Impulse Space is an in-space transportation company founded by former SpaceX propulsion chief Tom Mueller, building the spacecraft and engines that move satellites and payloads around once a rocket has dropped them in orbit. Based in Redondo Beach, California, it raised $500 million in a Series D round at a valuation of about $4.26 billion in 2026, pushing total capital raised past $1 billion.
The last mile of space
For most of the space age, the hardest and most expensive part of any mission was getting off the ground. The rise of reusable rockets has steadily driven launch costs down and, in doing so, exposed a different problem: once a rocket drops a payload at a single point in space, that object often cannot move quickly, precisely, or affordably to where it actually needs to go.
Impulse is built around closing that gap, which it frames as the "last mile" of the space economy. Its spacecraft act as orbital tugs and transfer vehicles, ferrying payloads from the orbit where a launch vehicle drops them to a final destination, whether a different altitude, a different orbital plane, or eventually the vicinity of the Moon. As more satellites launch on shared rides to cut costs, the need for vehicles that can reposition them afterward grows in step.
A growing fleet
The company has flown multiple missions of Mira, a maneuvering spacecraft for agile repositioning in low Earth orbit, and is developing Helios, a high-energy kick stage to carry heavier payloads to higher orbits such as geostationary. It is building a family of engines including the Saiph thruster, the Deneb engine, and a throttleable system called Rigel aimed at responsive maneuvers and potential lander applications.
The Series D was co-led by 137 Ventures and Banner VC, with participation from Founders Fund, Lux Capital, and Linse Capital. Impulse said it would use the money to expand manufacturing capacity and grow its workforce as it scales production.
Why investors are leaning in
The round is part of a broader surge of capital into space and defense startups. Demand for in-space logistics is rising alongside the number of satellites being launched, and the same maneuvering technology that serves commercial customers is increasingly relevant to national security buyers who want to move assets in orbit on short notice.
Mueller's track record gives the company unusual credibility. As one of SpaceX's earliest employees and the engineer behind its Merlin engines, he carries a reputation for building hardware that works, which helps explain why Impulse has raised so much capital so quickly for a business still early in its commercial arc. The risk worth naming is that operating a fleet of orbital vehicles is technically demanding and much near-term demand may depend on government contracts.
Frequently asked questions
What does Impulse Space do?
Impulse Space builds in-space transportation. Its spacecraft act as orbital tugs and transfer vehicles, moving satellites and payloads from where a launch vehicle drops them to their final orbital destinations, what it calls the "last mile" of the space economy.
How much did Impulse Space raise?
It raised $500 million in a Series D round at a valuation of about $4.26 billion, co-led by 137 Ventures and Banner VC, bringing total capital raised past $1 billion.
Who founded Impulse Space?
It was founded by Tom Mueller, a former propulsion chief and early employee at SpaceX who led development of the Merlin engines powering SpaceX's Falcon rockets.
What vehicles does Impulse Space build?
It has flown its Mira spacecraft for low Earth orbit maneuvering and is developing the Helios kick stage for higher orbits, supported by a family of engines including Saiph, Deneb, and Rigel.
Why is investment in space startups rising?
Falling launch costs have increased the number of satellites in orbit, raising demand for in-space logistics, while national security buyers want the ability to maneuver assets in space, benefiting companies like Impulse.