NASA plans to launch its first fission reactor for an interplanetary spacecraft, SR-1 Freedom, toward Mars in late 2028.
It marks a departure from decades of precedent: Voyager, New Horizons, Curiosity and Perseverance all ran on radioisotope power systems, harvesting heat from the natural decay of plutonium-238. Long-lived nuclear batteries, not reactors.
Decay power has kept spacecraft operating for decades in environments where solar panels fail and refueling is impossible. It works because of a physical fact with no substitute: nuclear material carries roughly a million times more energy per unit mass than chemical fuel.
The same physics applies on Earth. Strontium-90, a fission product found in spent nuclear fuel (SNF), generates heat through natural decay the same way plutonium-238 does aboard those spacecraft. Project Omega's first product is a small nuclear battery running on strontium-90 decay, built to power microprocessors in remote locations for years without maintenance or refueling, the kind of long-duration requirement that defines our work with DARPA.
The United States stores 90,000 metric tons of spent nuclear fuel. The material holds over 90 percent of its original energy, and it holds isotopes with a five-decade flight record powering the toughest missions humanity has attempted. What sits in storage is not a liability. It is inventory.
NASA reaching for fission beyond Earth orbit and our work recovering value from stored fuel are answers to the same question: where nuclear material already exists, put it to work.