SODA – A tool to predict storm-induced orbit decays for low Earth-orbiting satellites

Due to the rapidly increasing technological progress in the last decades, the issue of space weather and its influences on our everyday life has more and more importance. Today, satellite-based navigation plays a key role in aviation, logistic, and transportation systems. With the strong rise of the current solar cycle 25 the number and intensity of solar eruptions increasesd. The forecasting tool SODA (Satellite Orbit DecAy) is based on an interdisciplinary analysis of space geodetic observations and solar wind in-situ measurements. It allows the prediction of the impact of in-situ measured interplanetary coronal mass ejections (ICMEs) on the altitude of low Earth-orbiting satellites at 490 km with a lead time of about 20 h, which is defined as the time difference between measuring the minimum Bz component and the orbit decay reaching its maximum. Additionally, it classifies the severeness of the expected geomagnetic storm in the form of the Space Weather G–scale from the National Oceanic and Atmospheric Administration (NOAA). For the establishment and validation of SODA, we examined 360 ICME events over a period of 21 years. Appropriated variations in the thermospheric neutral mass density, were derived mainly from measurements of the Gravity Recovery and Climate Experiment (GRACE) satellite mission. Related changes in the interplanetary magnetic field component Bz were investigated from real-time measurements using data from spacecraft located at the Lagrange point L1. The analysis of the ICME-induced orbit decays and the interplanetary magnetic field showed a strong correlation as well as a time delay between the ICME and the associated thermospheric response. The derived results are implemented in the forecasting tool SODA, which is integrated into the Space Safety Program (Ionospheric Weather Expert Service Center; I.161) of the European Space Agency (ESA).