---
title: "Impulse Space’s $308M Series D Extension: Combined Round $808M"
description: "Impulse Space added $308 million to its Series D on September 16, 2026, taking the combined round to $808 million. The company did not print a new mark. Reuters, citing a source close to the company, put the extension at $5.6 billion versus $4.26 billion on the June $500 million close."
date: 2026-09-17T00:00:00.000Z
source: https://venturecapitaltracker.com/2026-impulse-space-308m-series-d-extension-808m
---

# Impulse Space’s $308M Series D Extension: Combined Round $808M

> Impulse Space added $308 million to its Series D on September 16, 2026, taking the combined round to $808 million. The company did not print a new mark. Reuters, citing a source close to the company, put the extension at $5.6 billion versus $4.26 billion on the June $500 million close.

**[Impulse Space](/startup/impulse-space)** added **$308 million** to its Series D on **September 16, 2026**, taking the **combined round to $808 million**. The company named returning checks from **137 Ventures**, **BANNER VC**, **DFJ Growth**, **Linse Capital**, **[Lux Capital](/fund/lux-capital)**, and **Valor Equity Partners**. It **did not** print a valuation. Reuters, citing a source close to the company, put the extension at **$5.6 billion** — against **$4.26 billion** on the June **$500 million** close, also Reuters and a person familiar. Last verified **September 17, 2026**. Sources: [company](https://www.impulsespace.com/updates/impulse-space-announces-308-million-series-d-extension-to-meet-increasing-demand-for-in-space-mobility), [Reuters Sep 16](https://www.reuters.com/legal/transactional/impulse-spaces-series-d-round-grows-808-million-backlog-expands-2026-09-16/), [Reuters June 2](https://www.reuters.com/business/autos-transportation/impulse-space-raises-500-million-426-billion-valuation-space-investing-surges-2026-06-02/).

Three months after a $500 million D that already pushed lifetime capital past **$1 billion**, Impulse stacked another $308 million from the same book — and still refused to put a mark in the release.

## Five-minute decision

| If you need… | Verdict |
| --- | --- |
| What happened | **Extension closed.** $308M added to Series D. Combined D = **$808M**. |
| New letter? | **No.** Not Series E. |
| Company valuation | **Not disclosed.** |
| Press mark | Reuters source **$5.6B** now vs **$4.26B** in June. Same reporter pattern. |
| Lifetime total | June post said **$1B+** after the $500M. This release **does not** restate lifetime. Do not invent $1.3B. |
| Directory funds | [Lux](/fund/lux-capital) and [Founders Fund](/fund/founders-fund) (June D). |

**Investigate further when:** you underwrite post-launch mobility against named Space Force / SSC awards.

**Wait or pass when:** you treat **$808M** as incremental new capital, or **$5.6B** as a company print.

## What the company did disclose

| Field | Detail |
| --- | --- |
| Company | [Impulse Space](/startup/impulse-space) — Redondo Beach. Founder/CEO Tom Mueller. Site: [impulsespace.com](https://www.impulsespace.com). |
| Financing | **$308M** Series D **extension** · combined D **$808M** · Sep 16, 2026 |
| Investors (named, existing) | 137 Ventures, BANNER VC, DFJ Growth, Linse Capital, [Lux](/fund/lux-capital), Valor Equity Partners, “among others” |
| Use | Product development, team, facilities. Headcount **more than doubled** over the past year (company; no absolute count here). |
| Vehicles | Mira (maneuvering), Helios (kick stage), Caravan (rideshare), **Electra** electric propulsion (unveiled; not a new close). |
| Government | Helios selected for U.S. Space Force **NSSL Phase 3 Lane 1** — company says first upper-stage prime on that lane. **$28M** Space Systems Command Space Safari extension for **VICTUS SALO 2 and 3**. |
| Finance hire | First CFO: **Adam Townsend**, from VIZIO (IPO and Walmart sale). |

June D was co-led by 137 and BANNER; [Founders Fund](/fund/founders-fund) and Lux participated. This extension lists 137 and BANNER as **participants**, not as fresh leads. Do not rewrite June as superseded.

## $500M vs $308M vs $808M

| | [June D](/2026-impulse-space-500m-series-d-propulsion) | This extension |
| --- | --- | --- |
| Date | Jun 2–3, 2026 | Sep 16, 2026 |
| Amount | **$500M** | **$308M** added |
| Combined D | $500M | **$808M** |
| Company mark | Omitted | Omitted |
| Reuters mark | **$4.26B** (person familiar) | **$5.6B** (source close to the company) |
| Lead language | 137 + BANNER **co-led** | Existing investors **participated** |

If both Reuters figures are right, the mark moved about **$1.3 billion** in 15 weeks while the company added **$308 million**. That is a press-source path, not a cap table. The company still has not printed either number.

Space tape this month: [Stoke](/startup/stoke-space) **~$1B** Series E ([memo](/2026-stoke-space-1b-series-e-point72-spark)); [The Exploration Company](/startup/the-exploration-company) **$450M** C; [Pixxel](/startup/pixxel) **$100M** C. Those are launch, capsule, and Earth-observation books. Impulse is **after insertion**.

## What remains undisclosed

No company valuation. No lifetime restatement. No new-vs-existing dollar split. No backlog dollar figure. No ARR or revenue. Headcount is a **rate**, not a count. NSSL Lane 1 and the $28M SSC extension are **awards the company named**, not independently priced here.

June history: [Impulse $500M Series D](/2026-impulse-space-500m-series-d-propulsion). Day index: [September 16–17](/2026-september-16-17-investment-news-impulse-bcv-portage).

**By:** [Venture Capital Tracker](https://venturecapitaltracker.com/editorial-policy)
**Last updated:** September 17, 2026

**Editorial note:** AI tools assisted with research, structure, or drafting. Venture Capital Tracker retains human editorial responsibility for factual accuracy, relevance, and source quality before publication.