A 110-W Stirling Radioisotope Generator (SRG110) is being developed by Lockheed Martin Astronautics of Valley Forge, Pennsylvania, under contract to the Department of Energy of Germantown, Maryland. The generator will be a high-efficiency electric power source for NASA space exploration missions that can operate in the vacuum of deep space or in a gaseous atmosphere, such as on the surface of Mars. The generator converts heat supplied by the decay of a plutonium heat source into electric power for the spacecraft. In support of the SRG110 project, the NASA Glenn Research Center has established a technology effort that will provide some of the key data to ensure a successful transition to flight for what will be the first dynamic power system to be used in space. High system efficiency is obtained through the use of free-piston Stirling power-conversion technology. Glenn tasks include in-house testing of Stirling convertors and controllers, materials evaluation and heater head life assessment, structural dynamics, evaluation of electromagnetic interference, assessment of organics, and reliability analysis. There is also an advanced technology effort that is complementary to the near-term technology effort, intended to reduce the mass of the Stirling convertor and increase efficiency.
To demonstrate the capability for long life, Glenn has been tasked with extended operation of a pair of flight prototype Stirling power convertors--Technology Demonstration Convertors (TDCs) #13 and #14. The TDCs were developed by the Stirling Technology Company of Kennewick, Washington. TDCs #13 and #14 recently surpassed 1 year of operation and now have over 9850 hr of extended operation. The power output and efficiency have remained nearly constant throughout this test. TDCs #15 and #16 are scheduled to begin extended operation at Glenn later this year following a vibration test that will simulate the dynamics of launch, and TDCs #5 and #6 will begin extended operation in a thermal vacuum environment intended to simulate operation in deep space. Extended operation of all convertors will continue in support of Lockheed Martin and the SRG110 project.
TDCs #13 and #14 on an extended operation test at Glenn.
Thieme, Lanny G.; and Schreiber, Jeffrey G.: Supporting Development for the Stirling Radioisotope Generator and Advanced Stirling Technology Development at NASA GRC. NASA/TM--2005-213409 (AIP Conf. Proc., vol. 746, 2005, pp. 674-681), 2005. http://gltrs.grc.nasa.gov/cgi-bin/GLTRS/browse.pl?2005/TM-2005-213409.html
Schreiber, Jeffrey G.; and Thieme, Lanny T.: Accomplishments of the NASA GRC Stirling Technology Development Project. AIAA-2004-5517, 2004.
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Glenn contact: Jeffrey G. Schreiber, 216-433-6144, Jeffrey.G.Schreiber@nasa.gov
Author: Jeffrey G. Schreiber
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