German Startup POLARIS Achieves Milestone with MIRA II Spaceplane's Aerospike Engine Test
In a significant step forward for reusable spaceflight technology, German startup POLARIS Raumflugzeuge has achieved a notable milestone with its MIRA II spaceplane. POLARIS conducted the first roll test of the spaceplane’s custom-designed AS-1F linear aerospike engine, marking a successful demonstration of this advanced propulsion system on October 29 at Peenemünde Airport. This achievement highlights the promise of the MIRA II, which leverages the aerospike engine’s efficiency to offer potential versatility in future spaceplane missions.
The AS-1F linear aerospike engine is a 1 kN rocket powered by a combination of liquid oxygen (LOX) and kerosene. In the recent test, the engine burned for three seconds, giving POLARIS crucial data on the aerospike’s performance and stability during roll maneuvers. Aerospike engines are distinctive in design, as they replace the conventional bell nozzle with a wedge-shaped, linear or toroidal “spike.” This design maintains a more efficient exhaust flow across various altitudes, unlike traditional engines that often experience performance drops at higher altitudes. This feature positions aerospike engines as a compelling option for spaceplanes that must perform efficiently both within and beyond the Earth’s atmosphere.
In the days leading up to the aerospike test, MIRA II also completed three turbine-powered test flights from October 25 to October 27. These preliminary flights validated the vehicle's turbine-based propulsion capabilities and demonstrated its agility and stability as a spaceplane. Following these flights, POLARIS quickly transitioned to rocket testing, integrating the aerospike engine and performing the roll test within 36 hours of the turbine flight series. This rapid turnaround demonstrates POLARIS’s operational agility, a quality that may become essential for space missions requiring quick reconfiguration.
The roll test marks the final ground-based trial for MIRA II before in-flight ignition tests, which will bring the aerospike engine into real-world flight scenarios. For POLARIS, this milestone signals readiness for more ambitious, high-altitude flight tests aimed at demonstrating the aerospike’s efficiency advantages over traditional rocket engines. Aerospike engines, while complex, present a major efficiency advantage because they naturally adjust to atmospheric pressure changes, eliminating the need for additional equipment to optimize thrust.
Looking forward, POLARIS’s goal is to validate the operational capability of the MIRA II with the aerospike engine fully engaged. If successful, the technology could help establish POLARIS as a leader in the field of high-performance spaceplanes designed for quick, efficient atmospheric and near-space operations. By bridging the gap between traditional turbine propulsion and rocket-based propulsion, MIRA II’s flexible design and rapid adaptability represent a potential step toward the broader adoption of reusable spaceplanes, possibly setting new standards for high-efficiency, multi-mission spaceflight.
As the spaceplane industry evolves, MIRA II’s development underscores a trend toward reusable, versatile spacecraft that can reduce launch costs and enhance mission capabilities. For POLARIS, the next steps will likely include testing the engine at varied altitudes and speeds, assessing the MIRA II’s performance across scenarios that mimic real-world spaceflight demands.
