Improving Thermosphere Density Data and Forecast Capability Through Utilization of Satellite Constellation

Thermosphere neutral density (TND) is important for studying coupling processes within the Earth’s Ionosphere-Thermosphere-Magnetosphere (ITM) and for orbit determination of satellites in the Low Earth Orbit (LEO). Predicting and estimating TND is challenging because of the variability in the solar radiation inputs at different wavelengths and energy dissipation by auroral electric fields and currents in the polar ionospheres, space weather events such as geomagnetic storms, the interactions between atmospheric neutral molecules/atoms and charged particles, can results in significant changes in the density of neutral atoms and molecules. Since satellite drag is directly related to thermosphere neutral density, there is a substantial interest for operational modeling and prediction of the thermosphere. Large constellations of commercial SmallSats equipped with Global Navigation Satellite System (GNSS) devices bring the opportunity and make them valuable sources of Precision Orbit Determination (POD) information. Additional ability to monitor satellite attitudes enables the construction of more accurate force model. These information can be combined to derive the TND and then use the derived TND to initialize and constrain physics based ITM models. To this end, NOAA NESDIS Office of Space Weather Observations (SWO) and Space Weather Prediction Center (SWPC) are conducting a study to explore the potential of using orbit ephemeris to derive on-orbit neutral density from a large number of SpaceX Starlink satellites and utilize these measurements in a data-assimilative system with the Whole Atmosphere Model-Ionosphere Plasmasphere Electrodynamics (WAM-IPE), and evaluate the performance improvement in the specification and forecasts of TND. We will discuss the status of the retrieval of the thermosphere neutral density data from the Starlink constellation, the validation of derived TND with the high accuracy satellite drag model (HASDM), and the progress towards the implementation of a data assimilative system with the WAM-IPE model.