NASA and DARPA announced they awarded Lockheed Martin and BWX Technologies to build and develop a nuclear thermal rocket (NTR) engine.
Lockheed Martin and BWX technologies under DARPA’s DRACO (the Demonstration Rocket for Agile Cislunar Operations) program and in partnership with NASA will build the nuclear thermal rocket. NASA and DARPA are committing up to $499 million towards this program.
While the overall size of this test bed was not revealed, during a press conference today, Dr. Tabitha Dodson of DARPA said it would not require a heavy lift vehicle and be able to fit in the fairing of a SpaceX Falcon 9 or United Launch Alliance Vulcan Centaur.
Dr. Dodson also said, “An NTR achieves high thrust similar to in-space chemical propulsion but is two to three times more efficient. With a successful demonstration, we could significantly advance humanity’s means for going faster and farther in space and pave the way for the future deployment for all fission-based nuclear space technologies.”
The engine will be powered by a fission nuclear reactor engine designed by BWX Technologies and fueled by High Assay Low Enriched Uranium (HALEU). This type of system is much different than RTG systems used on Mars rovers, for example. RTG systems provide no thrust and only convert heat to turn into power.
The NTR provides propulsion by directly transferring reactor heat to liquid hydrogen, then the heated gaseous hydrogen expands through the nozzle to provide thrust. The liquid hydrogen will go from -20° Kelvin (-253° Celsius) to 2,700° Kelvin (2,426° Celsius) in less than a second as it expanded out through the nozzle.
For the liquid hydrogen side of the engine, there will be about 2,000 kg loaded, and will also provide a test to see how long they will be able to maintain the correct temperatures for the liquid hydrogen.
The reactor for the engine will not be turned on until after it has reached a “nuclear safe orbit,” which is more than 700 km above Earth. International standards are that the rocket would need to stay in a circular orbit for around 300 years. There has been no specific orbit decided yet.
The United States Space Force will select the launch vehicle, most likely to be a Falcon 9 or Vulcan Centaur, but it is a bit too early for that announcement. The teams are also looking at the ability to refuel the test bed, as once the liquid hydrogen runs out, the mission would be over.
NASA and DARPA are looking at a launch target of late 2025 or early 2026.
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