SteamJet Space Systems is advancing spacecraft propulsion through a portfolio of water-based electrothermal thrusters designed for CubeSats and small satellites. Headquartered in Canterbury, United Kingdom, the company develops propulsion systems that utilize water as a non-toxic propellant, providing satellite operators with an alternative to conventional chemical and electric propulsion technologies. The product portfolio including the TunaCan Thruster, TunaTank Thruster and Thruster One focuses on maximizing spacecraft payload capacity, simplifying satellite integration and delivering flight-proven propulsion performance for a broad range of orbital missions. SteamJet Space Systems addresses these engineering challenges through innovative mechanical designs that optimize both internal and external spacecraft space while providing additive manufacturing and modular architectures to support diverse mission requirements.
SteamJet Space Systems specializes in electrothermal propulsion, a technology that generates thrust by heating a propellant and accelerating it through a precision-engineered nozzle. The company’s propulsion systems utilize low-pressure water as the working fluid. During operation, electrical energy converts the stored water into high-temperature steam, which expands through a supersonic nozzle to generate thrust. Water offers several practical advantages for satellite propulsion. It is non-toxic, readily handled during manufacturing and launch preparations and simplifies transportation and fueling logistics compared with many conventional propellants. One of the primary engineering challenges facing CubeSat developers is the limited internal volume available for propulsion systems. Traditional propulsion modules often occupy between 0.5U and 1.5U of valuable internal spacecraft volume, reducing the space available for payloads, instruments or additional mission hardware. SteamJet Space Systems has developed several innovative propulsion architectures specifically intended to overcome these limitations by relocating propulsion hardware outside the primary payload compartment or by optimizing propellant storage through custom geometries. This design philosophy enables spacecraft developers to maximize payload capacity while retaining onboard maneuverability and propulsion capability.
The SteamJet TunaCan Thruster is a space-qualified electrothermal propulsion system engineered found in many CubeSat deployers. Instead of occupying valuable internal spacecraft volume, the propulsion module is installed within the cylindrical deployment space that typically remains unused during launch. By utilizing this external volume, TunaCan allows satellite developers to preserve nearly all of the spacecraft’s internal payload area while adding propulsion capability without requiring migration to a larger and more expensive satellite platform. This innovative architecture enables a higher payload-to-volume ratio while maintaining compatibility with established CubeSat deployment systems. The TunaCan Thruster is designed to deliver a high thrust-to-power ratio, producing up to 20 millinewtons (mN) of thrust while consuming less than 20 watts of electrical power. This performance enables CubeSats to perform orbit maintenance, attitude adjustments, collision avoidance, formation flying and mission extension while operating within the limited power budgets typical of small spacecraft. The combination of efficient power utilization and meaningful thrust output makes the propulsion system suitable for a wide range of low Earth orbit missions where propulsion capability can significantly expand operational flexibility. The TunaCan Thruster features a lightweight cylindrical architecture measuring approximately 80 mm in diameter by 80 mm in length. The metallic outer shell functions as the structural propellant tank, integrating multiple spacecraft functions into a compact assembly. The aft section incorporates a precision-engineered thrust nozzle together with fueling ports that support pre-launch fueling operations using a dry-ship process. On the forward side, standardized structural mounting interfaces and an integrated data and power connector enable straightforward mechanical installation and a single-cable connection for spacecraft telemetry, command and firing control. This simplified integration approach reduces installation complexity while supporting compatibility with existing CubeSat bus architectures. A significant advantage of the TunaCan propulsion system is its established in-orbit flight heritage. The company also reports additional operational performance across several commercial low Earth orbit missions. These deployments provide valuable flight data demonstrating the functionality of the company’s water-based electrothermal propulsion architecture under operational orbital conditions.
