US military is the only entity that provides data to the public for free; but they only provide TLEs which aren't sufficient for close passes. TLEs are processe

US military is the only entity that provides data to the public for free; but they only provide TLEs which aren't sufficient for close passes. TLEs are processed (they are just like JPEGs in cameras, in a sense), what you need for reliable prediction is raw measurements (which they don't publish). There are also commercial networks used by satellite operators for precise orbit determination of objects of particular interest. (i.e. about to collide). Satellite laser ranging is also nothing new, it's used for GNSS and other satellites requiring determination accuracy. But current instruments mostly work with retroreflectors on the satellites, and the coverage is a problem since the orbit can only be predicted for a limited amount of time.