Interstellar Trade: Value, Resources & Unobtanium

[GTOM]

Lets suppose that in SF universe, due to hyperspace, travel between stars don't require planet killer energies.
A mothership can transport kilotons of goods with energy of a few Tsar bombs, travel takes months.
What could be valuable enough to transport between star systems? Are there solar systems that entirely lacks some kind of resource? (For example a gas planet that offers lots of energy and organic material for colonies, but no metal? ) Or is it a bit plausible, that neutron stars, black holes, extreme conditions created some kind of unobtanium?

 

[Drakkith]

Are there solar systems that entirely lacks some kind of resource?

I don't think it's necessary for a star system to completely lack a resource to make it viable for trade, only for the demand for that resource to outstrip production capability.

What could be valuable enough to transport between star systems?

Manufactured goods would probably qualify. As would foodstuffs in my opinion. A system with no habitable planets but vast material resources could possibly need to import most of its food, or at least give it a larger variety of food than it otherwise might have.

mothership can transport kilotons of goods with energy of a few Tsar bombs

Bump that capacity up to the megaton range. Modern cargo ships can already exceed 200,000 tons (that's 3-4 battleships!) and the lack of any air/water resistance in space would probably lead to a massive increase in the tonnage of a single vessel.

 

[GTOM]

I don't think it's necessary for a star system to completely lack a resource to make it viable for trade, only for the demand for that resource to outstrip production capability.
Manufactured goods would probably qualify. As would foodstuffs in my opinion. A system with no habitable planets but vast material resources could possibly need to import most of its food, or at least give it a larger variety of food than it otherwise might have.
Bump that capacity up to the megaton range. Modern cargo ships can already exceed 200,000 tons (that's 3-4 battleships!) and the lack of any air/water resistance in space would probably lead to a massive increase in the tonnage of a single vessel.

Megaton cargo bay for a single ship is ok.
Trading foods suppose that it is cheaper to expend the energy of a thousand tsar bombs (i don't want to make cheat known laws of physics too easy) for a megaton of food, than build a farm, that could produce regularly megatons of food.

 

[Noisy Rhysling]

Something on the order of melange, the "spice" from Dune. Single source of supply materials.

And slaves.

 

[newjerseyrunner]

Slaves would also be my input, then again, with that kind of technology, a robotic slave army would be far superior to a biological one. Technology might be traded between species, but eventually we'd be able to reverse engineers each other's tech.

Luxuries would most likely be the biggest market. England didn't need anything from India. The tea was just too good to not trade. Some exotic spice or drug would be my guess.

 

[Drakkith]

Trading foods suppose that it is cheaper to expend the energy of a thousand tsar bombs (i don't want to make cheat known laws of physics too easy) for a megaton of food, than build a farm, that could produce regularly megatons of food.

After crunching some numbers it appears that you'd need the equivalent of about 3 years of current world energy production for a single trip. A bit more than I was thinking. So perhaps foodstuffs would not be feasible for long-term trading unless it was really expensive food for the upper classes who are willing to pay that much for it.

Still, just because it's cheaper and easier to produce something in-system doesn't mean that it actually is being produced. If no one has gotten around to setting up production facilities for the Space Blanket 3000 then it will have to be shipped in if people want it. It's all about what people are willing to pay for something they want.

Also, remember Economy of Scale can kick in hard in space when applied to transportation. If the cost of transport scales slower than the profit gained per sale of a good, then it's cost effective to build super-massive transports, possibly even beyond the megaton range. Without having to support its own weight under gravity, a cargo vessel can grow to almost limitless size (depending on the exact details of the propulsion system of course).

 

[Noisy Rhysling]

Slaves would also be my input, then again, with that kind of technology, a robotic slave army would be far superior to a biological one. Technology might be traded between species, but eventually we'd be able to reverse engineers each other's tech.

Luxuries would most likely be the biggest market. England didn't need anything from India. The tea was just too good to not trade. Some exotic spice or drug would be my guess.

Kamino successfully exported clone slaves.

 

[GTOM]

Something on the order of melange, the "spice" from Dune. Single source of supply materials.

And slaves.

Slavery for produce goods will be surely outdated (although i will describe other forms of slavery, trash reprocessing prison, sexual slavery, gladiators)

AIs, robots and 3d printers, molecular level printers will advance too. Although that doesn't inevitably mean that produce exotic food with printer is cheaper than plants and animals.

