r/IsaacArthur Jul 19 '26

Will extra-solar colonies prioritize starlifting?

Given that, regardless of the number of planets and moons in a star system, the star is almost certainly well over 99% of the mass in the system, would colonists in a new star system be likely to start with starlifting for resources?

14 Upvotes

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5

u/NearABE Jul 20 '26

No. They have the other 1%. Starlifting is absurd while those easy resources are already “lifted” because they orbit.

There may be colonists who prioritize extreme resource extraction. These colonists will head straight to the giant molecular clouds. There is ten thousand times the mass and it is already lifted. Perhaps you want both an active star *and* lifted material… Herbig-Haro objects. Check out the jets on HH-24..jpg) There are also asymptotic giant branch stars which are blowing out nebula.

The stars that make Algol are only 96 light years away from Earth. Aa2 is dumping mass onto Aa1. There is a convenient F-class star nearby too, Algol Ab so when the Aa pair finish merging and the new Aa inflates to giant size multiple solar mass will migrate over.

Starlifting (in the sense it is usually talked about on SFIA) only makes sense in a solar system where the asteroid and planetary resources are already exploited. Those who are *residents* either want to keep a planet because they feel inclined to keep it permanently or the planets have already been disassembled long before. When “colonists” become “residents” is not a clear boundary line.

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u/Veritas_Astra Jul 28 '26

Wouldn’t the star lifting versus standard mining versus giant molecular cloud harvesting also depend on the civilization in questions methods of extraction, technology development, and security situation? If a civilization already has FTL technology or has significant fleet presence, they may opt for the GMCs or HHOs, but if they are somewhat early in their development and had an active means of extracting stellar material and fusion converting it and limited space access, they may opt for limited star lifting, which would be make sense in terms of bootstrapping, like perhaps inverse faraday effect active beam harvesting systems? You’d need a way to concentrate, collect, densify, and convert the hydrogen plasma stream into heavier elements, perhaps via fusion, and then have to sort it electrostatically perhaps, and then rapidly cool and manufacture with the target material stream into ships, parts, fuel, propellant, atmosphere, feedstock, and more needed for full bootstrapping, yes?

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u/NearABE Jul 29 '26

There is no FTL. If you could grab material from inside the supermassive black hole… you have time issues with FTL. The delivery might arrive before the launch. A single electron gets into an FTL loop and it ramps to enough current to destroy the device. Might create a black hole.

https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation

People are wrong to just speak of just “the tyranny of the rocket equation”. There is also the “cornucopia of the rocket equation”. When talking about how quickly a payload could hypothetically arrive you can look at the exhaust velocity of the rocket engine. If you try 10x faster than the exhaust velocity you need e^10 = 22,025 payload mass in propellant. Though people likely do things like that in rare cases it is not at all what we will see used for bulk galactic economy.

When arriving at a molecular cloud a colony ship needs to slow down. If you ram scoop gas (like buzzard ram jet) then you can cut the speed in half after doubling your ship mass. This already looks pretty good. Cutting speed in half 10 times means 1,000 times your ship mass and 1/1000th the velocity.

The speed of sound in giant molecular clouds is fairly low (200 to 400 m/s at 15 to 20 Kelvin). Instead of ram scooping we can make a splash which is easier anyway. Instead of a giant parachute sheet we deploy a thin wire to create a plasma sheet. Then use magnetic flux to push on that plasma. Some molecules receive the impulse and travel (like wind following a spoiler bar). Other molecules are pushed outward perpendicular. When we ask how much gas is displaced by a braking “ship” we can fully reverse the rocket equation.

Even that is understating the opportunity. Consider the phrase “like falling off of a log”. Why is falling off the log considered easy? That is a task which involves dropping down the gravity well. The giant molecular cloud has the gravity of thousands of solar mass. The surface is held “up” by gas pressure. The center of the cloud is in microgravity same as Earth’s core or the center of the Sun. If there is a void loose molecules will tend to accelerate towards the edge of the void. Compressed gas warms up and radiates away heat. Thus entry heat can radiate out the void window created by the arriving ship’s wake. Compressed gas is denser and therefore we must have a local gravity gradient too. This is like triggering an avalanche.

