General Atomics Electromagnetic Systems (GA-EMS) has completed the baseline design of a reactor and engine for a nuclear thermal propulsion (NTP) rocket and has successfully tested key reactor components under contract from the Defense Advanced Research Projects Agency (DARPA), the company announced on November 7. The work was performed under a Track A, Phase 1 contract for the Demonstration Rocket for Agile Cislunar Operations (DRACO) program; Phases 2 and 3 of DRACO could culminate in a demonstration of the nuclear-propelled spacecraft in cislunar space (the region between the Earth and the Moon) during fiscal year 2026.
Critical space: “The cislunar space domain is essential to our national defense, modern commerce, and scientific discovery. As opportunities in cislunar space continue to expand, more innovative propulsion technologies to access space are increasingly necessary,” said Christina Back, vice president of nuclear technologies and materials at GA-EMS.
NTP would use a fission reactor fueled with high-assay low-enriched uranium (HALEU) to heat hydrogen and produce thrust with greater efficiency, given its energy-dense fuel and compact size, than is possible with electrical or chemical rocket systems. The Department of Defense wants NTP rockets to provide maneuverability and speed for time-critical missions in cislunar space, but NTP could also support future NASA missions to more distant destinations, like Mars.
“We have leveraged our expertise in nuclear and space system technologies to design an NTP system and test the vital components of that system to confirm they will withstand the relevant design conditions,” said Scott Forney, president of GA-EMS. “Unlike electric and chemical propulsion technologies in use today, NTP propulsive capabilities can achieve two to three times the propellant mass efficiency, which is critically important for cislunar missions.”
How do you test spacebound reactor components? You test them with NASA’s Nuclear Thermal Element Environmental Simulator (NTREES), at Marshall Space Flight Center in Huntsville, Ala. NTREES was “designed to test fuel elements and materials in hot flowing hydrogen, reaching pressures up to 1,000 pounds per square inch and temperatures of nearly 5,000 degrees Fahrenheit—conditions that simulate space-based nuclear propulsion systems to provide baseline data critical to the research team,” according to NASA.
GA-EMS reports that “key components of the nuclear reactor, including the vitally important high-temperature fuel elements,” were successfully tested at NTREES.
Phased contracting: DARPA awarded the Track A Phase 1 contract to GA-EMS in April 2021 following a competitive solicitation process. GA-EMS’s $22.2 million cost-plus-fixed-fee contract carried an estimated completion date in October 2022 for the design of the nuclear reactor that would power DRACO. In the same contract announcement, DARPA awarded the Track B contract—to design a spacecraft to house and demonstrate the NTP system—to Blue Origin and Lockheed Martin.
DARPA’s solicitation for Phase 2 and 3 proposals was issued in May 2022 with an August 5 deadline that was later extended to September 2. Phase 2 was expected to take 24 months and include a complete preliminary and detailed design of the demonstration as well as construction and experimental validation of the flight engine—including the nuclear reactor, nozzle, controllers, and associated equipment to drive the propellant from its tank and through the reactor. Phase 3 would immediately follow, with fabrication and testing of the rocket’s hydrogen tank. Ultimately, Phase 3 would include the launch and in-orbit demonstration of the NTP engine at full power and full thrust.
No Phase 2 and 3 contracts have been announced at this writing.