Nuclear energy in space - a quick background on NASA RTGs & why we're pushing fission now!

Added: 2026-05-06

[00:00:00]So let's have a quick look at history of using nuclear power in space. So nuclear power in space started about 1961 when the US Navy launched Transit 4A, the first spacecraft powered by radioisotope thermoelectric generators, also known as RTGs. The ones we've used to date are mostly powered by plutonium 238, which is the radioisotope.

[00:00:20]And overall these things work by there's the radioactive element, it decays. As it decays, heat is released, capture the heat, electricity. That whole heat capturing process is done inside a little device called a thermal couple.

[00:00:33]It's pretty reliable, no moving parts.

[00:00:35]Under current development we have next generation RTG and it provides around 245 watts of electric power per unit.

[00:00:43]NASA Glenn is heading the project. And why nuclear? Because solar works near Earth but lunar nights, Martian dust storms, deep space hulls that need steady high density power far from the sun, they need something else besides just using solar. So guess what?

[00:01:00]The RTG nuclear electric is also not going to cut it.

[00:01:03]Um we need a lot more energy than that.

[00:01:05]So now we need nuclear reactors in space. What we're talking about here, what's being pushed in these new programs right now are microreactors, fission reactors. It's producing power in orders of magnitude that can power a neighborhood rather than charge a battery for a probe that is out in deep space.