The most difficult tasks would be produce rare elements, unobtanium like alloys, probably exotic particles used for some hyper stuff. Reverse engineer a device, or develop a formula for an exotic drug can take some time, but sure not impossible.

 

[Noisy Rhysling]

Owning humans will always be a thing, I think. Especially among the darker minds.

 

[Drakkith]

Slavery for produce goods will be surely outdated (although i will describe other forms of slavery, trash reprocessing prison, sexual slavery, gladiators)

AIs, robots and 3d printers, molecular level printers will advance too. Although that doesn't inevitably mean that produce exotic food with printer is cheaper than plants and animals.

The most difficult tasks would be produce rare elements, unobtanium like alloys, probably exotic particles used for some hyper stuff. Reverse engineer a device, or develop a formula for an exotic drug can take some time, but sure not impossible.

Well, it's a bit difficult to give you suggestions if we don't know anything about what can and can't be done in your story.

 

[Ophiolite]

You trade three things:

• Knowledge
• Art
• Scotch whisky

Everything else can be produced more economically locally.

 

[jackwhirl]

I can imagine some regions of space being poor in particular elements by chance. If those elements are necessary for some purpose I can see them being shipped in.

 

[Noisy Rhysling]

I can imagine some regions of space being poor in particular elements by chance. If those elements are necessary for some purpose I can see them being shipped in.

Could they be shipped in economically enough to the colony or whatever viable? That's the real question on anything being shipped interstellar, "is it worth it?"

 

[Gigaz]

There are a few exotic materials which might exist locally and could be harvested:

Primordial black holes could be a weapon, an energy source or something that curves spacetime in a desirable way, for example for wormholes (ok that one's a stretch). They should not cluster but who knows. Some type of supernovae explode the star completely, and if it contained some atomic scale black holes, those may remain at the supernova position like a tiny gravitationally bound cluster.

Magnetic monopoles could produce large magnetic fields and are also suspected to be proton decay catalysts, which would be a great energy source. They are probably just wandering around and might occur more frequently at some places due to strong magnetic fields of white dwarfs and neutron stars.

Strange matter is somewhat hypothetical. It should behave a bit like atoms with extremely high density. It could be weaponized. Look for it in the vicinity of neutron star collisions.

Some types of dark matter may have a magnetic dipole and could therefore be moved around with no big effort. That is ultimately plausible new physics. Use it as you please.

 

[jackwhirl]

Could they be shipped in economically enough to the colony or whatever viable? That's the real question on anything being shipped interstellar, "is it worth it?"

I was thinking along the lines of something that must be had, like iodine. I know that is somewhat of a bad example, because we need so little of it, but it is needed.

 

[Noisy Rhysling]

I was thinking along the lines of something that must be had, like iodine. I know that is somewhat of a bad example, because we need so little of it, but it is needed.

I agree. We're more likely to settle a planet that has too few trace elements than one that has too little water. I think the colony would have to have something worth going after. The out-bound leg of the freighter's trip would carry things like iodine, literature, school training materials, etc., to trade for the rare material the colonists have found. Black diamonds on Pern comes to mind.

 

[jackwhirl]

You trade three things:

• Knowledge
• Art
• Scotch whisky

Everything else can be produced more economically locally.

I like this answer. I imagine that a civilization that had developed hyperspace technology could manage to build a fantastic 3D printer, if not a full on Star Trek style replicator. Granted, this would assume an established colony. Bringing in Drakkith's answer...

I don't think it's necessary for a star system to completely lack a resource to make it viable for trade, only for the demand for that resource to outstrip production capability.

...When establishing those colonies, I could see it being reasonable to ship many megatons of building materials before facilities can be set up to produce steel, for example, locally.

 

[GTOM]

Well, it's a bit difficult to give you suggestions if we don't know anything about what can and can't be done in your story.

Besides FTL, i said nothing that don't exist now (As far as i know, experimental molecular printer already exists). Of course i expect that robots and printers advance further too.
But scaling still applies. For example if the special printers of a colony could produce a megaton of Spice in a year (supposed they don't ignore more basic needs), while transport it only takes three months, then it can be viable.

 

[Drakkith]

Besides FTL, i said nothing that don't exist now (As far as i know, experimental molecular printer already exists). Of course i expect that robots and printers advance further too.

You expect that robots and printers have advanced further? Don't expect, decide and tell us how far!

 

[rootone]

Or is it a bit plausible, that neutron stars, black holes, extreme conditions created some kind of unobtanium?

Not as far as we know.

 

[Noisy Rhysling]

Not as far as we know.

