Estimates of Spherical Satellite Drag Coefficients in the Upper Thermosphere During Different Geomagnetic Conditions

Satellite drag coefficients are crucial for determining the neutral mass densities that affect spacecraft operations in the thermosphere. Many studies typically utilize a constant drag coefficient of 2.2 to calculate the neutral density. However, due to the variability of space environment, uncertainties in the drag coefficient can lead to significant systematic discrepancies in neutral density measurements. Satellite drag coefficient may fluctuate in the thermosphere under various geomagnetic activities and altitudes. For the first time, we calculate the spherical satellite drag coefficient using data from the “Orbital Atmospheric Density Detection Experimental Satellite,” referred to as the QX satellite. Our findings reveal that the drag coefficient can be estimated by thermospheric temperature and density, which are dependent on geomagnetic activity and altitude. At an altitude of ∼510 km, drag coefficients are adjusted to around 2.425, instead of the constant value of 2.2. Furthermore, the drag coefficient may decrease due to the significant influence of increasing geomagnetic activity, such as geomagnetic storms, on thermospheric density and temperature. These estimates of the drag coefficient can also be used to reduce discrepancies when deducing the ballistic coefficient. Consequently, using the estimated drag coefficient can accurately determine the QX‐derived neutral density, which agrees well with the density from Swarm‐B satellite. Plain Language Summary Satellite drag coefficient is a key factor in advancing space engineering and understanding the impacts of space weather conditions on satellites in the thermosphere. It helps in calculating the neutral mass density associated with atmospheric drag force and estimating the satellite orbital lifetime. In this study, it is the first time calculating the spherical satellite drag coefficient using data from QX satellite, collected from 28 July 2022 to 30 June 2023. We investigate the response of the drag coefficient to thermospheric temperature and density under different geomagnetic activities and altitudes. These relationships allow us to estimate the spherical satellite drag coefficient, which in turn helps us improve the accuracy of determining the ballistic coefficient and the corresponding neutral mass density. Compared with the results of the drag constant of 2.2, the QX‐derived densities determined using the estimated drag coefficients, align well with the in‐situ observations from Swarm Pre