MHW-RTG

The Multihundred-watt radioisotope thermoelectric generator (MHW RTG) is a type of US radioisotope thermoelectric generator (RTG) developed for the Voyager spacecraft, Voyager 1 and Voyager 2.[1] The Voyager generators continue to function more than 45 years into the mission.[2]

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[3] 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.[4]

Each RTG initially generated about 2400 watts of thermal power.[5] Conversion of the decay heat of the plutonium to electrical power uses 312 silicon-germanium (SiGe) thermoelectric couples. The initial thermoelectric couple hot junction temperature was 1273 K (1000 °C, 1832 °F) with a cold junction temperature of 573 K (300 °C, 572 °F).[6]

Each Voyager spacecraft has 3 RTGs. Collectively, the RTGs supply each Voyager spacecraft with 470 watts at launch.[7][8]

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.

• 
  RTG heat source unit
• 
  RTG diagram 1
• 
  RTG unit

References

1. Heacock (1980). "The Voyager Space Craft". Proceedings of the Institution of Mechanical Engineers. 194: 267–270. doi:10.1243/PIME_PROC_1980_194_026_02. Archived from the original on 2014-03-31.
2. "NASA's Voyager Space Probe's Reserve Power, And The Intricacies Of RTG-Based Power Systems". Hackaday. 3 May 2023. Retrieved 22 November 2024.
3. "Space Nuclear Power" G.L.Bennett 2006
4. "NASA Celebrates 45 Years of Voyager 1, Enabled by Radioisotope Power". NASA. September 5, 2022. Retrieved December 11, 2022.
5. "Totse.com | Nuclear Power in Space". Archived from the original on 2008-06-19. Retrieved 2012-10-19.
6. Furlong, Richard R.; Wahlquist, Earl J. (1999). "U.S. space missions using radioisotope power systems" (PDF). Nuclear News. 42 (4): 26–34. Archived from the original (PDF) on 2018-10-16. Retrieved January 2, 2011.
7. "VOYAGER 2:Host Information". NASA. 1989. Archived from the original on July 21, 2011. Retrieved January 2, 2011.
8. "Voyager 2 Craft Details". NASA-NSSDC-Spacecraft-Details. NASA. Retrieved March 9, 2011.

See also

• Nuclear power in space