All that remains...

Eagle-20 explores the hidden chambers beneath The Lighthouse on Mercury. Perhaps Osiris himself once hid in this tiny alcove, before setting off in search of Oryx, the Taken King. All Eagle-20 and his Ghost find are the skeletal remains of an unknown person (perhaps a Disciple of Osiris), a small living space tucked within the alcove, and a couple of dead Vex Goblins near an inert Vex portal.

Some theorize that The Lighthouse will be populated with vendors and other characters once The Taken King launches; this seems likely, considering the many vacant stalls throughout the upper level, as well as a section that is sealed off by a Vex barrier.