Coopersworld was an inhabited planet.

In 2328, this was the point of embarkation for T. Roller. He traveled to Mars City Station on the SS Manoa. (TNG-R: "Inheritance", okudagram)

This planet was only mentioned in writing.
The planet was named after camera and electrical department electrician Brian Cooper.
In the original version of the episode, the original okudagram stated that Ronnie Knox boarded a transport ship at Coopersworld bound for Johnson Station.