And if they did, it would live up to its name.

 

[jackwhirl]

Does this civilization possesses some form of FTL communication technology to compliment their FTL drives?
If not, there would likely be a courier system for communications, let alone materials.

 

[GTOM]

You expect that robots and printers have advanced further? Don't expect, decide and tell us how far!

In my story in 22th century (no FTL travel, only FTL comm, based on direct "counterfactual" communication with entanglement and Zeno effect. Pretty narrow bandwidth, since info is carried in WHEN coherence broken), the printers of Olympos Mons produce a large army of cheap combat robots in two weeks against the martian rebels. Then the printers need maintenance, and they can't produce their own special parts.

In 31th century (FTL travel, so the time of OP) a family house can produce all its basic needs, maintain itself, most people don't have to work at all. (Maintenance of robots, printers sometimes requires rare materials, special technology. Basic printers can't produce everything.)

No wide band FTL comm. (Tachion/hyperwave signals pretty noisy, FTL jump breaks entanglement ) So it can be preferable to send info with ships.

 

[Noisy Rhysling]

How about "message bots", arrive in a solar system, broadcast their arrival and next destination. Encrypted messages sent to them. Courier ships for more sensitive material, of course. But "Happy birthday, Grandma!" would go by bot. You could have aliens follow a bot to it's destination and try to communicate with it.

Just a thought.

 

[snorkack]

Travelling by sailing ship from Europe around Cape of Good Hope to East Indies took around 8 months one way through 17th and 18th century, both for Dutch and English. (The time improved slightly in early 19th century with improved sailing ships and a lot after 1870 with steam and Suez).
From 1602 to 1795, Vergaan Onder Corruptie sent almost 4800 ships to East Indies, so average of about 25 ships per year, but the number was higher in 18th century than 17th. Under 150 of them were lost to shipwreck and enemies. But a significant fraction of the ships, IIRC almost a third in some periods, were unloaded and left behind in Indies, as fewer ships were needed for return. So under 4000 ships... ended up returning about 2,5 million tons of trade goods.
When in early 19th century the Dutch established their power in Dutch East Indies to the extent they were able to count their new subjects, they found something over 30 million people.

An average John Company East Indiaman of late 18th century had a crew of about 120. So consider the payroll costs - 120 men for 8 months one way (with stay and return, nearly two years). Vergaan Onder Corruptie sent out about a million people in the 200 years - meaning around 5000 per year, 200 per ship. That´s crew plus passengers - such as land soldiers, who did not work on the sea voyage.
Half of the million men sent out by Vergaan Onder Corruptie died. Meaning every 5 tons of trade goods cost a life of an European gone to find his fortune or die trying. Not counting the lives of East Indians the goods were taken from.

So... Someone has discovered 2017 Earth. A ship, or a small fleet of several ships, is there to load a few thousand tons of trade goods.

What would you load to get best prices, in a couple of years that the ship/fleet will take to return?

 

[stefan r]

Lets suppose that in SF universe, due to hyperspace, travel between stars don't require planet killer energies.
A mothership can transport kilotons of goods with energy of a few Tsar bombs...

After crunching some numbers it appears that you'd need the equivalent of about 3 years of current world energy production for a single trip. A bit more than I was thinking. So perhaps foodstuffs would not be feasible for long-term trading unless it was really expensive food for the upper classes who are willing to pay that much for it.

It was a kiloton for "a few tzar bomba's". The tzar bomba weighed 27 tons. A lot of that weight was lead. Around 40 to 1 mass ratio 20:1 round trip. Dehydrated food is light weight.

What could be valuable enough to transport between star systems? Are there solar systems that entirely lacks some kind of resource?

Red dwarfs lack deuterium and lithium. An important component of your tzar bombas.

Population II stars will have lots of energy but probably no planets/asteroids that can be used for extraction of heavy elements. Type O stars have lots of power and high energy radiation. Red giants have lots of energy. You could, for example, levitate a solar sail around some red giants. All would be net energy exporters.

Interstellar gas clouds should have deuterium and metals. They will be very short on energy unless they burn the deuterium, lithium, and uranium that they find. Gas clouds also do not have gravity wells. If your mother ship cannot operate on a planet surface then collapsing gas clouds would be a rich mining area. Rogue planets and comet/asteroid fields could have similar resource economics. Collapsing gas clouds would probably not be a good place to live. Agriculture would have to be entirely artificial and the large surface area would be vulnerable to meteor damage. Farms need some way to radiate heat even if you stack the growing spaces.

