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CubeSats have emerged as game-changers in space exploration, offering an accessible, low-cost entry point for universities, startups, and governments alike. Their standardized, modular design allows rapid development and deployment for a wide range of missions, from remote sensing and atmospheric monitoring to communications and deep-space experiments. Yet as the complexity and ambition of these missions increase, the absence of robust propulsion systems becomes a limiting factor. What was once a passive payload in a ride-share launch now requires active navigation, precision pointing, and safe end-of-life management.
The inclusion of propulsion systems transforms CubeSats from passive orbiters into agile spacecraft. Onboard propulsion enables critical capabilities such as orbit raising, station-keeping, formation flying, and precise attitude control—functions that extend mission lifespans and scientific output. Moreover, these systems are crucial for avoiding potential collisions in crowded orbital corridors and for controlled deorbiting at the end of a mission. Without these capabilities, CubeSats risk becoming space debris, further exacerbating orbital congestion and threatening the operational safety of other spacecraft.
The Burning Need: Why CubeSats Can’t Afford to Linger
Low Earth Orbit (LEO), once a relatively open expanse, is now heavily trafficked and approaching saturation. With more than 5,000 active satellites and tens of thousands more planned in upcoming mega-constellations, LEO is at risk of triggering the Kessler Syndrome—a runaway chain reaction of collisions and debris creation. As small satellites proliferate, so does the need for a sustainable orbital environment. CubeSats, which often operate in swarms or constellations, face particular scrutiny. Their small size makes them harder to track and maneuver, and their limited power budgets make traditional propulsion impractical.
The Federal Communications Commission’s (FCC) 2022 ruling, which shortens the deorbit timeline from 25 years to just 5, represents a pivotal regulatory shift aimed at curbing orbital congestion. This directive forces CubeSat developers to rethink mission architectures, balancing limited mass and volume against the need for autonomous end-of-life capability. As a result, innovation in propulsion technologies has accelerated, giving rise to micro-propulsion systems specifically engineered for 6U–12U CubeSat formats. These systems offer the agility and compliance CubeSats need—without sacrificing valuable payload space—ensuring that these small satellites can continue to operate effectively and responsibly in an increasingly crowded orbital ecosystem.
The 2022 FCC ruling shortened the acceptable deorbit timeline from 25 years to just five, marking a paradigm shift in satellite mission planning. Passive drag-based deorbiting strategies, once sufficient for altitudes below 600 km, fail to deliver at higher operational orbits of 700–1,000 km—where many CubeSats now operate. This elevation in altitude necessitates the use of active propulsion systems. Recognizing this, the European Space Agency issued an August 2023 call for disruptive propulsion solutions capable of deorbiting 12U CubeSats under rigorous operational and endurance conditions.
Electric Propulsion: Quiet Precision for Space Custodianship
Electric propulsion is rapidly emerging as the go-to solution for CubeSats seeking precise, low-thrust deorbit capability. One of the most promising developments in this domain is the Cube de ALPS (Additively Manufactured Low Power Spacecraft Thruster) from the University of Southampton. This system employs vacuum arc thrusters that vaporize solid metallic propellants such as magnesium or zinc into ionized plasma. The compact propulsion unit can be printed directly onto the satellite’s structure, consuming just 20 to 50 watts of power. With no moving parts or volatile fuels, Cube de ALPS offers a plug-and-forget solution, especially critical for CubeSats that experience communication failures or attitude control issues post-deployment.
What sets Cube de ALPS apart is its self-contained and redundant architecture. The module includes its own battery, onboard processor, and communication receiver, allowing it to activate and perform deorbit maneuvers even if the host satellite is otherwise unresponsive. Its printed electronics also allow for batch production and simplified integration during the CubeSat assembly process. This reduces overall mission costs while satisfying regulatory requirements such as the FCC’s 5-year deorbit rule. As satellite traffic in low Earth orbit (LEO) intensifies, such passive-safe failover solutions are becoming indispensable.
Complementing this approach are electrospray thrusters, pioneered by companies like Accion Systems. These miniaturized engines operate by accelerating ions from ionic liquid propellants—typically salts like EMI-BF₄—via electrostatic fields. Despite their diminutive size, often fitting within a 0.5U form factor, they provide total impulses exceeding 150 mN·s. This is sufficient to enable orbital decay from altitudes of 800 kilometers within three years, all while consuming less than 30 watts of power. Their operational principle ensures an ultra-clean plume, avoiding contamination of optics or sensors, which makes them ideal for astronomy payloads and Earth-observation missions.
