Erebus

Erebus, or Sol IX, is the largest rocky world in the Sol system and also its most remote resident, fully 1000 AU out from the star. The planet itself is geologically unremarkable and barren of strategic resources. These factors combined would typically make Erebus wholly unsuited for colonization, but its unique blend of proximity to Earth and remoteness to in-system traffic and scans made it a very appealing location for the nascent Starfleet Intelligence, searching for a permanent home in the early days after ratification in the 2160s.

While most administrative functions were relocated to the newly-built Kestrel Station in Luna orbit in the wake of Khitomer and the Cartwright Conspiracy for the purpose of "increased transparency", most day-to-day operations are still hosted by the 'black hole' found in the 30-kilometer Akiya crater. Famed for perhaps the tightest level of information security in the galaxy, Erebus Base is a multi-tiered pyramid capped with a large runabout hangar. A sub-surface 'crypt' hosts an assortment of the Federation's most powerful computer banks.

Erebus' small moon Thanatos (a measly 14 kilometers in diameter) hosts the cleverly named Thanatos Base, a pocket shipyard built inside a wide cavern and designed specifically to facilitate specialized refits and mission modules for SFI's fleet of vessels, a role it shares with the larger 'black yard' located at Sargasso.