Isar Aerospace

Spectrum is small by design: 28 metres tall, two across, a tonne to low orbit. Nine Aquila engines fly the first stage and one flies the second, burning oxygen and propane on a gas-generator cycle, which is a deliberately unexciting architecture. Propane is dense, which is why the airframe can be so slim. Isar builds about 80 per cent of the vehicle itself, engines included, in an automated composite factory outside Munich sized for up to forty rockets a year.

Isar is betting on the factory rather than the engine. Europe launched fewer than ten times in 2025 and has no independent commercial small launcher, and Isar's argument since 2018 has been that a startup can out-build the Ariane industrial system rather than out-invent it. The money has followed that framing: a European Commission prize, preselection for ESA's Launcher Challenge, the NATO Innovation Fund, and a partnership with the submarine builder TKMS aimed at a sovereign Canadian launch capability.

The factory is finished and the rocket has reached orbit zero times. Spectrum's first flight, in March 2025, ended thirty seconds after liftoff when a vent valve opened during pitch-over, attitude control was lost, and the flight termination system shut down all nine engines. Seventeen months later the second flight had still not happened, called off through 2026 for a pressurisation valve, a vessel straying into the range, weather, rising engine fuel temperatures, a suspected pressure vessel leak, and an unspecified glitch. Something near €800 million has now gone into a production line rated for forty vehicles a year that has yet to deliver a kilogram to orbit, and Spectrum is expendable in a market whose reference vehicles are not.