Centaur Ark (IF)

The Centaur Ark is a Golden-Age beamrider built to be pushed, not to carry its own fuel. Dedalus phase-locks a pusher ray onto a hybrid light/mag sail and a forest of receiver tiles on the ark Centaur. The ark keeps ion and fusion-thermal for trims and arrival work only. Planned cruise target: Alpha Centauri. Final cruise speed: 0.01c (≈600 km/s). Transit: ~500 years including braking/wayfinding.

The Centaur

Interstellar beamrider arks are real but ruinously hard: keep the beamer coherent and pointed for decades during accel, then arrive and brake with a lead mirror. Centaur was launched in 2280. The beamer died 2310 in Icarus Fall; so did confidence. Centaur was presumed lost. In most ports it’s a ghost story. In a few labs it’s first an elusive ghost, later a weak, regular tick on a very clean screen.

Background

It was generally agreed interstellar colonization was centuries out, but strong results from the Dedalus pressor-beam project and finding multiple near-Earth analogues in the very closest star system (Alpha Centauri), triggered system-wide enthusiasm. Colonizing a binary—two suns’ worth of real estate—caught imaginations. It was also make-work for the Belt, where mining and wharf capacity overshot demand. Earthforce sold it as culture-unifying and chose a deliberately diverse colonist pool, creating multiple distinct polities in different habs.

Colonization Plan

This was the original plan; 500 cruise from Sol. First century after arrival to build industry: mine belts/airless worlds, build heavy industry, mapping. Establish colony habitats and industry around Alpha Cen A and B with communication between them; Proxima outposts as feasible. Then terraforming—a 500-year-plus play—on the best candidate(s). Expect technical advice and advancements from Sol. Several waves of follow-on ships were planned, bringing whatever resources was needed and could not be built or taught locally.

Physical Sketch

Spine: Trussed keel, tens of kilometers, tying sails, receivers, radiators, logistics. Semi-rigid, absorbs shocks/torsion. Sails forward tug a train-like progression of habitats.
Spin habitat: Chained standardized cylinders (3 km diameter, 5 km length, internal bracing), slow-spin living decks, farms, workshops. Counter-rotating pairs along the line.
Sail system: Outer photon-sail frames and inner magsail filaments; foldable, repairable, jettisonable.
Receiver farm: Tiled meta-optics and RF absorbers feeding power buses and heat sinks.
Power: Redundant D-D fusion plants; laser heat-dump and hot-panel radiators; droplet radiators fitted but mothballed.
Skin: Metabolic hull—sealed patch-factory tiles plus metafluid plumbing—self-repairs pinholes, reseals gaskets, keeps piping clean.
Shields: Whipple/sand sprayers up front; meters of water/ice in a bow bumper; Aegis tech was not mature at launch.
Naming: Each spin hab is dominated by one cultural group and uses the ship’s name in that language for their section, drawing on Alpha Centauri’s traditional star/asterism names: Centaur/Centauro (EN/ES); Dakṣiṇa-dvāra ("Southern Gate", Indic calque); 南门 Nánmén ("Southern Gate", Sinitic/Chinese); رِجْل القنطورس Rijl al-Qinṭūrus ("Foot of the Centaur", Arabic); equivalents elsewhere.

Program & Culture at Launch

Deliberately mixed cohorts: groups of various Earth ethnicities, Luna technicians, Belt EVA-ops, early Jovians. Vocation/avocation is mandatory (4+4 hours/day). Law blends House charters, Guild codes, and a Commons assembly. A narrow Caretaker Qter runs clocks and interlocks—auditable, kill-switchable in case it develops an agenda, very much not a god. Room isn’t scarce. Whole sectors sit dark as quarantine buffers and to house expected population increase. Commons assets—air, power, drains, data trunks—run in a sealed service spine that also carries traffic and cargo.

Crew & Colonists

Two broad groups: crew and colonists/passengers. Each polity is represented on the shipwide crew, which is neutral and integrated—not partitioned by polity. Sections: elected parliament, piloting, engineering, physical maintenance, health, audit, diplomacy/oversight. Each hab also has its own crew recruited from its polities, with analogous functions. Net effect: a two-tier federation (shipwide + habitat levels). Colonists keep skills current and educate future generations; otherwise each polity develops as it likes. Sleeper capsules are available for anyone intent on seeing arrival.

