Deep Blue Aerospace reached a critical milestone on September 22 when its Nebula-1 rocket lifted off from the spaceport in Inner Mongolia’s Ejin Banner for what is said to be China’s first high-altitude vertical recovery test of an orbital-class rocket. But the mission wasn’t without challenges. As the rocket began its descent, an unexpected glitch with the first-stage booster led to a partial failure, casting a shadow over an otherwise promising performance.
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Video of Deep Blue Aerospace’s vertical recovery test of the Nebula-1 orbital-class rocket, conducted on September 22, 2024. Video and header photo courtesy of Deep Blue Aerospace.
The test had ambitious goals. Of the 11 key objectives outlined in the test plan, ten were met, with only one falling short.
At the heart of the mission was a crucial test: demonstrating whether the systems required for vertical recovery could work in harmony once the rocket reached orbit. Engineers focused on the transition from multiple engines to a single-engine configuration during flight—a key element in perfecting recovery for future missions.
Nebula-1 isn’t just any rocket. It’s Deep Blue Aerospace’s first reusable, liquid-fueled, orbital-class model built for commercial use. At 3.35 meters in diameter and with a first-stage height of about 21 meters, it’s powered by the homegrown Thunder-R liquid oxygen-kerosene engine—ostensibly China’s first reusable liquid rocket engine. Over 90% of the engine’s components were 3D printed from high-temperature alloys, allowing for quick maintenance and reuse in rapid launch cycles.
Adding to the significance of the test, this was China’s first deployment of an open-cycle liquid oxygen-kerosene pintle engine for high-altitude recovery. The choice of propellants wasn’t arbitrary—liquid oxygen and kerosene offer a balance of efficiency, safety, and cost-effectiveness, making them ideal for reusable commercial rockets.
Everything started as planned. Nebula-1 ignited its three engines and soared into the sky. Once it hit the targeted altitude, the side engines powered down, and a single engine took over to stabilize the rocket as it continued to climb. After reaching peak altitude, the rocket reversed course, descending smoothly under the control of the single engine. It even maneuvered about 200 meters horizontally before the landing legs deployed as expected. That’s when the problem arose. During the final shutdown phase, something went wrong, causing damage to the rocket’s body.
Despite the setback, the mission showed promise. The entire flight lasted 179 seconds, and before the anomaly, the deviation from the theoretical landing point was less than 0.5 meters. Nebula-1 still managed to touch down at the center of the recovery field. The overall flight profile followed the expected path, and safety protocols were adhered to without incident.
Initial analysis points to an issue with the thrust control servo during the final shutdown, causing the rocket to land at a higher-than-anticipated altitude, which led to the damage.
Interestingly, Nebula-1’s first-stage booster was only loaded with about one-fifth of its full propellant capacity for this test. Even so, the team demonstrated precise control during vertical recovery under challenging fuel conditions. Deep Blue Aerospace also tested high-precision self-alignment technology that allows the rocket to launch without altering its upright position—an efficiency that could simplify preparations for future missions.
Additionally, the test provided crucial data on an optimal control-based recovery trajectory and a meter-level precision guidance algorithm, setting the stage for future orbital recovery missions.
Looking ahead, Deep Blue Aerospace plans to apply the lessons from this test to address the technical issues. The team is gearing up for another high-altitude vertical recovery mission in November.
KrASIA Connection features translated and adapted content that was originally published by 36Kr. This article was written by Huang Nan for 36Kr.