Engineers often consider thrust, specific impulse, system mass, and total impulse when selecting a propulsion system for CubeSat. NASA’s Small Spacecraft Technology State of the Art report demonstrates that these are the key factors for small spacecraft propulsion systems. However, small satellites have another limitation that, in most cases, becomes the major one. Namely, the internal volume.
In simple terms, volume efficiency refers to how effectively the system utilizes the available space inside the satellite. If more propellant can be stored within the same CubeSat dimensions, the spacecraft gains additional maneuvering capability without increasing its external size.
As a result, this directly affects mission capability. If other parameters are unchanged, a larger usable propellant mass can increase the available ΔV margin. As a result, the satellite can support additional orbit adjustments, unscheduled maneuvers, extended mission duration, or end-of-life deorbit.
Therefore, engineers should evaluate not only the thruster parameters, but also how efficiently the propulsion system uses the satellite’s internal volume. A well-integrated fuel tank can enhance a mission’s capabilities even without modifying the engine itself.
Why Cold Gas Systems Limit CubeSat Volume Efficiency
In cold gas propulsion systems, the propellant remains in a pressurised gaseous state. The tank becomes a high-pressure container, rendering its geometric profile critical for uniform stress distribution and structural integrity under high pressure. Simple shapes, such as spheres or cylinders, are usually the most efficient for this type of tank. They distribute internal pressure better and help reduce structural risks.
However, for a CubeSat, it presents a design challenge. The interior of a satellite is typically rectangular and tightly packed with other systems, so a spherical tank does not fit well in such a space. There are empty spaces left around the tank that are impossible to use for payload, electronics, and additional propellant storage. Thus, even if a cold gas propulsion system fits well in terms of the thrust and the mass, its tank may be using the internal volume inefficiently.
Unpressurized Propellant Gives More Freedom in Tank Design
In SteamJet thrusters, the propellant is not stored under high pressure. Hence, engineers can design the tank in a wider range of shapes than in cold gas propulsion systems. This removes one of the main geometric constraints. A tank does not have to be spherical or cylindrical.
Instead, our engineers adapt tanks to the available space inside a CubeSat or Small Satellite. If there is an irregularly shaped space inside the unit, it is no longer a “dead space” but an additional propellant storage capacity.
Titanium Additive Manufacturing Enables Complex Tank Geometry
We use titanium direct metal laser sintering (DMLS) to manufacture tanks. It allows the production of tanks with complex shapes that are difficult or impossible to manufacture using traditional methods. Instead of adapting the satellite’s internal layout to fit a standard tank, the tank can be designed to fit a specific available space inside the satellite.
This is especially important for CubeSats and Small Satellites, where every centimeter counts. After electronics, payload, and other systems have been installed, the tank can be 3D-printed to match the space as precisely as possible. As a result, the satellite may carry more propellant without increasing its size.
Patented Tank Architecture Supports Сonformal Propellant Tanks for Small Satellites
Our patented tank design enables the engine to operate with tanks of various shapes, not just standard ones. This is important because the capability to 3D-print the tank doesn’t solve the issue. The thruster has to receive a steady supply of propellant and function properly with this configuration. The tank that may be adapted to the internal volume of the CubeSat or Small Satellite gives engineers greater flexibility when integrating the propulsion system.
More Usable Propellant Volume Without Increasing CubeSat Size
The custom tank’s main advantage is its capability to increase the volume of propellant without increasing the size of the CubeSat. It can replicate the available geometry inside the satellite. As a result, the custom tank converts more of the internal space into usable propellant capacity rather than remaining as “dead volume”.
For the mission, it means:
- greater flexibility for orbit adjustments;
- longer operational lifespan;
- additional margin for unforeseen maneuvers;
- the ability to perform deorbit at the end of the mission.
The deorbiting process is no longer optional. At the moment, it is a prerequisite. The FCC introduced a 5-year deorbit rule for LEO satellites, while ESA promotes sustainable mission design through its ESA Zero Debris Charter.
About SteamJet Space Systems
SteamJet Space Systems is a leading UK-based provider of high-performance satellite propulsion solutions. We specialise in green water propulsion for CubeSats and Small Satellites (SmallSats), with a strong focus on thruster safety.
By pioneering the use of green propellants and intelligent thermal engineering, SteamJet enables complex LEO (Low Earth Orbit) manoeuvres — including orbital maintenance, collision avoidance, and de-orbiting — without the risks associated with toxic hydrazine or high-pressure cold gas systems, advancing green propulsion for space missions.
Steamjet Propulsion Technology
Our modular systems are engineered for seamless integration and maximum safety compliance:
Steam TunaCan Thruster: A compact, high-efficiency solution for 1U-3U CubeSats.
Steam TunaTank Thruster: A safe, high-performance electrothermal propulsion system.
Steam Thruster One: Scalable propulsion for larger SmallSat constellations.
Discover how SteamJet’s sustainable space propulsion innovations are providing the safety and reliability required for the next generation of crewed and robotic missions. Contact our engineering team for technical specifications and ICDs.
