Mamoru Yamamoto, Takuya Sori
Abstract This study examines the feasibility of utilizing Two-Line Element (TLE) data from Starlink satellites to estimate thermospheric density. TLE data for satellites in orbital decay were collected from September 19 to November 6, 2024. Using the method of Picone et al., J Geophys Res, (2005), thermospheric density was derived from the time derivative of the satellites’ mean motion and assessed not as an absolute value, but as a relative variation to the NRLMSIS 2.1 model. The density estimates followed well with the model values below 400 km, although occasional deviations of a factor of 2–3 were found at higher altitudes. Three notable density increases were observed on October 8, 11, and 18–20, 2024. The first two events are well associated with geomagnetic storms. The density perturbations appeared across the most altitude range and lasted approximately one day. The third event, however, showed a weak association with the geomagnetic disturbance, persisted for several days, and was limited to altitudes above 400 km. Our findings confirm that contemporary TLE data are a valuable resource for monitoring thermospheric density dynamics. Graphical Abstract