At 12:30pm CEST on March 30th, 2024, Isar Aerospace launched the maiden flight of their Spectrum rocket. After successfully clearing the pad under the power of all its 9 lit engines, Spectrum experienced some attitude issues and loss of control at T+18 seconds, impacting the sea near the launch pad at about T+40 seconds.

Here, we’re going to dive into what happened and the steps forward.

Mission Overview

The mission was named “Going Full Spectrum,” and it was performed by Isar Aerospace’s Spectrum rocket, which has been under design, development, and testing since March 2018 (the date of the company’s foundation). Spectrum is a 2-stage, small-lift launch vehicle with an overall height of 28 meters and a width of 2 meters, able to launch up to 1000 kg to LEO and 700 kg to SSO under the power of its 9 Aquila engines on the first stage (675 kN of thrust in total) and its single, multi-reignitable, vacuum-optimized Aquila engine on the second stage (95 kN).

This launch was Spectrum’s maiden launch, and it was carrying no payload due to its test nature. According to the mission press kit, “The first test flight of Isar Aerospace’s launch vehicle ‘Spectrum’ is the first integrated test of all systems and tens of thousands of components. And that is how we approach it: as a test. No matter how far we will get with our first test flight, we will generate valuable data and experience, learn, iterate, and improve for future missions.”

The main goal of this launch was to get as far as possible into flight and gather as much data as possible on every component. Depending on this, the vehicle would’ve completed ascent, stage separation, and second stage engine ignition in order to get to a 95°-inclined LEO.

Launch

Spectrum lifting off the pad. Credit: Brady Kenniston, NSF

After receiving their launch license on March 14th, Isar Aerospace got ready for a launch window between March 20th and 30th, during a 3-hour window opening at 12:30pm CEST. Unfavorable weather dictated much of the schedule, bringing the first 2 attempts to a scrub (the first one on March 24th and the other on March 29th); their 3rd launch attempt was set for March 30th, and they were determined to go:

After the launch pad and range were determined to be clear, propellant loading began and was completed by T-1 hour. Engine chill began around T-22/25 minutes (per CEO post), while the commentary stream with NASASpaceflight began at T-15 minutes.

Spectrum after loss of control at T+28s. Credit: Isar Aerospace / NSF

At T-3.5 seconds, Spectrum lit up all its 9 Aquila engines, and it lifted off at T+1 second. The launch pad looked fine, with a few flames and fires on the launch mount and its surroundings following liftoff, but nothing too bad or concerning. After liftoff, Spectrum began to oscillate left and right, although it wasn’t much noticeable at first; then, at T+17 seconds, these oscillations were noticeable and clearly not nominal. At T+24 seconds, the vehicle lost control and began to pitch down; therefore, the FTS was activated, and the engines were shut down at T+28 seconds. After reaching apogee 2 seconds later, Spectrum went into free fall and impacted the water at T+40 seconds, causing a violent explosion that sent debris hundreds of meters away. Luckily, the vehicle didn’t fall back on the pad, so we can consider ground damages as “little.” Although there isn’t official confirmation, the maximum height likely was a few hundred meters.

Spectrum exploding on impact. Credit: NSF

What went wrong?

What went wrong? Well, we don’t know. But here’s what we know: the vehicle had oscillation and control issues since liftoff, and they got worse as it went up. For all we know, it might be a hardware issue, such as TVC control, or a software issue. Unfortunately, we won’t know until Isar makes an official statement; they, however, consider this a success… why? Because of what I said earlier: this rocket lifted off from the pad, it conducted a launch, and now they have found the first of many problems. This is something to be proud of.

What does the future hold?

Isar Aerospace stated that the launch vehicles for Flights 2 and 3 are already under development, although we don’t know at which stage; we know none of the stages have conducted static fires so far, which means it’s going to be at least a few months before we see Spectrum launch again. And let’s hope they can find the problem, solve it, and launch again!

Congratulations Isar!

References

Isar Aerospace (@isaraerospace) / X

Andøya Space (@AndoyaSpace) / X

Daniel Metzler (@danielmetzler) / X

Livestream: First test flight of Isar Aerospace

NSF - NASASpaceflight.com