Why We Invested in Venus Aerospace
A couple of weeks ago marked a major fundraising announcement for Venus Aerospace - $91M Series B fundraise led by Mercury Fund. Today marks another significant milestone for the company as Venus officially announced the signing of their first commercial partnership with Lockheed Martin. This is a watershed moment in the US defense industry, providing prime mission contractors the propulsion needed to compete and exceed the efforts of China and Russia, at a fraction of the cost of traditional short and long-range hypersonics. What has become a vision for years is closer than it ever has been to a true reality.
Venus launched with the bold idea to create a more efficient rocket engine. Five years later, they cracked the code by announcing the first US-based flight of a powerful new variety of rocket called an RDRE (rotating detonation rocket engine). What that test proved was that Venus could create RDREs with more efficiency than any other rocket engine ever built. Venus' efficient rocket engines will allow for hypersonic weapons with greater range and payload - 2x range for defense and 4x payload for space.
On a parallel path, Venus is working with several companies on solving space propulsion as well. RDREs are greatly needed in low and outer earth orbit to move everything around efficiently. Eventually, larger versions of the Venus rockets will be developed to more efficiently travel between planets, but we'll save that story for another day…
The propulsion problem nobody had solved
Rocket engines haven't changed fundamentally since the Apollo missions of the 1960s. Conventional engines burn propellant through subsonic combustion, a well-understood process, but one that's basically maxed out on efficiency. Every additional percentage point of performance has come from incremental refinement, not a fundamentally new architecture.
An RDRE works differently. Instead of steady subsonic burning, it sustains a continuous detonation wave that rotates around the combustion chamber at supersonic speed. That detonation process releases energy faster and more completely than conventional combustion, which translates into real gains: Venus's engine is more propellant-efficient than traditional alternatives, meaning more range and payload from the same tank of fuel. For defense and space customers, where every kilogram of propellant is a kilogram not spent on payload, that's not a marginal improvement,it's a different cost and performance curve entirely.
The idea of detonation-based propulsion isn't new; researchers have chased it for decades. What's new is the team in Houston of Venus Aerospace engineers who got it to fly.
The defense and space case for RDREs
The demand side of our investment is straightforward. The Pentagon has made next-generation propulsion a priority as it pursues hypersonic weapons and platforms, and the market has responded – Venus is one of several RDRE-focused companies to close funding recently, alongside startups like Stellar Alpina and Juno Propulsion. A few reasons the defense and space communities care specifically about this architecture:
- Range and payload, without new fuel. An efficiency gain lets a hypersonic vehicle or launch vehicle go farther or carry more, using the same propellant load, valuable for both strike systems and orbital transfer vehicles.
- Domestic, scalable manufacturing. The engine is built from additively manufactured (3D-printed) components using standard engineering materials, designed around established US supply chains rather than constrained or imported parts. That's directly relevant to a US defense industrial base trying to reduce foreign dependency.
- Space applications beyond weapons. The same efficiency gains apply to orbital transfer vehicles and, longer term, landers for the Moon and Mars, anywhere propellant mass is the limiting factor.
Why Venus, and why now
I first met Venus co-founder & CEO Sassie Duggleby at a YPO networking event in Houston a few years ago. I had been a fanboy of Venus from afar, and was very eager to talk with Sassie about her rocket company. When we met, she seemed to be as excited to meet me as I was to meet her. She half-joked about how Mercury had to become an investor in Venus. “It’s written in the stars…” she said, “and literally in our corporate names!”
The more I learned about Venus, especially their origin story, the more I wanted to invest - there was just one problem. Since the launch of Mercury Fund in 2013, we had been primarily a startup software investor. How could we possibly invest in a rocket startup?
Venus was founded in 2020 by Sassie and her husband, CTO Andrew Duggleby. They had spent their academic and professional careers in advanced manufacturing, new space (Virgin Galactic/Orbit), and the military/defense industry. As CTO, Andrew theorized then created models for a working RDRE. The rocket design, which had been theorized in academia for decades to greatly increase fuel economy in rockets, was only recently made practical by advances in additive manufacturing and AI-enabled design software. The more time I spent with Andrew digging into the core, enabling aspects of Venus, the more comfortable I became in making a venture investment in the company.
As CEO, Sassie set out to create a company and culture that every aerospace engineer would want to work for. A company that would help us traverse and protect the terrestrial earth while allowing for full discovery of what lies beyond. Over the last five and a half years, Venus has been capital-efficient in getting here. All this while Sassie and Andrew have created a modern-day Manhattan Project in Houston - talent from dozens of prime and new prime contractors and aerospace companies have descended upon the Houston Space Port to make Andrew’s propulsion vision a reality.
Mercury initially participated in an extension of Venus’ Series A round. I began to spend more and more time with the founders and team, becoming increasingly convinced with the company’s massive potential. In May 2025, Venus completed the first US test flight of a high-thrust RDRE, a 2,000 pound thrust engine launched aboard a test rocket from Spaceport America in New Mexico. That flight mattered because it moved RDRE technology out of the lab and off the whiteboard. Venus didn't just prove the physics works, they proved the engine can be built, integrated, and flown, with attention to manufacturability and scale from day one. That's a very different bar than a static test stand firing. After the company’s historic 2025 test flight, Lockheed Martin Ventures and Mercury Fund led a convertible bridge investment - before later coming back with Mercury leading the Series B.
In addition to its top-flight management team, Venus continued to add credibility to the organization: former NASA Deputy Administrator Pam Melroy recently joined the board, and the company has already built relationships with NASA and US defense agencies, including work with DARPA on engine testing.
The next chapter
The closing of Venus’ Series B isn't about proving the technology anymore – May 2025’s test flight did that. It's about the harder, less glamorous work of going from a flight-proven demonstrator to a production engine that can meet defense and space customers' delivery timelines: scaling manufacturing, hardening the design, and building out the commercial team to support near-term government and commercial contracts. Mercury believes Venus is positioned to lead this next chapter of rocket propulsion, and we're glad to be backing a team building breakthrough hardware (and software) right here in Texas.