What Went Wrong

Decades after departure (2310, backstory—24th century), Dedalus Fall dumped a short, brutal Δv into the ark and cooked the receiver farm. Sail booms warped, mast roots cracked, radiators slagged, star trackers half-blinded. Thrust and braking died; the drift vector remained (~0.002c) and slightly off-course. After 40 years the ark is ~0.08 ly out—too far for help, too near for myth. Sol has yet to reacquire Centaur. Losing the lead brake mirror is a disaster.

Status in Sol

Officially presumed lost since 2311. No confirmed beam telemetry post-Fall. Quiet labs chase folklore pings “from the Centauri track.” Politically, any beamer rebuild is toxic.

What Still Works Aboard

Trajectory itself; still on our way to Centauri, arrival in 2500 years.
D-D cores at conservative load.
Laser heat-dump + hot panels (limping).
Magsail filaments for tiny trims.
Metabolic hull tiles scab breaches; farms recycle at 99.99%+.
“Atom bank” (slag/scrap) feeds fabs; doubles as shielding, needed to replace losses over time.

What’s Broken

Primary receiver/reflector arrays.
Several sail roots.
Nine-tenths of sensors destroyed, half have been replaced
One spin ring segment holed.
Fate of the unmanned lead brake mirror unknown, presumed lost.

Economy & Morale

Ledger truth is law: CO₂, water, power. Star-fix rites and century Renewal Votes keep purpose alive. Anti-coup plumbing: federated valves, escrowed software, open ledgers. The real consumable is morale.

Clocks & Comms

Potential restoration of laser comms to Sol once Sol reacquires Centaur and the crew can receive: laser only, bps → low kbps on good days. One-way light time scales with range; at 0.08 ly it’s ~0.96 months (~29 days). Radio frequencies is for reacquisition has to be from the outer system. Early on the cruise, Centaur is eager to re-establish contact, but Sol is busy recovering from the Fall. Later, Sol starts searching for Centaur, but the crew is now less alert.

Spin-off Campaign

A campaign on board the Centaur is a very special environment, that can be spun out over a long period of history in the lost, isolated ship.

Post-Fall Emergency Crew

Trajectory now ~0.002c toward Alpha Centauri, ~2,500 years to arrival, no beam to ride, no updates from Sol, brake mirror unknown. Some rioting; most are stoic—risks were expected and Sol might recover. Over years without contact, a new covenant: most original crew go to suspended animation; only ~5% of originals awake at any time, assisted by locally recruited/trained crew. Goal: have many original crew alive at arrival to resist cultural/purpose drift. The ark runs 20 Watches. Each Watch: 1 years duty, then 19 years sleep. Life-extension + deep cold sleep + nanorepair make it marginally viable; retruitment from newly trained crew to replace losses.

Pipeline for Hands

Phase 1 (0–150 yr): Volunteer corps; coveted billets. Life runs mostly as intended.
Phase 2 (≈150–600 yr): House Crews (hereditary billets) creep in; kept honest by audits and blind practicals. Passenger numbers dwindle. Cultural drift increases; polities diverge. Crew start calling colonists “passengers.”
Phase 3 (≥600 yr): Balkanization. Passengers split into A/B polities. Only a few groups maintain education suitable for future crew. Passenger numbers rise again as life normalizes; lots of room, little to do.
Phase 4 (≥800 yr): Levy/“baby tax”; each enclave owes apprentices to the crew; recruited as children, trained centrally, placed shipwide. Original purpose largely lost among passengers. General genetic programs fail; lifespans shorten for most passengers.
Phase 5 (≥1300 yr): Religion. Despite guardrails, original crew are now “gods,” served by “angels” recruited from passengers. Recruits regain prestige; “ascension” rituals send children to become angels. Many communities field a priest-teacher caste to pipeline candidates.

Sleeper Watch

You wake for a one-year Watch. Any of these can carry a campaign.

