Gamemaster Sixth Orbital Zone: Jovian System (IF)

Solar Hard SF Setting

Jupiter dominates the sixth orbit, a vast gas giant whose gravity and radiation shape everything around it. No one lives on the planet itself, but its moons and surrounding space host one of the most important civilizations in the system. The four Galilean moons — volcanic Io, ice-shrouded Europa, massive Ganymede, and cratered Callisto — are the heart of Jovian space. Dozens of smaller moons carry outposts and mines, while the planet’s two great Trojan asteroid belts are lightly explored frontiers. Together, all this forms the Jovian system: fortified, industrious, and proud of surviving the Fall intact.

The Jovians weathered Icarus Fall better than almost anyone. They never relied on solar power, already lived under heavy shielding against Jupiter’s fierce radiation belts, so when the inner system faltered, the Jovians endured. More than that — they could afford to send aid, and in their eyes that settled the old debts to Earth. To Jovian thinking, they earned independence by survival and sacrifice. Earthforce disagrees, but in the outer system the Jovian view literally holds a lot of weight.

Jovian Society

Unlike the socially fragmented Belt, Jovians share a common culture. Colonies among the moons are close enough for constant travel and trade, and over generations this fostered a strong sense of shared identity. Many early settlers came from Luna, bringing the Lunar frontier ethic of tireless work and communal responsibility. While the Belt fractured into communes and sects, Jovians developed a more unified outlook: proud, industrious, and tightly knit. A few colonies remain under Earth or Belt cultural norms, tolerated as foreign concessions, but never considered truly Jovian.

Work shapes life. Every Jovian is expected to maintain both a vocation in service of the colony and an avocation in service of themselves or their community. The workday divides neatly: four hours for your trade, four hours for your chosen pursuit, whether art, music, education, or public service. This dual ethic keeps society cohesive: a miner might also be a poet, a pilot might serve in a gardening club, and your cab driver could share a debating hall with the local baron. Status comes not only from wealth but from the quality of your contributions through both work and culture.

Radiation remains a fact of life. Drones do much of the work, but solar storms and Jupiter’s magnetosphere demand close human oversight. To Jovians, risk is inseparable from reward, and stepping into danger earns respect. They have become masters of shielding, pioneering Aegis, a compact superconducting magnetospheres that supplement traditional armor. These fields cannot keep you safe forever, but they give hours where once you had only minutes. The catch is that they project far beyond the suit, interfering with each other when brought too close. As a result, Jovian workers and warriors operate with enforced spacing — alone, or in loose constellations. This fact of physics helped shape a culture of individual daring, where recognition belongs to those who face the void alone.

Jovians live densely. Habitats in the system hold half again as many people as comparable stations elsewhere. Private quarters are small, communal halls and parks are large, and most citizens are accustomed to finding relaxation in public spaces rather than behind walls. The result is a society that values connection, ritual, and the shared stage. It is more formal than the Belt, less rigid than Earth — a civilization both pragmatic and proud, conscious of its hard-earned independence and determined to hold it.

Jovian society is layered. The original pioneers, many still alive through life-extension, hold lasting power. Their descendants often call themselves barons, dukes, or counts, adopting the trappings of nobility. Customs vary — some colonies follow strict primogeniture, others scatter titles among a dozen heirs — but in every case, noble houses remain fixtures of local politics. Yet this is not a rigid aristocracy. Guilds of miners, pilots, and engineers wield their own power, and neural pilots — trained from childhood to operate machinery by direct nerve link — hold special prestige. These “knights of the void” combine technical mastery with ritual honor, and are celebrities. Nobility provides continuity, but merit and risk can still raise an outsider to high status.

Jovian Chivalry: Knights of the Void Aegis fields have created a chivalric attitude among Jovians. Using magnetic fields to deflect radiation in much the same way a planet does, an Aegis allows pilots to survive radiation that would normally require heavy shielding, making small craft feasible. On habitats or inside capital ships, where close quarters make Aegis fields unusable, Jovians rely on conventional arms. But in open space, chivalry and technology fuse. An Aegis is more than survival — it is a badge of status, a halo of honor — and the necessary space between shields defines both tactics and society.

Since two fields cannot safely overlap, Jovian warriors fight alone or in open order, never shoulder to shoulder. Recognition belongs to the one who dares the void in solitary combat. This fostered a knightly code: courage in danger, fairness in duels, and respect for rivals who stand under their own shield.

The elite are the “knights of the void,” neural-linked pilots trained from childhood, often scions of nobility. Their duels are both battle and ceremony, with plasma arcs and auroras flashing where fields collide. Melee is chaos, dangerous to victor and vanquished alike — and thus the highest proof of honor.

Civilian guilds also use Aegis fields and neural links for mining, rescue, and construction. Less prestigious than knights, they are still skilled, and in emergencies quick to fight.

Jovian Government

• Parliament (bicameral): Olympos Parliament

• Upper house: Senate Jovia (short: Senate)
• Lower house: Comita Jovia (short: Comita; reads like “committee,” which helps)

• Cabinet/Ministers: Curia Jovia (short: Curia)

• Admin complex (executive bureaus): Capitolium (on Olympos habitat)

• In speech: “Passed by the Senate and Comita of Jovia, signed in the Capitolium.”

Full sketch, needs revising: Jovian Government.

