Editing Aerospike engine (section)

=== Polaris Spaceplanes ===
The [[Bremen]]-based German startup [[POLARIS Raumflugzeuge GmbH]] received a [[Bundeswehr]] contract to design and flight test a linear aerospike engine in April 2023. The company is set to test this new engine on board of its fourth spaceplane demonstrator, DEMO-4 MIRA, in late 2023<ref>{{Cite web |title=POLARIS Raumflugzeuge - POLARIS receives Bundeswehr Study Contract for Linear Aerospike Rocket Engine Design and Flight-Testing |url=https://polaris-raumflugzeuge.de/News/POLARIS-receives-Bundeswehr-Study-Contract-for-Linear-Aerospike-Rocket-Engine-Design-and-Flight-Testing |access-date=2023-07-25 |website=polaris-raumflugzeuge.de |language=de-DE}}</ref><ref>{{cite web|url=https://europeanspaceflight.com/polaris-spaceplanes-begins-testing-its-mira-light-vehicle/|title=POLARIS Spaceplanes Begins Testing its MIRA-Light Vehicle|author=Andrew Parsonson|date=August 25, 2023|website=European Spaceflight}}</ref> at Peenemünde,<ref>{{cite web | url=https://www.bundeswehr.de/de/organisation/ausruestung-baainbw/aktuelles/wtd61-unbemanntes-raumflugzeug-getestet-5594484 | title=Aus "ATHENA" wird "NOVA" - Unbemanntes Raumflugzeug getestet | date=13 March 2023 }}</ref> where the [[V-2 rocket]]s were developed.

The original MIRA demonstrator was catastrophically damaged in a runway accident in February 2024.<ref>{{Cite web |title=POLARIS Raumflugzeuge - Demonstrators |url=https://www.polaris-raumflugzeuge.de/Technology/Demonstrators |access-date=2024-11-12 |website=polaris-raumflugzeuge.de}}</ref>

On 29 October 2024, the company was the first ever to ignite an aerospike engine in a flight over the Baltic Sea, powering a four-engine, kerosene-fueled, turbojet MIRA-II demonstrator. The test involved a three-second burn to collect data with minimal engine stress. The vehicle achieved an acceleration of 4&nbsp;m/s², producing 900 [[Newton (unit)|newtons]] of thrust.<ref>{{Cite web |last=Parsonson |first=Andrew |date=2024-11-12 |title=POLARIS Spaceplanes Complete First In-Flight Rocket Engine Ignition |url=https://europeanspaceflight.com/polaris-spaceplanes-complete-first-in-flight-rocket-engine-ignition/ |access-date=2024-11-12 |website=European Spaceflight |language=en-US}}</ref><ref>{{Cite web |last=Salas |first=Joe |date=2024-11-08 |title=World's first aerospike rocket test mid-flight successful |url=https://newatlas.com/aircraft/worlds-first-successful-aerospike-rocket-flight-test/ |access-date=2024-11-12 |website=New Atlas |language=en-US}}</ref>

On February 27, 2025, it was announced that the company had been commissioned by the Bundeswehr procurement office [[Federal Office of Bundeswehr Equipment, Information Technology and In-Service Support|BAAINBw]] to develop a two-stage, horizontal take-off and fully reusable hypersonic research aircraft. In addition to its use as a hypersonic testbed and experimental platform for defense-related and scientific research, the aircraft can also be used as a small satellite carrier. POLARIS Spaceplanes plans to develop a prototype of a fully reusable spaceplane capable of transporting loads of up to 1,000 kilograms into space by 2028.<ref>{{Cite web |date=2025-02-27 |title=Bundeswehr beauftragt POLARIS mit der Entwicklung eines wiederverwendbaren Hyperschallflugzeugs |url=https://www.hartpunkt.de/polaris-hyperschallflugzeug-bundeswehr/ |access-date=2025-03-06 |language=de}}</ref>