Nuclear thermal propulsion and the DRACO program

Chemical rockets have been the workhorses of space exploration for over half a century. They got us to the Moon, they keep the International Space Station stocked, and they launch satellites every week. But if humanity is serious about reaching Mars and beyond, chemical propulsion has a hard ceiling. The fuel is heavy, the energy density is limited, and the transit times are brutal. Enter nuclear thermal propulsion, or NTP, and the DRACO program that aims to make it a reality.

Nuclear thermal propulsion is not a new idea. In fact, the United States tested NTP engines on the ground during the 1960s and 1970s under the Rover and NERVA programs. The basic principle is straightforward. Instead of burning chemical propellants, a nuclear reactor heats a working fluid, usually hydrogen, to extreme temperatures. The superheated gas expands out of a nozzle and generates thrust. The key advantage is efficiency. NTP engines deliver roughly twice the specific impulse, a measure of propellant efficiency, of the best chemical engines. That means you can move more payload or get to your destination faster using less fuel.

For a Mars mission, this is a game changer. Current chemical propulsion would require a massive spacecraft with enormous fuel tanks. The trip to Mars takes about seven to nine months, exposing astronauts to significant radiation and bone loss. With nuclear thermal propulsion, the same trip could be cut to three to four months. Less time in deep space means less risk. It also means you can carry more supplies and scientific equipment because you are not hauling as much propellant.

So why arent we already using NTP? The answer comes down to politics, cost, and safety concerns. After the Apollo program ended, the government lost interest in nuclear propulsion. The tests from the 1960s proved the technology worked, but no flight-ready system was ever built. The reactors used highly enriched uranium, which raised proliferation and safety issues. And the idea of launching a nuclear reactor into space made a lot of people nervous, even though the reactor is cold and fully inert until it reaches orbit.

That is where the DRACO program comes in. DRACO stands for Demonstration Rocket for Agile Cislunar Operations. It is a joint project between NASA and the Defense Advanced Research Projects Agency, better known as DARPA. The goal is simple: build and flight-test a nuclear thermal propulsion engine by the end of this decade. DRACO is focused on a practical, near-term demonstration. It uses a new reactor design that relies on high-assay low-enriched uranium, or HALEU, instead of the weapons-grade material used in the old NERVA tests. HALEU is enriched to less than twenty percent, making it significantly less risky for launch. The reactor is also designed to remain completely non-radioactive before it is turned on in space, which eliminates the worst-case launch accident scenarios.

Under DRACO, the nuclear engine will be integrated into a spacecraft built by Lockheed Martin. The reactor itself is being developed by BWX Technologies, a company that has decades of experience building nuclear reactors for Navy submarines and aircraft carriers. The plan is to launch the demonstration vehicle sometime in 2027 and operate it in orbit. No lunar landings, no Mars shots, just a clear proof that nuclear thermal propulsion works in the vacuum of space and can be operated safely.

The advantages of DRACO reach beyond Mars missions. The word Cislunar in the programs name is intentional. The United States military has shown increasing interest in maneuverability around the Moon. A nuclear thermal engine could allow satellites to change orbits, dodge threats, or move between the Earth and Moon far more efficiently than chemical thrusters. For NASA, the Artemis program plans to build a permanent presence on the lunar surface. Nuclear propulsion could support cargo deliveries and crewed missions with shorter transit times and heavier payloads.

Critics will point out that NTP is not the only advanced option. Electric propulsion, like ion thrusters, is already in use and offers even higher efficiency. But the tradeoff is thrust. Ion engines produce gentle pushes over long periods. They work well for deep space probes but not for moving large crews quickly. Nuclear thermal propulsion combines high thrust with high efficiency. It fills a gap that chemical and electric systems cannot cover on their own.

The DRACO program is not just about building a better engine. It is about rebuilding the institutional knowledge for nuclear propulsion that was lost decades ago. The engineers who worked on NERVA are mostly retired. The test facilities are gone. DRACO forces the United States to reestablish the design, fabrication, and safety protocols for space nuclear reactors. That expertise will be needed for every future nuclear space program, from propulsion to surface power on Mars or the Moon.

The timeline is aggressive, but the stakes are high. If DRACO succeeds, it will open the door to serious Mars planning for the 2030s. It will give the military a new kind of space mobility. And it will prove that nuclear technology, handled responsibly, has a place in the future of spaceflight. For anyone paying attention, nuclear thermal propulsion is not a distant fantasy. It is the next engine waiting to be fired.