From Destinypedia, the Destiny wiki
Eternity is a large facility within the Bray Exoscience. It is disconnected from the main Exoscience facility as it suffered destruction near the connecting areas. The facility served as depository to store Exo mind scans and later became a target for House of Salvation, who were conducting their own research on Exo's. The location is prominently featured in the Empire Hunt: The Technocrat, where Praksis, the Technocrat attempted to secure access to the main Exo memory bank.
Following the Technocrat's defeat, the Fallen continued to patrol the facility and enlisted the Salvation Elites such as Teraks and Weniks to safeguard a few Crux of Darkness. Drake, Charge Courier also patrols the facility and defeating the Dreg will help gain access to a Penguin Souvenir. Augment Drones can also be found in the location and require an Augment Scanner to destroy.