This was the transfer stage that carried IP ComSat II up towards its initial placement orbit above the pole of Kerbin, there it was detached and de-orbited. However, it appears that the force of the decoupler was enough to lift it back out of the atmosphere. Initially planned for a 65km periapsis, the debris now has a periapsis roughly 500m outside of the atmosphere. It will remain in orbit, perhaps used for a new astronaut training mission like previous orbital debris.
