Stellar Alpina Raises $4.1M for Detonation Rocket Engines

Jan de Vries · 2026-05-28

A Swiss startup is taking a radically different approach to rocket propulsion, and it just got the funding to prove it works. Stellar Alpina, based in Zurich, has raised $4.1 million (converted from EUR 3.8 million) in a pre-seed round to build rotating detonation rocket engines (RDREs) that could make moving satellites between orbits faster, smaller, and far more efficient. The round was led by Founderful, with participation from LP&E and a handful of strategic investors from the DeepTech space. It’s a vote of confidence in a technology that sounds almost too sci-fi to be real: using controlled explosions to power spacecraft. ### What Is Detonation Propulsion, Exactly? Here’s the simple version. Every rocket engine in space today burns fuel through deflagration — the same slow, subsonic combustion that happens in your car’s engine. It works, but it’s been the only game in town for decades. Stellar Alpina is betting on detonation, where the flame front moves at supersonic speeds. Think of it like the difference between a campfire and a bomb. Detonation extracts more energy from the same amount of propellant, meaning you can build engines that are smaller, lighter, and more powerful. “The space economy is moving beyond the question of access to orbit. The next challenge is movement after launch,” said Victor Elliesen, co-founder of Stellar Alpina. “We believe detonation-based propulsion can provide the step change this requires.” The company’s technology is called a rotating detonation rocket engine. Instead of a single explosion, it creates a continuous wave of detonations spinning around a ring-shaped chamber. That sounds complex because it is. But the payoff is huge: more thrust from a smaller package, fewer moving parts, and the ability to handle missions that current systems just can’t touch.  ### From Student Project to Startup Stellar Alpina wasn’t born in a corporate lab. It was founded in 2026 by Rick Röthlisberger, Simi Y. Wespi, Victor Elliesen, and Patrick Egli — all alumni of ARIS, the Academic Spaceflight Initiative Switzerland. In 2024, while still students, they built the world’s first student-developed rotating detonation rocket engine. That’s the kind of moonshot that usually stays in a university showcase, but this team kept pushing. Co-founder Simi Wespi spent years advocating for RDREs in Switzerland, facing repeated rejections. Instead of giving up, he assembled a team within ARIS and proved the concept. That persistence paid off. After incorporation, Stellar Alpina built its test infrastructure and completed a full engine test campaign with Engine 0 — its first RDRE — in just 82 days. Eight detonative hotfires later, they had footage of up to five stable detonation waves, the first known commercial RDRE milestones in Europe. ### Why In-Space Mobility Matters Now Here’s the problem Stellar Alpina is solving. Right now, if a satellite operator needs to move a payload from low Earth orbit to geostationary orbit, they’re stuck with propulsion systems that haven’t changed much in decades. Thousands of satellites need repositioning and orbit management. Lunar programs like NASA’s Artemis and ESA’s exploration roadmap depend on reliable transfer and landing capabilities. In-space servicing and manufacturing are moving from concept to procurement. Governments are investing in resilient, maneuverable space architectures. The infrastructure to support all of this doesn’t yet exist at scale. That’s the gap Stellar Alpina wants to fill. Its RDRE technology could reshape which missions are viable and what costs operators face when moving between orbits. - **Smaller engines** mean more payload capacity or lower launch costs. - **Higher efficiency** means less propellant for the same mission. - **Fewer mechanical components** means higher reliability and lower manufacturing costs. ### The Road Ahead The $4.1 million pre-seed round will help Stellar Alpina turn its early milestones into a real product. The company is already working on in-space vehicle architectures for orbital mobility, high-energy transfers, and future deep-space infrastructure. If they succeed, we could see a new class of spacecraft that can zip between orbits like buses between city stops. Detonation propulsion isn’t just an incremental improvement. It’s a paradigm shift in how rocket engines look and operate. And for a space economy that’s growing fast but still relying on old tech, that kind of shift can’t come soon enough.