The Caretaker's Array is a space station built by the entity known only as the Caretaker. It was built in order to allow the Caretaker to bring ships from all over the galaxy (we are only aware of Alpha Quadrant captures) in order to try to extend his life and find a way to keep his species from dying out. The array sent energy to the Ocampa planet in order to power the systems in the Ocampa habitat under the surface.
The array was destroyed by Captain Janeway in order to keep it out of the hands of the Kazon. This act stranded the USS Voyager in the Delta Quadrant. Before it was destroyed the array was damaged by the battle with the Kazon and Chakotay's ship crashing into it possibly rendering it unable to have been used to send them home. However they were not able to determine how to operate the systems on the station and with the death of the Caretaker made using it much more difficult.