Continuous Electrokinetic Mitigation of High-Voltage Tribocharging in Lunar EVA Spacesuits

Polar Extravehicular Activities (EVAs) in Permanently Shadowed Regions (PSRs) at the Lunar South Pole introduce severe electrostatic hazards. Triboelectric interaction between outer suit fabrics and regolith, combined with low ambient plasma density, can drive spacesuit potential to ≤ -100 kV. Upon returning to a sunlit lander sitting at ≈ +100 V, this extreme potential difference (∆V ≈ 100 kV) risks destructive Electrostatic Discharge (ESD), threatening suit pressure layers, avionics, and crew safety.

This article proposes a low-mass, non-invasive retrofit architecture: the Thermal-Decoupled LCVG Electrokinetic Charge Sink. By utilizing high-aspect-ratio Carbon Nanotube (CNT) yarn stitching across the Multi-Layer Insulation (MLI) blanket to interface with a functionalized ionic Liquid Cooling and Ventilation Garment (LCVG) fluid loop, triboelectric charge is continuously routed and neutralized via a micro-electrolysis cell embedded in the Portable Life Support System (PLSS). This clamps suit potential to the lander baseline while introducing zero structural redesign and less than 0.5 kg of dry parasitic mass.

1. Problem Formulation & Environmental Kinetics

During lunar surface traversal, walking action continuously transfers electrons from regolith particles to the outer fabric layer (TFL-coated Ortho-Fabric), generating a triboelectric charging current:

In PSRs, the absence of photoemission allows charge to accumulate rapidly on the suited astronaut (C_suit ≈ 200 pF), scaling voltage up to -100 kV:

Traditional transient discharge solutions attempt to bleed this 20 µC energy upon physical lander contact. However, suspended lunar dust (0.02 µm - 10 µm) drastically lowers vacuum dielectric breakdown thresholds, encouraging premature spark formation across large gaps.

2. System Architecture: LCVG Electrokinetic Sink

Instead of managing high-energy transient arcs at the lander contact interface, the proposed architecture continuously drains charge at the generation rate, clamping the equilibrium voltage at a safe, low-potential state throughout the EVA.

3. Key Mechanical & Electrochemical Subsystems

3.1. Thermal-Decoupled Conduction Paths (CNT Stitching)

Standard metals follow the Wiedemann-Franz Law, meaning high electrical conductivity creates a thermal bridge across the MLI blanket, causing severe metabolic heat loss.

To break this coupling, high-aspect-ratio Carbon Nanotube (CNT) yarns (e.g., DexMat CNT thread) are used as functional assembly stitches across the layup. Operating near their electrical percolation threshold, these micro-threads provide high electrical conductivity for micro-ampere currents (R ≈ 100 MΩ) while keeping thermal conductivity virtually zero (k < 0.05 W/m · K). Total parasitic thermal leakage across the MLI is restricted to < 0.15 Watts.

3.2. Ionic Fluid Transport & Micro-Electrolysis Neutralization

The circulating LCVG cooling water is functionalized with a non-toxic trace salt (0.01 M Na₂SO₄), raising electrical conductivity to ∼ 2 mS/cm without impacting fluid viscosity or pump work.

Charge Pickup: Micro-pins embedded in the LCVG tubing transfer surface electrons into hydrated sodium cations in the moving fluid stream.

Electrochemical Reduction: In the PLSS, fluid passes through an inline microfluidic reaction cell where excess electrons are consumed at a platinum-coated titanium mesh cathode:

Recombination Loop: Trace gases pass across a hydrophobic membrane into a palladium catalyst chamber, recombining into liquid water (2H₂ + O₂ → 2H₂O) and preventing gas lock or pressure accumulation in the pump.

4. Continuous Voltage Clamping Performance

Because the charge removal rate matches the triboelectric generation rate, the floating potential of the astronaut never reaches -100 kV. It clamps to a steady-state equilibrium matching the lander reference:

When the suited astronaut makes contact with the +100 V lander structure, the potential differential is zero, completely eliminating spark arcing hazards.

5. Mass, Power, and Operational Impact

Conclusion

The Thermal-Decoupled LCVG Electrokinetic Charge Sink resolves the lunar extravehicular charging problem by shifting from high-energy transient discharge to continuous electrokinetic mitigation. By converting the existing cooling loop into an active charge carrier, this approach eliminates the need for heavy high-voltage generators, external contact booms, or high-power ion guns—delivering a plug-and-play solution well within NASA’s mass, power, and safety bounds.