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SteamJet Space Systems developed the TunaTank Thruster, a customizable semi-external propulsion system that combines an externally mounted thruster module with an internally integrated water tank. TunaTank employs a custom-designed internal fuel tank that can be shaped to occupy otherwise unused spacecraft volume. This approach allows satellite developers to make more efficient use of available internal space while significantly increasing propellant storage compared with purely external propulsion systems. The additional propellant capacity enables longer mission durations and increased maneuvering capability without requiring larger spacecraft. Traditional spacecraft propellant tanks are often cylindrical, making them difficult to integrate efficiently within the rectangular internal structure of CubeSats. Using customized tank geometries, the TunaTank architecture allows fuel storage systems to conform to the unique layout of each spacecraft. By utilizing irregular or previously unused internal spaces, the propulsion system improves overall volumetric efficiency while preserving room for scientific instruments and mission-specific payloads. The TunaTank propulsion system incorporates a 3D-printed architecture designed to maximize structural and volumetric efficiency. The propulsion system is divided into two primary assemblies: a customizable internal water tank and an external cylindrical thruster module optimized for the deployer’s tuna can volume. These sections are connected through a robust mechanical interface that enables straightforward installation within the spacecraft. The aft portion incorporates a precision supersonic nozzle together with an accessible fueling port, while onboard communications utilize a high-reliability RS-422/TTL electrical interface that supports plug-and-play integration with the spacecraft bus.
SteamJet’s Thruster One provides another approach to spacecraft propulsion by integrating customizable fuel storage directly into a modular propulsion system. Thruster One delivers up to 20 mN of thrust while consuming less than 20 watts of power, but its architecture emphasizes customized internal integration using additive manufacturing. Thruster One employs bespoke conformal fuel geometries created through 3D printing. These tanks can be designed to wrap around payloads and structural components, maximizing utilization of available spacecraft volume while preserving mission flexibility. This capability allows satellite developers to optimize propulsion system integration according to the unique geometry of each spacecraft. Thruster One is typically configured within a 2U CubeSat form factor, utilizing a modular chassis that combines customized water tanks with the propulsion module. The aft section contains the supersonic steam nozzle and fueling interface, while the forward side incorporates the RS-422/TTL electrical connector that enables straightforward integration with spacecraft avionics. The modular construction simplifies installation while supporting a wide range of CubeSat mission architectures requiring efficient propulsion without excessive engineering redesign. SteamJet Space Systems’ propulsion technologies are designed to support numerous satellite operations, including orbit raising, station keeping, collision avoidance, constellation maintenance, formation flying, end-of-life disposal, technology demonstrations and mission extension. The combination of water-based propellants, modular mechanical architectures, additive manufacturing and customizable tank geometries enables satellite operators to design propulsion systems according to mission-specific requirements while minimizing the impact on payload capacity. These capabilities are particularly valuable for commercial satellite constellations, Earth observation missions, scientific research spacecraft and technology demonstration platforms where efficient use of spacecraft volume directly affects mission capability. SteamJet Space Systems is advancing water-based electrothermal propulsion technologies that combine compact engineering, green propellants, flight-proven operation and innovative mechanical architectures. By utilizing external spacecraft volumes, conformal fuel tanks and modular 3D-printed designs, the company is helping satellite developers maximize payload capacity while providing reliable propulsion solutions for the next generation of low Earth orbit missions.
About SteamJet Space Systems
SteamJet Space Systems is a space propulsion company headquartered in Canterbury, United Kingdom, specializing in the development of water-based electrothermal propulsion systems for CubeSats and small satellites. The company designs compact, space-qualified thrusters that use low-pressure water as a non-toxic propellant, providing propulsion solutions for orbit maintenance, collision avoidance, formation flying and end-of-life disposal. The product portfolio includes the TunaCan Thruster, TunaTank Thruster and Thruster One, which feature modular architectures and customizable propellant storage designed to maximize available payload volume. By combining electrothermal propulsion technology with additive manufacturing and innovative spacecraft integration concepts, SteamJet Space Systems develops propulsion solutions for commercial, scientific and government satellite missions.
