Following the March 30th failure of its Spectrum rocket, Isar Aerospace has completed its investigation. The company's executives revealed the primary cause was a loss of attitude control, stemming from inadequate modeling of the vehicle's bending modes at liftoff. Alexandre Dalloneau, vice president of mission and launch operations, explained: “The controllability has to be tuned in order to counter such behavior. We were outside the environment that we expected, so that the controllability does not succeed.” This led to the rocket exceeding the safety zone, triggering its flight termination system.
A secondary issue involved an unintentionally opened vent valve, allowing cryogenic vapor escape. This problem is being addressed by switching valve control from ground software to flight software. Despite the unsuccessful orbital insertion, Dalloneau considers the launch a successful test, highlighting the successful functionality of the in-house developed flight termination system: “We demonstrated that our system was safe and in line with what was simulated. That’s a huge criterion for us to come back on the pad because we can guarantee a safe system if something goes wrong.”
Isar is preparing for a second launch, aiming for late 2023 or early 2024. The first stage is at Andøya for testing, while the second stage undergoes final assembly. The launch, pending licensing, will carry cubesats under the European Space Agency’s “Boost!” program, marking a crucial step towards operational qualification. Stella Guillen, chief commercial officer, anticipates a gradual increase in launch frequency, targeting six to eight launches annually by 2028, driven by high demand, particularly from European defense programs. “The demand is so huge right now, especially on the defense side in Europe,” she stated. “If you want to launch in 2029, we need to talk right now.”
Isar's long-term vision includes producing 30 to 40 vehicles yearly, utilizing the Andøya Spaceport and a shared launch pad at Kourou, French Guiana. While acknowledging the competitive European launch market, Guillen emphasizes reliability and meeting market needs as key priorities: “I think it’s important that we can get to the cadence that the market needs and that we do it reliably. We are in the front right now, anyway.”