• Not a state: the Concord is contracts + standards + ports. Sovereignty stays local (houses, habitats, guilds).
• Curia (bicameral): Chamber of Houses (founder lineages/charters) + Chamber of Commons (guilds, co-ops, syndic captains).
• Joint organs: Concord Court; Standards Board; Port & Accelerator Authority; Registry/Transponder; Treasury/Bond; Stormwatch; Aegis Safety Commission.
• Executive: tiny Secretariat runs the machinery; emergency Wardenate with time-boxed authority.
• Law in layers: House Law (internal), Guild Code (commercial/technical), Concord Law (inter-colony standards/safety).
• Enforcement without cops: escrow forfeits, port denial, accelerator embargo, transponder revocation, sanction writs; last resort = knightly interdiction in open space.
• Knights of the void: neural-linked pilots as quasi-gentry; duels legal outside habitats under Aegis rules; in-hab violence = felony.
• Foreign concessions: Earthforce/Belter enclaves under extraterritorial charters; still bound by safety closures and Stormwatch.
• Civic norm: vocation/avocation (≈4+4 hours); public service buys faster dockets and petition priority.
• Curia’s day job: keep beacons/charts synced, set storm posture, write/enforce Aegis standoff rules, coordinate ports/rails, arbitrate fast.
• Why compliance sticks: escrow-by-default, public registry/blacklists, port-master solidarity — cheat and every port closes to you.
• Failure modes: no central force, house title games, guild code capture, and storm chaos pushing decisions back to local captains.

Colonies of the Jovian System

The first Jovian outposts were scientific, to map and explore. Europa in particular was intensely explored for native life, with a ban on colonization.

True colonization began with wide-orbit habitats and ships, sending shuttles down for ice, sulfur, and metals. These extraction sites grew into colonies. Today the moons support industry, science, and culture, while heavy industry sits in free habitats beyond Jupiter’s grip. Each moon has carved out its niche, surviving through focus rather than sheer abundance.

The innermost moons of Io and Europa are inside Jupiter's radiation belt, making surface habitation impossible. The further out you go, the less of a problem this is, radiation on Ganymede is still dangerous while Callisto and the outer moons are no more irradiated than interplanetary space. Outside the four Gallilean moons, the rest are captured asteroids similar to those in the asteroid belt, irregular rocks or collections of regolith with microgravity.

The problem here is matching velocities with the moon. Using ion engines to move a habitat can take years. Instead you build a habitat in place and use ion engines for station-keeping, or to move to a nearby moon that is a part of the same cluster. These clusters are the remains of an asteroid that split into parts when it was captured by Jupiter's gravity and give the best mining opportunities.

Io: The Dragon’s Hoard

Io is no place to live. The innermost Galilean moon is a volcanic inferno, shaken by quakes and bathed in lethal radiation. Subsurface colonies are impossible, and free habitats cannot survive the belts. Instead, Io became a raiding ground — a land of dragons where danger and treasure are one.

Volcanic plumes loft exotic vapors into the acid atmosphere, where chemistry runs wild. Rare crystals, reflective “sulfur snows,” and volatile sulfide-metal compounds condense, drifting down in radiant, short-lived layers. These cannot be synthesized at such a scale and variety: only Io’s insane mix of heat, pressure, and radiation can forge them in quantity. But they are transient. Every quake, every new eruption threatens to bury, melt, or transmute the prize.

Jovian knights descend in mechs to snatch these fleeting hoards, their Aegis shields aglow from the radiation. The wealth feeds niche industries, but the true prize is honor: to survive Io is proof of mastery. To claim a trove is to risk the dragon's fury, and this danger has elevated Io from mine to myth.

Europa: The Moon of Vaults

Europa? Lovely ice, silly people — let’s not go there.

— Andry, Ganymedean entrepreneur

Long before the Fall, before any Jovian colonies, Earth declared the moon interdicted to preserve its subsurface ocean and prevent contamination of any Europid life. Drilling was done for research only. But once colonization began in earnest interdictions mean little to the colonists. By the 2180s, independent crews were already drilling through the crust, sending submersible drones into the abyss. Contamination followed — Earth microbes, engineered strains, and human industry mingling with fragile mats of native life. But something more immediately valuable grabbed human attention - Exotic ice.

Europa has transformed from the forbidden laboratory of the early Jovian era into a crowded world of exotic ice and slow feuds. The surface remains lethal — scoured by radiation and shifting crust — but far below it, cities cling to the walls of extinct cryovolcanoes that plunge hundreds of meters through the crust. These “pits” are connected to other descent routes to the buried ocean. Each began as a scientific shaft or thermal vent, later widened into a vertical harbor. Fliers and shuttles descend in luminous spirals through narrow ice shafts to reach the galleries and caverns below, where pressure and shielding make life possible.

The great pits are spaced irregularly across the hemisphere facing Jupiter. Each forms a self-contained world — a cluster of habitation rings, workshops, and hangars wrapped around the bore. Within a pit, clans share blood, labor, and danger; between pits they are rivals. Allegiance is hereditary and personal, rooted in kin oaths sworn before the ice. Politics on Europa is clan against clan, pit against pit, each guarding its ice farms in the abyss below. The strongest rule the descent shafts; the poorest sell flight rights or data. Disputes are rarely fought in the air — the true wars are waged underwater.

Below every pit lies a tethered fleet of submarines that tend the under-ice farms where exotic ices grow. In the dark ocean these fleets raid one another’s holdings, stealing seed crystals or sabotaging rival growth matrices. These “water wars” are ritualized — quick strikes for honor or vengeance, rarely total destruction — but the boundaries blur when pride or discovery is at stake. The ice beneath Europa’s crust is mapped like ancestral pasture; trespass is cause enough for battle.

Launch Windows

Europa lives by the rhythm of Jupiter’s storms. The belts above seethe with radiation, rising and falling in ten-hour tides as the giant’s magnetosphere turns. Between these surges come brief calms — narrow corridors of safety when the sky thins and ships dare to climb or descend. Every pit measures time by them: bells mark the opening, warning lights the close. Miss the moment, and the ice becomes a prison until the next lull.

During the storm hours, no craft moves. Airlocks seal, surface beacons dim, and radio fades into static. The pits turn inward, their people waiting out the surge beneath hundreds of meters of ice. Some call these the dark hours, when Europa forgets the rest of the System exists. They are feared, and sometimes cherished — a time when nothing outside can reach you.