Moreover, electrospray systems offer high reliability due to their solid-state architecture and absence of complex valves or pressurized tanks. They are modular, scalable, and can be deployed in clusters for increased thrust, depending on mission needs. As the space industry pushes for miniaturization without compromising on control authority, electric propulsion technologies like Cube de ALPS and TILE (Tiled Ionic Liquid Electrospray) are redefining what’s possible for small satellite mobility in a sustainable orbital ecosystem.
Chemical Propulsion: High-Impact Simplicity
For missions requiring rapid deorbiting or aggressive maneuvering, chemical propulsion remains a dependable workhorse. The spin-stabilized solid rocket motor, developed by Aerospace Corporation, is one of the most compact yet effective solutions for CubeSats operating above 900 kilometers—where atmospheric drag alone won’t suffice. The system includes a preloaded deflector plate that imparts rotational stability at rates between 200–400 RPM. Once stabilized, a solid propellant motor ignites, delivering more than 100 m/s of delta-V in a single impulse. This allows a 10-kilogram CubeSat to deorbit from 1,000 km altitude within minutes, offering a lifeline to operators when telemetry is lost or reentry is mandated quickly due to orbital congestion.
The elegance of this design lies in its simplicity: no moving parts, no pressurized tanks, and no complex thermal control mechanisms. It is purely mechanical, highly reliable, and immune to power or communication failures. Because it can be activated via ground command or onboard timers, it also serves as an emergency kill switch, satisfying even the most stringent regulatory conditions like ESA’s Zero Debris Charter. As a fallback or end-of-life system, spin-stabilized solid propulsion adds a layer of mission assurance for constellation managers operating large fleets of small satellites.
Meanwhile, the next wave of chemical propulsion is taking a green turn. At SRM Institute, engineers are developing solid propellants that eliminate hazardous substances like ammonium perchlorate. One standout candidate is HTPE (hydroxyl-terminated polyether), which delivers high performance with significantly lower toxicity and environmental risk. Another is paraffin-based hybrid fuel, which combines solid wax fuel with gaseous oxidizers. These materials are safe to handle, self-extinguishing, and offer impressive specific impulses around 250 seconds—competitive with more traditional composite propellants.
These green propellant systems are being engineered into compact “snap-on” propulsion modules designed specifically for CubeSats. Measuring just 10×10 cm and weighing under 1.5 kg, these units use spark ignition or resistive heating to initiate burn. Once fired, they rapidly decelerate the satellite, initiating controlled reentry within compliance windows. As more space agencies prioritize environmental stewardship in orbit, these sustainable propulsion solutions are likely to become baseline technologies in future CubeSat deployments.
Drag-Augmentation: Passive Solutions for Lower Altitudes
As orbital traffic increases in low Earth orbit (LEO), passive deorbiting systems offer a low-power, low-risk option for satellites operating at altitudes where atmospheric drag is still effective. Among the most innovative solutions is NASA’s Exo-Brake, a tension-stabilized drag sail first deployed aboard the TES-22 CubeSat in early 2025. The system increases the satellite’s cross-sectional area by up to 400%, significantly accelerating orbital decay at around 400 kilometers altitude. Unlike traditional sail mechanisms that rely on motors or articulated booms, Exo-Brake uses shape-memory alloys to unfurl the sail autonomously, reducing the complexity and potential failure points of the deployment process.
Exo-Brake’s compact footprint and passive operation make it an attractive solution for missions where onboard power is limited or where the satellite lacks propulsion capabilities altogether. It operates without active attitude control and relies on atmospheric density variations to modulate descent rates. This simplicity is precisely what makes it so valuable in the post-mission phase—it’s reliable, predictable, and doesn’t require continued satellite functionality after the payload has completed its objectives.
Another significant entrant in the drag augmentation space is the Roll-Out DeOrbiting Device (RODEO), which functions much like a reverse party streamer. This technology stores a biaxially coiled polymer tape within a 1.5U enclosure and unspools a high-surface-area sheet, typically around 10 square meters, once triggered. RODEO has been successfully tested aboard the International Space Station (ISS), where it demonstrated the ability to reduce deorbit time by up to 60% compared to unassisted CubeSats. Its scalable and modular design means it can be integrated into a wide range of CubeSat bus architectures, especially for missions under 600 km that benefit from atmospheric drag.
