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Impulse Space funding, valuation and investors
Tom Mueller's in-space mobility company — Mira maneuvering spacecraft and Helios kick stage for orbital transfer.
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Funding, valuation & investors
Answer-first snapshotLatest funding
Series D extension
$308M · September 2026
Latest known valuation
$5.6B (Reuters source; company omitted)
Series D extension · September 2026
Total disclosed equity funding
$1.1B
Excludes debt, grants, acquisitions, secondaries, and IPO proceeds.
Current status
private
growth · Redondo Beach, California
Investors in latest funding
Other: 137 Ventures , BANNER VC , Lux Capital , Valor Equity Partners , DFJ Growth , Linse Capital
Overview
Impulse Space is a Redondo Beach, California company founded in 2021 by Tom Mueller — SpaceX's first employee and chief architect of the Merlin and Draco engines — to solve in-space transportation after launch. The company builds flight-proven Mira agile spacecraft for precision orbital maneuvering and the Helios high-energy kick stage for rapid transfer from LEO to GEO and beyond. June 2026 Series D was $500 million co-led by 137 Ventures and BANNER VC (Reuters $4.26 billion, person familiar), taking lifetime capital past $1 billion. On September 16, 2026 Impulse added a $308 million Series D extension from existing investors including Lux Capital, taking the combined D to $808 million. The company omitted the new mark; Reuters printed $5.6 billion from a source close to the company. Founders Fund and Lux Capital participated in the June close. Impulse has flown Mira missions on SpaceX Transporter rideshares and says Helios is the first upper-stage prime on U.S. Space Force NSSL Phase 3 Lane 1.
Why Impulse Space is interesting
On September 16, 2026 Impulse added $308 million to Series D, taking the combined round to $808 million. The company omitted a mark; Reuters, citing a source, printed $5.6 billion versus $4.26 billion on the June $500 million close.
Product & use cases
Two core vehicles: Mira (high-thrust maneuverable spacecraft with eight Saiph nitrous-based thrusters for hosting, deployment, and repositioning) and Helios (kick stage with Deneb LOX/methane engine delivering up to 4–5 tons from LEO to GEO in same-day timelines). Vertically integrated propulsion and composite tanks.
- Last-mile orbital delivery after rideshare launch to precise slots
- GEO transfer for communications satellites (SES multi-launch agreement)
- Defense and national-security orbital maneuvering and servicing
- Deorbit and space-traffic management for constellation operators
Key facts
- Series D extension (Sep 16, 2026): $308M; combined D $808M — company. $5.6B is Reuters source, not a company print
- Series D (June 2026): $500M co-led by 137 Ventures and BANNER VC — total funding then $1B+
- Founder Tom Mueller was SpaceX employee #1 and Merlin/Draco engine lead
- Mira flight-proven on SpaceX Transporter-9; Helios first flight targeted 2026–2027
- SES multi-launch agreement to lift four-ton satellites from LEO to GEO via Helios
- Named U.S. Space Force National Security Launch Program provider (2026)
Funding history (newest first)
Series D extension
2026-09 $308M Valuation: $5.6B (Reuters source; company omitted)- 137 Ventures (participant)
- BANNER VC (participant)
- Lux Capital (participant)
- Valor Equity Partners (participant)
- DFJ Growth (participant)
- Linse Capital (participant)
Source: Read source · impulsespace.com
Series D
2026-06 $500M Valuation: $4.26B (Reuters, person familiar)- 137 Ventures (lead)
- BANNER VC (lead)
- Founders Fund (participant)
- Lux Capital (participant)
- Linse Capital (participant)
Source: Read source · impulsespace.com
Competitive landscape
Edge: Tom Mueller's propulsion pedigree plus flight-proven Mira platform — team designed the most reliable rocket engines in history and applies same vertical-integration philosophy to in-space mobility.
Falling launch costs create demand for everything that happens after orbit insertion. Impulse targets the 'plumbing' layer — less glamorous than launch but essential as constellations and defense payloads multiply. Mueller's track record and $1B+ raised give credibility competitors in in-space mobility lack.
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Momentus direct
In-space transportation via Vigoride; faced operational setbacks while Impulse achieved larger orbital maneuvers.
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Rocket Lab (space systems) adjacent
Launch plus Photon kick stage; Impulse focuses purely on post-launch mobility at larger delta-v.
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SpaceX (internal transfer) adjacent
SpaceX could extend Starship or dedicated tugs; Impulse bets specialized in-space vehicles win the logistics layer.
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Astroscale adjacent
Orbital servicing and debris removal; overlaps on maneuvering but different primary mission (servicing vs. transport).
Notable stories
- Tom Mueller founded Impulse because 'launch mostly being solved' — the next opportunity is moving payload and cargo around in space, extending to lunar landers (Sourcery VC tour, 2026).
- Impulse's Mira performed two of the largest orbital maneuvers ever by a nitrous-based propulsion system — validating Mueller's bet on non-toxic, high-thrust Saiph thrusters.
Market / IPO context
Editorial / static context — not a live quote.
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