ISO 23129:2021

Overview

ISO 23129:2021 - Space systems: Thermal control coatings for spacecraft - Atomic oxygen (AO) protective coatings on polyimide film - defines general requirements, test methods, property descriptions and selection guidance for AO-protective coatings applied to polyimide thermal control films. The standard provides a property map of common coatings (for example indium tin oxide (ITO), SiOx, germanium, and silicone) and sets out quality assurance practices to improve reliability of spacecraft exposed to the low Earth orbit (LEO) environment.

Key topics and technical requirements

• Coating types and properties: Descriptions and comparative characteristics of ITO, SiOx, germanium, silicone and other AO-protective coatings on polyimide film.
• Performance requirements: Visual characteristics, acceptable coating thickness, thermo-optical properties, thermal vacuum stability, and atomic oxygen resistance.
• Environmental resistance: UV resistance, radiation resistance, thermal cycling behaviour, and outgassing considerations.
• Electrical and surface properties: Adhesion, volume and surface resistance, secondary electron emission (SEE) yield, and photoelectron emission yield.
• Maintenance and lifecycle: Repair/retouch, cleaning guidelines, protective covers and packing recommendations.
• Test methods: Defined procedures for visual inspection, coating thickness measurement, thermo‑optical testing, thermal vacuum stability, AO resistance testing (qualification and life estimation), UV/radiation resistance tests, and electrical property measurements.
• Quality assurance: Production program requirements, change control, and record-keeping to ensure consistent coating performance and product traceability.
• Selection guidance: Annexes provide practical selection criteria and a property map to help balance trade-offs (e.g., optical properties vs. AO durability).

Applications and who should use it

ISO 23129:2021 is intended for:

• Spacecraft systems and thermal control engineers designing LEO satellites, smallsats and CubeSats.
• Thermal control film manufacturers and coating suppliers selecting AO-protective solutions for polyimide substrates.
• Materials and test laboratories performing AO resistance, thermo‑optical and outgassing assessments.
• Procurement, quality assurance and programme management teams responsible for supplier specification, acceptance testing and long-term reliability. Practical benefits include improved coating selection, reduced mission risk from AO erosion, standardized test criteria, and clearer supplier acceptance requirements.

Related standards

Normative references cited include ISO 16378 (thermo‑optical measurements), ISO 27025 (quality assurance for space programmes), ASTM D257, ASTM E595, ASTM E1559, and ECSS-ST-Q70-02 (thermal vacuum outgassing). These documents are commonly used together with ISO 23129 for comprehensive material qualification and verification in space applications.

Keywords: ISO 23129:2021, atomic oxygen protective coatings, polyimide film, thermal control coatings, spacecraft, ITO, SiOx, AO resistance, thermo-optical properties, outgassing, thermal vacuum stability.