- Impulse Space has raised $500 million in a Series D co-led by 137 Ventures and BANNER VC, bringing total funding to over $1 billion.
- The round values the company at $4.26 billion — and comes just one year after its $300 million Series C, signalling sharply accelerating investor conviction in post-launch orbital infrastructure.
- With three missions flown, hundreds of millions in customer contracts, and 200+ open roles, Impulse is the only well-capitalised private company building chemical propulsion spacecraft purpose-designed for rapid orbit changes at scale.
For two decades, Tom Mueller built the rocket engines that got things into orbit — the Merlin that powers every Falcon 9 and the Raptor that powers Starship. He was SpaceX’s first employee, recruited by Elon Musk in 2002 after Musk found him test-firing a 13,000-pound-thrust engine he had built in his garage. Now Mueller has turned his attention to the problem that comes after launch: what happens when your spacecraft is in the wrong orbit, or needs to move.
Redondo Beach, California-based Impulse Space has raised $500 million in a Series D co-led by 137 Ventures — the San Francisco growth firm that has backed SpaceX across roughly two dozen rounds since 2010 and recently closed $700 million in new funds — and BANNER VC, with additional participation from returning investors Founder’s Fund, Lux Capital, and Linse Capital. The round values Impulse at $4.26 billion post-money. Total funding now exceeds $1 billion, following a $300 million Series C led by Linse Capital just one year ago.
Tom Mueller founded Impulse Space in September 2021 after retiring from SpaceX, where he served as CTO of Propulsion and led the development of the Merlin, Kestrel, Draco, SuperDraco, and early Raptor engines. Before SpaceX, Mueller spent 15 years at TRW as lead engineer on the TR-106 engine and rose to Vice President of Propulsion. He holds a BS and MS in Mechanical Engineering from the University of Idaho and Loyola Marymount University respectively. Impulse is headquartered in Redondo Beach, California, with additional facilities in Boulder, Washington D.C., and a test environment in Mojave. The company has more than doubled headcount over the past year and currently has over 200 open roles across propulsion, avionics, autonomy, and manufacturing.
The problem Impulse is solving
Launch has been solved — or at least dramatically improved. SpaceX’s Falcon 9 launches dozens of times per year at costs that would have seemed impossible a decade ago. But getting to orbit is only the first step. Once there, spacecraft have historically had little ability to move: changing orbits is slow, expensive, and often impossible with onboard propulsion alone. Most satellites are locked into the orbit their rocket delivers them to, or face months-long transfers to reach their intended destination.
Impulse builds spacecraft specifically designed to fix this. Its Mira precision maneuvering vehicle has flown multiple missions, executing record-setting orbit changes and autonomous rendezvous and proximity operations. The company has also been named as a collaborator on Anduril Industries’ team to prototype technologies for space-based interceptors — a government contract that underscores the dual-use demand for rapid in-space mobility. Helios, a high-energy kick stage scheduled for first flight in 2027, targets rapid delivery to GEO, lunar, and heliocentric orbits. The Caravan rideshare programme reduces the cost of access to higher-energy destinations by pooling payloads.
In their own words
“We’re building more than spacecraft: we’re building the economic and technical engine that will power humanity’s expansion into space. From Earth orbit to the Moon and beyond, the ability to move quickly, precisely, and affordably on orbit is the fundamental capability that will unlock a true space age.” — Tom Mueller, founder and CEO, Impulse Space.
“Tom helped transform access to space at SpaceX, and now he’s tackling the industry’s next major challenge: in-space mobility. Mobility in space is strategic and will define the next phase of the space economy, and Impulse is building the infrastructure to make that possible.” — Justin Fishner-Wolfson, Managing Partner, 137 Ventures.
The investors
137 Ventures, which recently closed $700 million in new funds and now manages over $15 billion in AUM, has previously backed SpaceX, Anduril, Cognition AI, Hadrian, Ramp, and Gusto. Founder’s Fund, Peter Thiel’s vehicle which led Impulse’s original seed round in 2022, returns here alongside Lux Capital and Linse Capital. BANNER VC joins as a new investor. The continuity of backing from Founder’s Fund across every round — from the $20 million seed to this $500 million Series D — is an unusually strong signal of inside conviction.
The competitive landscape
Impulse’s closest direct peer in the US is Momentus, a publicly traded in-space transportation company that uses microwave-electrothermal propulsion. Momentus generated just $1.1 million in revenue in 2025 and forecasts $10 million for 2026 — a fraction of Impulse’s “hundreds of millions in customer contracts.” The technical difference is meaningful: Momentus uses electric propulsion, which is fuel-efficient but slow; Impulse uses chemical propulsion, which is fast but consumes more propellant. For time-sensitive government and defence missions, speed wins. D-Orbit, the Italian in-space logistics company that has raised $408 million and operates the ION Satellite Carrier, focuses on LEO deployment services and operates primarily on ion propulsion. Astroscale, the Japanese on-orbit servicing company that has partnered with NASA and ESA, focuses on debris removal and satellite life extension rather than rapid orbital transport. None of these companies flies chemical propulsion spacecraft at the scale and with the mission complexity that Impulse has already demonstrated.
Market context
According to Research and Markets, the in-space manufacturing, servicing, and transportation market was valued at $2.18 billion in 2025 and is projected to reach $5.23 billion by 2030, growing at a CAGR of 19.1%. That figure likely understates actual demand: as satellite constellations scale and government defence spending in space grows, the market for rapid orbital repositioning is structurally linked to some of the largest budget lines in aerospace.
The deeper question is not whether Impulse can move spacecraft faster and cheaper than its competitors. Three missions and hundreds of millions in contracts already answer that. The question is whether the commercial space economy — with its recurring launch cadence, growing constellation density, and newly urgent defence requirements — will scale fast enough to justify the $1 billion in capital Impulse has now absorbed, before the next generation of launch vehicles makes some of those transfers cheaper to do at the point of launch itself.
