Epsilon Eridani

The Epsilon Eridani system, located 10.5 light years from Sol, is a notable slipspace crossroads system of the Human Sphere and formerly one the most notable human-inhabited system outside SolCore.

Cartography
The Epsilon Eridani system located in the Kepler Sector is one of the important slipspace junctions controlled by the Phoenix Initiative. From here, huge amounts of traffic passes through from Sol to either flow down the Via Serena towards the Perseus-side Inner Colonies, the furthest reaches of the Orion-Eridanus Quadrant, and almost a dozen other systems of both minor and major importance. Its position used to be far more important, but the destruction of Reach and decimation of its other major worlds have forced traders to find new routes that bypass the system.

The Via Serena trade route directly connects Epsilon Eridani to Sol and Tau Ceti. The Eridanus Spine links up with the former colony of Verne in the Gliese 185, which used to be the most popular route to the Eridanus-Orion Region. However, the recent discovery and rapid development of the New Eridanus Route, which diverts through the Gliese 86 system, has since eclipsed it. Although not the most loyal of worlds, merchants and tourists frequently make direct trips to the corporate paradise-worlds of Andesia and Gilgamesh in the Asimov and Anu systems, respectively. Epsilon Eridani can also be reached from the Sirius, Procyon, Sigma Octanus, 61 Ursae Majoris, Gliese 176, and UV Ceti systems. The Soell system, home to the wreckage of Halo Installation 04, can be reached by military vessels from Epsilon Eridani as well.

Planetary system
The Epsilon Eridani system is home to four inhabited planets, two asteroid belts, and several gas giants and minor planets. Planets are listed in order of orbital position.

Hadur
A small, metal-rich rocky planet orbiting close to Epsilon Eridani. Hosts a minor mining colony and orbital refineries.

Reach
One of humanity's oldest and formerly prosperous colony worlds, Reach served as the nexus of the UNSC military until its glassing in the Fall of Reach. Since the war, a recovery effort has been ongoing, though this is projected to take around two centuries. Reach has two moons, Csodaszarvas and Turul.

Tribute
The most prominent civilian colony in the Epsilon Eridani system and a notable hub of commerce and industry. Though it was attacked, Tribute was spared full glassing and was reclaimed for human habitation in the post-war decades.

Circumstance
A large ocean world that lies at the edge of Epsilon Eridani's Goldilocks zone, Circumstance's surface is entirely covered in a vast ocean which freezes toward the poles, leaving only a narrow temperate band around the planet's equator. While famous in the modern day for high courts and academies of justice, Circumstance was originally important for the resources and the industry needed to tame the Epsilon Eridani system. Its peculiar orbit keeps it near known slipspace jump points, which made the planet a crossroads of the system and the first step for colonists from Earth. Befitting its nature as a waystation, most of Circumstance's settlements are atop its gravity well in several orbital stations, though the planet also hosts surface cities on floating seasteads, along with various undersea research stations. Natively home to a rather primitive aquatic ecosystem, Circumstance also hosted a notable cetacean transplantation and intelligence research project early on in its history.

Today, Circumstance hosts several aquatic farms created during the Covenant War to feed the rest of the Epsilon Eridani system due to shortages created by the loss of out-system agri-worlds. During the Covenant invasion of the Epsilon Eridani system, Circumstance was attacked by Jiralhanae-led raiding parties, though it never received the attention given to the larger colonies in the system. Still, much of the population either escaped or were killed, and many of the seaborne arcologies were destroyed. After the retake of the Epsilon Eridani system, plans were laid for the recolonization of the planet and the restoration of the more intact seastead cities and orbital habitats. The surface colonies expanded in the post-war era as a dumping ground for refugees from Reach and Tribute, as well as migrants and refugees from elsewhere in the human sphere. A portion of the refugees who did not go on to settle on other worlds now inhabit vast raft-cities built in and around the ruins of the world's seastead arcologies, as the influx of population too fast for the formal rebuilding and expansion of those seasteads to accommodate. Yet more have crowded the orbital communities awaiting for the Phoenix Initiative's resettlement plans to come to fruition.

