SpaceX publishes Starlink orbit files three times a day so its satellites do not collide with anything else, and one week of them was enough to reconstruct the density of the air 482 kilometres up, lo

A researcher at Kyoto University says the technique had only ever been tested on numbers a computer generated. He has now run it 19 times on public Starlink data and checked the answer against two European satellites that derive density from their own GPS tracking. Every eight hours, a set of files is refreshed on a SpaceX server. Each one predicts where a Starlink satellite will be for the next 72 hours, minute by minute, with its velocity and a covariance matrix alongside. The point of the exercise is to keep... [7406 chars]