Ohhhhhhh, Destiny's Traveller.The Traveler's origins are unknown. When it arrived, humanity first discovered it on Mars. It sparked a Golden Age of humanity that allowed humans to migrate from Earth to colonize other planets within the Solar System. Some speculate that the Traveler is a large vessel; others believe that it is a sentient being or artificial intelligence and some may even consider it a deity. As of yet its true nature is unknown.
The Traveler is credited with humanity's survival during the Collapse of the Golden Age. After the Traveler sacrificed itself to save humanity, it remained in low orbit over the Earth, and became silent and dormant. The City was built in its shadow and under its protection, where its inhabitants are temporarily safe from the threat of the Darkness.
Source- destiny wiki
As you say.