Watch Astrobotic perform a major test of its “ring of fire” rocket engine
Rotary detonation rocket engines work differently than traditional rockets to maximize thrust while using less fuel, an advantage that could help spacecraft explore further into the solar system.
By Adam Kovac edited by Claire Cameron
Astrobotics
A new generation of space rockets is getting closer to launch. Private space company Astrobotics recently revealed that it had conducted a successful test of two of its Rotary Detonation Rocket Engines (RDRE), igniting both engines for more than 470 seconds, including a 300-second continuous burn that the company says sets a record for RDRE designs.
Like conventional rocket engines, RDREs use liquid fuel, but the difference is how the engines use the liquid to produce thrust. Traditional engines work by pumping propellant and oxidizer into a combustion chamber, where they combine and burn to produce exhaust gases that propel the rocket forward. In RDREs, on the other hand, the fuel is compressed and heated by a supersonic shock wave, resulting in an explosion—hence the “detonation” in the rocket’s name—that produces more powerful thrust. The promise of RDREs is that they can move a spacecraft faster and more efficiently, allowing them to carry heavier payloads and travel greater distances than conventional rockets.
The test took place at NASA’s Marshall Space Flight Center. In a video, the company’s twin motors, which Astrobotic calls Chakram motors, can be seen igniting with a bright blue flame – this achievement brings the RDREs closer to a real test launch.
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A hot fire test of an Astrobotic Chakram rotary detonation rocket engine.
“Chakram has more than exceeded our expectations,” Bryant Avalos, Astrobotic’s principal investigator for the Chakram program, said in a statement. statement. “With any advanced technology like an RDRE, moving from design to testing, you’re always worried about unknown factors that might be critical to performance. But the engine performed even better than expected. The 300-second burn was icing on the cake.”
Ultimately, Astrobotic wants to perfect the rocket design for future missions to the Moon, Avalos said. This could include integrating the engines into its Griffin lunar landers; the first Griffin mission to the moon is expected to launch no earlier than July using a SpaceX Falcon Heavy rocket.
“Demonstrations like this show how RDRE technology could support a wide range of astrobotic missions, from propulsion on future lunar landers to orbital transfer vehicles in space, and other capabilities that will help expand operations throughout cislunar space,” Avalos said.
However, the engines are not quite ready for takeoff. During testing, the Chakram engines each generated more than 4,000 pounds of thrust, which pales in comparison to SpaceX’s Falcon Heavy rocket, which uses 27 engines to generate more than five million pounds of thrust at launch. Much more testing will be needed before the company is ready to try removing its engines from a launch pad, but the data from these trials is encouraging.
Astrobotic isn’t the only company tinkering with rotating detonation engines. For example, Venus Aerospace, which has touted applications of its engine under development for potential use in commercial and military rockets and aircraft, completed the first flight test of a U.S.-based RDRE in May 2025. And in 2021, the Japan Aerospace Exploration Agency (JAXA) tested a rotating detonation engine in space, successfully firing it for six seconds.
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