But when the window opens, all changes. For an hour or two the sky is clear, and those who move quickly can trade, flee, or strike while others still hide. Each pit’s window comes a little early or late depending on its place around the moon, giving advantage to those who know the cycles best. More than one battle, rescue, or disappearance has turned on the minute hand of a launch clock.

The Ice Treasures of Europa

Europa’s true wealth lies not in water, but in the forms water can take. Dozens of exotic ice phases — Ice-VII through Ice-XX and the continually discovered “Jovian” series beyond — appear at specific pressures and temperatures deep within the crust. By seeding their growth with trace gases, salts, or engineered molecules, Europan foundries breed ever-new lattices with strange properties: superconductivity at cryogenic ranges, radiation absorption, or near-perfect optical clarity.

Each phase is fragile, its miracle conditional. Remove it from its native pressure or chill, and the lattice collapses — sometimes releasing a pulse of stored energy or cracking into shards. Vibration, radiation, or even a shift in magnetic field can ruin a batch. What thrives beneath the ice becomes useless, or explosive, elsewhere. Every stable piece in circulation is a relic of the depths.

Spiritual Europans regard these ices as proofs of divine or ancestral favor. A pit clan’s prestige rests on the quality of its “breed” of ice, and some rare forms are treated like heraldic metals: the Knight of Valens’ armor plated in Ice-XVIII, or Sir Jarvis’ famous fighter whose Ice-XXVI shield once rendered him invulnerable to coherent beams — for three glorious minutes. No two samples are quite alike; none can be mass-produced.

To researchers across the System, Europan ice is a treasury of potential — prototypes of technologies humanity may one day reproduce at scale. To the Jovians, it is proof that their world alone still gives birth to wonders.

The Pits Clans of Europa

Each pit is a city-state, a spiral descent wrapped in habitation galleries and lit by ice-filtered glow. The upper levels house markets, hangars, and communal halls where travelers meet under vaulted ice roofs. Mid-levels contain living quarters and refineries; the lowest hold pressure locks and sub docks leading to the ocean. Sound carries far — most architecture uses curves and baffles to keep noise from echoing into madness.

A mature pit supports tens of thousands, with farms and oxygen bioreactors woven into the walls. Ice carving and rope-flight between galleries are daily arts. Evenings are marked by auroral glow through translucent ceilings — the only hint of Jupiter’s storms above. Every pit maintains a heraldic beacon at its mouth, visible to orbiting craft: an emblem projected in laser light into the haze.

Neighboring pits may unite under a charter for trade or defense, but true unity is rare. Europa’s clans prize independence as fiercely as the Belters do. Their speech borrows from old Terran dialects, proud of archaic phrasing and titles that sound centuries out of date.

Clans on Europa are branches of off-moon clans, who support their Europan brethren at their hunt for the perfect ice. They send the noblest of their young to experience the wonder and terrors of the depths.

Lattice Herding and Raiding

New exotic ices occur naturally, but most are cultivated in immense lattices: pressure-rated frames where ice is grown from “root” crystals under arcane schedules of depth, temperature, and trace dopants. Some breeds only form during pressure change, so sections of a lattice drift between levels to step the phase.

These farms lie beyond reliable wireless links; radio is useless and sonar is short-ranged. Cabled buoy lines are not stable over time, the work needs herders: deep specialists riding pressure-easing workpods. The pods cut ambient pressure by roughly an order of magnitude — enough for structure — while pilots breathe oxygenated liquid inside flooded cabins, their bodies bearing the remainder that an air-filled hull could not. Most labor is done by dogs, drones that handle routine tasks autonomously and accept close-range whistles — encrypted acoustic cues — from the herders.

The kings of the depths are the raiders — fast, single-crew subs (often scions of off-moon houses) who strike for seed and secrets. Weapons are rare; a challenged herder yields the lane, and raiders lift select samples and data without scarring the frame. Defenders scramble their own boats to harry the thieves and force jettison. Away from lattices, both sides use shock charges to stun crews and shatter captured ice before it can be stolen.

The Earthforce Pit

Earthforce maintains a single neutral pit at Euboea Regio, the site of the earliest pre-Fall drilling. The Earthforce flag still flies there, but the Navy long since withdrew; only a handful of scholars, technicians, and old ships remain. Their radio beacons provide standard time and navigation for the whole moon, and their chapel is said to contain a sample of every ice phase ever grown. Far from the power of Earthforce, this settlement focuses entirely on science, only rarely rousing themselves to the formality of protesting the continual breaks of Earthforce isolation protocols.

Known by Europans as The Monastery, it functions half as a research base, half as a sanctuary. Its crews are respected by all and attacked by none — the science monks of the deep. Jovians at odds with the clans can seek refuge here, now making up much of the personnel. Many Jovians believe that the Monastery’s quiet endurance proves divine favor; others whisper that its archives contain lattice blueprints too dangerous to share. They study the evolution of ice forms, maintain the official lattice registry, and act as neutral mediators between warring pits. Their main task is actually to observe the life growing deep within Europas oceans, the reason the moon was once interdicted, but they keep silent about this these days to avoid brining attention to the deepest depths.

Native Life

Originally sprawling colonies of simple cells clustered around hydrothermal vents, metabolizing sulfur and metals. Over hundreds of thousands of years, these mats secreted silicate and exotic ices denser than water, creating labyrinthine “reef vaults” on the ocean floor.

When humans brough terran biocontamination, hybrids rapidly appeared; small motile grazers feeding on the mats and huge mobile mats drifting like dark carpets or translucent veils. Hybrids are unstable and localized; each unexplored vent may hold something entirely new. The speed of this process is amazing and confusing to science, it is as if Europa's life was just waiting for a purpose to start acting on its own.

