The CubeSat propulsion system is a critically important component that determines the satellite’s capabilities in orbit.
Orbital mobility encompasses active collision avoidance maneuvers (CAM), station-keeping, and post-mission disposal (PMD) to comply with international mitigation standards. In fact, a satellite is just a passive object in space without a propulsion system.
The propulsion system allows for expanding the range of satellite applications. As a result, the satellite can change its orbit to perform various tasks. In addition, it can participate in formation flying and extend the mission’s lifespan.
Today, a space mission has to comply with regulatory requirements that are increasingly stricter. Current international standards, the FCC introduced a 5-year deorbit rule and the ESA Zero Debris Charter, require operators to ensure that a satellite is deorbited after the end of its mission. Therefore, without a propulsion system, adhering to the new standards is impossible.
A CubeSat loses most of its useful functions without the propulsion system. And it can’t meet the modern requirements of the space industry.
Key Parameters to Consider When Choosing CubeSat Propulsion
Several critical characteristics directly affect the success of the mission. Thus, they have to be taken into account when selecting a propulsion system.
Thrust Level
Contemporary CubeSat propulsion systems offer a wide thrust range. From micro-newtons for electric thrusters (0.1 – 5 mN) to hundreds of millinewtons for chemical propulsion systems (100 – 1,000 mN). For instance, emergency evasion manoeuvres require high thrust. On the other hand, precise positioning needs low thrust.
Δv (Velocity Change) Budget
Δv (delta-v) is the primary indicator of a satellite’s manoeuvring margin. Engineers calculate it using the Tsiolkovsky rocket equation, which depends on the thruster’s specific impulse and the satellite’s propellant mass fraction.
Response Time
The time from receiving a command to the start of the manoeuvre can range from a few seconds to hours, depending on the type of propulsion.
If an emergency happens, for example, when operators receive a collision warning 12–24 hours in advance, the system must respond rapidly. It takes minutes to activate chemical and water-based systems. Electrical systems require a lengthy warm-up period and respond slowly.
Power Consumption
Different types of thrusters necessitate varying amounts of electrical power. Electric propulsion systems demand tens of watts of continuous power for hours or days. In contrast, chemical and cold-gas systems consume minimal energy, primarily for control electronics and valve actuation. Water electrothermal systems, however, require peak electrical power during operation to vaporize and heat the propellant, though their standby power remains low.
Size and Mass Limits
CubeSats have standardised dimensions. Therefore, every cubic centimetre counts. In general, there are two ways to house a propulsion system. The first one is to place it inside the satellite and take up valuable payload space. Second is external mounting. It is also necessary to account for the mass of the system itself and the propellant supply. Typically, it ranges from 0.5 to 3 kg for a 6U satellite, which accounts for 5–25% of the total mass.
Safety & Launch Approval
Launch service providers impose strict safety requirements on propulsion systems. Firstly, the certification process for chemical systems is complex and lengthy. This propulsion system uses toxic propellant and high storage pressures (over 100 bar). Gas systems are approved more quickly and easily due to non-toxic propellants but high pressure.Water systems are the fastest to approve as a green satellite propulsion, since the propellant is non-toxic and is contained under lowest pressure.
Cost and Development Timelines
Commercial Off-the-Shelf (COTS) space hardware is the optimal option for many missions. Its cost is $50,000–$200,000 and can be integrated in a few months.
On the contrary, in-house development is much longer and usually increases the overall price. However, for certain missions, it is justified.
Types of CubeSat Propulsion Systems
Chemical Propulsion
High thrust (100–1,000 mN) and rapid response, which is ideal for urgent manoeuvres. However, they have a few disadvantages. Namely, high toxicity propellants (e.g., hydrazine), complex fluid handling, and rigorous launch range safety certification (e.g., AFSPCMAN 91-710). Overall, this type of propulsion system is good for major orbital changes and emergency collision avoidance manoeuvres.
Cold Gas Propulsion
Cold gas propulsion systems are safe and easy to use. However, their main disadvantage is low efficiency (Isp ~50–70 s) and a requirement for a large fuel tank. As a result, these systems work well for demonstration missions and simple short manoeuvres.
Electric Propulsion (Ion, Hall, FEEP)
This type of thrusters have a high efficiency (Isp 1,500 – 5,000 s). However, its thrust level is low (0.1–5 mN) and energy consumption is high. Moreover, these systems have a slow response; it may take hours or even days to manoeuvre. Electric propulsion is well-suited for long-term missions, orbit maintenance, and slow orbital transfers.
Water Electrothermal Propulsion (SteamJet TunaCan, TunaTank, and Thruster One)
SteamJet thrusters are completely safe because they use water as a propellant at low storage pressure. The TunaCan thruster takes up zero internal volume (0U) because it is mounted outside the satellite. The thrust level is moderate (~20 mN), which provides a balance between speed and efficiency. Our water-based thrusters for small satellites are perfect for 3U – 16U satellites to facilitate collision avoidance, formation flying, and rapid deorbiting.
Mission Profiles: Which Propulsion System to Choose
Mission Type | Key Requirements | Recommended Propulsion |
|---|---|---|
Collision Avoidance (CAM) | High thrust, fast response (<1–5 hours) | Chemical, Water-based |
Station-Keeping | Moderate Δv, frequent small burns | Electric (Ion), Water-based |
Orbit Transfer | High Δv budget | Electric (long burns), Chemical (fast), Water-based (fast, moderate Δv) |
Deorbiting | Compliance with deorbiting requirements | Electric (high Δv, slow descent) or Water-based / Chemical (high-thrust rapid clearance) |
Formation Flying | Precise, repeatable maneuvers | Water-based , Cold Gas |
Technology Demonstration | Low cost, simplicity | Cold Gas, Water-based |
Choosing the right propulsion system will determine the success of the entire CubeSat mission. And the system that fits all types of missions simply doesn’t exist.
For example, chemical propulsion systems work well for emergency manoeuvres. Meanwhile, electric propulsion systems are good for long-term missions with limited propellant supplies. Finally, cold gas systems suit simple demonstration projects.
Water-based electrothermal propulsion systems, such as SteamJet (TunaCan, TunaTank, and Thruster One), offer an optimal balance for modern compact satellites. They combine safety, fast response, sufficient thrust, and a compact design that doesn’t take up internal space – a critical factor for small 3U–16U satellites.
About SteamJet Space Systems
SteamJet Space Systems is a leading UK-based provider of high-performance satellite propulsion solutions. We specialise in water-based propulsion solutions designed specifically for CubeSats and Small Satellites (SmallSats), prioritising operational safety and rapid launch integration.
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.