Impulse Space, a US company that builds vehicles to move spacecraft around once they are in orbit, raised a $308m extension to its Series D round, it said on 16 September 2026. The addition brings the Series D to $808m in total.
The extension was funded by existing investors, among them 137 Ventures, BANNER VC, DFJ Growth, Linse Capital, Lux Capital and Valor Equity Partners. No lead investor was named for the new tranche.
Impulse did not disclose a valuation. Payload, citing Reuters and a source close to the company, reported that the extension valued Impulse at about $5.4bn, up from the $4.26bn valuation attached to the $500m first part of the Series D announced in June.
“This continued support from our investors strengthens our ability to build the systems that will unlock the space economy.”Eric Romo, President and COO, Impulse Space
What Impulse Space does
Impulse, which is led by founder and chief executive Tom Mueller, describes itself as an in-space mobility company. Its vehicles take payloads from the orbit where a rocket drops them to the orbit where they need to operate, a job that launch providers do not always handle.
Its product line includes Mira, a manoeuvring spacecraft; Helios, a high-energy kick stage designed to carry payloads from low Earth orbit to geostationary orbit; and Caravan, a rideshare programme. According to Payload, two flight-proven Mira vehicles recently flew within about 200 metres of each other, and Helios is scheduled to launch for the first time in 2027. The company has also unveiled Electra, an electric propulsion system intended to work alongside its chemical engines.
Law firm Fenwick, which advised Impulse on the deal, said it had represented the company since its incorporation in 2021. The company is based in Redondo Beach, California, according to Exterra.
Government contracts and a growing backlog
The extension followed a run of US government work. Helios was selected for the US Space Force's National Security Space Launch Phase 3 Lane 1 programme, which the company said made it the first upper-stage prime contractor in the programme. Impulse also received a $28m contract extension from Space Systems Command for the VICTUS SALO 2 and 3 missions, building on earlier Mira awards.
Payload reported that the company's Caravan 2 and 3 Helios rideshare missions for 2028 had sold out, and that Helios is due to fly dedicated missions for satellite operators Astranis and SES. Payload also reported that Anduril picked Impulse in May as a partner on a Space Force space-based interceptor award.
Eric Romo, Impulse's president and chief operating officer, said the company had more than doubled its headcount over the past year and expanded its footprint across the US. It did not give a total number of employees.
What the money is for
Impulse said the new capital would go to product development and growing its team as it serves commercial, civil and government customers. Payload reported that most of the money would be spent on hiring and manufacturing, including increasing production of Mira and Helios.
The company also hired its first chief financial officer, Adam Townsend, who previously held the same role at television maker Vizio.
Company website: impulsespace.com