The Earthforce Pit

Earthforce holds a single neutral pit at Euboea Regio, the site of the earliest pre-Fall drilling. The Earthforce flag still flies there, but the Navy long since withdrew; only a handful of scholars, technicians, and aging ships remain. Their radio beacons set standard time and navigation for the whole moon, and their data chapel is said to hold a sample of every ice phase ever grown. Far from Earth’s politics, the settlement devotes itself to study — though the inhabitants still rise, with measured ceremony, to protest violations of Earthforce isolation law that no one heeds.

Known to Europans as The Monastery, it is half research base, half sanctuary. Its crew are respected by all and attacked by none — the science monks of the deep. Jovians at odds with the pit clans may seek refuge there, swelling the ranks of the quiet order. To many Europans, the Monastery’s endurance proves divine favor; others whisper that its archives conceal lattice blueprints too dangerous to release. The scholars record new ice breeds, mediate feuds, and tend the fragile links between surface and sea.

Most of their time is spent not among the pits, but in the abyss. The Monastery alone mounts expeditions to the true deep, where the lattice farms end and Europa’s own life begins. To reach such places they deploy long strings of temporary relay buoys — singing beads that carry slow speech through the water. These lines last only a few days before shifting ice and silt choke them, forcing each mission to lay a new chain on the way down. Through them, surface crews can follow a Melusine pilot’s dive by faint echoes, each link passing word to the next until the voice fades into noise. The chains are never stable; they hum and drift, and when the song breaks, the diver is alone. For a role in such missions, outsiders may join the surface watchers — tending the buoy-strings, reading their tones like auguries, guiding the descent from far above. When the string fails, only faith and calculation remain.

No other faction uses Melusines, and the monastery avoids drawing attention to them, grateful for the one advantage they have over the clans.

Native Life

Long before humans came, the ocean floor was home to sprawling colonies of simple cells feeding on sulfur and metal at hydrothermal vents. Over ages they secreted silicate and exotic ices denser than water, raising labyrinthine “reef vaults” that entombed the vents in crystal.

After the Fall, Terran microbes mingled with these ancient forms. Hybrids soon appeared — small motile grazers feeding on the mats, immense drifting veils that move with the tides. Each vent spawns its own ecology; each discovery defies repetition. Evolution here runs unnaturally fast, as if the ocean had waited eons for an audience. The Monastery keeps silent about what it learns, for the clans above would prize such life as fiercely as their own lattices — and in seeking it, would destroy it.

Hazards and Opportunities

Europa remains perilous despite its beauty.

• Radiation storms scour the surface; power failure in a pit means death within hours.
• Cryotectonic shifts can shear descent shafts or flood them with meltwater.
• Pressure breaches in sub docks can implode whole fleets.
• Chemical ghosts — residues from ancient experiments — drift through the ocean, mutating or binding to new ices.
• Acoustic combat below the crust is a delicate art; too much sonar or shockwave risks destabilizing the lattice farms themselves.
• Subsurface caverns may trap oxygen from radiolysis, sometimes mixed with sulfur or organics. Normally harmless in vacuum, these pockets can erupt if ignited by thrusters or torches.
• Cryotectonic movement fractures the crust into canyons and twisted, maze-like fissures. If a pit is blocked, escape may be possible through this maze, at a cost of life, limb, and time.
• Exotic types of ice can have strange properties, sometimes transparent to the point of invisibility or acting as natural mirrors or lenses.
• Ferroelectric ice (Ice XI) sometimes forms in long-sealed ice caves. It is valuable, but can distort radio signals, scramble sensors, and even store dangerous electric charge.
• Aeons of mineral deposition have turned fissures and reef vaults into natural treasure vaults.

Yet fortune favors those who dare. A single new phase of ice, if stabilized, can make a clan rich for a generation. The dream of the next Ice-XXI drives Europa’s restless spirit — part science, part faith, and all ambition.

Adventure Hooks

• The Ice Treaty — A fragile peace pact between three pit clans teeters on collapse after a stolen lattice sample is displayed as a wedding gift.
• The Monastery Vault — Rumors claim Earthforce monks have found a stable metastable ice that can survive open space. Every faction wants a piece of it.
• The Depth Raiders — Sub fleets from rival pits vanish in the same trench. Something down there is hunting the hunters.
• The Shattered Shaft — A cryotectonic quake opens a new descent near a dormant vent; treasure and disaster await those who claim it first.
• The Siren’s Lattice — A new ice phase emits low-frequency tones that entrance those who hear it. Scientists call it resonance; locals call it song. Both may be right.
• The Awakened Pit — Engineers deepen an old cryovolcano pit to reach the ocean “direct,” and the conduit begins to vent on tidal cycles — geysers of slush and flash steam blasting the shaft, icing bulkheads, and cracking galleries. Evacuations clash with clan pride and sunk costs. The PCs can: seal the throat with cold collars and burst panels; cut lateral “S-bend” relief tunnels to a dock cavern; or ride herder pods to install check doors from below. Rivals may sabotage repairs to force abandonment — or steal a live lattice farm exposed by the new flow. Every fix must beat the next launch window before the pit ices shut for good.
• The Vaults Above — Cryotectonic fissures in the ice promise rare deposits. But as explorers push deeper, the ice begins to scream and shift.
• The Vaults Below — A coral-like labyrinth built by native life on the ocean floor hides under their mats. Mapping the maze could yield silicate treasures — if explorers survive.
• The Forbidden Vent — Drilling into a “dead” vent found it crawling with hybrids. Scientists want samples, knights seek honor, and everyone fears what will emerge.
• Oxygen Firestorm — A stranded crew hides in an ice cavern, unaware it holds a pocket of oxygen and volatile organics trapped by cryotectonic shifts. Normally inert, the mix only becomes explosive if ignited by a fusion thruster or plasma torch — turning the cavern into a brief but deadly inferno.
• The Smuggler’s Haul — Black-market organics from Europa’s depths are rumored to enhance neural interfaces. Earthforce wants them destroyed, scientists want them preserved, nobles want them monopolized.
• The Lost Dome — A pre-Fall research station lies buried in ice. Its records may reveal the first contamination site — or worse, what the researchers found.
• Franz's Plasma Tunneler — A Jovian inventor wants a live test of his new plasma tunnel rig to “outrun refreeze.” It works for a few hundred meters — then the bore self-chokes, pressure climbs, and the rig starts to freeze into the ice.

