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Still in the harbor

Key mission for Europe’s commercial space enterprise scrubbed again

Isar Aerospace is not hurting for money, but it is sorely lacking in the currency of flight experience.

Stephen Clark – | 41
Isar Aerospace's Spectrum rocket rolls out to its launch pad at Andøya Spaceport in northern Norway. Credit: Isar Aerospace
Isar Aerospace's Spectrum rocket rolls out to its launch pad at Andøya Spaceport in northern Norway. Credit: Isar Aerospace
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Isar Aerospace still commands top position among a new generation of European rocket startups, but the company’s efforts to launch a critical test flight of its Spectrum rocket continue to encounter roadblocks.

The latest delay came Monday, when Isar scrubbed a launch attempt after “detecting off nominal behavior in the vehicle’s fluid systems,” according to a social media post. “The teams are analyzing the new data to isolate the root cause.”

The two-stage, 92-foot-tall (28-meter) Spectrum rocket was awaiting liftoff from Andøya Spaceport in northern Norway. It was the fourth time in five months that Isar Aerospace, headquartered near Munich, Germany, had reached a target launch date for the second test flight of the Spectrum launch vehicle.

Andøya Space, the company that owns the launch site, said on its website that the current launch window runs through June 21. Isar did not immediately announce a new schedule for launching the second Spectrum test flight.

Gravity still winning

The Spectrum rocket has missed three launch windows so far this year. Isar called off a launch attempt on January 21 due to an issue with a pressurization valve, and then halted a countdown on March 25, moments before liftoff, when engineers detected rising temperatures in the rocket’s liquid propane fuel. Isar officials attributed the problem to a delay earlier in the countdown caused by an unauthorized boat in restricted waters along the rocket’s flight path.

Managers stood down from another launch attempt on April 9 to evaluate a suspected leak in a composite overwrapped pressure vessel. That led to Isar’s latest try to launch the Spectrum rocket on Monday.

“Scrubs are part of the business,” Isar founder and CEO Daniel Metzler said in April. “Each attempt gives us valuable experience and lessons learned.”

This statement will ring true for anyone with a casual interest in rocket launches. But launch availability is proving to be a headache at Andøya Spaceport. The remote site is often used as a military testing range. That was the case last month, when missile testing took priority at the base inside the Arctic Circle, according to local media reports.

Andøya’s location near a rich offshore fishery has also generated tension. The skipper of the longline fishing boat within the launch hazard area during Isar’s March launch attempt told local media he stayed in the keep-out zone to retrieve tangled gear. He also refused to leave the area where a German bombing exercise was set to occur last October, but rejected any accusation of sabotage.

The test range is an important part of Norway’s military partnership with Germany. Olafur Einarsson, captain of the fishing vessel, argued for local interests in an interview with the newspaper Kyst og Fjord: “For us fishermen, this is our workplace, and then they come here and want to use the same area. We have gotten a bad neighbor, you could say.”

Friction between the launch and fishing industries is nothing new. In the early years of Japan’s space program, launches from the country’s primary spaceport were limited to certain months based on fishing seasons near Tanegashima Island. The restrictions remained for decades until an agreement in 2010 opened the way for year-round launches.

Isar Aerospace is at the head of a pack of emerging European rocket companies seeking to make the continent’s once-strong commercial launch industry competitive again. Several other companies—Germany’s Rocket Factory Augsburg, France’s MaiaSpace, and Spain’s PLD Space, among others—are developing their own small satellite launchers to provide a lower-cost alternative to Arianespace and Avio, Europe’s incumbent launch providers.

Isar’s Spectrum rocket is the only one that has launched on a test flight. The rocket’s first launch in March 2025 lasted less than a minute before crashing near the launch pad. Engineers identified the unintentional opening of a vent valve and a loss of attitude control as the cause of the failure.

There were no customer payloads onboard the failed Spectrum launch last year. This time, Isar has placed five small CubeSats and a non-separating technology experiment into the Spectrum rocket’s payload fairing. The second test flight is supported by the European Space Agency’s “Boost!” program and the German Aerospace Center’s Microlauncher Competition, which provide funding for commercial space transport initiatives.

Isar Aerospace is set to receive up to 205 million euros ($238 million) from ESA through the European Launcher Challenge program, augmenting the company’s private fundraising and financing rounds worth more than 800 million euros (nearly $1 billion), including 270 million euros ($313 million) announced just last week. This makes Isar, by far, the most well-capitalized private launch company in Europe.

Isar is not hurting for money, but it is sorely lacking in the currency of flight experience. When it finally happens, the next launch will seek to remedy that problem.

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Stephen Clark Space Reporter
Stephen Clark is a space reporter at Ars Technica, covering private space companies and the world’s space agencies. Stephen writes about the nexus of technology, science, policy, and business on and off the planet.
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