Isar Aerospace Spectrum

History

Isar Aerospace Spectrum is a German two-stage orbital launch vehicle developed for small and medium satellites and satellite constellations. The vehicle is 28 m long and 2 m in diameter, with a stated payload capability of up to 1,000 kg to low Earth orbit.

Spectrum is designed and manufactured largely in-house by Isar Aerospace. Its propulsion system uses liquid oxygen and propane, and the two stages employ ten Aquila engines in total.

The rocket made its first flight from Andøya Spaceport in Norway in March 2025. That test ended after about 30 seconds, but a second Spectrum launched from Andøya on 5 September 2026 and successfully reached orbit with payloads aboard.

Development and testing

Isar Aerospace developed Spectrum as a commercial orbital launcher intended to serve small and medium satellite missions. According to the company's Spectrum information, the launch vehicle and its Aquila engines were developed and manufactured in-house.

By March 2023, Isar Aerospace had reported extensive hot-fire testing of the Aquila engine. The engine family uses high-pressure turbopump-fed propulsion. Spectrum's first stage carries nine engines, while its second stage uses one engine.

A static-fire test of the first flight vehicle was conducted on 21 February 2025. The first launch attempt scheduled for 24 March was scrubbed because of high winds. Spectrum eventually lifted off from Andøya Spaceport on 30 March 2025. The test vehicle cleared the launch pad but lost control several seconds later and fell into the sea. The flight lasted about 30 seconds. Although the rocket was destroyed, the test provided flight data for subsequent missions.

The second Spectrum was prepared as a qualification flight carrying actual payloads. The European Space Agency described the mission as carrying five commercial and educational CubeSats together with an experiment intended to demonstrate technologies in orbit and provide educational experience.

On 5 September 2026, Spectrum launched from Andøya Spaceport at 22:12 CEST. The rocket reached orbit just over seven minutes after liftoff. The mission was Spectrum's first successful orbital flight and its first flight carrying payloads. Deutsche Welle reported the achievement as the first time a privately developed rocket had reached orbit from continental Europe.

Design

Spectrum is a two-stage liquid-propellant orbital launch vehicle. It is 28 m long and 2 m in diameter. Isar Aerospace states that it can carry up to 1,000 kg to low Earth orbit and up to 700 kg to Sun-synchronous orbit.

Structure

The rocket uses a carbon-composite structure. Its compact dimensions are combined with liquid oxygen and propane propulsion, which Isar Aerospace selected for the vehicle's Aquila engine system.

Propulsion

The first stage is powered by nine Aquila engines. The second stage uses a single Aquila engine. The engines are high-pressure turbopump-fed units designed and manufactured by Isar Aerospace.

The second-stage engine has multi-ignition capability. This allows the engine to be shut down and restarted when required by the mission profile, reducing the need for a separate kick stage for some missions.

Payload capability

Spectrum is intended for small and medium satellites, including constellation deployment missions. The manufacturer's stated maximum payload is 1,000 kg to low Earth orbit and 700 kg to Sun-synchronous orbit.

Operational history

Spectrum's first flight on 30 March 2025 was a test mission without a payload. The rocket successfully lifted off and cleared the launch site, but the vehicle lost control shortly afterward and was destroyed after falling into the sea.

The second flight on 5 September 2026 was both a qualification mission and Spectrum's first payload-carrying flight. It carried five CubeSats and one non-deploying technology experiment and successfully reached orbit. The flight established Spectrum as an operationally demonstrated orbital launch vehicle, although Isar Aerospace was still working toward expanded production and future commercial missions after the qualification launch.

Specifications (Spectrum)

General characteristics

• Type: Two-stage orbital launch vehicle
• Length: 28 m
• Diameter: 2 m
• Stages: 2
• First-stage engines: 9 Aquila engines
• Second-stage engines: 1 Aquila engine
• Propellants: Liquid oxygen and propane

Payload performance

• Payload to low Earth orbit: Up to 1,000 kg
• Payload to Sun-synchronous orbit: Up to 700 kg

Upper-stage capability

• Engine restart: Multi-ignition second-stage engine capable of shutdown and restart according to mission requirements