Some roleplaying materials suggest that the Empire blows up an Ewok village while clearing the area for their Garrison and Shield Projector complex. Than this scary looking skeletal sphere with the ominous eye came and stayed in the sky over the new metal platform where there was once an Ewok village. The Ewoks don't know what to make of it, but its kind of scary. The Empire may or may not have cared what they were clearing out to put in the garrison, since all they needed was a reasonable surface location for the Death Star II to remain in orbit over. One wonders if they built the frame there at Endor, or if they had been building it elsewhere, and moved it to the remote Endor system later.