Scaling Nova

Today, we’re announcing our $1 billion Series E round of financing to accelerate the development and scaling of Nova, our family of fully and rapidly reusable launch vehicles. This milestone reflects years of extraordinary work by the Stoke team, as well as the conviction of our customers and investors who share our belief that fully and rapidly reusable space transportation is both possible and necessary. We are deeply grateful for their trust, and more energized than ever by the work ahead.

Nova Pathfinder, our first orbital configuration, is moving quickly through integration and qualification, and it remains on track for first flight in the first part of 2027. Pathfinder is designed to reach orbit, demonstrate the technologies needed for full reuse, give our team operating experience, and carry real customer payloads during a period of significant launch shortage.

Today we are also sharing details of Nova Block 2 publicly for the first time. Nova Block 2 is a larger configuration that our team has been developing in parallel for the past several years. Block 2 delivers 15 metric tons to low Earth orbit (LEO) in a fully reusable configuration, while carrying forward the propulsion, manufacturing, reentry, and operating principles that Pathfinder demonstrates.

State of play

The launch market is limping through a period of sustained and unmet demand. The space economy can only scale as fast as rockets can fly, and over the last few years the availability of launch for independent commercial parties has been stagnant while demand has exploded. As a result prices are rising, not falling, and availability is as scarce as ever. Commercial satellite companies are already struggling to secure capacity within this decade, and recent reporting suggests availability beyond 2028 may tighten further.

The demand extends well beyond the current shortage. Satellite systems increasingly operate as constellations that require continuous deployment and replenishment. National security architectures are moving toward proliferated systems for communications, missile warning, tracking, and intelligence collection. Commercial constellations are also being planned at a scale that would have sounded unrealistic only a few years ago.

For years, our commercial team has been hearing the same message from satellite operators: the constellations being planned for the end of the decade would require far more independent launch capacity in a larger payload class. Those customer conversations, together with the technical work already underway, helped shape Block 2’s capabilities, capacity, and schedule. At 15 metric tons to LEO in a fully reusable configuration, Nova Block 2 can deploy and replenish constellations in bulk, often one orbital plane at a time, while giving customers greater control over schedule and destination.

Capacity per flight is one variable in the equation; flight frequency is the other. It’s not enough to just get to orbit. The vehicles of tomorrow need to fly again and again with aircraft-like frequency to meet the ambition of the industry. Nova Block 2 is designed with this in mind.

Getting there: what Pathfinder is built to do

Pathfinder is Nova’s first orbital flight configuration. We designed it to get the hardest rapid reuse technologies into an integrated flight vehicle as early as possible, to give our team real operating experience, and to serve an important segment of the market. Pathfinder is unusually ambitious. In addition to being designed for full & rapid reuse, it is the largest first rocket undertaken by a U.S. launch company, exceeding the initial vehicles developed by today’s incumbents and newer entrants alike. When we started Stoke, we could see the need for a larger rocket, but we also knew that the first vehicle had to be one our team could credibly build, test, and fly. Pathfinder was our answer: large enough to prove the architecture and serve real missions, while remaining executable for a young company with finite people, capital, and time.

A good example is Zenith, our Stage 1 engine. Zenith is a full-flow staged combustion (FFSC) engine fueled by liquefied natural gas (LNG) and liquid oxygen (LOX). FFSC is perhaps the most difficult rocket engine cycle to develop, particularly through startup, shutdown, and deep throttling. We chose it because it is the right engine cycle for a fully and rapidly reusable booster. In FFSC, all of the propellant passes through the turbomachinery before reaching the main combustion chamber. Because the work is spread across the full fuel and oxidizer flow, the turbines can produce the required power at comparatively lower temperatures and pressure ratios than in other high-performance engine cycles. That gives FFSC the highest-possible performance while minimizing the thermal and mechanical stress placed on critical components during every flight.

Lower component stress means less wear, fewer inspections, less frequent cleaning, and longer life. LNG also burns cleaner and leaves fewer residuals than kerosene, which reduces soot deposits within the engine and eliminates the need for cleaning cycles after tests or flights. Those operating conditions matter when an engine is expected to fly many times. The development problem may be harder, but it gives us an engine designed around the economics and operating tempo of rapid reuse. Pathfinder flies with seven Zenith engines, while the larger Nova will fly with fourteen. The Zenith architecture flying on Pathfinder is the same architecture on the larger vehicle, so every Zenith engine we build, test, qualify, and fly on Pathfinder directly advances the Block 2 program. This allowed us to begin developing the production system and operational history for Zenith several years before the larger vehicle reaches the pad.

