Design and analysis of RTGs for CRAF and Cassini missions
- Fairchild Space, 20301 Century Blvd., Germantown, MD 20874 (US)
The paper describes the design and analysis of Radioisotope Thermoelectric Generators (RTGs) integrated with the Jet Proplusion Laboratory's CRAF (Comet Rendezvous and Asteroid Flyby) and Cassini Spacecraft. The principal purpose of the CRAF mission is the study of Asteroids and comets, and the principal purpose of the Cassini mission is the study of asteroids, Saturn, and its moons (particularly Titan). Both misions will employ the Mariner/Mark-2 spacecraft, and each will be powered by two GPHS-RTGs (General Purpose Heat Source-RTGs). JPL's spacecraft designers wish to locate the two RTGs in close proximity to each other, resulting in mutual and unsymmetrical obstruction of their heat rejection paths. To support JPL's design studies, the U.S. Department of Energy asked Fairchild to determine the effect of the RTGs' proximity on their power output. As described in the paper, this required the development of novel analysis methods and computer codes for the coupled thermal and electrical analysis of obstructed RTGs with axial and circumferential temperature, voltage, and current variations. The code was validated against measured data of unobstructed RTG tests, and was used for the detailed analysis of the obstructed CRAF and Cassini RTGs. Also described is a new method for predicting the combined effect of fuel decay and thermoelectric degradation on the output of obstructed RTGs, which amounts for the effect of diminishing temperatures on degradation rates. For the 24-degree separation angle of JPL's original baseline design, and for the 35-degree RTG separation of JPL's revised design, the computed results indicate that the mutually obstructed GPHS/RTGs with standard fuel loading and operating temperatures can comfortably meet the JPL-specified power requirements for the CRAF mission and almost meet the specified requirements for the Cassini mission.
- OSTI ID:
- 5380591
- Report Number(s):
- CONF-910116-; CODEN: APCPC; TRN: 91-024102
- Journal Information:
- AIP Conference Proceedings (American Institute of Physics); (United States), Vol. 217:2; Conference: 8. symposium on space nuclear power systems, Albuquerque, NM (United States), 6-10 Jan 1991; ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
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Design and Analysis of RTGs for CRAF and Cassini Missions
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Related Subjects
30 DIRECT ENERGY CONVERSION
SPACECRAFT POWER SUPPLIES
THERMOELECTRIC GENERATORS
DESIGN
PERFORMANCE TESTING
RADIOISOTOPE HEAT SOURCES
THERMAL ANALYSIS
WASTE HEAT
DIRECT ENERGY CONVERTERS
ELECTRONIC EQUIPMENT
ENERGY
EQUIPMENT
HEAT
HEAT SOURCES
POWER SUPPLIES
TESTING
WASTES
NESDPS Office of Nuclear Energy Space and Defense Power Systems
070300* - Isotopic Power Supplies
300302 - Thermoelectric Generators- Performance & Testing