Multi-Mission Radioisotope Thermoelectric Generator

Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) are a type of Radioisotope Thermoelectric Generator developed for NASA space missions^[1] such as Mars Science Laboratory (scheduled to be launched November 26, 2011) and may be used on the Jupiter Europa Orbiter. They are produced by Rocketdyne Propulsion and Power, currently under the umbrella of Pratt and Whitney, for NASA.^{[2][dead link]}

Like the earlier GPHS-RTGs (made by Teledyne) they are powered by Pu-238 dioxide GPHS modules (8 for MMRTG).^[3] Initially an MMRTG will generate about 2 kW thermal power.

The GPHS-RTG used SiGe thermoelectric elements but these are no longer in production and the MMRTG will use PbTe/TAGS thermocouples (from Teledyne Energy Systems). The MMRTG is designed to produce 125W electrical power at the start of mission, falling to about 100W after 14 years.^[4] With a mass of 43 kg^[5] they provide about 2.8 We/kg (just over half of the earlier GPHS-RTG units).

References

1. ^ http://www.jpl.nasa.gov/news/fact_sheets/radioisotope-power-systems.pdf
2. ^ http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/38246/1/04-0191.pdf
3. ^ Expanding Frontiers with Radioisotope Power Systems (excerpt from JPL report) (NASA)
4. ^ http://pdf.aiaa.org/preview/CDReadyMIECEC06_1309/PV2006_4187.pdf
5. ^ http://nuclear.gov/pdfFiles/MMRTG.pdf