NASA is planning crewed missions to Mars within the next decade, but the 140-million-mile journey could take several months to years using current rocket technology. The long transit time is due to traditional chemical rocket fuel, but there’s a faster alternative in development: nuclear thermal propulsion (NTP). This technology, powered by nuclear fission, could potentially cut the trip to Mars in half.
Nuclear fission, the process of splitting an atom to release immense energy, is already widely used in power generation and nuclear submarines. NASA and the Defense Advanced Research Projects Agency (DARPA) are now collaborating to bring this technology to space. They aim to demonstrate a prototype NTP system in space by 2027, which would be a groundbreaking achievement for U.S. space exploration.
NTP could offer more than just faster Mars missions—it may also power maneuverable space platforms to protect American satellites. However, the technology is still in development, and researchers are working to optimize its design. As an associate professor of nuclear engineering at the Georgia Institute of Technology, my team specializes in modeling and simulating NTP systems to improve their efficiency and performance.
Conventional rockets rely on a chemical reaction between a light propellant, like hydrogen, and an oxidizer. While effective, these rockets need to carry oxygen, which adds weight. In contrast, nuclear thermal propulsion systems use nuclear fission to heat the propellant, which is then expelled to generate thrust.
In NTP, uranium-235 undergoes fission when hit by a neutron, splitting into fragments and releasing energy. This energy heats the propellant, which escapes through the rocket nozzle at high speeds, propelling the spacecraft forward. Compared to traditional chemical rockets, NTP engines have about 10 times the power density, allowing for much higher thrust and efficiency.
NTP systems also boast a higher specific impulse, meaning they use propellant more efficiently. In fact, NTP could double the specific impulse of chemical rockets, cutting travel time to Mars by a factor of two.
The U.S. government has explored NTP technology for decades. Between 1955 and 1973, NASA and other agencies tested 20 NTP engines. However, these early designs relied on highly enriched uranium, which poses proliferation risks.
Today, NASA’s Demonstration Rocket for Agile Cislunar Operations (DRACO) program, in collaboration with DARPA, is developing new NTP engines using safer high-assay, low-enriched uranium (HALEU) fuel. Lockheed Martin and BWX Technologies are working on reactor and fuel designs for DRACO, with plans to launch the first rocket in 2027.
The challenge with HALEU is that it requires more fuel to achieve the same power as highly enriched uranium, making the engine heavier. Researchers are looking into advanced materials to improve fuel efficiency and reduce engine weight.
Designing a functional NTP engine involves extensive modeling and simulations. Engineers need to understand how the reactor will behave during rapid temperature and pressure changes, particularly when starting up and shutting down. These models are crucial for ensuring both safety and performance during a Mars mission.
My research team focuses on creating computational tools to simulate how NTP reactors operate under extreme conditions. Our goal is to develop efficient models that can handle the complexity of NTP systems without requiring vast amounts of computing power. These simulations will help optimize the engine’s design and potentially enable autonomous control of the rocket during future space missions.
With continued research and development, nuclear thermal propulsion could revolutionize space travel, enabling faster and more efficient missions to Mars and beyond.
By Impact Lab
