From Space Weather to Spacecraft Anomalies: Validating PAGER’s Internal Charging Models in GEO

The prediction of adverse effects of geomagnetic storms and energetic radiation (PAGER) project aims to provide a framework for space weather and related effects forecasts. An innovative feature included in PAGER involves integrating an automated process downstream of space weather models to assess both surface and internal charging, enabling the forecasting of spacecraft charging risks for geostationary earth orbit (GEO) and medium earth orbit (MEO). Relying on the versatile electron radiation belt (VERB) code to reproduce the relativistic electron flux spectrum evolution and on spacecraft plasma interaction software-internal charging (SPIS-IC) to deduce the internal charge conduction in sensitive devices from this flux, the PAGER simulation chain is also able to reproduce the electric field evolution over a long period of time in the past and for a given orbit. This simulation chain has been used to reproduce the maximum electric field strength evolution from <monospace xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2015-08-01T00:00</monospace> to <monospace xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2015-12-01T00:00</monospace> in a coaxial cable with Teflon insulation embedded on a spacecraft in GEO. This simulation has been carried out using two different conductivity models. In the first model, the radiation induced conductivity classically depends on the dose rate following a power law, while the second model uses a more refined assumptions of the material, relying on the computation of free charge carriers through a band conductivity description. The evolution of the electric field was compared with internal electrostatic discharge events that actually occurred on a satellite. The correspondence between these events and the periods of highest electric field intensity demonstrates the validity of the PAGER modeling chain for internal charging.