Aside from global access to cat videos, the presence of thousands of Starlink broadband internet access satellites in LEO has a very pleasant side effect for atmospheric researchers. Starlink publicly publishes near-real-time ephemeris data on its individual satellites. From this data you can deduce many details about the atmosphere at that altitude, including its density at specific altitudes at specific times, information which otherwise would be very hard to gather. Recently, this allowed [Mamoru Yamamoto] to determine the density of the thermosphere using tomography.

In a similar 2025 paper by [Zhuoliang Ou] et al. as published in Remote Sensing, this same data source was used to investigate details of the thermosphere. With Starlink publishing this data since 2021, this provides an invaluable dataset for studying this outermost part of the atmosphere.

Commencing just before the generally recognized transition into ‘space’ at 100 km altitude and below the Earth’s exosphere, the thermosphere‘s thickness fluctuates due to factors like solar irradiation and, with it, the exact altitude at which the exosphere begins. Generally, though, it is well above 600 km altitude. This places Starlink satellites as well as both active space stations (ISS and Tiangong) in the thermosphere.

[Zuholiang Ou] et al. established that the Starlink data matches well with that from a dedicated research satellite like SWARM-B, thus making it a useful source of scientific data.

The innovation in [Yamamoto-san]’s paper is that instead of using the typical two-line element (TLE) set, a more comprehensive tomographic approach was used, which essentially uses more data for a larger reconstruction, with the resolution claimed to be about on par with that of the SWARM satellites. This implies that although these Starlink satellites were never designed to be more than data relays, they may have accidentally become the biggest development in thermospheric research in a long time.

Of course, you can’t please everyone.