The 2022 Starlink Geomagnetic Storms: Global Thermospheric Response to a High-Latitude Ionospheric Driver

In this study, we present ionospheric observations of field-aligned currents from AMPERE and the ESA Swarm A satellite, in conjunction with high-resolution thermospheric density measurements from accelerometers on board Swarm C and GRACE-FO, for the third and 4 February 2022 geomagnetic storms that led to the loss of 38 Starlink internet satellites. We study the global storm time response of the thermospheric density enhancements, including their decay and latitudinal distribution. We find that the thermospheric density enhances globally in response to high-latitude energy input from the magnetosphere-solar wind system and takes at least a full day to recover to pre-storm density levels. We also find that the greatest density perturbations occur at polar latitudes consistent with the magnetosphere-ionosphere dayside cusp, and that there appeared to be a saturation of the thermospheric density during the geomagnetic storm on the fourth. Our results highlight the critical importance of high-latitude ionospheric observations when diagnosing potentially hazardous conditions for low-Earth-orbit satellites. Upwards of a 100 km altitude lies the boundary between Earth's atmosphere and space, where the density of air exponentially decreases and many satellites constellations orbit. One of these constellations is Starlink, which provides satellite internet to customers on Earth. In February 2022, a pair of geomagnetic storms stuck Earth shortly after the launch of 49 Starlink satellites, heating the upper atmosphere and causing its density to drastically increase. The higher air density at the initial staging altitude of Starlink caused fatal drag conditions for 38 of the spacecraft, resulting in their destruction a few days later. This paper examines how the air density of the upper atmosphere changed globally in response to space weather energy being deposited at high latitudes during the Starlink geomagnetic storms of February 2022. Ionospheric field-aligned current and thermospheric neutral densities are examined for the 2022 Starlink geomagnetic storms The field-aligned currents changed quickly, whilst the density decayed slowly and with differing timescales Asymmetric latitudinal density distributions are consistent with asymmetries in the field aligned currents