Starlink Drag Data Mapped Earth's Thermosphere in 2D

Even hundreds of kilometers above Earth, the atmosphere does not abruptly stop. In the thermosphere, trace gas molecules exert drag on low Earth orbit satellites, gradually eroding their altitudes. Researchers at Kyoto University have turned this drag into a scientific probe, using public orbit records from roughly 1,200 Starlink satellites operated by SpaceX to map variations in atmospheric density.

Led by Mamoru Yamamoto, the team reconstructed the density of the thermosphere at altitudes around 482 to 500 kilometers. By applying tomographic analysis to standard two-line element (TLE) orbital tracking sets, they tracked how drag decelerated satellites across different latitudes and longitudes. This generated what researchers describe as the first two-dimensional horizontal density map of this elusive atmospheric layer.

To check their results, the team cross-referenced the 2D density structures against direct in-situ measurements taken along the flight paths of the European Space Agency's Swarm research satellites. The derived patterns showed high consistency with the dedicated research craft.

Accurate knowledge of upper-atmosphere density is critical for predicting satellite trajectories and modeling orbital decay. Unmodeled density spikes driven by space weather can push spacecraft unexpectedly off course, complicating collision avoidance in increasingly congested orbital corridors. The researchers note that scaling the technique toward near-real-time monitoring could refine orbital tracking models without requiring dedicated atmospheric sensor payloads.

Source: habr; primary study: Springer