Triangle trade. Mine in dense deep space. Transport raw materials (all elements sans helium/neon) to high energy industrial areas around giant or pop II stars. Then transport high energy products (food, deuterium, plutonium, lithium, maybe anti-matter) to civilizations around k-dwarf stars. Pick up advanced manufactured goods like electronics, GE-seeds, drugs, engines, magnetic ram scoops, and workers/slaves at civilization. Civilization is also probably were you deposit cash and plan to retire.

 

[Drakkith]

It was a kiloton for "a few tzar bomba's". The tzar bomba weighed 27 tons. A lot of that weight was lead. Around 40 to 1 mass ratio 20:1 round trip. Dehydrated food is light weight.

True, but it should be a lot less than 27 tons if you're just talking about the fuel used to power the ship. The fuel-payload mass ratio will probably be much higher.

 

[Noisy Rhysling]

On the gripping hand, how complicated would dumb haulers have to be? By automating them and stripping away everything not needed (starting with the airlocks) the margin just might improve. Put them in containers that can be used on the target world for housing or storage or whatever ("Beware the stobors!") and only the important bits make the return flight. Or reload the containers with something we need back here, like clear air or potable water.

 

[stefan r]

True, but it should be a lot less than 27 tons if you're just talking about the fuel used to power the ship. The fuel-payload mass ratio will probably be much higher.

...how complicated would dumb haulers have to be? ...

Is better to use exact replicas of the Tzar Bomba. A reader has to accept the FTL premise. Compare to "the long earth" Terry Pratchett and Steven Baxter where a potato powers the Willis Linsay stepper. The books included technical drawings.

If the "physics package" includes the mass, volume, and shape of a Tzar Bomba then you could go into excessive detail about the loading mechanism and storage racks. A chat with someone who works with overhead cranes can give you many pages of text: common problems, newby mistakes, freak instances. Modify their stories slightly to include low/0 g environments. Crane safety manuals, training videos, and OSHA regulations are widely available. At the other end of each FTL event you have the Tzar Bomba going off. You can get detailed descriptions of nuclear tests which means you can include lots of real physics at the jump point immediately after the event. You can also describe each of the three stages in a three stage nuclear bomb.

I would suggest using a real location like a micro brewery. You could also use a yogurt or cottage cheese vat. Breweries are more fun and easier to get into. Position the "Tsar Bomba" in the vat and give the FTL microbes three months[7.6±0.3 x 10⁶ seconds at 352°K] to incubate. You can add lots of detail about GMP practices to sterilize equipment and prevent contamination. Taking a culture would be valuable too. If you know the location you can place characters and interactions consistently.

You have to decide which end of FTL jumping gets the blast. That could effect your story a lot. Need to find some way to avoid irradiating the customer's family. You could interview some anti-nuclear activists. Tell them you are writing sci-fi and want to find out how they would respond to a company's proposal to detonate nuclear bombs in low Earth orbit. Show them some descriptions/diagrams of project Orion or the open cycle thermal nuclear rocket.

...stripping away everything not needed...

Would make a big difference if your kiloton was the total ship plus the cargo instead of just cargo.

The energy in a Tzar Bomba is 2 x 10¹⁷J a kiloton of typical food has around 2 x 10¹³J. High efficiency grasses can capture 1% of sunlight. Food output can be around 10% of that. A nuclear reactor might get higher than 10% efficiency. Would barely break even. The farms, ecosystems, shields, nuclear reactors are all massive and expensive infrastructure. Is quite plausible that a colony living someplace similar to the Kuiper belt would import grain. They probably should have some plants around to recycle air and bio waste. A Mercury colony (or equivalent exoplanet) might import compostable bio waste.

The energy needed to make something like red Himilayan cliff honey would be higher. The required infrastructure would likely be cost prohibitive for many colonies.

 

[Drakkith]

Is better to use exact replicas of the Tzar Bomba.

The OP said the energy of Tzar Bomba, not that he was literally using nuclear weapons as a propulsion method.

 

[stefan r]

The OP said the energy of Tzar Bomba, not that he was literally using nuclear weapons as a propulsion method.

Could we use textbook or a bag of apples? 2½ kilograms should be enough if E = mc².

