The Heat Is On: How New Horizons Got Its Power

Feature by feature, they revealed themselves: the plains of Sputnik, the Norgay Montes and the vast and forbidding Cthulu Regio.
When the New Horizons spacecraft finally buzzed Pluto at roughly 30,000 mph last summer, it sent back snaps of an untamed land of craterless plains and jagged ice mountains beyond our imagining. And those pictures of the dwarf planet traveled the expanse of space thanks to a 125-pound power plant that doesn’t know the meaning of quit.

It’s called the RTG, or Radioisotope Thermoelectric Generator.