By Jéssica José Xavier
Martian atmospheric dust presents significant challenges for human exploration and in-situ resource utilization (ISRU) systems due to its fine particulate nature and low atmospheric pressure. This study evaluates the feasibility of electrostatic precipitation as a dust filtration method under simulated Martian conditions. Two prototype precipitators were tested, achieving collection efficiencies between 94% and 99%. Despite voltage constraints imposed by the CO₂-rich low-pressure environment, results demonstrate that electrostatic precipitation is a promising approach for effective dust removal in Martian ISRU applications.
Introduction
The Martian atmosphere, primarily CO₂ at 7–10 mbar, contains fine dust particles from frequent storms that pose risks to equipment and human health. Effective dust removal is critical for ISRU systems, especially those processing atmospheric gases. Traditional mechanical filters require energy-intensive pressurization, making them impractical on Mars. Electrostatic precipitation offers a low-energy alternative but is limited by reduced breakdown voltages under Martian conditions. This article details the design and testing of two electrostatic precipitator prototypes adapted for Mars, analyzing plasma behavior, particle charging, and flow effects on dust collection efficiency. It also addresses the toxicity of Martian dust and its impact on human systems and EVA suits, evaluating electrostatic precipitation as a viable dust management strategy.
Keywords: Martian atmosphere; electrostatic precipitation; in-situ resource utilization (ISRU); dust mitigation;Martian Atmospheric Environment
The atmosphere of Mars is extremely dusty, a result of the constant redistribution of particles by dust storms and dust devils. These particles vary in size: suspended dust (1 to 2 μm), wind-blown dust (up to 5 μm), and larger saltating particles (above 40 μm). In addition, Mars’ low atmospheric pressure (between 7 and 10 mbar) limits the electric potential that can be applied without causing dielectric breakdown of the gas (Townsend breakdown), a process that ionizes the gas between electrodes and leads to electrical conduction.
Due to the characteristics of the Martian atmosphere—composed mainly of carbon dioxide (about 95%) and with pressures near 9 mbar—dust composed of extremely fine particles remains easily suspended, posing a challenge for any filtration system.
Charging of Dust Particles
Due to the low atmospheric pressure, the particle charging regime transitions from the continuum phase (where air fully envelops the particles) to the transition phase, altering how these particles interact with the electric field. This affects both the amount of charge they can acquire and the drag they experience while moving through the gas. Drag is calculated using specific corrections (Cunningham slip correction factor) to account for the increased mean free path between gas molecules.
Adapted Electrostatic Precipitators
Conventional mechanical filters would require compression of the Martian air to operate efficiently, which would incur a high energy cost. As an alternative, electrostatic precipitation was considered, although its application on Mars imposes significant limitations. For example, in tests with 9 mbar of CO₂, electrical breakdown occurred with only 3 kV of voltage across a 10 cm electrode gap—significantly lower than the 30 to 70 kV typically used in terrestrial precipitators.
The first prototype was a static system in which dust fell by gravity into a tube containing concentric cylindrical electrodes. Tests were conducted in a simulated Martian atmosphere and showed collection efficiencies between 94% and 99%, despite the environmental limitations. This high efficiency was attributed to adjustments in electrode geometry (using wires 70 to 100 μm in diameter) and pressure control inside the device.
Following the promising results from the static system, a second prototype was developed with forced airflow, better representing practical applications in Martian environments. This new device consists of a cylindrical tube 91.44 cm in length and 6.985 cm in diameter, through which dust-laden air is directed across an electric field generated by a high-voltage wire of 100 μm diameter. The system was equipped with laser particle counters at the inlet and outlet, enabling precise measurement of dust concentration before and after the collection process. Dust was introduced via a removable mechanical feeder before the chamber was evacuated to the desired pressure.
In initial tests with simulated dust, although the material contained particles up to 10 μm, sensors indicated that only particles up to 5 μm became aerosolized. According to researchers, this is because the larger, heavier particles were not sufficiently affected by gas drag under reduced pressure and thus remained at the bottom of the feeder.
The first experimental run with the new prototype was promising. With the electric field turned off, significant counts were recorded at both the inlet and outlet sensors, indicating that particles were passing through the system. However, when high voltage was applied, outlet sensor counts nearly disappeared, indicating that most particles were successfully captured.
Researchers noted that the required efficiency (close to 99%) still depends on the CO₂ input flow rate, currently set at 88 g/h in existing systems. This work contributes to the design of dust intakes and filters for future ISRU (In-Situ Resource Utilization) systems.
Technical Challenges on Mars
- Compared to Earth, Mars has low atmospheric pressure (7–10 mbar), making traditional particle filtration methods difficult.
- Terrestrial electrostatic precipitators operate at 30–70 kV, whereas on Mars, dielectric breakdown occurs at much lower voltages (~3 kV at 10 cm electrode spacing) due to Paschen’s Law.
- Atmospheric pressure and composition (primarily CO₂) limit the maximum applicable electric potential.
- In the experiments, dust collection relied primarily on gravity, but real-world applications will require removal from continuous airflows (e.g., 9.4 L/min for a demonstration reactor).
Impact of Martian Dust on Human Health
- A) Toxicological Aspects of Exposure
Exposure to toxic dust can cause a range of pathological effects in various organs. Some of these effects may be reversible (such as inflammation, thyroid dysfunction, and renal impairment), while others may be irreversible (such as pulmonary fibrosis, allergic sensitization, organ damage, or cancer).
The main concern is the inhalation of particles smaller than 10 μm, which can cause severe pulmonary toxicity. However, particles of all sizes can affect the gastrointestinal tract, eyes, and skin. There is also concern about heavy metals such as manganese, which can reach the central nervous system through inhalation via the nasal passages.
Experts point out that environmental factors on Mars—such as low gravity, cosmic radiation, reduced atmospheric pressure, and high UV radiation—can exacerbate toxic effects. For example, low gravity affects how inhaled particles deposit in the lungs, and UV radiation may increase the toxicity of certain dust compounds.
- B) Effects on EVA Suits and Human Health
Experience from the International Space Station has shown that contact areas between spacesuits and the human body are prone to skin and nail damage. The abrasiveness of Martian dust could intensify this issue. Future studies should investigate how Martian dust interacts with fabrics and other materials used inside the suits.
Damage to skin and nails at pressure points can increase the risk of infection and compromise the skin’s barrier function, leading to water loss by evaporation and requiring enhanced performance from the environmental control systems of the suits.
For this reason, precursor robotic missions should be equipped with instruments capable of directly measuring the mechanical properties of Martian dust.
The results obtained throughout this study confirm the feasibility of using electrostatic precipitation as an efficient solution for air purification under the harsh conditions of the Martian atmosphere. The construction of a functional prototype demonstrated that it is possible to operate an electrostatic precipitator in a low-pressure environment, with satisfactory performance in capturing atmospheric dust particles, particularly in the 2 to 10 μm range. The most efficient configuration featured a cylindrical collecting electrode with a 7 cm diameter and a high-voltage wire of 100 μm, showing excellent performance in charge generation and application.
These findings are particularly relevant for in-situ resource utilization (ISRU) systems, which require clean air for atmospheric gas processing in the production of oxygen and other essential consumables for human exploration. With further adjustments in design and airflow control, the developed precipitator can fully meet the operational requirements of future Mars missions, establishing itself as a promising technology to support sustained human presence on the Red Planet.