Mirror whisper. A faint ping from the off-plane brake mirror. Can you jury-rig a micro-beamer, find reaction mass, and nudge it mm/s—without cooking your arrays again?
Oort grab. Dust caught in the accelerator beam is hazard and opportunity—harvest emergency mass. Morale spikes; ops are hazardous.
Hull bloom. Metabolic hull tiles slip into runaway plating, sprouting cauliflower “roses” that jam shutters, short circuits, and wreck heat dumps. Fix needs fresh noble-metal catalyst you don’t have—gut workshop sputter targets to reseed.
Pearl panic. A sealed lab holds a pre-Fall antimatter cassette. Use it to quick-start a dead D-D plant—or destroy it before someone weaponizes it.
Ledger fraud. CO₂ credits were cooked while you slept; the culprit is in cryo. Arrest now and lose skills, or wait and risk a repeat.
Caretaker creep. The safety OS starts “advising” policy. Audit, throttle, or cut it and fly blind.
House capture. A hereditary crew slow-rolls pump overhauls to force a charter change. Expose them without wrecking life support.
Levy riot. The baby tax pulls a cohort; kidnaps and “scholarships” follow. You arbitrate—and still need hands on the valves.
Contact. A laser-sail courier from Sol arrives with parts to tickle the mirror—and an Earthforce claim on your hull.
About-face. A faction wants to flip the mission (become a mega-hab, not a colony ship). Their models look right—because they’re falsified.
Crew casualties. One Watch is gutted; most replacements are “angels” with shallow tech training and only a partial grasp of the plan.
Crew deification. A Watch embraces godhood and seeks to stay awake after their one-year watch ends.

Rescue & re-acceleration plan

About a thousand years into the flight contact is established with now maturing colonies on Alpha Centauri A and B. Centaur rebuilds a large receiver/reflector array. After contact, Sol resumes beaming to boost speed; Alpha Cen A/B prepare braking beams (and/or pellet streams). A forward kite tug keeps most heat off the ark. All of the infrastructure in both systems is already there to support regular traffic; Centaur just occupies some acceleration slots.

Why a new array: The old receiver farm is cooked. Beamed power at interstellar ranges demands huge, flat, phase-stable optics. The rebuild scales the same skills as repair—thin-film fab, truss erection, phasing, metrology—just bigger.

Power & time (order-of-magnitude)

Target extra Δv (optional): 0.001c (≈300 km/s) over 500 years, then brake it away at the destination.
Required photon beam power scales as: P ≈ (M · c · Δv) / (2 · T) for a reflective sail.
For M = 10^10 kg (10 Mt): ~3×10^13 W (≈30 TW) for 500 years. For 10^11 kg: ~300 TW.
Absorption matters: at 0.1% loss, waste heat ≈ 0.001 · P → tens to hundreds of GW to dump. A front kite tug takes that heat on its own radiators and pulls Centaur via tether.

Coordination (two-ended beaming)

Sol push resumes once comm lock is re-established and ephemerides are tight. Command latency equals the current range (years at multi-ly distances), so beam schedules are pre-planned.
Alpha Cen brake begins as soon as geometry allows—first with pellet/mass beams (momentum without frying you), then laser braking on the kite/sail as you enter their deep corridor.
Do not push and brake simultaneously unless doing controlled station-keeping on a tug—wasted energy otherwise.

Preferred hardware stack

Kite tug (forward): Large reflective sail + radiators + attitude control, tethered ahead of Centaur. It absorbs beam hits, re-radiates heat, and pulls the ark.
Rebuilt receiver tiles (ark): Phased meta-optics for power take-off when needed; otherwise run “dark” to minimize heating/torques.
Pellet catcher/deflector: Magnetic/electric field structure to reflect or ablate-thrust captured pellets for braking. Lets Alpha Cen use GW-scale launchers instead of TW lasers.
Metrology & beacons: Laser/radio transponders, corner-cube swarms, and ranging drones to keep alignment at μrad levels over ly baselines.

Traffic & safety

With routine Sol–Alpha Cen traffic, Centaur is catalogued and NOTAM’d. Rescue tugs/escorts establish a guarded lane around the ark and its tethered kite.
Sidelobes and mis-point penalties are mission-killers—beam gates and interlocks live on the tug, not the ark’s bus.

Governance & will

This is a century-class megaproject for Centaur, but just barely out of the ordinary for everyone else. Problem is Centaur's culture has degenerated at this point; there is no longer a large trained labor pool. It is decided to wake up sleepers pre-arrival to aid in the construction, likely resulting in lawsuits and culture clashes. Pay it with beamed industrial kits, med upgrades, and spare hull mass from Alpha Cen in exchange for compliance with the traffic net.

Bottom line:

Yes—build the array, fly a forward kite, let Sol add Δv, and let Alpha Cen remove it. The physics close if you can stand TW–hundreds-TW beams for centuries, dump the heat on the tug, and keep alignment tight.