If we assume a fusion reactor powering a steam punk mechanical FTL device is the 2 x 10¹⁷J the energy released by deuterium during fusion or the energy needed to crank the pistons? Does the reactor just generate electricity which then gets consumed? Could we slowly accumulate 2 x 10¹⁷ joules and then make a 3 month jump or does the reactor have to run steady at over 33 gigawatt? If this is a carnot cycle how do you unload 3 times the power of the space shuttle? In noisy rysling's version we only have 10⁶ kilo of ship, 33 kilowatt per kilogram. Could get toasty.

I like my version better. light off the reaction then escape through hyperspace were the explosion cannot keep up.

 

[snorkack]

For example, a Liberty ship has a payload of 10 200 t. Needs a crew of 40...60. Normal endurance of about 1800 hours, meaning 75 days of cruise.

So, suppose you do build a spaceship. Try to consider the breakdown of major cost items over one mission:

1. Fuel expended for ship and payload
2. Salaries, food and air of the crew
3. Wear and tear related depreciation of the ship
4. Financial depreciation of the initial investment of the ship

What´s the total, and what´s the breakdown between those 4 groups?

 

[GTOM]

Could we use textbook or a bag of apples? 2½ kilograms should be enough if E = mc².

If we assume a fusion reactor powering a steam punk mechanical FTL device is the 2 x 10¹⁷J the energy released by deuterium during fusion or the energy needed to crank the pistons? Does the reactor just generate electricity which then gets consumed? Could we slowly accumulate 2 x 10¹⁷ joules and then make a 3 month jump or does the reactor have to run steady at over 33 gigawatt? If this is a carnot cycle how do you unload 3 times the power of the space shuttle? In noisy rysling's version we only have 10⁶ kilo of ship, 33 kilowatt per kilogram. Could get toasty.

I like my version better. light off the reaction then escape through hyperspace were the explosion cannot keep up.

I think only antimatter or exotic particles can have enough energy density, they don't literally blow up a real nuclear bomb. But yeah they jump very far from any gravity well.

Energy dense areas. Theoretically Sun could also give very much energy with a Dyson sphere, although i find the ideas of theese megastructures pretty irreal, at least with my constraints, interstellar trade is magnitudes easier than build such a thing.

 

[Noisy Rhysling]

The OP said the energy of Tzar Bomba, not that he was literally using nuclear weapons as a propulsion method.

Namu amida butsu! I thought I was going to be ringside at a cosmic calamity.

 

[Noisy Rhysling]

For example, a Liberty ship has a payload of 10 200 t. Needs a crew of 40...60. Normal endurance of about 1800 hours, meaning 75 days of cruise.

So, suppose you do build a spaceship. Try to consider the breakdown of major cost items over one mission:

1. Fuel expended for ship and payload
2. Salaries, food and air of the crew
3. Wear and tear related depreciation of the ship
4. Financial depreciation of the initial investment of the ship

What´s the total, and what´s the breakdown between those 4 groups?

If you use robot haulers the second item is "zero".

 

[stefan r]

If you use robot haulers the second item is "zero".

The robots consume energy and need replacement parts and servicing. You could lump #2 in with #s 1 and 3 as fuel, depreciation, and wear but you could say that for a human crew too. "Food" is just a special type of fuel used for autonomous meat robots.

The FTL drive itself is pure fiction. It might as well need food.

I think only antimatter or exotic particles can have enough energy density, they don't literally blow up a real nuclear bomb. But yeah they jump very far from any gravity well.

Energy dense areas. Theoretically Sun could also give very much energy with a Dyson sphere, although i find the ideas of theese megastructures pretty irreal, at least with my constraints, interstellar trade is magnitudes easier than build such a thing.

All components of a Dyson swarm have already been demonstrated. The technology was available in 20th century. The DOE and NASA wrote a report on it in 1978. On page i:

The concept presented is considered to be in the proper "direction," but is not optimum at this time. The system definition studies, however, indicated technical feasibility of the reference concept...

Self supported living in space has not been demonstrated. If you have technology sufficiently advanced to allow space colonies then the technology for a Dyson swarm is primitive. The limitations I am aware of are time, Kessler syndrome, and the mass of "expendable" planets. Dyson swarm would make a good thread.

If you have FTL you can choose any position. Around AGB stars and near the barycenter of binary you can levitate foil. Easy to keep orbital velocities well below velocities that weak tethers can handle. This gets overlooked in discussions about SETI because there is not a plausible explanation for the evolution of life suspended at the barycenter of two stars. AGB stars have short duration and are not stable enough for evolutionary timelines. A space based civilization that can choose to jump around anywhere in the galaxy will have an easy time building megastructures. Using ±5° area you can capture 2.4% of luminosity. For sun like stars that is around 10²⁶ watts. If you can make one millionth of the energy available for interstellar trade you can move 500 mother ships per second. An AGB star could handle millions of motherships per second.

