1. A ship full of systems that must not talk to each other

James S. A. Corey’s The Expanse returns as the recalled work because the Rocinante is a ship where power, communications, life support, and weapons all share hull metal and cable runs. The crew spends a lot of time making sure those systems do not interfere with each other at the wrong moment. The desktop has the same problem on a smaller scale: high-current power, high-speed data, and sensitive sensors all live in the same rack.

This entry applies the EMC and charging literature to the desktop.

2. The desktop’s EMC risk areas

The desktop has several areas where EMC and charging must be managed:

  • High-voltage solar array and power bus: any bus above a few tens of volts can drive plasma currents and arcing in LEO.
  • Switching power converters: DC-DC converters generate conducted and radiated emissions that can couple into data lines.
  • High-speed data harnesses: Ethernet or similar interfaces are susceptible to common-mode noise and crosstalk.
  • Sensitive sensors and navigation electronics: star trackers, IMUs, and GPS receivers can be upset by conducted or radiated noise.
  • Exposed dielectric surfaces: thermal blankets, connector inserts, and printed circuit substrates can charge differentially.

3. Derived requirements

The EMC and charging literature gives the desktop six practical requirements:

  • Keep the power bus voltage low enough, or design for high-voltage plasma interaction. If the bus exceeds 55 V, apply NASA-STD-4005 design rules, including spacing, shielding, and testing.
  • Use a unified grounding and bonding strategy. The rack structure is the reference plane; every cell shell, cable shield, and power return is bonded to it with controlled impedance.
  • Separate noisy and sensitive harnesses. Power cables and high-speed data lines should not share bundles with sensor or timing lines without shielding or adequate spacing.
  • Terminate cable shields properly. 360-degree backshell termination is the default for shielded cables.
  • Filter power entry points. Each cell’s power input should include filtering to keep converter noise local.
  • Control exterior surface conductivity. Large dielectric areas should be made conductive or coated to prevent differential charging; avoid floating conductors in exposed locations.

4. Interaction with earlier arcs

The EMC arc connects to several earlier decisions:

  • The galvanic arc already required a galvanic compatibility map; the EMC arc adds a grounding and shielding map.
  • The connector arc selected gold-plated contacts and low-outgassing inserts; those same connectors must provide 360-degree shield continuity.
  • The power distribution arc placed high current through cell-to-rack connectors; EMC requires that the power return path is as low-impedance and quiet as possible.
  • The thermal control arc uses blankets and coatings; some of those materials may need conductive surfaces or grounding to prevent charging.

5. What this changes

  • The desktop inherits explicit EMC and spacecraft-charging requirements.
  • Power bus voltage, harness routing, grounding, shielding, and exterior coatings become controlled items.
  • The next entry will close the EMC arc and record the decision.