Ganymede, the Moon of Opportunity

Ganymede is the largest moon in the solar system — a world of rock sheathed in ancient ice. Beneath its frozen plains lie silicate mountains and buried seas; its weak magnetic field hints at a molten core still turning below. To miners it is solid ground in a realm of drift; to settlers, a cold but steady frontier.

Ganymede is Callisto’s smart but comparatively resource-poor sister — an America to Callisto’s Russia. It has a mean radius of 2,634 km, slightly larger than Earth’s Moon. Surface gravity is 1.43 m/s², about 15% of Earth’s gravity and too low for long-term health. A Ganymede day is about 7.155 Earth days long, since it is tidally locked and rotates once per orbit around Jupiter. Seen from a particular spot on Ganymede, Jupiter is always in roughly the same spot in the sky. On Ganymede's dark side Jupiter is never visible at all, while on the bright side it provides the light of a murky day on Earth. Ganymede is eclipsed by Jupiter abut every seven days, in almost total darkness for three hours called "mirk". This gives Ganymede a "week". Gamies live more on the surface than most Jovians, and they have developed a "sky pride", a fancy for seeing the sky and marking Jupiter's position at their site with pride, while telling ghost stories of the mirk.

Ganymede is culturally and genetically diverse. Ganymedians (Gamies in daily speech) live in habitats that lack Callisto’s homogeneity but show much more economic opportunity. Everybody wants to get rich and there is real opportunity here, but also literal robber barons and a streak of lawlessness. Jovian nobility is informal and often self-proclaimed. Settlement is spread across the moon in small sites that tap local resources. Long-term living needs spin gravity and thus can’t be too small, but prospectors and shift crews work from land crawlers — slow homes and extraction machines. These rigs are too cramped for more than rudimentary Regrav, so crews commute back to larger towns. When a site proves particularly valuable or strategic, it draws more crawlers and becomes permanent: rigs sell off the parts that make them mobile, bolt together, and tie into on-site builds. If a field runs out, crawlers get their legs back and move on. Ghost towns are common.

In successful settlements the population grows and a central spin habitat is built, but that comes late; as long as commuting is cheaper, people commute. In frontier belts — which is most of Ganymede — everyday Regrav happens in small local hubs linked by rail or ice-covered roads for wheeled traffic. Preferred overland travel is rail laid in tubes inside covered trenches: rough, jury-rigged, and able to flex with minor ground shifts. With no atmosphere, pressurized “bullet train” cars run fast through vacuum tubes, moving passengers quickly between connected towns. This has opened a market for eco-communes: surface spin habitats paired where visitors take their Regrav in comfort surrounded by large domed parks at Ganymede gravity for leisure.

Ganymede Settlements by Scale

Overview

• A land of scattered sites tied to spin habitats. Big money lives in orbit; ground sites tap pockets and ship value up.
• Contracts: Tier III and below run on investor funding (carried interest, syndicates), not blanket offtake. Ganymedians reject Callisto-style output options, keeping the market nimble.
• Accelerators: Only Tiers I–II host mass drivers and clear exports; lower tiers route cargo upward by hopliner/rail.

Tier VI — Galileo (capital eco-commune, surface)

• Role: Ground capital and resort. Parks, arts, baths, clinics. Spin rings for Regrav; a 1 g Skyview Park uses derotated mirror arrays to present a non-rotating sky.
• Layout: Twin spin rings (0.9–1.0 g) with an inboard Skyview Park. External periscope heads feed K-mirror/derotator optics so the stars don’t wheel; utility galleries below.
• Siting: Built along the Jovian limb (≈±85° from the sub-Jovian meridian) so Jupiter hangs a few degrees above the horizon — matching miners’ lived sky.
• Economy: Hospitality, clinics, lithium/borate certification labs, arbitration annexes. Galileo Accelerator throws high-value cans to Olympos.
• Governance: Circles Council (guilds + co-ops + resident lots). Robber-baron money whispers, but courts sit close.
• Civic rite: Mirror Day — community service polishing periscope heads and sky mirrors; visiting officials and celebrities take shifts to signal commitment.
• Links: Hopliner pads; covered-trench rail to nearby belts; priority route to Olympos (Compact Ring).
• Reputation: Ground view — capital and resort. Orbit view — coarse, cashy, go to earn then leave.

Tier V — Regional Eco-Habs (surface rehab/leisure hubs)

• Role: Rehab + leisure + staging for nearby belts (100–600 km from Galileo) and the primary export hubs outside Galileo.
• Build: One medium spin ring plus domes; clinics, schools, courts-lite.
• Accelerator: Yes — regional launcher, customs, and assay.
• Trade: Each pairs with an off-world buyer (yard, chem stack, freeport) and books export slots.
• Examples:

• Valhalla Springs: ring-arc resort; feldspar/Fe feed. Buyer: Helios Yard 3.
• Bright Chaos: lithium/borate brine town. Buyer: Ringport Aleph.

Tier IV — District Hubs (work towns)

• Role: Service nodes where 3–5 extraction spurs meet; warehousing, assay houses, repair bays; off-shift leisure for crews.
• Build: Small spin ring; pad cluster; trench-switchyard. No accelerator — exports route upward to Tier I/II.
• Finance: Investor syndicates (carried interest, offtake windows purchased ad hoc), not blanket options.
• Examples:

• Ridgegate: double-ridge corridor; steady sill taps. Lead investor: Olympos Chem Annex syndicate.
• Groove Junction: grooved-terrain crossroads; mixed plays. Lead investor: Yard Six capital pool.

