Power Generation (Cont)
•Another type of power generation used on long distance and duration spaceflights like probes and satellites is a “RTG” (Radioisotope thermoelectric generator).
http://upload.wikimedia.org/wikipedia/commons/0/03/Cutdrawing_of_an_GPHS-RTG.jpg
•RTG’s use the decay of radioactive material and covert the heat by use of the Seebeck effect into electricity.
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•This conversion of heat into electricity is accomplished by using thermocouples.
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•Upside is you don’t need bulky reactant chemicals or delicate and bulky/large solar cells. Relatively low maintenance power source.
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•Downsides are radioactive decay only occurs for a “finite” amount of time and the possible environmental effects on a launch failure or contamination if it crashes into another planet. Radioactive material such as Plutonium is extremely difficult and costly to produce and in low reserves.
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Crowd Questions:
1. Why is plutonium so rare and expensive? – Mostly Man-Made, very rare in nature. Produced with a short half-life from Uranium reactions in reactors or uranium explosions.

2. What is another useful side effect of the heat from an RTG for probes far from the sun?

3. What well known Mar’s rover and What well known Space Probe use RTGS? (Next Slide for Answer)