What makes both Exo-Brake and RODEO especially appealing is their fail-safe architecture. Once deployed, these devices require no additional commands or adjustments, functioning passively until the satellite naturally reenters Earth’s atmosphere. As regulatory agencies like the FCC and ESA tighten guidelines for post-mission disposal, drag-augmentation systems are becoming standard features in CubeSat design—ensuring even the smallest spacecraft can make a clean, responsible exit from orbit.
Comparative Analysis: What to Choose and When
Choosing the right deorbit strategy for a CubeSat mission involves navigating a complex landscape of tradeoffs—between delta-V capability, form factor, power consumption, altitude, and mission duration. Each deorbit technology excels under specific conditions. For instance, vacuum arc thrusters and electrospray propulsion systems provide precise control and low-thrust maneuverability, making them ideal for medium-altitude CubeSats (600–800 km) or for constellations requiring coordinated orbital phasing. These systems also support delicate missions, such as astronomical payloads, where contamination and vibration must be minimized.
On the other end of the spectrum, solid rocket motors like those tested by Aerospace Corporation offer brute-force simplicity and instantaneous results. With no power requirements and the ability to operate autonomously, they’re optimal for emergency scenarios—such as communication loss or end-of-life disposal above 1,000 km—where rapid intervention is essential. However, their one-time use and limited controllability make them less suited for missions that require precise orbital adjustments over time.
Meanwhile, drag augmentation devices such as Exo-Brake and RODEO shine in low-altitude missions under 600 km, where passive decay can be accelerated effectively without consuming onboard power. These systems are particularly beneficial for CubeSats with limited mass and energy budgets or those flying in educational or technology demonstration missions. They are also ideal as redundant fail-safes for satellites that already employ active propulsion but need a guaranteed end-of-life pathway in the event of failure.
Ultimately, the best deorbit solution often involves a hybrid approach. A CubeSat operating at 700 km may incorporate a low-power electric thruster for controlled orbit lowering during its mission, supplemented by a drag sail that passively finishes the deorbit process post-operation. This layered strategy not only enhances compliance with IADC and FCC regulations but also reduces operational risk. As the orbital environment becomes more crowded and rules more stringent, mission planners must consider deorbit systems not as optional extras, but as mission-critical components from the earliest stages of design
Comparative Analysis: Choosing Your CubeSat’s Farewell
Table: Deorbit Technology Tradeoffs for 12U CubeSats
| Technology | Delta-V (m/s) | Power Req. | TRL | Deorbit Time (from 700 km) |
|---|---|---|---|---|
| Vacuum Arc (ALPS) | 50-80 | 20-50 W | 6 | 2-3 years |
| Electrospray | 40-60 | 10-30 W | 8 | 1-2 years |
| Solid Rocket | >100 | None | 7 | Minutes |
| Drag Sail (Exo-Brake) | N/A | None | 9 | 6-18 months |
Regulatory Realities: The Pressure to Perform
Regulatory frameworks are evolving rapidly. The FCC’s five-year deorbit mandate applies to all U.S.-licensed satellites under 2,000 km. Meanwhile, the Inter-Agency Space Debris Coordination Committee (IADC) aims for 90% deorbit compliance reliability by 2030, and ESA’s Zero Debris Charter requires that satellites contribute no new debris post-2030. These policies are no longer theoretical—they are reshaping mission architectures and propulsion procurement strategies.
Table: Regulatory Impact on Mission Design
| Regulation | Effective Date | Key Requirement | Propulsion Implication |
|---|---|---|---|
| FCC 25-year rule | 2004 | Natural decay ≤25 years | Passive systems sufficient |
| FCC 5-year rule | 2022 | Active deorbit ≤5 years | Active propulsion essential above 500 km |
| ESA Zero Debris Charter | 2030 | No new debris after 2030 | Redundant deorbit systems required |
Engineering Challenges: Solving for Constraints
As CubeSats grow in capability and responsibility, integrating propulsion systems into their tightly packed architectures presents formidable engineering challenges. One of the most pressing is thermal management. Electric propulsion systems—particularly microthrusters such as vacuum arc and electrospray units—can generate internal temperatures exceeding 300°C during operation. These elevated thermal loads, if unmanaged, risk degrading critical subsystems including batteries, avionics, and structural adhesives. To mitigate this, engineers are employing pulsed operation techniques that allow short bursts of thrust interspersed with cool-down periods. Advanced thermal interface materials like synthetic diamond composites and carbon-based aerogels are also being integrated into thruster mounts to distribute heat more efficiently across the satellite body.