Tier III — Outpost Towns (fixed sites over a single play)

• Role: One resource, one payroll; grows or dies with the lens or pit; crews still find baths, beds, and a bar.
• Build: No proper spin early; bunk domes, small Regrav wards; tools on skids. No accelerator — export by hopliner to Tier II or trans-ship via a Tier III hub.
• Finance: Outside investors back plant and pads; locals hold work shares with anti-dilution clauses (on paper).
• Examples:

• Limbview: Jovian-horizon tourism + logistics; pads over rails. Lead investor: Hesperia Freeport leisure trust.
• Chimney Haven: guarded ocean-chimney outpost; pads only; NDAs everywhere. Lead investor: Blackgate Labs consortium.

Tier II — Crawler Communes (3–12 rigs; worker-owned)

• Structure: Outside investor fronts seed capital and the claim beacon. Crews hold work shares; communal charter; decisions by weighted vote (shares + shifts).
• Pay: Subsistence (food/hab/med + small stipend). Real upside is share value if the play proves.
• Ops: Live in crawlers; rudimentary Regrav drums; weekly trips to a district hub for proper Regrav.
• Exports: No accelerator — courier hopliners up to the nearest Tier II; routine freight via Tier III consolidation.
• Exit paths: Cash-out — sell shares when profitable and roll to the next wildcat. Stay-on — convert rigs into fixed plant; early holders become local barons (informal nobility).
• Risks: Dilution when new capital arrives; liened gear; claim-jump lawfare.
• Examples:

• Three Sisters Co-op: three bonded rigs on a young chaos lens; charter forbids outside managers; sells brine to Bright Chaos.
• Pallet Jack: scrap-built brine skimmer on a ring arc; investor is a Helios Yard foreman; commune keeps 22% carried interest.

Tier I — Solo Claims (one rig, one family)

• Structure: A single crawler, one beacon, one household. Investor leases the rig; family holds 15–25% carried interest.
• Ops: Prospect, tap, and haul to the nearest outpost; Regrav at pay-by-the-hour wards.
• Exports: No accelerator — sell to a district hub or book courier runs to a Tier II buyer.
• Fate: Most fold within a year; a few strike rich, sell a majority to a hub, keep title and a stipend.
• Examples:

• Marrow Moth: lone vacuum-screw rig skimming chloride rime; sells drumloads to Ridgegate.
• Blue Tusk: father–daughter pit saw on a feldspar seam; hauls to Valhalla Springs.

Network and Transport

• Primary commute: fusion-thermal hopliners (water-heated) for 50–500 km; pressurized icebuses for <50 km.
• Rails: Covered-trench spurs between clusters; flex joints; access ports every 300–500 m.
• Exports: Only Tiers I–II ship off-world; lower tiers forward cargo to them by hopliner/rail.
• Customs: Export customs at Tier I–II accelerators. Olympos handles federal; Galileo runs local. Claim beacons and Salvors’ Court rulings propagate via the Ring.

Law and Order

• Courts: Assay houses plus Ganymede Port Authority adjunct bench in Galileo; appeals go up-ring.
• Badges: Guild wardens, co-op rangers. Nobles exist, but deeds beat crests.

Degrav / Regrav

• Daily Regrav at hubs; outposts and communes make do, so commuters cycle back often.

Hooks (small-community scale)

• An investor forces a dilution round on Three Sisters; prove the assay or lose the commune.
• Blue Tusk’s beacon goes dark for four hours — a legal window for a jump. Keep it alive.
• A trench culvert near Pallet Jack kinks 8 mm; fix it before a courier car derails and voids your insurance.
• A buyer at Bright Chaos starts salting the brine numbers; catch the fraud before your carried interest evaporates.

Callisto, the Serf Moon

Callisto is the bulk yard of the Jovian system: safe radiation, big flats, deep ice and rubble. It exists to move mass — water, iron, aluminum — and to hurl it toward orbit on schedule. Callisto’s society is feudal with a rigidly restricted underclass. Callisto was colonized by a series of very large colony ships from Russia and has an unusually homogeneous population, and the class differences on Callisto are brutal, with a working class that is functionally serfs and a privileged noble class of administrators and warriors. No Tsar, no unity, a number of very rich families.

Names and people Officially they are the Callisti; formal adjective Callistic. Locally, the endonym is Kalistóytsy (sing. Kalistóyets/Kalistóyka). Class language is blunt: the ground-born serf majority call themselves the Nekruchyónye (the Unspun, short: Nekrúty), proud of never taking the wheel of gravity therapy. Their term for the administrative/military/managerial spin class is Kruchyónye (the Spun), or dock slang Kolesníki (wheelers).

Gravity and the lock-in Surface gravity is ~0.126 g (≈1.24 m/s²). You can live here without spin — and that’s the trap. Long-term ground life deconditions you for 1 g ships and habitats. Therapy can reverse this for individuals, but this is not practical for the whole population. On paper there is a Right to g-therapy. In practice, therapy is delivered in tiny rings at brutal rpm: Coriolis hell, vomiting, tunnel vision. There’s no adaptation ramp, no large-radius time. It is therapy as deterrent. The Rite of Refusal is public; Nekrúty line up each year to sign the opt-out and make a point of identity: we don’t whirl. Advancement carries pain and community derision. That’s enough to keep most ground-born “voluntarily” gravity-bound.

Habitats The major ground settlements are engineered icecrete vaults carved into mined-out hollows 10-30 meters below the surface, walls braced and actively cooled to fight creep. Vault train tunnels connect to depots and mass drivers. Overhead, the spin class and off-moon specialists live in the usual spin habitats. Most of these house the Callisti upper class, a few are off-world colonies of entrepreneurs and experts.

