Space Exploration with Radioisotope Power

How do you provide power to spacecraft in the deep reaches of space far from the sun? For the past 50 years the United States has been using radioisotope thermal generators (RTG). Deep space missions using RTGs include the Voyager Spacecraft that was launched in 1977 and is currently still transmitting data from distances far beyond Pluto. More recently the New Horizon’s spacecraft was launched in 2006 has just flown by Pluto offering the first images of the dwarf planet close up. RTGs were used on the moon during the Apollo mission with astronauts, the Curiosity rover, the Viking Mars Landers and more. The United states has launched around thirty spacecraft and landers that have used RTGs to for electricity and heat. How do RTGs work? RTGs have two main parts. The Radioisotope First is the radioisotope which produces heat through radioactive decay. There are many different isotopes with different amount of heat that are generated from them.Plutoninum-238 (Pu-238) is the ideal choice for most space missions because it produces a steady amount of heat and a half life of 87 years. The half life is important because a radioisotope must last long long enough to complete the mission. A half life of 87 year is nearly perfect because it will take a few decades before the isotope begins to decrease much in power. The video below shows an interview with Stacy McLaughlan a scientist at Los Alamos National Laboratory who worked on the New Horizons radioisotope power system. She talks more about Plutonium 238.   The Thermal Generator The second piece of an RTG is the part that...