Miniaturization poses another critical hurdle. Most propulsion systems rely on tanks or reservoirs for storing fuel or propellants, which must be compact yet capable of withstanding extreme internal pressures. Traditional metal tanks are often too bulky or heavy for CubeSats. To address this, engineers have begun utilizing Composite Overwrapped Pressure Vessels (COPVs)—carbon fiber-reinforced tanks with thermoplastic liners capable of withstanding pressures over 5,000 psi. These COPVs are increasingly produced using additive manufacturing, which not only reduces mass but also enables customized geometries that better fit into small satellite layouts.
Contamination control is a lesser-known but equally critical challenge, particularly for CubeSats with optical payloads or solar panels. Thruster exhaust plumes—especially from electric propulsion systems—can coat sensitive surfaces with microscopic residues that reduce optical clarity or power efficiency. This is particularly concerning for missions involving Earth observation, astronomy, or laser communication. Engineers are now implementing angled nozzle designs, so that plumes are directed away from vital systems. Meanwhile, alternative propellants like iodine, which sublimates directly from solid to gas, offer cleaner exhaust and eliminate the need for pressurized tanks, further simplifying the integration challenge.
Together, these constraints form a tight engineering box: propulsion systems must be small, safe, clean, and robust, all while functioning autonomously and reliably in one of the harshest environments known. As CubeSats continue to take on more complex roles in Earth observation, scientific exploration, and telecommunications, solving these engineering puzzles is essential—not just for individual mission success, but for long-term orbital sustainability
Looking Ahead: New Horizons in CubeSat Mortality
The next frontier in CubeSat propulsion is defined by sustainability, autonomy, and elegance. One of the most promising developments is the use of green monopropellants, such as those based on ammonium dinitramide (ADN). Currently under trial by the European Space Agency (ESA), these propellants offer performance comparable to hydrazine but decompose into non-toxic byproducts like water vapor and nitrogen, drastically reducing the environmental impact of deorbit burns. Additionally, their lower handling risk simplifies ground operations and launch integration, making them more attractive to commercial CubeSat developers.
Meanwhile, propellant-less systems like electrodynamic tethers are gaining momentum, particularly for long-duration or passive deorbiting missions. Japan’s JAXA has been at the forefront with its De-Orbit Mechanism (DOM), which uses an electrically conductive tether to harvest electrons from the ionosphere. This interaction generates a Lorentz force that gradually slows the satellite without consuming any onboard fuel. Such systems are exceptionally lightweight and resilient, offering a “fail gracefully” solution for CubeSats even if primary power or communications are lost.
The incorporation of artificial intelligence into deorbit planning adds yet another dimension of sophistication. Lockheed Martin is currently testing AI-based navigation algorithms that adjust propulsion sequences in real time by analyzing thermospheric density, solar flux, and space weather forecasts. These systems can dynamically optimize the timing, duration, and direction of each thruster firing to ensure efficient fuel usage and compliance with evolving deorbit timelines. By embedding machine learning directly into onboard flight software, CubeSats gain an edge in autonomy, ensuring responsible end-of-life behavior even if Earth-based control is unavailable.
Together, these emerging strategies mark a shift in the way the industry views CubeSat end-of-life management. No longer an afterthought, deorbiting is becoming a mission-critical function, integrated from the very first stages of design. Whether through propellant-less methods, eco-friendly combustion, or intelligent control systems, the future of CubeSat propulsion is one of smart, seamless exit strategies—helping to preserve low Earth orbit for the generations of spacecraft to come.
Conclusion: The Ethics of Orbit
Next-gen propulsion isn’t just about performance—it’s a moral imperative. As CubeSats evolve from testbeds to indispensable nodes in commercial and defense networks, their responsibility to mitigate space debris becomes non-negotiable. Technologies like Cube de ALPS, electrosprays, and solid motors demonstrate that innovation under constraint is not only possible but also essential. The time has come for every CubeSat to leave orbit as thoughtfully as it entered. As Dr. Minkwan Kim aptly stated, “In the race against debris, the best propulsion is the one that fires when you need it—not when physics allows it.”
For technical resources and deorbit system testing data, visit NASA’s Small Spacecraft Technology Program or ESA’s Technology Development Portal.
