe and the Galileo Probe Development Programs. The Pioneer Venus Probe entered and descended through the Venus atmosphere measuring the characteristics of the atmosphere to the surface on December 9, 1978. The Galileo Probe entered the atmosphere of Jupiter on December 7, 1995 making measurements of the Jovian atmosphere to a pressure of 25 bars. Both missions were highly successful in meeting the mission goals and requirements. Data collected by the science instrument payloads provided detailed information to increase our understanding of the planetary atmospheres (structure, composition, cloud makeup, wind characteristics, energy balance, etc.). The two probes were similar in overall size, shape and mass. However, the designs were significantly different due to differences in the entry and descent conditions, and in the mission requirements. There were also dramatic differences in the character of the development programs, driven primarily by decisions and events outside the control of the Galileo Project. This paper compares the major features of the two projects, including changes driven by outside events/decisions, the mission environments, and resulting designs. Design challenges and surprises, and major test issues encountered are described along with resolution of problems. Finally, lessons learned and general reflections are presented.