Venus Mobile Explorer with RPS for active cooling: A feasibility study

This paper presents the findings from a study to evaluate the feasibility of a radioisotope power system (RPS) combined with active cooling to enable a long-duration venus surface mission. On-board power with active cooling technology featured prominently in both. the national research council's decadal survey and in the 2006 NASA solar system exploration roadmap as mission enabling for the exploration of Venus. Power and cooling system options were reviewed and the most promising concepts were modeled to develop an assessment tool for Venus mission planners considering a variety of future potential missions to Venus, including a venus mobile explorer (either a balloon or rover concept), a long-lived venus static lander, or a venus geophysical network. The concepts modeled were based on the integration of General Purpose Heat Source (GPHS) modules with different types of Stirling cycle heat engines for power conversion and cooling. Unlike prior investigations which reported on single point design concepts, this assessment tool allows the user to generate either a point design or parametric curves of approximate power and cooling system mass, power level, and number of GPHS modules needed for a ldquoblack boxrdquo payload housed in a spherical pressure vessel. Input variables include altitude, pressure vessel diameter, payload temperature, and payload power on Venus. Users may also specify the number and type of pressure vessel windows, use of phase-change material for additional (time-dependent) payload cooling, and amount of (rechargeable) battery power for peak power demand operations. Parameter sets that would enable a Venus surface mission with fewer than 16 GPHS modules were identified. Thus, the study provides guidance for design practices that might enable a long-duration Venus surface mission with an attainable quantity of
²³⁸
Pu, and with achievable operating parameters.