Culture The Kalistóytsy dialect is Russian-rooted and spare. Church/union networks fill the gaps the charter leaves; icons of Saint Range hang next to safety metrics. Memorial bells toll for clean launches and dead crews — many families wear rail-widow black. Festivals follow the slot calendars; marriages and funerals avoid maintenance windows. Groundfast aesthetics prize stillness: high-headroom halls, communal dances, honorifics for Deep Still (years without spin). Departure shame is ritualized: a clay shoes ceremony for those going spin; family names covered on the community wall. Callisto is still a material abundance society but with restricted movement and rights. Shortages are rare and there is plenty of space in old mine shafts. Food, alcohol, and cheap entertainment are free. There is work for everyone, but hours are pretty lenient. Family is secure and encouraged, though patriarchal with many housewives and large families. Kalistóytsy contracts can be sold, but only entire households at a time and by custom never off-world. Life extension and health care are available, if low quality. This is a serf society, not a slave society.

Power and industry Callisto keeps the smelters, slab/billet mills, pressure-vessel lines, and tankage plants — big, hot, continuous. Rails throw ice and ore cans to catcher wheels in low Callisto orbit; fusion tugs retarget the cans to industrial habitats. Courts, high command, and most high-value industry are in orbital habitats.

Education and productivity Low productivity isn’t a mystery; it’s policy. Ground school tops out at literacy, numeracy, and equipment SOPs. There is limited social mobility at the price of leaving the community. There is a constant need for clergy, administration, military, and engineering personnel; clever children are given scholarships. The family holds a ceremony almost like a funeral as such children very rarely return. Still, in the wider world, these stipendiats form an intelligentsia, but are still looked down on by high society. This keeps accident rates tolerable, sabotage rare, and the workforce dependent. It also keeps margins thin and output mediocre per head, competing with volume and reliability rather than quality or opportunism.

Governance and the wider Compact There is no Tsar. Power is fragmented and feudal-corporative. Few people have a full vote. Olympos Parliament apportionment uses the Qualified Elector (QE) rule. To vote at full weight you need a clean G-Passport (no active labor lien, gravity adaptation). Non-QE residents do not vote and only count at 0.25 toward apportionment. This was meant to pressure enfranchisement. It backfired. By keeping Nekrúty “non-QE by choice,” Callisto surrenders vote weight but, by sheer population, still seats a large but divided Comita Jovia delegation.

Throughput wins wars and keeps lights on. A safe low-rad yard that can throw kilotons per day of water and metal into orbit cannot be replaced by plucky co-ops. Every reactor dome, truss spar, and tankage ring from Ganymede to the Ring still starts with a Callistic can screaming up a rail. Other Jovians tolerate the serfdom because they don't see it directly and "the rails must run".

External friction Callisto and Ganymede need each other and hate each other’s leverage. Callisto wants quotas and fixed freight rates; Ganymede pushes purity and certification standards that expose Callisto’s education caps. Brain siphon is constant: the best stipendiats defect to Ganymede and never look back. Capitolium sells box-residency and QE packages; Callisto blacklists the vendors and flags their transponders but cannot make them illegal.

Security and risk Hazards are real and local: cryo-subsidence under depot slabs; high-voltage rail arcing through conductive dust that leaves icecrete laced with branching burn cracks; timing drift and micrometeors that turn payloads into kinetic grief; vault roof delamination when cooling fails. The police force is a militia, large but poorly trained and equipped. Serious issues are solved by the Boyary (Callisti knights), usually with extreme violence.

Military and crisis management When storms, strikes, or sabotage hit, Callisto prioritizes rails and catchers. Noncritical vaults go dark; fusion barges feed the launch grid first. In true emergencies the Corps will force-spin Nekrúty crews for evacuation or repair. Deaths from those rotations feed the Martyrs of the Whirl stories that keep the next generation Groundfast. The military consists of knights (Boyary) and gravity-bound militia that can still operate on other Galilean moons. Naval Nekrúty must undergo therapy to function in higher gravity, making the navy inefficent.

Hooks

• Range Safety halts a line for “investigation” — really a price rig. Prove it.
• A G-Passport server admin wants out; extract her and rewrite a few hundred liens on the way. The community reacts with xenophobia.
• An ascent-rights lottery is cooked; swap the slates before the ceremony. The corrected lottery then provokes riots when favorites do not win.
• A catcher misfires; recover a hot can before Rail Marines “sanitize” the witnesses.
• A bell keeps tolling the wrong count — someone’s hiding slot timing in the peals.

Jovian Irregular Moons

Beyond Callisto, most “moons” are really captured asteroids: small, lumpy bodies with almost no gravity. The practical way to mine them is to build a station in the right Jovian orbit, then send shuttles to the rocks. Ion thrusters keep the station on track and let you slide around within the same group of moons. Exports go out by freighter; if a moon has solid bedrock you might add a short rail to throw cargo cans.

How colonization works — Build one rotating forced-Jupiter hub — a station whose path matches a family of moons in both average distance from Jupiter and orbital tilt. Keep the hub in that co-orbit. Short-range shuttles make quick trips to individual targets. Most rocks are harvested inside containment bags rather than with people on the surface; only firm, coherent outcrops get a few anchors or a tiny rail that tosses cans back to the hub.

Typical shuttle burn is how much Δv is needed to move from the hab to the local irregular moon(s). Possibly this should be deleted as too technical.

1) Himalia Core Yard (prograde, Himalia family — inner band)

Targets Himalia (milli-g), Elara (milli-g).

Typical shuttle burns 50–150 m/s.

What pays Water and carbon turned into propellants; tank parts; bulk plastics feedstock.

Notes A few anchors on solid knobs; short rails throw cans to the hub or inward.

2) Himalia Petites (prograde, same band — outer petals)

Targets Lysithea, Leda, Dia.

