Upper thermosphere is a tenuous region compared with the lower atmosphere, yet its interaction with the outer space and its drastic variability have made it a very challenging domain for atmospheric modelers. Although increasing number of dedicated ground-based, aerial and space-borne missions to study this region is a promising sign for the improvement of current models at these altitudes, yet limited spatiotemporal coverage of related missions ties scientist’s hands with very limited observations, in particular at high solar/geomagnetic activity periods.

To compensate for this shortcoming we use ephemerides of NORAD-indexed objects observed over the past five solar cycles to study how the Earth’s space-atmosphere interaction region (SAIR) responds to solar activity. We present a computationally simplified technique that simultaneously solves the motion equations for Daily Decay Rate (DDR) and cross‐sectional area to mass ratio (A/m) of orbiters from consecutive two line element (TLE) records.

With this technique we evaluate more than 50 million TLE records to estimate (for the first time) A/m of more than 15,000 orbiters (including non-functional satellites and debris) and determine how DDR varies. We develop two models based on two widely used density models, i.e. NRLMSISE‐00 and DTM-2013, and compare the observed DDRs with them. Our results show consistency with previous studies in terms of general thermospheric behavior such as the thermospheric “Natural Thermostat”. We discuss possible sources of uncertainties in the results and provide some suggestions for the improvement of current models with the data that are already in hand.