Mars Rover Power Supply

A multi-mission radioisotope thermoelectric generator (MMRTG) is essentially a nuclear battery. It consists of eight standard individually shielded general-purpose heat source (GPHS) modules containing a total of 4.8 kg of plutonium-238 dioxide. The radioactive decay of plutonium-238 generates 2000-watts of thermal heat energy, which when converted by an array of thermocouples produces 120-watts of electrical power.

A heat source liner draws the heat away from the GPHS modules, and the heat distribution block uniformly distributes the heat to the thermocouple layer, which consists of hundreds of thermocouple devices that convert the heat energy into electrical energy. The thermocouple principle is nothing new and anyone who studied GCSE Physics should know that a thermocouple converts heat energy into electrical energy. Thomas Seebeck discovered this 100 years ago, that when two dissimilar metals are joined, they produce an electrical current when the junction is heated. The current from thousands of such thermocouples adds together to produce a large useful current.

I was thinking of the warp core engine when I designed the animation shown above, however, it is more interesting than an army-grey cylinder!

MMRTG Nuclear Battery

Here is a photograph of the MMRTG nuclear battery used on the Mars Rover Curiosity. It is 64 cm in diameter fin-tip to fin-tip, 66 cm in height, and mass 43 kg. These batteries are modular and there is facility to connect multiple batteries together to produce greater power.

The additional pipes are for the heat exchanger, which allows the waste heat from the battery to circulate around the rover. This keeps its computer systems and components within normal operating temperature at night during sub zero temperatures.

Installing the MMRTG Battery

This image, the Mars Rover is in an inverted position, and the engineers are installing a new MMRTG battery. Nuclear power worked well also on the Apollo missions, Viking missions, Voyager, Ulysses, Cassini, Galileo, and many more.

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