alt Hacker NewsIt's not exactly the first, this is the first (unclassified, that we know about) satellite to go up and grapple a satellite in geostationary and provide stationkeeping functions for it, which did so back in 2020:
https://en.wikipedia.org/wiki/Mission_Extension_Vehicle
This is all very novel because in the relatively long history of humans sticking stuff in geostationary orbit, not once until 2020 had any sort of mission gone out to geostationary and intentionally grappled or docked with another satellite.
The multi-purpose robotic manipulation makes this a bit more advanced and experimental than the dedicated MEV attachment, as useful and performant as the MEV has been. China also demonstrated robotic grappling and towing in GEO in 2021. A few other US and European experimental robotic servicing missions in the pipeline, involving both Active Debris Removal grappling and robotic arms playing with designated payloads and attachment interfaces, but mostly planned for LEO.
There's a tendency for such experimental servicing missions (e.g DARPA Orbital Express) to take place in lower orbits, along with all the crewed space station docking and shuttle servicing missions. LEO is cheaper for servicing demonstrations, more human-friendly and also where the Hubble Space Telescope that took a fair bit of servicing happens to be based. But for the robotics, sufficiently advanced autonomy for the latency not to be a major issue is also important.