Nearly three years ago, the US Defense Advanced Research Projects Agency announced plans to develop a steerable nuclear thermal propulsion system. The goal was to develop more responsive control of spacecraft in Earth orbit, lunar orbit, and everywhere in between, giving the military greater operational freedom in these areas.
The military agency called the program a Demonstration Rocket for Agile Cislunar Operations, or DRACO for short. The program involves developing two things: a nuclear fission reactor and a spacecraft to fly it. In 2021, DARPA awarded $22 million to General Atomics for the reactor and awarded small grants of $2.9 million to Lockheed Martin and $2.5 million to Blue Origin for the spacecraft system .
At the same time, NASA was beginning to realize that if it really wanted to send humans to Mars one day, it would be nice to have a faster, more fuel-efficient way to get there. An influential report published in 2021 concluded that the space agency’s only realistic path to sending humans to Mars in the coming decades was to use nuclear propulsion.
Thermal nuclear propulsion involves a rocket engine in which a nuclear reactor replaces the combustion chamber and burns liquid hydrogen as fuel. It requires significantly less fuel than chemical propulsion, often less than 500 metric tons, to reach Mars. This would be useful for a Mars mission that would include several advanced missions to prepare cargo on the Red Planet.
So, this week, NASA said it was partnering with the military agency and joining the DRACO project.
“NASA will work with our longtime partner DARPA to develop and demonstrate advanced nuclear thermal propulsion technology as early as 2027,” NASA Administrator Bill Nelson said. “With the help of this new technology, astronauts could travel faster to and from deep space. than ever, a major capability to prepare for crewed missions to Mars.”
The US space agency will not provide any direct funding at this time. However, its Space Technology Missions Directorate will lead the technical development of the nuclear heat engine, a key part of the spacecraft that will harness energy from the nuclear reactor. DARPA will still lead overall program development, including rocket system integration and procurement.
Nuclear thermal propulsion has long been a goal of spaceflight advocates, dating back to the days of German rocket scientist Wernher von Braun and NASA’s NERVA project. These plans were never realized, and the idea lay dormant for decades. Now, this joint project is the most serious American effort to develop the technology since then. It has the added benefit of interest from the US Congress, which has prompted the space agency to get involved.
None of this will happen quickly. The technology is difficult and unproven, and of course there are regulatory issues associated with launching a nuclear reactor into space. The year 2027 looks optimistic for a demonstration, and the technology is unlikely to be used to send humans to Mars until at least the very end of the 2030s.
But something is finally happening. For now, that’s enough.
. NASA join military program for develop propulsion nuclear thermal