On May 4, the Defense Advanced Research Projects Agency published a request for proposals for the next step of a nuclear-powered spacecraft demonstration. DARPA picked a preliminary design for a rocket engine reactor built by General Atomics, as well as two hypothetical spaceship designs by Blue Origin and Lockheed Martin, for the DRACO (Demonstration Rocket for Agile Cislunar Operations) project, which began over a year ago.
The design, development, manufacture, and assembly of the nuclear thermal rocket engine will be the emphasis of the program’s next stages. According to a representative for DARPA, the competition will be “full and open,” meaning that this opportunity will not be limited to organizations that engaged in the first phase. The deadline for proposals is August 5. In the fiscal year 2026, the goal is to launch a flying demonstration with nuclear thermal propulsion.
“A single award is expected” in DRACO phase 2, according to the spokeswoman. The goal is to finish “the preliminary and comprehensive design of a demonstration system, as well as the construction and experimental validation of the nuclear thermal rocket flight engine.” The demonstration system will be created in phase 3 to accommodate a nuclear thermal rocket for the in-orbit flight test.
DARPA is investing in nuclear propulsion for spacecraft in the hopes of successfully showing an engine capable of flying across huge distances in cislunar space, the region between Earth and the moon.
“Nuclear thermal propulsion achieves a high thrust-to-weight ratio equivalent to chemical propulsion, but at two to five times the efficiency,” according to DARPA. NASA is a partner in the project, which aims to use nuclear thermal propulsion for long-duration human spaceflight flights.
“In space, maneuvering is more difficult due to propulsion system limits,” said Maj. Nathan Greiner of DARPA’s Tactical Technology Office. “The United States needs leap-ahead propulsion technology to preserve technological leadership in space.”
DARPA claims that DRACO’s nuclear thermal propulsion system could allow for quick maneuvering in space, which is impossible with spaceships powered by chemical or electric propulsion. Nuclear thermal systems combine both features, making them excellent for cislunar missions.
The RFP stated, “This enables NTP systems to be both quicker and smaller than chemical and electric systems, respectively. The propellant capabilities provided by NTP will allow the US to sustain its space interests while also expanding the possibilities for NASA’s long-duration human spaceflight missions.”
NASA is particularly interested in NTP technology, according to DARPA, since it has the potential to shorten mission travel time and return astronauts to Earth much more quickly in the event of an emergency. The two agencies are working together on DRACO, and NASA has agreed to collaborate with firms bidding on the program’s later phases, providing subject matter expertise and testing facilities.