skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Evaluation of the SNAP-19 performance on Nimbus III including pre-launch characteristics

Abstract

A portion of the Nimbus III electrical power is supplied by two radioisotope fueled thermoelectric generators. Initial performance of these generators was precisely predicted by the manufacturer. Expected system power was 50 W and 49.40 W was obtained. Initial system temperatures and pressures were also as predicted. The power supply has demonstrated excellent stability during several temporary interruptions of the solar power supply. It also has enabled the spacecraft to be operated normally. Experimentation has not had to be curtailed because of a lack of power. Were the RTG's not on board, such curtailment would have been required as the combination of less favorable solar angle and decreasing solar flux decreased the electrical power from the solar paddles. Extensive analyses of the pre- and post-launch data have been conducted which explain minor differences between the apparently identical radioisotope fueled generators. These analyses have made possible an accurate insight into some of the performance parameters and have been applied to predicting future behavior. The present trends show a power degradation rate which is somewhat higher than expected. The system was expected to produce 45 W after one year of orbital operation. If the present trend continues, it will produce 38 W.more » Internal pressure also is decreasing in a somewhat different manner than anticipated. The pressure should reach a value of roughly 1.5 psia at the end of one year if the present rate of decrease continues.« less

Authors:
;
Publication Date:
Research Org.:
Hittman Associates, Inc., Columbia, Md. (USA)
OSTI Identifier:
5314801
Report Number(s):
HIT-407
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
07 ISOTOPES AND RADIATION SOURCES; 30 DIRECT ENERGY CONVERSION; SNAP 19 BATTERY; PERFORMANCE; SPACECRAFT POWER SUPPLIES; RADIOISOTOPE HEAT SOURCES; THERMOELECTRIC GENERATORS; DIRECT ENERGY CONVERTERS; ELECTRONIC EQUIPMENT; HEAT SOURCES; POWER SUPPLIES; RADIOISOTOPE BATTERIES; SNAP BATTERIES; NESDPS Office of Nuclear Energy Space and Defense Power Systems; 070300* - Isotopic Power Supplies; 300302 - Thermoelectric Generators- Performance & Testing

Citation Formats

Fihelly, A W, and Lyon, W C. Evaluation of the SNAP-19 performance on Nimbus III including pre-launch characteristics. United States: N. p., 1969. Web.
Fihelly, A W, & Lyon, W C. Evaluation of the SNAP-19 performance on Nimbus III including pre-launch characteristics. United States.
Fihelly, A W, and Lyon, W C. Fri . "Evaluation of the SNAP-19 performance on Nimbus III including pre-launch characteristics". United States.
@article{osti_5314801,
title = {Evaluation of the SNAP-19 performance on Nimbus III including pre-launch characteristics},
author = {Fihelly, A W and Lyon, W C},
abstractNote = {A portion of the Nimbus III electrical power is supplied by two radioisotope fueled thermoelectric generators. Initial performance of these generators was precisely predicted by the manufacturer. Expected system power was 50 W and 49.40 W was obtained. Initial system temperatures and pressures were also as predicted. The power supply has demonstrated excellent stability during several temporary interruptions of the solar power supply. It also has enabled the spacecraft to be operated normally. Experimentation has not had to be curtailed because of a lack of power. Were the RTG's not on board, such curtailment would have been required as the combination of less favorable solar angle and decreasing solar flux decreased the electrical power from the solar paddles. Extensive analyses of the pre- and post-launch data have been conducted which explain minor differences between the apparently identical radioisotope fueled generators. These analyses have made possible an accurate insight into some of the performance parameters and have been applied to predicting future behavior. The present trends show a power degradation rate which is somewhat higher than expected. The system was expected to produce 45 W after one year of orbital operation. If the present trend continues, it will produce 38 W. Internal pressure also is decreasing in a somewhat different manner than anticipated. The pressure should reach a value of roughly 1.5 psia at the end of one year if the present rate of decrease continues.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1969},
month = {8}
}

Technical Report:
Other availability
Please see Document Availability for additional information on obtaining the full-text document. Library patrons may search WorldCat to identify libraries that may hold this item. Keep in mind that many technical reports are not cataloged in WorldCat.

Save / Share: