As we near closer to the touchdown of the #Mars2020 rover Perseverance, I want to note the key role that nuclear science plays here: Perseverance is powered by the radioactive decay of plutonium-238
The power source of Perseverance is not a nuclear reactor, and in fact Pu-238 isn't be a good choice for nuclear reactors because it doesn't readily fission. But its rate of radioactive decay is great for space exploration: it takes 87.7 yrs for half of the material to decay
#Mars2020 is powered by a Pu-238 radioisotope thermoelectric generator. The 87.7 year half life of Pu-238 means that RTG's can operate for a long time, for example Voyager 1, launched in 1977, is still sending signals back from its RTG. What % of the Pu mass at launch remains?
Answer: Voyager 1 currently has about 70.9% of the plutonium mass that it had at the day of its launch, September 5, 1977
RTG's give off a few hundred watts of electrical power, are relatively light, and robust with long lifetimes. They are perfect for rovers and space probes because they last longer than solar panels and are lighter than small nuclear reactors. Curiosity is powered by a similar RTG 
Making a plutonium-238 RTG for #Mars2020 relies on several US national labs:
⚛️ @ORNL produces and separates the Pu in their High Flux Isotope Reactor
👩🔧 @LosAlamosNatLab fabricates the Pu-238 fuel pellets
💡 @INL puts the Pu inside the RTG and tests it
⚛️ @ORNL produces and separates the Pu in their High Flux Isotope Reactor
👩🔧 @LosAlamosNatLab fabricates the Pu-238 fuel pellets
💡 @INL puts the Pu inside the RTG and tests it
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