Design, Analysis, and Spacecraft Integration of RTGs for CRAF and Cassini Missions
This report consists of two parts. Part 1 describes the development of novel analytical methods needed to predict the BOM performance and the subsequent performance degradation of the mutually obstructed RTGs for the CRAF and Cassini missions. Part II applies those methods to the two missions, presents the resultant predictions, and discusses their programmatic implications.; The results indicate that JPL's original power demand goals could have been met with two standard GPHS RTGs for each mission. However, JPL subsequently raised both the power demand profile and the duration for both missions, to the point where two standard RTGs could no longer provide the desired power margin. Each mission can be satisfied by adding a third RTG, and in the case of the Cassini mission the use of three RTGs appears to be unavoidable. In the case of the CRAF mission, there appears to be a possibility that modest modifications of the RTGs' design and/or operating scheme and meet the missions' power demand without the addition of a third RTG. The potential saving in cost and schedule pressure prompted Fairchild to undertake a study of various obvious and not-so-obvious stratagems, either singly or in combination, to determine whether they would make it possible to meet the specified power demand with two RTGs.; The various stratagems investigated by Fairchild and their effect on performance are presented. The analytical results indicate that a combination of relatively modest RTG modifications could come very close to meeting the JPL-specified CRAF power demand goals. However, since even with the modifications the two RTGs did not provide sufficient margin for possible further growth in power demand, the JPL project team ultimately decided to use three RTGs for the CRAF mission also. This had the decisive advantage of eliminating the need for load switching to reduce the power demand peaks. The report documents the various power enhancement schemes and their computed effectiveness for possible future applications, and predicts the power output of the three obstructed RTGs over the life of each mission.; There are four duplicate copies.
- Research Organization:
- Fairchild Space
- Sponsoring Organization:
- NE Office of Space and Defense Power Systems
- OSTI ID:
- 1033414
- Report Number(s):
- FSC-ESD-217-91-483B; Orbital ID: 10245; Call Number: 34-05
- Country of Publication:
- United States
- Language:
- English
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Design, Analysis, and Spacecraft Integration of RTGs for CRAF and Cassini Missions
Design and Analysis of RTGs for CRAF and Cassini Missions