Thermal and Electrical Analysis of MARS Rover RTG, and Performance Comparison of Alternative Design Options.

Abstract

The paper describes the thermal, thermoelectric and electrical analysis of Radioisotope Thermoelectric Generators (RTGs) for powering the MARS Rover vehicle, which is a critical element of the unmanned Mars Rover and Sample Return mission (MRSR). The work described was part of an RTG design study conducted by Fairchild Space Company for the U.S. Department of Energy, in support of the Jet Propulsion Laboratory's MRSR Project.; A companion paper presented at this conference described a reference mission scenario, al illustrative Rover design and activity pattern on Mars, its power system requirements and environmental constraints, a design approach enabling RTG operation in the Martian atmosphere, and the design and the structural and mass analysis of a conservative baseline RTG employing safety-qualified heat source modules and reliability-proven thermoelectric converter elements.; The present paper presents a detailed description of the baseline RTG's thermal, thermoelectric, and electrical analysis. It examines the effect of different operating conditions (beginning versus end of mission, water-cooled versus radiation-cooled, summer day versus winter night) on the RTG's performance. Finally, the paper describes and analyzes a number of alternative RTG designs, to determine the effect of different power levels (250W versus 125W), different thermoelectric element designs (standard versus short unicouples versusmore » multicouples) and different thermoelectric figures of merit (0.00058K(superscript -1) to 0.000140K (superscript -1) on the RTG's specific power.; The results presented show the RTG performance achievable with current technology, and the performance improvements that would be achievable with various technology developments. It provides a basis for selecting the optimum strategy for meeting the Mars Rover design goals with minimal programmatic risk and cost.; There is a duplicate copy and also a duplicate copy in the ESD files.« less