ISO 19923:2017

Overview

ISO 19923:2017 - Space environment (natural and artificial) - Plasma environments for generation of worst case electrical potential differences for spacecraft - defines realistic space plasma environments and procedures for estimating worst-case surface potential differences (differential charging) on spacecraft. The standard focuses on external surface charging in GEO, PEO and MEO, provides environment models (including a GEO double‑Maxwellian case), and specifies how to use spacecraft‑charging simulation codes to estimate maximum potential differences. ISO 19923:2017 does not provide LEO plasma descriptions (LEO charging is often dominated by spacecraft high‑voltage systems) and deals only with external surface charging.

Key topics

• Worst‑case environment definition: Worst‑case is the measured space plasma condition that produces the maximum potential difference between the spacecraft grounding body and external non‑conductive or isolated surfaces. Conditions must be realistic, literature‑based, and physically valid.
• GEO, PEO, MEO coverage: Includes plasma energy and density for GEO (with a specified double‑Maxwellian distribution in the standard) and guidance for PEO/MEO; LEO is excluded.
• Simulation procedures:
  • Use worst‑case environments from Clause 7 as input.
  • Perform charging simulations early in spacecraft design, preferably before selecting exposed surface materials.
  • Start simulations from zero‑charge initial conditions and run until differential potentials fully develop.
  • Use spacecraft geometry, up‑to‑date material data (including post‑ageing properties), and account for radiation‑induced conductivity where possible.
• Verification and criteria: Candidate worst‑case combinations of densities and temperatures must be from published measurements, physically realistic, and verified with validated charging codes (examples: COULOMB‑2, MUSCAT, SPIS, NASCAP‑2k).
• Informative annexes: Annex A lists charging analysis tools; Annex B contains round‑robin simulation examples; Annex C addresses material properties; Annex D offers tailoring guidance.

Applications

ISO 19923:2017 is practical for:

• Space systems engineers performing spacecraft charging risk assessments and design mitigation.
• Thermal/electrical/materials engineers selecting and qualifying external surface materials and coatings.
• Mission assurance and systems engineering teams integrating charging simulations into early design and verification plans.
• Software teams validating spacecraft charging codes or running worst‑case scenario analyses for GEO/PEO/MEO missions.

Practical outcomes include identification of maximum differential potentials, selection of surface materials and grounding strategies, and informed mitigation measures (e.g., conductive coatings, grounding designs).

Related standards and tools

• Normative references: none are listed in ISO 19923:2017, but the standard references established spacecraft‑charging simulation codes and measured environment datasets.
• Key simulation tools noted in Annex A: COULOMB‑2, MUSCAT, NASCAP‑2k, SPIS - used to verify worst‑case charging scenarios and validate environment selections.

Keywords: ISO 19923:2017, spacecraft charging, plasma environments, worst‑case potential differences, GEO charging, PEO, MEO, surface charging, charging simulation, SPIS, NASCAP-2k.