Rolls-Royce’s new micro-reactor design could send humans to Mars

The future of deep space exploration is near.

Rolls-Royce revealed a new image of a micro-reactor for space that it says is “designed to use an inherently safe and extremely robust fuel form.”

The iconic engineering firm recently tweeted the image alongside a caption. It is designing the nuclear fission system as part of an agreement it penned with the UK Space Agency in 2021.

Nuclear propulsion systems for space, which harness the energy produced during the splitting of atoms, have great potential for accelerating space travel and reducing transit times. This could be of particular importance when sending humans to Mars.

Rolls-Royce’s new space micro-nuclear reactor

Rolls-Royce’s image shows an early-stage design of a micro-nuclear reactor that was produced following the company’s 2021 agreement with the UK Space Agency. Under that agreement, Rolls-Royce is experimenting with nuclear propulsion technologies for space.

“Each uranium particle is encapsulated in multiple protective layers that act as a containment system, allowing it to withstand extreme conditions,” Rolls-Royce wrote alongside the image of its micro-nuclear reactor design.

Scientists and large organizations are increasingly looking at nuclear fission for space. Last month, for example, NASA and DARPA announced plans to build a functioning nuclear thermal rocket by 2027.

NASA also recently selected a nuclear propulsion concept for Phase I development as part of its Innovative Advanced Concepts (NIAC) program for 2023. The U.S. space agency has a long history of considering nuclear propulsion for spacecraft. For example, the Nuclear Engine for Rocket Vehicle Application (NERVA) concept was successfully tested but then defunded around the same time the Apollo Era came to a close in 1973.

More recently, NASA’s Project Prometheus in the early 2000s tested nuclear propulsion concept technologies for long-duration space missions. The project was canceled in 2005 due to budgetary constraints.

Private firm Ad Astra, meanwhile, which was founded by former NASA astronaut Franklin R. Chang Díaz, completed a record 88-hour high-power endurance test of its Vasimr VX-200SS plasma rocket at 80 kW in 2021. Ad Astra claims its nuclear rocket technology could eventually take humans to Mars at speeds of roughly 123,000 mph (197,950 km/h).

Why use nuclear fission for space travel?

Safety is, of course, a top priority when sending a nuclear fission reactor to space. Most firms experimenting with the technology have suggested their systems will only start the fission reaction once they are already in space. As in Rolls-Royce’s description, there is also a strong emphasis on robust materials that can withstand the harsh conditions of space.

The benefit of using nuclear propulsion would arguably outweigh that risk. In a 2010 interview with Popular Science, Ad Astra’s Chang Díaz stated that “chemical rockets are not going to get us to Mars. It’s just too long a trip.”

Nuclear propulsion could reduce the roughly 8-9 months of travel it would take to get to Mars — using current technologies — to about 45 days or less. This would vastly reduce the amount of time astronauts are exposed to radiation and the amount of time during which a potentially catastrophic issue could occur.

Essentially, nuclear propulsion would make spaceflight vastly safer for astronauts. Space will always be an inherently risky pursuit, but faster travel times could greatly reduce the risk while allowing humans to attain the many rewards of far-reaching human spaceflight.