8 September 2026

^{Photo; Isar Aerospace}

 

Nine engines ignited beneath a 28-metre rocket on a small Norwegian island above the Arctic Circle.

For a few seconds, Isar Aerospace’s Spectrum rocket remained clamped to the ground while computers checked that its engines had built sufficient thrust. Then the restraints released.

At 10.12 pm Central European Summer Time on 5 September, the rocket began to rise from Andøya Spaceport in Norway.

Its task was not simply to reach space. Space is generally considered to begin about 100 kilometres above Earth, but an object sent straight up will eventually fall straight back down. To enter orbit, Spectrum needed to turn sideways and accelerate to nearly eight kilometres per second.

It had just over seven minutes to do so.

Along the way, the rocket would pass through the most aerodynamically violent part of its flight, empty most of its fuel tanks, shut down nine engines, split itself in two, start another engine and discard the shell protecting its satellites.

Every step depended on the previous one succeeding. A component opening a fraction too early, a sensor producing an incorrect reading or an engine pointing in the wrong direction could end the flight.

Eighteen months earlier, something close to that had happened.

 

T+0: why launch a rocket from Arctic Norway?

 

Spectrum lifted off from Andøya Spaceport, situated on Norway’s Atlantic coast, roughly 300 kilometres north of the Arctic Circle.

It might seem an unnecessarily remote place to build a spaceport. The region has strong winds, rapidly changing weather and long, dark winters. It also has something launch operators struggle to find in densely populated Europe: a clear route over the sea.

Rockets do not continue vertically upwards. Soon after launch, they begin leaning into a curved trajectory that gradually turns their vertical climb into horizontal speed. A launch site therefore needs a long, unobstructed corridor in the direction the rocket will travel.

Rockets heading towards low-inclination or equatorial orbits generally launch eastwards. Earth itself rotates towards the east, giving them a free speed boost. The effect is strongest near the equator, which is one reason Europe’s large Ariane rockets fly from French Guiana in South America.

Andøya serves a different type of mission. Its position allows rockets to fly over open water into high-inclination, polar and Sun-synchronous orbits without passing over major population centres.

Satellites in these orbits travel over or close to the poles. As Earth rotates underneath them, they can eventually observe most of its surface. This makes them particularly useful for weather forecasting, climate research, mapping, maritime monitoring and surveillance.

Spectrum was built to carry small and medium-sized satellites into these kinds of orbits. On this flight, named Onward and Upward, it carried five CubeSats and one technology experiment selected through a German Space Agency competition supported by the European Space Agency.

First, it had to clear the tower.

 

T+10 seconds: how the Spectrum rocket steers

 

At liftoff, Spectrum was heavier than it would ever be again. Most of that mass was propellant that would disappear within minutes.

Its nine first-stage Aquila engines burn liquid oxygen and propane. Together, they had to lift the rocket, its upper stage, its payload and all that propellant against gravity. The vehicle initially rose comparatively slowly, balanced on columns of fast-moving exhaust.

Rockets have no conventional rudders during this part of the flight. Spectrum steers by changing the direction of its engine thrust. Small adjustments alter the direction in which the entire rocket travels.

Motion sensors continually measure its orientation and acceleration. Flight computers compare those readings with the planned trajectory and issue corrections.

The process happens many times each second. A rocket may look rigid from a distance, but it flexes and vibrates as it climbs. Its control system must distinguish between harmless movement and the beginning of a dangerous deviation.

For Spectrum, one manoeuvre was particularly significant. Shortly after clearing the pad, it began to roll, orientating itself for the planned flight path.

This was where the first Spectrum flight had started to go wrong.

 

Why Isar Aerospace’s first Spectrum launch failed

 

On 30 March 2025, Spectrum rose from the same launchpad on its maiden test flight. Soon after liftoff, the rocket began tilting and rotating away from its intended path.

The mission was terminated at around 30 seconds. Spectrum fell into the sea and exploded on impact. Nobody was injured, and the launchpad remained intact.

To spectators, the flight looked like a short-lived failure. To Isar’s engineers, it also delivered 30 seconds of information that no computer simulation or ground test could fully reproduce.

The company’s subsequent investigation identified two initiating events: the unintended opening of a vent valve and a loss of attitude control at the start of the roll manoeuvre. The findings were reviewed with the Norwegian Civil Aviation Authority.

A vent valve is not among the most spectacular parts of a rocket. It does not produce thrust, navigate or carry a satellite. It regulates pressure by allowing gas to escape from a tank or another part of the vehicle’s fluid system.

But rockets depend on carefully controlled pressures. Fuel and oxidiser must reach the engines at the correct rates, while tanks must withstand rapidly changing forces without becoming dangerously overpressurised. A valve opening at the wrong moment can disturb that balance and affect the vehicle’s behaviour.

The guidance system then has to respond. Sensors detect the unexpected movement, computers calculate a correction and the propulsion system attempts to return the rocket to its planned attitude. If the disturbance develops faster than the control system can compensate, the vehicle may become unrecoverable.

