The Ohio State University is developing a new nuclear thermal propulsion system called the centrifugal nuclear thermal rocket (CNTR). 

Rather than solid fuel elements, this new design uses liquid uranium to heat the rocket propellant directly.

The result is an engine that could be twice as efficient as conventional nuclear designs.

In a statement released on September 11, Dean Wang of Ohio State said the CNTR system stands out from other nuclear propulsion developments. 

While many focus on making the technology more affordable, the CNTR prioritizes performance by doubling an engine’s efficiency.

Shortening the Mars trip

In the new space race, space agencies like NASA are developing nuclear thermal propulsion to reach the solar system’s most distant regions.

Interest in nuclear thermal propulsion is growing as space agencies look to send humans back to the Moon and beyond. 

The limitations of standard chemical engines—low thrust and high fuel consumption—make them impractical for long-distance missions. 

As a result, missions to the outer solar system can take many years, as seen with the New Horizons probe’s nine-year journey to Pluto.

For future human missions to distant destinations, it is integral to find a way to reduce travel time, increase cargo capacity, or both. 

This is vital because prolonged time in space increases health risks for astronauts. 

Therefore, developing more efficient propulsion systems is required to make deep-space travel safer and more feasible.

The CNTR’s potential looks promising.

As per the study paper, it is projected to have a high specific impulse of 1800 seconds, compared to approximately 450 seconds for chemical engines and 900 seconds for 1960s-era nuclear designs. 

The CNTR could enable viable human missions to Mars with round-trip times shortened to 420 days. 

Spencer Christian, a PhD student leading prototype construction, envisions a safe one-way trip to Mars in just six months.

“Depending on how well it works, the prototype CNTR engine is pushing us towards the future,” said Christian in the press release.

Beyond Mars, this powerful thrust could facilitate quicker scientific rendezvous missions to the outer planets and Kuiper Belt objects via direct injection orbits.

Engineering challenges

In addition to being faster, nuclear thermal propulsion gives rockets more flexibility in flight paths than chemical engines can reach distant targets. 

Moreover, the CNTR could also use various propellants, such as ammonia, methane, propane, or hydrazine. This ability could pave the way for utilizing in-space resources from asteroids and Kuiper Belt objects, developing a self-sustaining presence in space.

These advanced capabilities of nuclear thermal propulsion could also support new one-way robotic missions to distant outer planets like Saturn, Uranus, and Neptune.

At present, the CNTR concept faces major engineering challenges. 

According to Wang, the team needs to solve technical hurdles before the design is ready. 

These challenges include ensuring stable startup, operation, and shutdown, as well as minimizing the loss of uranium fuel and managing potential engine failures. The team hopes to have the design ready within five years. 

“We need to keep space nuclear propulsion as a consistent priority in the future, so that technology can have time to mature,” said Wang. 

The Ohio State team’s efforts are supported by a grant provided by NASA, which showcases the national importance of this advanced propulsion technology in shaping the future of space exploration.