Common engineering practices involve the assessment, through computer simulation (with software like NASCAP 0 or SPIS 0), of the levels of absolute and differential potentials reached by space systems in flight. This is usually made mandatory by customers and by standards for the orbits most at risk such as GEO or MEO and long transfers to GEO by, for example, electric propulsion.

The ECSS‑E‑ST‑20‑06 standard requires the assessment of spacecraft charging but it is not appropriate in a standard to explain how such an assessment is performed. It is the role of this document ECSS‑EHB‑20‑06, to explain in more detail important aspects of the charging process and to give guidance on how to carry out charging assessment by computer simulation.

The ECSS‑E‑ST‑10‑04 standard specifies many aspects of the space environment, including the plasma and radiation characteristics corresponding to worst cases for surface and internal charging. In this document the use of these environment descriptions in worst case simulations is described.

The emphasis in this document is on high level charging in natural environments. One aspect that is currently not addressed is the use of active sources e.g. for electric propulsion or spacecraft potential control. The tools to address this are still being developed and this area can be addressed in a later edition.