Starlink Satellites Used to Map Earth’s Hidden Upper Atmosphere

Mapping the Invisible Layer 500 Kilometers Up

Researchers have mapped Earth’s upper atmosphere using orbital data from approximately 1,200 Starlink internet satellites, creating a detailed density profile roughly 500 kilometers above the surface. Published in Earth, Planets, and Space, the new tomographic approach captures thermospheric changes that are notoriously difficult to observe directly. The breakthrough provides critical data to sharpen satellite tracking and mitigate growing collision risks in crowded low Earth orbits.

Spacecraft in low Earth orbit travel through an extremely thin, invisible layer known as the thermosphere. Spanning from about 100 to 1,000 kilometers above the planet, the region appears to be empty space. Yet sparse residual gas particles create aerodynamic drag that gradually reduces a spacecraft’s speed and altitude. Solar activity and geomagnetic storms heat and expand this upper atmosphere.

Treating a Megaconstellation as a Sensor Network

To capture these invisible shifts, researchers at Kyoto University treated the massive Starlink constellation as a vast network of moving sensors. The team calculated the tiny losses in orbital energy experienced by roughly 1,200 satellites using publicly available ephemeris data. By applying tomography—a mathematical reconstruction method typically used in medical scans—the researchers mapped how atmospheric density varied across different geographic coordinates.

Corresponding author Mamoru Yamamoto noted that the breakthrough stems from bridging two distinct disciplines. Reading papers from both space science and space engineering, Yamamoto explained that deeper dialogue between researchers from both fields is necessary to unlock these insights. Most previous spacecraft observations gathered data strictly along a single satellite’s individual path, comparable to learning about a landscape by following a single road.

Verifying Data Against ESA Satellites

The new two-dimensional map covers both latitude and longitude, offering a significantly wider snapshot of thermospheric behavior than past single-track observations. The team verified their results against density variations measured by the European Space Agency’s SWARM satellites, ensuring an independent check on the reconstruction method. This work builds on an earlier study by the Kyoto University team that utilized Two-Line Element records to examine density changes over time and altitude.

Real-Time Tracking for Crowded Orbits

Future iterations of this technique could eventually track thermospheric density variations close to real time. These high-resolution maps could substantially improve space weather forecasting, satellite reentry predictions, and the safety of maneuvers designed to dodge space debris in increasingly congested orbital corridors.