WASHINGTON — The Defense Advanced Research Projects Agency is kicking off the next phase of a program to demonstrate the feasibility of nuclear-powered propulsion systems operating between Earth and the moon in what’s known as cislunar space.

DARPA awarded contracts for Phase 1 of the Demonstration Rocket for Agile Cislunar Operations in April 2021. General Atomics received a $22 million order to develop a design for a nuclear thermal propulsion reactor and subsystem, the centerpiece of the program.

Blue Origin and Lockheed Martin won contracts valued at $2.5 million and $2.9 million, respectively, to independently design a spacecraft using the propulsion system.

DARPA expects to choose one provider for the next two phases, which according to a May 4 solicitation are focused on finalizing the detailed nuclear thermal rocket design and building the spacecraft and its flight engine. Once completed, DARPA plans to conduct an on-orbit demonstration in fiscal 2026.

The agency’s fiscal 2023 budget request includes $57 million for DRACO, a $20 million increase from last year, which will support the transition to the next phase.

In the last few years, the U.S. Department of Defense has changed its posture toward cislunar space, shifting from viewing deep-space threats as part of a distant future to recognizing that they could present much sooner. That change has led to projects such as DRACO, as well as other research and development efforts within the Air Force Research Laboratory and the Space Force, which expects to have a cislunar domain awareness capability on orbit in the next five to 10 years.

According to DARPA, DRACO’s nuclear thermal propulsion system could enable rapid maneuver in space, which is difficult to perform with spacecraft powered by electric or chemical propulsion. While chemical systems provide a high thrust-to-weight ratio and electric systems offer high efficiency, a nuclear thermal system combines both features, making it ideal for cislunar missions.

“This enables NTP systems to be both faster and smaller than electric and chemical systems, respectively,” the solicitation states. “The propulsive capabilities afforded by NTP will enable the United States to maintain its interests in space and to expand the possibilities for NASA’s long-duration human spaceflight missions.”

DARPA notes that NASA has a particular interest in NTP technology because of its potential to reduce the travel time of its missions and return astronauts to Earth much faster in the event of an emergency. The two agencies are cooperating on DRACO, and NASA has offered to partner with companies bidding on the later phases of the program, offering its subject matter expertise as well as testing facilities.

Courtney Albon is C4ISRNET’s space and emerging technology reporter. She has covered the U.S. military since 2012, with a focus on the Air Force and Space Force. She has reported on some of the Defense Department’s most significant acquisition, budget and policy challenges.