One of the original stations built to support the colonization of the Epsilon Eridani system. Niven Station is also the largest spin-gravity station ever built in Human territory, having been built with three 770-meter rings and expanded until the Dzhanibekov Effect threatened its stability.
 * Niven Station

Inner Asteroid Belt
The system's inner asteroid belt houses Epsilon Eridani's longest-lasting asteroid mining operations. While these operations are largely automated, a handful of more developed asteroid colonies exist there, serving as waystations between the inner and outer system.

Aegir
A gas giant classically designated Epsilon Eridani b. Orbiting fairly close to the system's inner asteroid belt, Aegir (formally Ægir) is home to the system's primary helium-3 and hydrogen scooping operations and several lesser colonies on its moons. The most prominent moons are named after figures associated with Ægir from Norse mythology.

The second-largest moon of Aegir, Snaer (formally Snær) is an icy moon hosting a relatively small surface colony in the form of various subsurface warrens and domes.
 * Snaer

Beta Gabriel
A small, uninhabitable ice planet with a subsurface ocean. A smattering of arcologies (including a peculiar domed-off artificial 'wilderness preserve' created by a private corporation as a retreat for the wealthy) brought the planetary population up to a few hundred thousand. Prohibitive cost of development prevented settlement even by desperate evacuees from the outer colonies.

Outer Asteroid Belt
While the mining claims in the outer belt are more recent than those in the inner one, development of the infrastructure at Tantalus has steadily increased interest in the outer belt's riches since the mid-25th century.

Tantalus
Gas/ice giant classically designated Epsilon Eridani c. Tantalus serves as the hub of commercial operations in the outer Epsilon Eridani system. The planet is scooped for fusion fuels, largely serving mining efforts in the outer asteroid belt. Tantalus houses various mining and scientific colonies and outposts on its moons and in orbit. Despite Covenant raids, these emerged relatively unscathed from the invasion, though small groups of Kig-Yar and Unggoy set up shop on the moon-colonies of Broteas and Niobe; shortly after Operation: FORTRESS SIEGE, these groups surrendered with little resistance. The most prominent moons are named after figures associated with Tantalus from Greek mythology. Was defended by a Naval flotilla before the Fall of Reach.

The most massive of Tantalus' moons, Broteas is a metal-rich rocky world. The moon houses a mining colony whose products are sent to the inner system via mass drivers.
 * Broteas

Tantalus' second-largest moon, Niobe is an icy body relatively analogous in structure and size to Sol's Ganymede.
 * Niobe


 * Pelops


 * Dascylus

Jericho
Gas/ice giant classically designated Epsilon Eridani d. Scooped for fusion fuels for local use and housed orbital UNSC outposts along with a defense flotilla. Jericho had no civilian presence; following the initial surveys of the planet in the 24th century, the UNSC promptly declared it off-limits, followed by the establishment of an Office of Naval Intelligence base, Teller Station, on the moon cryptically designated Site 17. Numerous rumors surround this facility and Jericho, with many conspiracy theories claiming that the planet was sequestered due to the presence of ancient alien technology or questionable experimentation.

Early-warning system
The Epsilon Eridani early-warning network was extensive, comprising various automated and manned remote-sensing and reporting satellites with a focus on monitoring likely slipspace entry points and inbound trajectories. In the 2550s, these systems were supplemented with early wavespace communicators connected to the system's nascent slipstream comm buoy network, enabling them to get messages across to Reach much faster than before. Some of the more notable platforms included:


 * RSOs Fermion, Boson, Axino, and Dyon in the inner cometary belt.
 * RSOs Hadron, Baryon, and Meson in the L3, L4, and L5 Lagrange points, respectively, between Aegir and Epsilon Eridani.