Starlink Satellites Used to Measure Atmospheric Density

Starlink satellites, numbering over 11,000 in orbit, are utilized to measure atmospheric density through their aerodynamic drag. As these satellites orbit Earth at approximately 480 km, they experience drag that affects their altitude, providing data on air pressure. The sink rate, which indicates how many meters a satellite would lose in altitude if its thrusters were turned off, varies daily based on solar activity. For instance, during a G4 geomagnetic storm on January 20, 2026, the sink rate peaked at 127.6 m/day, while it dropped to 19.7 m/day on August 10, 2026, the quietest day of the year. The data collected from Starlink satellites is complemented by measurements from other satellite constellations, including Planet Labs' SuperDoves, Amazon's Kuiper satellites, and Eutelsat's OneWeb satellites. This collaborative effort allows researchers to monitor changes in the atmosphere in response to solar activity, providing insights into atmospheric dynamics and improving orbit prediction models. The index measuring atmospheric density is updated daily based on tracking data from the US Space Force's 18th Space Defense Squadron, which monitors all objects in orbit. The measurements have shown that the thermosphere's density can vary significantly, impacting satellite operations and collision avoidance strategies.