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

=== Assistant: 17-11-25 03:09 ===
17-11-25 03:09
GPT-5.1 Thinking

Got you. You’re asking:

: 

Short answer:
* Yes, if the “circle” is an orbit around a star (like the Sun or Alpha Cen).
* No, if you mean a passive, fuel-free loop floating in the middle of the interstellar gulf. That part of space has nothing to orbit around, so you need continuous propulsion, not just a ‘comet-style’ coast.

Let’s separate the two regimes.

==== This is physically straightforward: ====
* At departure, your full generational ship accelerates outward.
* At some distance, you detach a huge depot module (your “comet half”).
* You adjust its velocity so it ends up on a big, stretched elliptical orbit around the Sun that: - dips into the inner system every X centuries - swings out far into the outer system along roughly the same outbound corridor the ark ship takes.

That depot-half can be:
* a shielded hulk full of frozen water, fissile material, structural metals, seed banks;
* powered by long-life reactors + passive systems;
* “cometified” by using its water as low-thrust reaction mass to tweak its orbit.

Then:
* Early on, other missions can rendezvous with this depot as it swings through the inner system.
* On a longer horizon, your first generational ship might intersect it once on the way out (if you’ve timed orbits and burns carefully).

So: Solar-system scale loop? Yes.
It’s just orbital mechanics plus a big, dumb, automated supply ship.

==== Here’s where physics blocks you. ====

Between stars:
* There’s no central mass to give you a natural Keplerian loop.
* An object with no thrust just moves in a straight line in the galactic frame.
* To “go in a circle” across the gap you need continuous propulsion or some external field to orbit.

So your options are:

===== - Once it leaves the Sun’s hill sphere, it’s basically on a near-straight escape trajectory. =====
* It will not loop back and re-cross the same line unless it falls into another star’s gravity well.
* You can aim it so it passes through some region, but not circle there on its own.

So no simple comet-like repeat loop in mid-gap.

===== In hard-ish sci-fi, you could say: =====
* The “comet-half” is a slow cycler: - it has low but continuous thrust (fusion drive, beam-driven sail, etc.); - it follows a long-period engine-driven cycle that roughly shuttles between the two stars, or oscillates around their barycenter.

But that’s no longer “we turned half our ship into a rock on a nice orbit.”
That’s a second starship:
* its own reactors
* its own guidance
* its own propellant chain

In which case, conceptually, you haven’t made “half a comet”; you’ve created a logistics cycler that happens to be slower and more massive than the main ark.

==== If we keep it as grounded sci-fi: ====
# Inside Solar System / origin system - Yes, you can peel off a huge depot section and put it on a long-period orbit. - It becomes a returnable “comet station”: other missions can visit when it comes back around. - This matches your “they don’t have to die, they can come back on the remaining supplies” pattern: ships go out, seed, return.
# Inside destination system (Alpha Cen) - Once you arrive and have infrastructure, you can do the same: - detach hulks into long orbits around Alpha Cen A/B; - those become local comet-like depots.
# Across the interstellar gulf - You cannot rely on passive comets “circling” in empty space. - Any depot in mid-gap must be: - either a one-way dead drop (you fire it along the same corridor and it drifts forever), or - an actively propelled logistics craft (a slow, heavy cycler ship).

So the clean, honest answer:

: 

If you want, next step we can sketch a two-component architecture:
* Core ark (straight-ish interstellar trajectory)
* Bound “comet depot” in the origin system that supports multiple waves of outbound missions and maybe one last refuel of the ark as it exits the Sun’s reach.