Isar Aerospace delays Spectrum rocket test flight again
The German startup scrubbed another launch attempt in Norway after detecting abnormal behavior in the rocket’s fluid systems.
By Hana Yoshida · Markets Reporter
3 min read
Isar Aerospace called off another attempt to launch its Spectrum rocket from northern Norway on Monday, delaying a test flight that Europe’s private launch sector is watching closely. The mission matters because Isar is the best-funded of a group of European startups trying to build a cheaper commercial path to orbit for small satellites.
The German company said on social media that it stopped the countdown after detecting “off nominal behavior” in the vehicle’s fluid systems. Isar said its teams were reviewing data to identify the cause, and it did not immediately set a new launch time.
The 92-foot, two-stage Spectrum rocket was on the pad at Andøya Spaceport, a launch site above the Arctic Circle in Norway. Andøya Space, which owns the spaceport, said the current launch window runs through June 21.
Repeated delays at the launch site
Monday’s scrub was the fourth time in five months that Isar had reached a planned date for Spectrum’s second test flight, according to Ars Technica. The company ended a Jan. 21 attempt because of a pressurization valve issue, then stopped a March 25 countdown shortly before liftoff after engineers saw rising temperatures in the rocket’s liquid propane fuel.
Isar officials linked the March problem to an earlier delay caused by an unauthorized boat inside the restricted area along the rocket’s flight path, Ars Technica reported. On April 9, the company stood down again to examine a suspected leak in a composite overwrapped pressure vessel.
Isar founder and Chief Executive Daniel Metzler said in April that launch scrubs are part of the business and that each attempt gives the company experience and lessons, according to Ars Technica.
Andøya’s operations have faced scheduling pressure beyond the rocket itself. Ars Technica reported that the remote site is also used for military testing, and local media said missile testing took priority there last month.
The spaceport’s location near fishing grounds has also created friction. The captain of a longline fishing boat that was inside the hazard area during the March launch attempt told Kyst og Fjord that he stayed there to recover tangled gear. In the same Norwegian newspaper, captain Olafur Einarsson said fishermen view the area as their workplace and described the launch range as a difficult neighbor.
A test flight with payloads aboard
The upcoming mission is Spectrum’s second test flight. Isar’s first Spectrum launch, in March 2025, lasted less than a minute before the rocket crashed near the pad, according to Ars Technica. Engineers later identified an unintended vent valve opening and loss of attitude control as the cause.
Unlike that first flight, the next Spectrum launch carries payloads. Ars Technica reported that Isar has placed five small CubeSats and a non-separating technology experiment inside the payload fairing.
The mission has support from the European Space Agency’s Boost! program and the German Aerospace Center’s Microlauncher Competition, both of which fund commercial space transport efforts, according to Ars Technica.
Isar is among several European companies developing small launch vehicles, alongside Germany’s Rocket Factory Augsburg, France’s MaiaSpace and Spain’s PLD Space. Ars Technica reported that Spectrum is the only rocket in that group to have flown a test mission so far.
The company has also attracted significant public and private funding. Ars Technica reported that Isar is due to receive up to 205 million euros, or $238 million, from ESA through the European Launcher Challenge, in addition to more than 800 million euros in private fundraising and financing rounds. Isar announced 270 million euros in new financing last week.
This story draws on original reporting from Ars Technica.