The tanks and primary structures follow a similar path. Both vehicles use stainless steel skin-and-stringer construction, and the methods Pathfinder establishes to design, analyze, build, and test large flight structures carry directly into Block 2. This approach requires almost no fixed tooling, allowing us to iterate quickly and increase production as the vehicle scales. Nova Block 2 has moderately increased dimensions without requiring us to replace the underlying design and manufacturing system. It took an enormous effort from our design and manufacturing teams in order to write that sentence.

The larger vehicle also remains sized for over-the-road transportation. That was an important constraint from the beginning. It allows us to move major vehicle elements among manufacturing, testing, and launch facilities without depending on barges and the Panama Canal. This simplifies operations, reduces deployment time (and cost), and gives us more flexibility in how the production system grows.

Nova Pathfinder and Block 2 carry forward the same propulsion, manufacturing, reuse, and operating principles. Pathfinder gives us an opportunity to build flight experience and continue to make iterative improvements to the operational system. Block 2 allows us to serve an important and growing segment of the market.

Evolving the Andromeda engine

Rapidly reusable orbital vehicles must manage the intense heat of reentry without requiring a refurbishment process that limits cadence. The traditional approach of using a passive ceramic tile heat shield is subject to catastrophic failure, which creates many individual failure points that must be inspected and refurbished between flights. By contrast, industry has (for decades) protected the inside of rocket engines by actively cooling the metallic surface. The intensity of the heating inside a rocket engine can be twenty times higher than the heating experienced during reentry. Active cooling has proven to be a robust and resilient solution under the severe thermal conditions inside rocket engines.

On Nova, we extend this proven approach to the reentry thermal protection system (TPS), which is embedded within the upper stage engine. Thrust chambers are distributed circumferentially around and integrated into an actively cooled metallic base heat shield (BHS). Liquid hydrogen, which is already carried onboard as fuel, also is used as a coolant by flowing through the BHS to absorb heat during reentry. Pathfinder development has strengthened our conviction that this architecture is well suited to an upper stage intended to return to Earth, fly again rapidly with limited inspection and refurbishment, and live a long service life.

To that end, the Block 2 upper stage engine (Andromeda Block 2) will look familiar. It retains 24 hydrogen thrust chambers arranged circumferentially around and embedded within the actively cooled BHS, but the internal architecture is evolving. On Pathfinder, a common set of turbopumps feeds the thrust chambers through the BHS. That arrangement requires the engine to manage start and shutdown transients across a large, shared flow path while maintaining pressure throughout the heat shield.

Though visibly similar to its predecessor, Andromeda Block 2 will use 12 independent engines, each with two thrust chambers. This allows us to scale the Stage 2 thrust by over a factor of five without having to scale the turbomachinery. Moreover, since each engine has its own turbomachinery, they can each operate independently to create engine-out resilience at the vehicle level. If one engine suffers a failure, Nova Block 2 is designed to shut down the affected unit and continue the mission on the remaining engines. This capability is unusual for an upper stage, where an engine failure typically ends the mission.

Andromeda retains the precise differential throttle-thrust vector control (DT-TVC) that we first demonstrated with Hopper in 2023, when we used independently throttled thrust chambers to control the vehicle without a conventional gimbaled engine. It also makes the start and shutdown sequence more manageable and reduces the amount of tightly coupled plumbing and pressure management across the base of the stage. A separate reentry pump will circulate LH2 through the liquid-cooled surfaces when cooling is required. Propulsion and reentry cooling still share hydrogen as the working fluid, but each system can now be designed around its specific operating conditions.

The distributed mini-engine architecture also allows us to close the hydrogen expander cycle, raising specific impulse (Isp) to more than 440 seconds. That performance has a large effect on missions beyond LEO; Nova can deliver more than four metric tons to geosynchronous transfer orbit (GTO). Just as important, the vehicle is being designed for dynamic space operations. High performance and precise orbital maneuvering give Nova the flexibility to deploy, reposition, and service payloads in orbit while preserving the vehicle for return and reuse. We believe this capability can materially change the economics of access to high-energy orbits and enable a more responsive, operational approach to deliver critical cargo to any orbit, any time. There is more work underway in this area, and we will have more to share in due time.

Deleting the taper

One of the most visible changes is the shape of the reusable upper stage. Pathfinder’s upper stage is tapered and capsule-like, such that the conical sidewalls are shielded from the free-stream by the BHS during reentry. This keeps sidewall heating to a minimum.

