The Concept and Importance of the Planetary Barometer
Astronomer Tony Phillips has devised a novel way to monitor changes in the density of Earth’s upper atmosphere by analyzing orbital data from hundreds of Starlink satellites. This innovative metric, called the 'planetary barometer,' measures variations in air density at roughly 480 kilometers altitude, reflecting conditions that influence satellite drag. Updated every day and publicly available, this tool offers a continuous view of the upper atmosphere without requiring new satellite launches.
Since early 2026, the descent rates of Starlink satellites, as recorded by the planetary barometer, have ranged from 19.7 meters to 127.6 meters per day. The peak descent speed of 127.6 meters was observed during a strong geomagnetic storm in January 2026. To validate these findings, data from other satellites—including Planet Labs’ SuperDove (which lack propulsion systems), Amazon’s Kuiper, and Eutelsat OneWeb—are also used, allowing accurate tracking of altitude changes.
Challenges and Benefits of Continuous Monitoring
While the planetary barometer provides valuable insights, it smooths out abrupt atmospheric changes over several days, which is a noted limitation. Nonetheless, leveraging Starlink’s extensive satellite network enables effective, ongoing surveillance of the upper atmosphere’s state. Tony Phillips highlights this measurement as a crucial tool for understanding atmospheric dynamics at high altitudes.
"This measurement is a vital tool for studying changes in Earth's upper atmosphere." – Tony Phillips
This advancement exemplifies the growing role of satellite technology in scientific research. Beyond atmospheric studies, the planetary barometer holds promise for forecasting space weather conditions that impact satellite operations. Given the critical dependence of modern technology on satellite communications, maintaining real-time awareness of atmospheric variations is essential for ensuring the reliability and safety of orbital systems.