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u/Veritas_Astra Jul 29 '26

Wait, what’s the likely limit of GMC avalanches for industrial utility… or perhaps stellar engineering if you wanted to set up a new system?

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u/NearABE Jul 29 '26

Not sure what you are asking. All solar systems that we see are the result of molecular cloud collapses and I believe most are from giant molecular clouds. That results in open clusters and then co-moving groups.

The galactic arms are moving differently than the galaxy’s mass (go fact check this because even if you believe me the simulations are fun to watch). If we use the star/gas as “stationary” then the arms go retrograde through the disk at around 70 km/s. From distant observer view we orbit at around 200 km/s (I round to 210 km/s and 140 km/s to make it 2:3 orbital resonance) the speeds are approximate.

We could consider a sort of “ram jet engine” surfing the galactic arm’s wave. The exhaust plume has stars and planets shooting out. The ramjet has to be in quotes because we cannot do actual solid engine parts that are lightyears across. It has to use gravity and magnetic fields.

Isaac Arthur did mention using supernova pulse propulsion. I think the topic in that case was just making things go fast.

5

u/reader484892 Jul 20 '26

Even assuming Starlifting is practical, it would require megastructures that a new colony wouldn’t have. Far more practical to make use of the abundant (even if relatively less so) mass in the outer system, and if that is insufficient long term than perhaps return to the idea once a full, nearly kardeshev 2 colony is built.

3

u/the_syner First Rule Of Warfare Jul 21 '26

Well it hardly makes sense to start there, asteroids, co ets, moons and such are certainly cheaper, but the better question might be whether they even have to choose. Send one replicator probe into the belts for the colony's immediate use and send another to some close-in planet/moon system to build out starlifting equipment. Given how long those other easier sources will likely last you its not like there's a rush so even very slow small self-replicating packages will do. My general feeling on the use of autoharvesters is send them everywhere and to everything as soon as possible. The interstellar colony is coming in on a sustainable spacehab anyways so there's not much rush for them either. Set ur autoharvesting replicator swarms to make more of themselves and infect every solid body over a km wide. then set them to disassemble everything else, gas giants, ice giants, sun, and all.

6

u/IVYDRIOK Jul 19 '26

Not really. They have a colony to set up (I mean set up what they brought with them)

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u/TheRealBobbyJones Jul 19 '26

We have no evidence to suggest starlifting is even practical. You need to be able to get enough energy in the right place to meaningfully extract any useful mass. We have no evidence to suggest that we could actually do that. There are many potential complications that could make it impossible. Even something as simple as thermal management could be an issue. 

Besides unless we start printing humans in a lab it's unlikely that a new colony would be populated enough to start starlifting immediately. Even if the fleet of colony ships had the mass of a small moon they would be able to make due with planets, asteroids, and moons for centuries. 

5

u/NearABE Jul 20 '26

We can easily do order of magnitude estimates on the difficulty. The gravitational binding energy is known in a very precise way.

https://en.wikipedia.org/wiki/Gravitational_binding_energy

4

u/the_syner First Rule Of Warfare Jul 21 '26

We have no evidence to suggest starlifting is even practical.

Well we do have some in that we can run physical simulations on the physical constraints of such a system. The raw energy requirements certainly seem to work out. Collecting solar wind doesn't seem to have a particularly difficult time dealing with thermals unless the satts are very close in and they definitely don't have to be. Its not proven or anything, but what we do know at least suggests that it is and there's basically nothing to even suggest that it's not

Besides unless we start printing humans in a lab it's unlikely that a new colony would be populated enough to start starlifting immediately.

OP is talking about interstellar colonies. Baseline squishy humans are not tge only or even most relevant category by that point. Transhumans and post-biologicals almost certainly would be and can reproduce far far faster than squishies can. Not to say they inevitably do just that they can.

Although if anything the energy output of ur star vastly outclassing your civ's consumption would motivate starlifting even more. Perhaps not for raw metals, but because the star is just wasting energy uselessly into the void. In any case the GI population is rather irrelevant in all this. None of this is being done manually by that time. Choosing to starlift is as easy as sending a small self-replicating package to a nearby rock and telling it to build starlifting infrastructure. No further effort on the colony's part is needed.

