On June 26, 1968, a nuclear reactor the Phoebus 2A was tested at the Nevada Test Site. Although the test demonstrated the reactor’s capability to transport humans to Mars, the project was ultimately abandoned. Phoebus 2A was too costly and did not align with President Nixon’s vision of limiting space exploration to low-Earth orbit.
Contrary to popular belief, NASA wasn’t the first to envision nuclear-powered rockets. The concept originated with the military, aiming to utilize them for intercontinental ballistic missiles. The US Air Force initiated the Rover program in the mid-1950s, developing NTRs that used liquid hydrogen heated by a nuclear reactor to generate thrust. This method offered significant fuel efficiency advantages, but translating stationary reactor technology to flight was challenging.
In the late 1950s, the program shifted to NASA and the Atomic Energy Commission (AEC), where it was rebranded as NERVA (Nuclear Engine for Rocket Vehicle Applications). Despite significant progress, including the construction and testing of 23 reactors, the program faced persistent technical issues like fuel rod cracking and hydrogen-induced corrosion. Ultimately, changing priorities at NASA led to the program’s cancellation in 1973.
Decades later, the potential of nuclear propulsion resurfaced with NASA’s plans for Mars exploration. Compact reactors could significantly reduce travel time to Mars, mitigating radiation exposure for astronauts and reducing mission supply requirements. In 2017, NASA initiated a small-scale NTR research program, which gained momentum when DARPA (Defense Advanced Research Projects Agency) joined in 2020 with the DRACO (Demonstration Rocket for Agile Cislunar Operations) project.
Building and operating a nuclear-powered spacecraft poses substantial challenges. The DRACO project utilizes high-assay low-enriched uranium (HALEU) to address safety concerns, reducing the risks associated with highly enriched uranium used in earlier reactors. Lockheed Martin and BWXT Technologies are at the forefront of designing and constructing the DRACO spacecraft, integrating lessons from past NERVA designs with modern advancements.
Safety is paramount in deploying a nuclear reactor in space. DRACO’s design includes contingencies for potential failures, such as deploying neutron-absorbing materials to prevent accidental fission reactions in the event of a crash. The spacecraft will undergo rigorous testing in orbit, gradually increasing reactor power to gather critical data and ensure operational reliability
The DRACO project represents a significant step toward establishing nuclear propulsion as a viable technology for space exploration. The potential benefits extend beyond military applications, offering promising advancements for civil space missions. Innovations like bi-modal propulsion systems and wave rotor superchargers could further enhance performance, paving the way for faster and more efficient interplanetary travel.
Lockheed Martin’s Kirk Shireman rightly puts it, “DRACO has great potential for the future, for the world. This could open up something. It’s setting on a path that maybe your grandchildren are going to finish. We hope to make a little history.”