Isar completed its investigation within two months and said it had implemented corrective measures. Now, as another Spectrum performed the same early roll above Andøya, the modified systems faced the test that could not be reproduced on the ground.

The rocket remained under control.

 

Around T+1 minute: surviving maximum aerodynamic pressure

 

Spectrum was now accelerating through dense air. Although the atmosphere became thinner with altitude, the rocket’s rapidly increasing speed meant the forces on its body continued to grow.

At some point during this part of the ascent, it reached maximum dynamic pressure, better known as max q: the moment when speed and air density combine to produce the greatest aerodynamic stress.

Before max q, the atmosphere is denser but the rocket is moving more slowly. Afterwards, the rocket is travelling faster, but the surrounding air has thinned. At max q, the balance between the two is at its most punishing.

The rocket’s body, fuel tanks and connections were being pushed, shaken and bent. Engineers could make these structures stronger by adding more material, but that creates another problem. Every additional kilogram requires extra propellant. That propellant needs larger tanks, which add still more weight.

Rocket engineering is therefore not a search for maximum strength. It is a search for sufficient strength, with a carefully calculated margin for conditions that may never be reproduced exactly.

Spectrum passed through the dense lower atmosphere intact. Its acceleration continued as the atmosphere loosened its grip.

 

A few minutes after launch: why rockets separate into stages

 

By now, the nine first-stage engines had consumed most of their propellant. The rocket was travelling at several thousand kilometres per hour, but it was still far short of orbital speed.

The first-stage engines shut down.

Then the rocket deliberately broke apart.

Mechanical systems released the connection between the stages and allowed them to move away from each other. The enormous first stage, which had done most of the initial lifting, was now little more than an empty collection of tanks and engines. Continuing to carry it would waste propellant.

Staging works because a rocket becomes more efficient by discarding everything it no longer needs. Most of the vehicle that leaves the launchpad never reaches orbit.

The manoeuvre is also an opportunity for failure. The stages must separate cleanly despite travelling at immense speed. If they remain too close, they could collide. If the upper-stage engine ignites at the wrong moment, its exhaust could interfere with the discarded first stage and destabilise the vehicle. If it fails to ignite, the remaining rocket and its satellites will fall back towards Earth.

Spectrum’s two stages separated. The upper stage’s single vacuum-optimised Aquila engine started and continued accelerating towards orbit.

 

Around T+4 minutes: crossing the boundary of space

 

As Spectrum climbed above 100 kilometres, it passed the Kármán line, the commonly used boundary between Earth’s atmosphere and space.

It was a symbolic moment, but not the decisive one.

Reaching space is comparatively straightforward. A sounding rocket can rise above 100 kilometres and still fall back to Earth. Remaining there requires enormous sideways velocity.

Orbit is essentially continuous falling. Gravity is always pulling a satellite down, but the satellite travels horizontally so quickly that Earth curves away beneath it at approximately the same rate. It keeps falling without reaching the ground.

Spectrum therefore continued to accelerate, with an increasingly large part of its motion directed horizontally. By this point, the atmosphere was too thin to justify carrying the payload fairing—the protective shell covering the satellites.

The fairing had shielded them from aerodynamic pressure, heating and noise during the ascent. In space, it was dead weight. The shell separated and fell away.

The satellites were exposed to space for the first time, although they remained attached to the upper stage.

 

Just over T+7 minutes: how Spectrum achieved orbit

 

Just over seven minutes after leaving Andøya, Spectrum reached an initial orbit.

The rocket was no longer fighting to avoid falling. It had acquired enough sideways speed to fall continuously around the planet.

The upper stage subsequently adjusted its trajectory before releasing the five satellites. Isar Aerospace and the European Space Agency confirmed that the payloads had been delivered into low Earth orbit.

Isar had become the first European commercial launch company to place satellites into orbit with its own rocket from a launch site in continental Europe—and had done so on only Spectrum’s second flight.

The qualification mission was also the first Spectrum flight to carry payloads.

 

What the successful Spectrum launch means for Europe

 

When MTN covered Isar Aerospace's 270 million fundraise in June 2026, the company represented Europe’s determination to regain more control over access to space.

Spectrum has now shown that the vehicle can reach orbit. One successful flight, however, does not establish a reliable commercial launch service.

Satellite operators need predictable schedules and precise orbital delivery. They need confidence that the fourth, tenth and twentieth rockets will behave like the second. Isar must also manufacture vehicles consistently, maintain launch infrastructure in Arctic conditions and bring costs down as production increases.

The company says five more rockets are already in production and ultimately wants to conduct around 40 launches a year. It is also developing a second launch site in Nova Scotia, Canada, which could be ready for launches in 2028, according to Reuters.

That requires turning an extraordinary flight into a repeatable industrial process.

On 5 September, Spectrum survived its seven unforgiving minutes. Isar’s next task is to make those seven minutes boring.