ISTR the genesis of the project was a days-long Galileo outage, back when it was in "testing but probably usable" phase, and a stark lack of transparency or upd

ISTR the genesis of the project was a days-long Galileo outage, back when it was in "testing but probably usable" phase, and a stark lack of transparency or updates from the folks running the network. But it's not exactly hidden, you can infer quite a lot of things about the satellite status, if you just listen to what they're telling you. The trouble is, they're all over and moving fast, so you need a lot of friends with receivers to feed you the data, then you can put together a picture of the constellation health. Ergo, Galmon. Since then, it's turned out that a bit of sunlight on the operation of all four GNSS constellations, not just Galileo, has revealed quite a lot about their inner workings, availability, and health of individual satellites. One bird in particular was launched into a wrong-but-not-useless orbit by a rocket failure that juuuuust barely got it up there but didn't finish the job. Trouble is, most receiver software assumes the orbits are very nearly circular, and a highly elliptical orbit is both problematic if used for general navigation, and a useful source for testing more robust receiver software that can compensate for it. (Maybe the software wasn't correcting for other satellites' slight ellipsity as well as it could either.) So Galmon provides a view of that satellite's status as observed by receivers all over.