Kyoto team maps thermosphere density with drag from about 1,200 Starlink satellites

Kyoto University researchers used orbital changes from about 1,200 Starlink satellites to produce a tomographic map of thermospheric density near 482 kilometers above Earth, SciTechDaily reported, citing Earth, Planets and Space. Drag from sparse upper-atmosphere particles slowly lowers satellite speed and altitude, and the effect strengthens when solar activity and geomagnetic storms expand the region. The team treated the constellation as a sensor network, deriving energy loss from public ephemeris records and applying tomography to estimate density across latitude and longitude. Corresponding author Mamoru Yamamoto called the work multidisciplinary space science and engineering. Results aligned with density variations measured by ESA SWARM satellites. The thermosphere spans about 100 to 1,000 kilometers and is more than 99 percent electrically neutral gas there. Future versions could track density near real time for space-weather forecasts and debris path estimates.