ISO 21348:2007

Overview - ISO 21348:2007 (solar irradiance process)

ISO 21348:2007, "Space environment (natural and artificial) - Process for determining solar irradiances," defines a process-based standard for producing and specifying solar irradiance products for space systems and materials users. It applies to measurement sets, reference spectra, empirical and theoretical models, and solar irradiance proxies/indices that represent parts or the whole of the solar electromagnetic spectrum. The standard establishes common definitions, spectral categories, product types, compliance criteria and a certification framework to ensure consistent, traceable solar irradiance data for engineering and scientific applications.

Key topics and technical requirements

• Scope and definitions: Clear definitions for solar irradiance, spectral irradiance, total solar irradiance (TSI) and related units (see Clauses 1–3).
• Process-based approach: Emphasizes procedural specification over selecting a single “standard” dataset - promoting continual improvement and multiple compliant products (Clauses 4, 5).
• Solar irradiance product types: Formalizes product categories (measurement sets, reference spectra, empirical/theoretical models, proxies/indices) so suppliers and users can identify compliant outputs (Clause 5).
• Spectral categories: Classifies the solar electromagnetic spectrum into bands relevant to space systems - TSI, gamma-rays, X-rays, ultraviolet, visible, infrared, microwave and radio (Clause 6).
• Compliance criteria and reporting: Requires documentation, reporting, publication and archiving practices for traceability and reproducibility of solar irradiance products (Clause 7).
• Certification process: Outlines how a solar irradiance product can be certified as compliant with ISO 21348:2007 (Clause 8).
• Robustness and evolution: Designed to accommodate advances in instrumentation, models and community practices; process ownership assigned to ISO/TC 20/SC 14/WG 4.

Applications and who uses ISO 21348

ISO 21348 is targeted to organizations and professionals who require standardized solar irradiance data:

• Space system designers and mission engineers - orbit/attitude modeling, thermal control, materials selection.
• Space weather and atmospheric scientists - ionospheric and thermospheric modeling, radiative transfer.
• Solar physicists and instrumentation teams - measurement validation, reference spectra development.
• Manufacturers of solar simulators, spacecraft materials, solar cells and filters - performance testing and degradation studies.
  Practical uses include TSI inputs for orbit determination, solar-driven atmospheric density models, photon‑induced effects analysis, and solar cell power simulation.

Related standards and references

• World Radiometric Reference (WRR) and Space Absolute Radiation Reference (SARR) are noted as calibration/transfer references for TSI.
• ISO 21348 complements other ISO space-environment standards developed by ISO/TC 20/SC 14 for consistent environmental specification and product certification.

Keywords: ISO 21348:2007, solar irradiance, space environment, reference spectra, solar spectrum, total solar irradiance, solar irradiance models, compliance, certification.