Here is a RadioLab podcast [0] about the system from company Persistent Surveillance Systems [1].
An interesting dimension to systems similar to the US military's Gorgon Stare [2] program is that they are generalized rather than specific, unlike a quad following a specific person(s).
0. https://radiolab.org/podcast/eye-sky
2. https://longreads.com/2019/06/21/nothing-kept-me-up-at-night...