Impulse Space, the in-space transportation startup founded by former SpaceX propulsion chief Tom Mueller, has raised $500 million in Series D funding, more than doubling its total capital raised to over $1 billion and valuing the company at roughly $4 billion, according to Bloomberg.
The round was co-led by 137 Ventures and Banner VC. Impulse said the money will fund hiring and manufacturing as it scales what it calls "in-space mobility infrastructure" — the vehicles, propulsion, and operations that decide where and how a satellite goes after a rocket drops it off in orbit.
What Impulse actually does
Rockets are good at reaching low Earth orbit, but most satellites need to end up somewhere else — a higher orbit, a different plane, eventually the Moon. Today that "last mile" of space is slow and costly. Impulse builds the orbital tugs and kick stages that move spacecraft around once they're up there.
Its first vehicle, Mira, is a precision maneuvering spacecraft that has already flown three times aboard SpaceX Falcon 9 rockets, carrying up to 300 kilograms (about 660 pounds) of payload and performing record-setting orbit changes and autonomous rendezvous-and-proximity operations. Its more ambitious vehicle, Helios, is a high-energy "kick stage" set for a first flight in 2027 and powered by Impulse's Deneb engine. Helios is designed to rapidly ferry payloads from low Earth orbit out to medium and geostationary orbits — and on to lunar, heliocentric, and other planetary destinations — far faster than conventional transfers.
The Tom Mueller pedigree
Impulse's credibility rests heavily on its founder. Mueller was SpaceX's founding propulsion engineer and the architect of the Merlin engine that powers Falcon 9, the most-flown and most reliable orbital rocket in history. When he started Impulse in 2021, he bet that as launch costs fell and satellite counts exploded, the bottleneck would shift from getting to orbit to moving around once there.
In a market flooded with artificial-intelligence pitches, Impulse stands out for a hardware-first message: the raise, as its founder framed it, is about hiring people and building engines — not chasing an AI narrative. That's a pointed contrast in a venture environment where AI has dominated the flow of capital.
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Why space logistics is suddenly investable
Three forces are converging. First, launch is cheap and frequent: SpaceX has been launching roughly every couple of days and is expanding to overseas launch sites to push cadence higher, flooding orbit with satellites that need to maneuver. Second, defense and national-security customers want to reposition assets quickly in orbit, a capability with obvious strategic value. Third, the early lunar economy needs reliable ways to push cargo beyond Earth orbit.
The capital pouring into space mirrors the broader market's appetite for "picks and shovels" — the infrastructure layer beneath a boom. Just as SpaceX prepares for what could be the largest IPO ever, investors are betting that the companies building the road network of space — not just the rockets — will capture durable value.
Why it matters to you
In-space mobility sounds esoteric, but it underpins the satellites that deliver internet, GPS, weather data, and Earth imaging that daily life increasingly depends on. Cheaper, faster orbital transport means more capable satellite constellations deployed more flexibly — and, on the security side, a more contested orbital environment. Impulse's $4 billion valuation marks the space economy maturing from "launch" into a full logistics network, much as the early internet matured from connectivity into infrastructure.
Bottom line
Impulse Space raised $500 million at roughly $4 billion to build the orbital tugs and kick stages that move spacecraft after launch. Led by the engineer who built Falcon 9's engine, it's a hardware-first bet that the next big space business isn't getting to orbit , it's everything that happens once you're there.
Frequently Asked Questions
What is "in-space mobility"? It's the transport layer of space: tugs, kick stages, and propulsion that move a satellite from where a rocket drops it to its final orbit — or beyond, toward the Moon and other destinations.
Who founded Impulse Space? Tom Mueller, SpaceX's founding propulsion engineer and the designer of the Merlin engine that powers Falcon 9. He started Impulse in 2021.
How much did Impulse raise and at what valuation? $500 million in Series D, co-led by 137 Ventures and Banner VC, at roughly a $4 billion valuation — bringing total funding past $1 billion.
What are Mira and Helios? Mira is Impulse's maneuvering spacecraft, already flown three times on Falcon 9. Helios is a high-energy kick stage, first flight targeted for 2027, designed to move payloads quickly to high orbits and beyond.
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