PARIS — A loss of attitude control and an open valve contributed to the loss of Isar Aerospace’s first Spectrum rocket in March as the company gears up for a second flight.
In a Sept. 15 briefing held in conjunction with World Space Business Week, company executives discussed the outcome of the investigation into the March 30 launch of Spectrum from the Andøya Spaceport in northern Norway. The vehicle activated its flight termination system about half a minute after liftoff, shutting down its engines and plummeting into waters just offshore of the pad.
The primary issue with the rocket was a loss of attitude control. Alexandre Dalloneau, vice president of mission and launch operations at Isar, said that the company had not properly characterized bending modes of the vehicle at liftoff.
“The controllability has to be tuned in order to counter such behavior,” he said. That environment was not fully modeled and incorporated into the vehicle’s control system. “We were outside the environment that we expected, so that the controllability does not succeed.”
That loss of attitude control caused the vehicle to go outside the safety zone at the launch site. That, in turn, triggered the flight termination system on the rocket. He said the company has revised its modeling of vehicle modes at liftoff to correct the problem.
A second, unrelated issue was a vent valve in the rocket that was unintentionally opened before liftoff, allowing cryogenic vapors to escape. That would have caused problems later in the launch if the flight had continued, Dalloneau said. Isar is fixing that problem by having flight software, rather than ground software, close the valve.
Despite the failure to get to orbit, Dalloneau considers the first Spectrum launch a successful test flight. “This flight test for Spectrum was a fully successful story for the company,” he said, exercising vehicle systems and demonstrating the professionalism of the team.
What was most important, he argued, was the successful demonstration of the vehicle’s flight termination system, which Isar developed in-house. “We demonstrated that our system was safe and in line with what was simulated,” he said. “That’s a huge criterion for us to come back on the pad because we can guarantee a safe system if something goes wrong.”
The company is working towards a second flight of Spectrum. The first stage of that vehicle is at Andøya for pre-launch tests while the second stage completes assembly at Isar’s factory in Germany. Isar is also working with Norwegian regulators for a license for the second launch.
That launch will take place “as soon as possible,” Dalloneau said. He did not give a specific target launch date but officials indicated they were hoping to launch near the end of this year or early next year.
The goal of the second launch will be to get to orbit, he said, qualifying the vehicle for operations. The launch will carry several cubesats as part of the European Space Agency’s “Boost!” program.
Isar is proposing a gradual increase in launch cadence, said Stella Guillen, the company’s chief commercial officer, reaching six to eight launches in 2028. “We’re hoping for more as we’re trying to figure out how to produce and launch faster.”
That is driven by the strong interest the company is seeing in Spectrum, particularly from European programs like the Flight Ticket Initiative and European Launcher Challenge. “The demand is so huge right now, especially on the defense side in Europe,” she said. “If you want to launch in 2029, we need to talk right now.”
The company has long-term plans to produce 30 to 40 vehicles a year. The Andøya launch site has a cap of 15 launches a year, but Isar also plans to use a shared launch pad at the European spaceport in Kourou, French Guiana, that will be able to accommodate up to 20 launches annually among several companies.
Isar is one of several European launch startups competing to be the first to successfully reach orbit. “I think it’s important that we can get to the cadence that the market needs and that we do it reliably,” Guillen said when asked if it was a goal for the company to be first. “We are in the front right now, anyway.”
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source: spacenews.com