Curiosity’s Power Source

We’ve all heard by now the exciting news of Curiosity safely landing on the surface of Mars at Gale crater. This rover is about the size of a small SUV, weights nearly 2000 pounds (900 Kg), and carries a variety of science instruments including a geology lab, a rock-vaporizing laser, and of course, lots of cameras. The prime mission is expected to last for one Mars year which is nearly equivalent to 23 months on Earth. So, where is the energy coming from that is required to move the rover and operate all its instruments? Solar panels would be a good guess, but if you look carefully at a picture of Curiosity you will see that there are none.

Curiosity’s power is in fact nuclear and it comes from an onboard Multi-Mission Radioisotope Thermoelectric Generator (MMRTG). The MMRTG provides electrical power by directly converting the heat generated by the decay of plutonium-238 dioxide into electrical energy using thermocouples at an operational efficiency of 6 to 7 percent. The MMRTG carries 10.6 pounds (4.8 Kg) of plutonium-238 dioxide and produces 110 Watts of electrical power (twice as much as the maximum power provided by the charger on a 13-in MacBook Pro). The MMRTG also provides heat to maintain a proper operating temperature of all the instruments and systems in the rover. Here is a schematic of a MMRTG


So, where is the MMRTG in the Rover? Take a look and see if you can find it






The MMRTG in Curiosity is capable of producing power for over 14 years, it weights 99 pounds(45 Kg), and it measures about 63.5 cm in diameter and 66 cm long. A great advantage of thermoelectric generators is that there are no moving parts associated with them. However, typical energy conversion efficiencies are quite low.
(Photo credits: NASA)