Editing Openai/691a2d9f-c044-8012-bccf-942bfce6334d (section)

=== Assistant: 17-11-25 01:21 ===
17-11-25 01:21
GPT-5.1

Yep, now you’re converging on the “practical sci-fi” version of the idea:

: 

Let’s stress-test this.

==== 1. Pick a periodic comet that comes reasonably close to Earth (or at least to the inner solar system) on a predictable orbit. ====
# During a convenient pass, send up an expedition that: - matches velocity with the comet - lands / anchors a station on or around it - installs: - power systems (solar, RTGs, maybe future fusion) - ISRU gear to process ices into fuel (H₂/O₂, methane, etc.) - comms + navigation beacons
# From that point on, the comet becomes a mobile fuel/power bank that: - charges itself over years between perihelia - stores propellant and/or batteries
# A generational ship (or long-range convoy) chooses its outbound trajectory so that: - it can rendezvous with that comet on one or more future passes - it uses the comet station to refuel, recharge, or take on extra reaction mass.

So the comet is basically a scheduled, moving truck stop on a known ephemeris.

==== ### ====
* Comet orbits are predictable enough (for known periodic comets) to plan centuries of encounters, though outgassing can perturb trajectories over time.
* A generational ship isn’t in a hurry. Having refuel windows decades apart is acceptable on that timescale.
* You don’t need to “turn the comet into a rocket”; you just use it as: - a local mass source (water/volatiles for propellant) - a pre-positioned energy + propellant factory the ship can dock with.

So at the bare level of Newton + chemistry, yes: it’s not forbidden by physics.

==== ### ====
# Rendezvous and anchoring tech at comet level - Rosetta/Philae showed how hard it is to just land and stay attached. - We’d need robust methods to: - harpoon/anchor into low-gravity, volatile outgassing ice - maintain position despite “jets” changing rotation and local gravity.
# Long-life, autonomous ISRU systems - Machines that: - mine ice - melt, filter, separate - electrolyze water, liquefy gases - store cryogenic propellant - and run for decades with minimal maintenance in a nasty environment.
# Serious orbital infrastructure - You’d likely stage from high Earth orbit or Lagrange points. - Right now we’re barely at the “occasionally visit an asteroid” phase.
# Navigation + long-term ephemeris robustness - Outgassing can perturb comet orbits. - Your depot needs either: - station-keeping propulsion to correct the comet’s actual orbit vs predicted - or continuous tracking + updated rendezvous planning on the ship side.

All of this is multiple tech generations away, but not in the “violate physics” category. It’s “extreme engineering and reliability” territory.

==== Interestingly, it might be more useful for “merely” long-range solar system logistics than for true interstellar generational ships: ====
* Within the solar system - You can exploit short-period comets (orbital periods of a few–tens of years). - You can have multiple depot-comets, forming a kind of sparse, moving logistics web in the outer system and Kuiper belt. - This helps support: - outer-planet colonies - Kuiper-belt mining - Oort-cloud science missions
* For interstellar generational ships - Once you’re well past the Sun’s deep gravity, periodic comets are mostly behind you. - You might intersect Oort Cloud objects, but: - their orbits are poorly constrained - they’re 3D random rather than a nice predictable 2D belt. - Using them as scheduled depots becomes much harder.

So the sweet spot is probably:

: 

Think: a slow ark built to crisscross the outer solar system, topping up from comet-depots on the way, rather than a ship to Alpha Centauri.

==== If I compress your intuition into a crisp “design pattern”: ====

: 
* “Event-locked” = they are only useful during certain orbital configurations.
* “Mobile depots” = the infrastructure moves with the small body.
* “Predictable small bodies” = periodic comets, some asteroids, Trojans.

Practical blueprint:
# Stage 1 – Tech demo - Attach a micro-ISRU unit to a small near-Earth asteroid. - Prove decades-scale autonomous resource extraction + storage.
# Stage 2 – Comet outpost - Land a more robust ISRU + power station on a short-period comet. - Use the volatile mix to produce propellant over several perihelia.
# Stage 3 – Logistics mesh - Select multiple comets with useful orbits. - Equip them over time. - Ships plan routes that opportunistically intersect this moving mesh.

Your “generational ship charging via comets” becomes a natural extreme case of that network.

==== : ====
* Conceptually: Yes, that’s a legitimate, physically plausible scheme.
* Technologically today: No, we’re missing: - durable long-life ISRU on comets - robust anchoring and operation in crazy outgassing environments - big-scale orbital industry.
* On a sci-fi engineering roadmap: Absolutely belongs there, and it’s more grounded than 90 percent of hand-wavy FTL stuff.

If you want, next step we can:
* Turn this into a concrete mission concept (timeline, key subsystems, failure modes), or
* Push a more extreme variant: “design a 3-comet refuel chain that a slow ark-ship could realistically use between Jupiter and Kuiper belt.”