By contrast, Block 2's upper stage uses cylindrical propellant tanks. Internally, we call this transition to cylindrical tanks “deleting the taper,” and it’s a challenge we’ve been wrestling with for years. The cylindrical design provides substantially more propellant volume and allows Nova to accommodate a 5-meter payload fairing.Mass frequently gets more attention in launch discussions, but many times volume is the actual constraint. The need for both the full deployment hemisphere and traditional payload fairing volume drives the cylindrical upper-stage architecture. The fairing provides the payload community with a familiar deployment environment, while our base-first reentry architecture preserves a 180-degree-by-360-degree deployment hemisphere – customers should not have to redesign their satellites around the launch vehicle to benefit from the economics of full and rapid reuse.

The cylindrical tanks provide more propellant and fairing volume, but the upper stage must still manage sidewall heating during base-first reentry. Our approach uses the BHS and the vehicle’s reentry geometry to shade the sidewalls from the peak heat flux. Again, our work on Pathfinder has given us further conviction that active cooling with liquid hydrogen is the right approach. The Pathfinder flights will provide data and operating experience that directly inform how we extend active cooling to Nova Block 2.

The same return architecture also gives us a path toward meaningful downmass capacity. Downmass is critically constrained today, even as microgravity manufacturing is poised for massive growth if we can unlock the bottleneck of routine Earth-return. Pathfinder will help validate the reentry and operational foundations, while future Nova configurations will provide the volume and recurring return service needed to move microgravity manufacturing toward commercial scale.

Test & Launch Infrastructure

The Series E also allows us to expand the test and launch infrastructure required to develop Nova without slowing Pathfinder’s path to flight. At our Moses Lake Test Site (MLTS) in Moses Lake, WA, we are expanding our footprint from 75 acres to 550 acres. Expanding onto adjacent undeveloped land allows both efforts to move forward in parallel. The additional space will support purpose-built facilities for testing everything from individual engine components to complete Nova stages. It also allows each stand to have the clear area needed to operate without interfering with other test programs, enabling faster and more continuous hardware development with future elements planned to manage testing volume. As the site grows, we are also designing new facilities and operating practices to reduce noise and other impacts on our neighbors. Moses Lake has been an important partner in Stoke’s progress, and we are committed to growing responsibly as a long-term member of the community.

Our launch and recovery infrastructure at the Cape Canaveral Space Force Station (CCSFS) is purpose-built to enable fast-turn, high-cadence launch and recovery operations. While Pathfinder operations continue at the Cape, planning for Block 2 has been advancing in parallel behind the scenes from the outset. This deliberate, dual-track approach ensures the investments we've already made, and continue to make today, scale directly into Block 2 operations. Much of the critical long-lead ground support equipment is already on order for Block 2.

A new payload processing facility (PPF) is underway and is intentionally sized to support both Pathfinder and Block 2 and enables us to prove our processes on Pathfinder while standing up the capacity for Block 2. Likewise, our offshore recovery platform is being designed and built to support both vehicles, and critical system procurement is already in motion.

Our infrastructure and teams are scaling to support payload processing, vehicle processing, launch operations at rate, and recovery operations, and the teams are heads-down executing. We can't wait to share more on this front.

The flight plan from here

Our immediate focus is flying Pathfinder. We plan to fly multiple Pathfinder missions in 2027 and 2028, giving us a growing body of flight data while we build and test Nova in parallel. Block 2’s first flight is scheduled for 2029.

This new funding round gives us the ability to move faster and execute more work in parallel. We can expand the teams working on Nova, accelerate hardware development and testing, increase manufacturing capacity, and prepare the production and launch systems required for an operational fleet. At the same time, the Pathfinder team is moving quickly toward flight and the series of missions that will follow.

Pathfinder’s role does not necessarily end when the larger vehicle arrives. We see value in having more than one way to serve the market, since some missions are particularly well suited to the Pathfinder configuration. Its longer-term flight cadence will be informed by what we learn over the next two years and by the needs of our customers.

While the market’s need for launch is now greater than ever before, Stoke’s pursuit of a fully and rapidly reusable launch system to deliver critical cargo to any orbit, any time has always been priority #1. Pathfinder establishes the flight foundation, and Nova Block 2 scales that work to the capacity customers need this decade, and the next.

Across Kent, Moses Lake, and the Cape, our team is turning ambition into flight hardware every day. We could not be prouder of what we’re building. And now, with fresh funding in hand, we continue building bigger than ever.

Ad astra per aspera!