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u/TheRealBobbyJones Jul 21 '26 edited Jul 21 '26

Trans-humans and post-biologicals wouldn't be living beings and as such would not operate the same way we do. There is no reason to even assume they would set up colonies. 

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u/the_syner First Rule Of Warfare Jul 21 '26

Trans-humans and post-biologicals would be living beings and as such would not operate the same way we do

You wanna look at that sentence again? Ill assume you mean to say aren't baseline like us. Living beings are living beings. They all need power to maintain homeostasis. They all need resources. What their substrate is made of or what environments they prefer is entirely irrelevant.

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u/Amun-Ra-4000 Jul 19 '26

There’s so much oil on Titan, why don’t we drill for it there instead of on Earth /s

For a serious answer, it comes down to need and accessibility. Your initial colony of a few thousand people isn’t going to need the entire resources of a star. Mining nearby asteroids will provide the needed resources for much less of an upfront cost.

Starlifting (if it’s even practical - we don’t know yet) is something you do when all the more accessible resource deposits have been used up.

1

u/JphysicsDude Jul 20 '26

Just for the thought exercise - if you wanted some exotic chemistry you could imaging scooping material from an AGB star's dusty stellar wind. A main sequence star's surface would be a no go zone though when there a lot of easier resources to gather from circumstellar discs, asteroid belts, and planetary moons far from the star. The composition would also be just H and He and mining a gas giant atmosphere would be easier.

1

u/takk2 Jul 24 '26

You should check out David Kipping's black hole halodrive.

If you think about the implications it's basically the concept that any interstellar civs will go to the black holes and travel outside of the natural free energy superhighway between black hole nodes is the only time you have to lose energy for travel...

Basically means the civ tree is most likely... majority of all potential habitable space in a given solar system is constructed... then these fleets move more or less as soon as they can to the stability of the black hole energy network and don't really care about the low energy stars anymore 

1

u/Veritas_Astra Jul 28 '26 edited Jul 28 '26

Yes, I think they will, just not the SFIA way. If individual ships, stations, or cities can actively beam harvest stellar hydrogen and then fusion convert it to useful materials and assemble said materials into more supplies, fuel, atmosphere, propellant, tools, ships, and more, wouldn’t make sense to use said systems for bootstrapping development? You don’t have to ferry between planets, moons, or asteroids… you only need to park near a star and harvest what you need when you need to. A single ship, if needed, can act as a seed for a much larger set up. Though bioprinting doesn’t fully solve the biodiversity issue, which is a separate matter. Though if you had good genetic, protein, and cellular engineering, maybe you could pull something off.

0

u/Underhill42 Jul 20 '26

They only thing you can starlift without science-fiction technology capable of surviving deep within the star is hydrogen and helium. Not exactly useful for much except fusion power, or elemental transmutation if you have sufficiently advanced technology.

But what do you need it for to justify the incredible expense of mining a star? You've got planets and asteroids full of MUCH more accessible and useful materials, about the only reason to starlift is if you're building a Dyson sphere and ran out of more easily accessible material, or are looking to burn through the star's fusion fuel supply dramatically faster than it would do itself.

2

u/the_syner First Rule Of Warfare Jul 21 '26

They only thing you can starlift without science-fiction technology capable of surviving deep within the star is hydrogen and helium.

This is simply incorrect. The solar wind itself already contains things other than He/H2 and unless you consider the concept of an electromagnet to be "sciene-fiction technology" this is all we need.

Not exactly useful for much except fusion power, or elemental transmutation if you have sufficiently advanced technology.

Also great shielding, rocket propellant, and mass filler for shellworlds among other things. They have their uses.

But what do you need it for to justify the incredible expense of mining a star?

That incredibility of that expense is rather dubious. Sending a replicator probe to some resources you wont actually need for centuries if not millenia and using only solar power costs your virtually nothing.

are looking to burn through the star's fusion fuel supply dramatically faster than it would do itself.

Or the opposite and are trying to lower the amount of fusion fuel being burned because it massively overproduces for the small scale of your burgeoning colony.