MHW-RTG

The Multihundred-watt radioisotope thermoelectric generator is a type of US radioisotope thermoelectric generator developed for the Voyager spacecraft, Voyager 1 and Voyager 2. The Voyager generators continue to function more than 45 years into the mission.
Image:MHW-RTGs.gif|right|thumb|Radioisotope thermoelectric generators for the Voyager program.
Each RTG has a total weight of 37.7 kg, including about 4.5 kg of Pu-238 and uses 24 pressed plutonium-238 oxide spheres to provide enough heat to generate approximately 157 watts of electrical power initially – halving every 87.7 years.
Each RTG initially generated about 2400 watts of thermal power.
Conversion of the decay heat of the plutonium to electrical power uses 312 silicon-germanium
thermoelectric couples. The initial thermoelectric couple hot junction temperature was 1273 K with a cold junction temperature of 573 K.
Each Voyager spacecraft has 3 RTGs. Collectively, the RTGs supply each Voyager spacecraft with 470 watts at launch.
MHW-RTGs were used on the Lincoln Experimental Satellites 8 and 9.
Subsequent US spacecraft used the GPHS-RTG, which used similar SiGe thermoelectric devices but a different packaging of the fuel.
The MMRTG is a newer RTG type, used on the Curiosity rover.