plutonium-238

Russia plans to bring people back to the Moon
The Russian Space Agency Roscosmos is planning to build a high-tech base on the moon starting in 2024.
Space exploration with 19th-century motives
Researchers have experimented with a small version of a nuclear engine design that can help satellites explore deep into the universe.
The US makes materials that the spacecraft used for 88 years does not run out
With a long half-life, Pu238 can provide an abundance of energy for spacecraft for nearly nine consecutive years.