Harnessing the power of the atom for space-based power sources is nothing new but radioisotope thermoelectric generators (RTGs) are so last century, micro-reactors are the next big (little) thing.

That is if Lockheed Martin and Rolls-Royce are able to build a small enough and light enough reactor to fit into existing rockets.

A panel of Rolls-Royce, Lockheed Martin, U.S. Space Force, NASA and Defense Advanced Research Projects Agency (DARPA) employees discussed how nuclear-powered spacecraft may soon launch at a panel during the 2023 Space Symposium in Colorado Springs.

In all space projects, mass is a problem. With chemical rockets, a large amount of equipment can be packed in and sent to earth orbit using platforms like Falcon Heavy, the Ariane 5 or Space Launch System. However, the higher you go, the more fuel you need, which adds mass, reducing the payload capacity drastically.

Despite it being cheaper than ever to launch things into space, it’s still expensive, said Kirk Shireman, vice president for the Lockheed Martin lunar exploration campaign.

“Efficiency is really critical and if you’re going far away you need power and efficiency,” he said. “Nuclear electric and nuclear thermal in particular is phenomenally more efficient than chemical propulsion, but it’s high priced.”

Cost has long been the Achilles heel for nuclear power, and a longstanding argument against its widespread adoption. Though likely more expensive, nuclear-based propulsion systems are the only way to make getting to Mars feasible, according to a Lockheed report from 2022.

Nuclear thermal rockets use the heat generated by the nuclear reactor to excite a fuel source, likely hydrogen, and fire it out the back of the craft, allowing higher speeds and faster transits to the Moon and Mars. 

A manned mission to Mars is the next giant leap for humanity, and NASA has partnered with DARPA for assistance making that leap. The partnership manifested in the Demonstration Rocket for Agile Cislunar Operations (DRACO) which the agencies hope will launch in 2027. 

“The strategy that NASA is pursuing right now is that we look at gaining experience and knowledge with the DRACO demonstration and use that to advance critical technologies into an operational system,” said Dr. Anthony Calomino, NASA’s space nuclear propulsion technologies portfolio lead. “That would give us an ability to evolve that system… And hopefully as the Mars mission begins to have more definition, we’ll have a better idea of the requirements.”

He added a surplus of power from nuclear reactors may exist, but shouldn’t be seen as a negative since uses will be found. 

Rolls-Royce, well known for their luxury vehicles and airline engines, is also heavily involved in the micro-reactor field. Jake Thompson, the firm’s chief innovation officer, said the key to the technology’s success will be international cooperation.

“There’s a fantastic template already in existence for this: We’ve been collaborating on the nuclear-powered submarine program since 1958,” he said. “I think we should absolutely use that template of collaboration to accelerate and keep the momentum on space.”