Stellar Alpina Raises $4.5M Pre-Seed to Build Rotating Detonation Engines
What's the deal? Stellar Alpina, a Swiss propulsion startup, has raised a CHF3.5M ($4.5M) pre-seed round to develop rotating detonation rocket engines (RDRE) — a technology that promises more efficient in-space mobility than traditional chemical propulsion. FounderfulDealroom has a profile for this one. Try Dealroom → led the round, joined by fellow Swiss VC LP&EDealroom has a profile for this one. Try Dealroom →.
Founded in February by four engineers with roots in Switzerland's Academic Spaceflight Initiative, the company set a goal of designing and hotfiring an RDRE within 100 days. It did it in 82.
The funds will go toward hiring more than a dozen employees and building a higher-class test stand for larger engine tests starting next year. Stellar Alpina aims to have a spaceflight-ready RDRE by 2028.
"It's definitely going to go beyond LEO. The question is just how fast," cofounder Victor Elliesen said.
Why now? The benefits of detonation engines have been understood in academic circles for decades. Compared to traditional chemical engines, RDREs offer greater thermodynamic efficiency in a more compact form, with a potentially higher thrust-to-weight ratio. But translating theory into hardware is hard — no one has built a commercial-scale RDRE yet.
The race is heating up. In 2021, a team of Japanese universities demonstrated the first in-space RDRE firing with help from JAXA. Washington-based Juno Propulsion won a $500,000 NASA TechLeap prize in July to bring an RDRE to space this summer. And in April, Astrobotic said it broke the record for longest RDRE hotfire.
"Who says the first RDRE can't come from Europe?" Elliesen said.
What could go wrong? RDRE technology remains unproven at commercial scale. The leap from lab demonstrations to reliable, spaceflight-ready hardware is substantial, and demand for the engines is still uncertain. Stellar Alpina's 2028 timeline is ambitious for a pre-seed company working with a technology that no one has yet productised.
The signal: Founderful, which backs pre-seed companies across Switzerland, is placing an early bet that Europe can build its own propulsion supply chain rather than depend on US providers. Stellar Alpina's Dealroom profile frames its mission around European lunar access — a focus that aligns with growing institutional demand for beyond-LEO capabilities and suggests the startup sees cislunar logistics, not just satellite servicing, as its primary market.
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