Nuclear reactors in space may sound like something out of science fiction, but they are likely to prove important for powering long-term space missions.

NASA announced plans to build a nuclear reactor on the moon on Tuesday, in an attempt to stay ahead of China and Russia in a new space race. The goal is to have the reactor built before 2030, a timeline set during the Biden administration.

Placing an atomic energy source on the lunar surface is “not science fiction,” experts say, but does pose technical challenges.