Typical shuttle burns 80–200 m/s.

What pays Tholin organics into binders/sealants; filament for printers; good place to train crews in visual sweeps and debris-zone discipline.

Notes All micro-g; pure bag-and-chew.

3) Themisto Corridor (prograde one-off, high tilt)

Targets Themisto plus nearby chips with similar tilt.

Typical shuttle burns 60–180 m/s.

What pays Laser-link relays, mirror polishing, light volatiles.

Notes Strong charting and beacon node; modest mining.

4) Pasiphae–Sinope Core (retrograde, Pasiphae family — inner core)

Targets Pasiphae (can reach borderline milli-g if dense), Sinope (borderline).

Typical shuttle burns 70–200 m/s.

What pays Nitrogen and ammonia processing; radio-quiet telescope time; cold-chem feedstocks.

Notes Science rules may cap or ban rails; hubs focus on tanker runs.

5) Pasiphae Fringe Chain (retrograde, same family — outer chain)

Targets Autonoe, Megaclite, Callirrhoe, Eurydome.

Typical shuttle burns 80–220 m/s.

What pays High-dielectric ceramics, piezo stacks, precision salts; tanker cross-dock.

Notes Keep debris maps current — lots of orphan junk out here.

6) Carme Core Yard (retrograde, Carme family — dense cluster)

Targets Carme, Taygete, Eukelade.

Typical shuttle burns 50–150 m/s.

What pays Tholin cracking into pharma precursors and specialty polymers.

Notes Tight biocontainment audits; rich margins if you stay clean.

7) Carme Outer Petals (retrograde, same family — spread rim)

Targets Kale, Erinome, Aitne, Pasithee.

Typical shuttle burns 80–250 m/s.

What pays Tank farms; hose/valve fabrication; top-ups of organics; arts festivals that also move cargo and crews.

Notes Very low-mass rocks — no surface teams beyond quick anchor swaps.

8) Ananke Core Mill (retrograde, Ananke family — inner trio)

Targets Ananke, Praxidike, Iocaste.

Typical shuttle burns 60–180 m/s.

What pays Boutique metals (platinum-group specks), high-spec alloy feeds, small billets.

Notes “Recoil poisoning” is the classic sabotage: one heavy unscheduled rail shot pushes the rock outside limits. You must publish how you’ll counter-thrust.

9) Ananke West Chain (retrograde, same family — dispersed)

Targets Harpalyke, Thelxinoe, Euporie, Orthosie (examples).

Typical shuttle burns 80–250 m/s.

What pays Slag reprocessing, wire stock, battery housings.

Notes Import tailings from the Belt; keep up the visual sweeps or you’ll eat your own chaff.

10) Retrograde Crossroads Freeport (where Carme and Ananke bands overlap)

Targets Mixed small moons from both families that share a workable tilt and distance.

Typical shuttle burns 70–220 m/s; hopping to a different family from here costs about half to one kilometer per second.

What pays Escrow court, bonded warehousing, salvage arbitration, a lively crew market.

Notes Enforcement is simple: port denial and blacklists. No need for soldiers.

11) High-Tilt Prograde Skew (prograde oddballs)

Targets Carpo, Valetudo clusterlets.

Typical shuttle burns 70–200 m/s.

What pays Optics and sensors (star trackers, laser-ranging heads); calibration ranges; light volatiles.

Notes Great navigation school; thin mining margins — pair production with sales to inner hubs.

12) Outer Dark Fringe (most distant retrogrades, low traffic)

Targets Far-rim smalls on the tails of the Pasiphae/Carme groups (Herse-like chips).

Typical shuttle burns 100–300 m/s.

What pays Cold storage and quarantine vaults, rare salts, odd organics; overflow tanker staging.

Notes Best long-baseline radio; rails are usually banned by charter.

The Jovian Trojans

Jupiter’s twin swarms of Trojan asteroids trail and lead the planet by sixty degrees in its orbit — vast, ragged clouds of carbonaceous and icy rubble caught in the balance between Sun and giant. The leading swarm, L4 or the Greek Camp, is roughly twice as populous as the trailing L5, the Trojan Camp. Both are immense, diffuse volumes: thousands of asteroids above a kilometer across, drifting through tens of millions of kilometers of near-empty space.

These places are too far from everywhere to be commercially viable. The time and Δv to reach them is too expensive for all but the most devoted.

Earthforce holds a scientific reserve and forward observation base in the the L4 swarm, stringing a loose network of detectors and research outposts across its brighter bodies. Here, deep observatories listen for neutrinos, gravitational waves, and interstellar wanderers — small objects occasionally trapped by Jupiter’s gravity, bearing isotopic signatures older than the Sun. L4 serves as the System’s furthest scientific frontier, a place for patient measurement and uneasy peace. Earthforce claims jurisdiction, but in practice the stations are almost autonomous, supplied twice a decade by long-haul convoys.

Between the leading swarm and the rest of the outer system diplomacy flickers and fades. Earthforce tries to share sensor data with Jovian and Saturnian observatories — the former wary but cooperative, the latter too distant and underfunded to answer half the time. Each transmission window becomes a negotiation: access to raw neutrino feeds traded for reactor parts, a year’s telemetry paid for with medical isotopes. The work continues because it must — the triangulated arrays need all three worlds to map the deep sky — but cooperation never lasts longer than the next political storm.

The L5 swarm is smaller, darker, and nearly ungoverned. The paranoid and the exiled make their homes here: rogue AIs, outlawed researchers, and smugglers who prefer silence to law. Hiding among cold rocks and thin radio shadows, they call themselves Drifters. Their habitats are patched together from old Belt rigs and Jovian wrecks, and they keep their beacons dark. L5 is too large to police; Earthforce interceptors could search a century and never find a thing.

The Trojans are quiet, scientific, and strange — half monastery, half spy station — their scattered domes listening for voices from beyond the stars.