$1 billion. That's how much Impulse Space has raised since Tom Mueller left SpaceX's engine bay to build something the orbital economy didn't know it needed: a mobility layer.
Its Mira orbital transfer vehicle has flown three missions, proving that post-launch mobility is a commercially viable category.
The company now holds hundreds of millions in government and commercial contracts, from the U.S. Space Force to SES and NASA.
From rocket engines to space tugs
Mueller was SpaceX's first employee and the propulsion architect behind the Merlin and Raptor engines, the hardware that powers every Falcon 9 and every Starship. In 2021 he left to start the company. The thesis was simple: launch was solved. Everything after launch was not.
Most satellites spend weeks or months maneuvering themselves into final position after separation. Some burn propellant they could have used for station-keeping. Others never reach their optimal orbit at all. Impulse builds vehicles that solve this: spacecraft that move other spacecraft.
TIMELINE: Impulse Space
─────────────────────────────────────────────────────────────
2021 ──── 2023 ──── 2024 ──── 2025 ──── 2026
🚀 🛰️ 💰 💰 ◉ NOW
Founded Mira LEO Series B Series C Series D
by Tom Express-1 $150M $300M $500M
Mueller launches ($1B total)
Company funding and milestones, 2021–2026
The company announced the Series D on June 2, 2026, co-led by 137 Ventures and BANNER VC with participation from Founders Fund, Lux Capital, and Linse Capital. Total capital raised now exceeds $1 billion.
Mira and Helios: the vehicles
Impulse operates two spacecraft families. Mira is a maneuverable orbital transfer vehicle roughly the size of a dishwasher, weighing around 300 kilograms when fully loaded with propellant. It has flown three missions since November 2023, deploying payloads and demonstrating responsive maneuvers in low Earth orbit. An upgraded version, announced in August 2025, adds radiation-tolerant avionics, more powerful solar arrays, and a 25 percent increase in delta-V, enough to operate in geostationary orbit.
Helios is larger. A high-energy kick stage designed to move payloads from LEO to GEO in under 24 hours, it can lift over 5 tons. Its Deneb engine is the most efficient hydrocarbon engine ever built, according to the company. First flight is scheduled for late 2026.
Impulse funding trajectory
From $525M after Series C (June 2025) to over $1B after Series D (June 2026). The company raised nearly as much in one round as it had in its entire history. · Impulse Space, June 2026
Customers and contracts
Impulse has signed over 30 contracts worth nearly $200 million. The customer list spans commercial, civil, and defense domains.
The U.S. Space Force awarded Impulse two tactical missions under the Tactically Responsive Launch program: Victus Surgo and Victus Salo. The two missions are worth a combined $34.5 million. The former will use Helios to deliver Mira to geostationary orbit; the latter operates in LEO with a payload from MIT Lincoln Laboratory.
SES signed a multi-launch agreement to use Impulse vehicles for moving communications satellites from LEO to GEO in under eight hours. NASA selected Impulse for orbital transfer vehicle studies under its VADR contract. The company also partnered with HEO for non-Earth imaging and with Orbit Fab for in-orbit refueling demonstrations.
In-space mobility: the competition
Key differentiator: Three flown Mira missions provide flight heritage that competitors at similar funding levels cannot match.
The market for in-space mobility
In-space mobility sits at the intersection of two growing markets. The orbital transfer vehicle segment, still in its infancy, is projected to reach $2.8 billion by 2032 according to industry analysts. The broader on-orbit servicing market, which includes life extension, refueling, and debris removal, adds another $5 billion by the same horizon.
The demand driver is simple: mega-constellations. SpaceX has launched over 7,000 Starlink satellites. Amazon's Project Kuiper, the Chinese megaconstellation Qianfan, and the European IRIS2 program will add tens of thousands more over the next decade. All of these satellites need to reach precise orbits, station-keep, and eventually deorbit. When each satellite maneuvers on its own, the approach becomes inefficient and risky at scale.
Impulse's value proposition rests on aggregating that mobility. Instead of every satellite carrying its own propulsion and fuel for orbital adjustments, a dedicated transfer vehicle can handle the movement for many payloads at once. The economics improve with volume, and Impulse's production scaling plans, from 8 vehicles per year toward 40, suggest the company is betting on exactly that math.
What the $1B milestone means
Impulse's trajectory mirrors a broader shift in the space economy. Investor capital is moving from launch vehicles, where SpaceX has established an insurmountable cost advantage, to the infrastructure layer that operates after launch. In-space mobility, on-orbit servicing, and orbital data centers are the categories attracting the largest rounds in 2025 and 2026.
The $8.17 billion in space venture funding recorded in 2025, more than double the 2024 total, was concentrated in late-stage rounds for companies with demonstrable hardware and revenue. Impulse fits that profile. So do Stoke Space, Vast, and Axiom Space. The era of PowerPoint-based space startups is over.
"We're building more than spacecraft," Mueller said in the Series D announcement. "We're building the economic and technical engine that will power humanity's expansion into space."
For Impulse, the next test is execution. The company must scale production from its current rate to meet a growing backlog, launch Helios for the first time, and convert its government contracts into recurring revenue. The $500 million gives it the runway to try.