Impulse Space has secured a $308 million extension to its Series D funding round, bringing the total round value to $808 million. The in-space mobility company announced the new capital injection following a $500 million initial raise in June, which valued the firm at $4.26 billion. According to a source close to the company speaking with Reuters, the valuation for this latest extension has climbed to $5.4 billion.

What Happened

The extension round attracted several returning investors, including 137 Ventures, BANNER VC, DFJ Growth, Linse Capital, Lux Capital, and Valor Equity Partners. Impulse founder and CEO Tom Mueller stated that the additional funding reflects demand from both customers and investors, citing momentum across the business. The company plans to allocate the majority of the new funds toward hiring and manufacturing to support its vehicle fleet, which includes the Mira maneuvering vehicles, the Helios kick stage, and the Electra electric propulsion system.

Impulse reported that two flight-proven Mira vehicles, LEO-2 and LEO-3, recently flew within approximately 200 meters of each other. The company is preparing for LEO Express 4, the fourth flight of the Mira system. Meanwhile, the Helios high-energy kick stage, designed to move payloads from Low Earth Orbit to Geostationary Earth Orbit in under a day, is slated for its first launch in 2027. Impulse noted that its Caravan 2 and 3 Helios rideshare missions for 2028 are already sold out.

Why It Matters

The capital raise underscores growing commercial and government interest in in-space mobility solutions. Impulse’s recent contracts highlight its expanding role in the national security sector. In July, Space Systems Command (SSC) awarded Impulse an NSSL Phase 1 Lane 1 contract, making it the program’s first upper-stage prime. Additionally, SSC’s Space Safari Office granted Impulse a $28 million SBIR Phase III contract extension in August to support VICTUS SALO 2 and 3 missions. Earlier in May, Anduril selected Impulse as a partner for its Space Force space-based interceptor award.

To manage this growth, Impulse has hired Adam Townsend as its first Chief Financial Officer. Townsend previously served as CFO and head of HR operations at smart TV company VIZIO. Mueller emphasized that the company is focused on executing for customers and meeting demand, with Helios production ramping up alongside Mira, which currently has about half a dozen units in the factory.

The Bottom Line

Impulse Space’s $308 million Series D extension brings its total round to $808 million and its valuation to $5.4 billion. The funds will accelerate the production of its Mira and Helios vehicles, supporting a pipeline of commercial missions for clients like Astranis and SES, as well as significant national security contracts with the U.S. Space Force.