 

[Noisy Rhysling]

Okay, that stuff about fuel being food is just silly.

 

[GTOM]

The robots consume energy and need replacement parts and servicing. You could lump #2 in with #s 1 and 3 as fuel, depreciation, and wear but you could say that for a human crew too. "Food" is just a special type of fuel used for autonomous meat robots.

The FTL drive itself is pure fiction. It might as well need food.
All components of a Dyson swarm have already been demonstrated. The technology was available in 20th century. The DOE and NASA wrote a report on it in 1978. On page i:Self supported living in space has not been demonstrated. If you have technology sufficiently advanced to allow space colonies then the technology for a Dyson swarm is primitive. The limitations I am aware of are time, Kessler syndrome, and the mass of "expendable" planets. Dyson swarm would make a good thread.

If you have FTL you can choose any position. Around AGB stars and near the barycenter of binary you can levitate foil. Easy to keep orbital velocities well below velocities that weak tethers can handle. This gets overlooked in discussions about SETI because there is not a plausible explanation for the evolution of life suspended at the barycenter of two stars. AGB stars have short duration and are not stable enough for evolutionary timelines. A space based civilization that can choose to jump around anywhere in the galaxy will have an easy time building megastructures. Using ±5° area you can capture 2.4% of luminosity. For sun like stars that is around 10²⁶ watts. If you can make one millionth of the energy available for interstellar trade you can move 500 mother ships per second. An AGB star could handle millions of motherships per second.

Dyson swarm that capture a few percent of light is ok, i just think a full sphere requires too much material.

Well even on rogue planets and gas clouds they can still fusion hydrogen, so i don't think they would require imported energy.
But if we look at really high energy applications like produce antimatter, and material/technology needs extreme energy density, it can be more practical to move mined stuff around AGB (What that exactly means?) stars, where they process it, then send it to pleasant Solar system like places.
And the pleasant places can send luxury stuff (spice, courtesans ? ) to mining outposts, where there arent enough capacity to produce large quantities.

 

[stefan r]

Dyson swarm that capture a few percent of light is ok, i just think a full sphere requires too much material.

Well even on rogue planets and gas clouds they can still fusion hydrogen, so i don't think they would require imported energy.
But if we look at really high energy applications like produce antimatter, and material/technology needs extreme energy density, it can be more practical to move...

The turn around on a solar collector would be a major factor. Not far from 13.4 kg per m² for current market panels and solar irradiance at Earth is about 1340 W/m² so orbiting near Earth silicon panels can get 100 W/kg. Film panels could do much better and you can use mirrors. Some current satellites are getting 300 W/kg. We get 10⁶ kg per trip in this thread and the trip is 2 x 10¹⁷ J so the energy is recovered with 2 x 10¹¹ J/kg so 6.6 x 10⁸ second or 21 years. If you place the panels 10x closer the the sun or concentrate light with mirrors you can recover the energy in 0.2 years instead. Assuming they do not melt.

...AGB (What that exactly means?) stars,

Asymtotic giant branch stars. Is the last phase in the life of a star with mass close to solar mass. The fusion rate is going so fast that it blows the shell out into space and forms planetary nebula. It is a red giant but different from the red giant stages. Totally unrelated to red dwarf or red supergiant but the same temperature. The sun should become an AGB star eventually. You have some choices for moving around an AGB star system using either electric and magnetic sails that deflect the stellar wind or you could sail with just pressure from the light.

For example the star Mira. It has 1.18 solar mass (so 1.18 solar gravity) and around 9000 solar luminosity. So in a Jupiter like orbit you still have more than 300 times the irradiance. You might be able to collect some of the matter in the solar wind. Mira is blowing out 3 x 10-7 solar mass per year. About 10% of Earth's mass annually. Mira has a companion white dwarf star which is accreting matter and may be forming new planets. Lots of material for solar panels and habitats.

...A mothership can transport kilotons of goods with energy of a few Tsar bombs, travel takes months... Or is it a bit plausible, that neutron stars, black holes, extreme conditions created some kind of unobtanium?

Okay, that stuff about fuel being food is just silly.

If you drop a 1 kilo brick of anything into a "large" white dwarf star it will be traveling over 6.3 x 10⁶ m/s and has kinetic energy 2 x 10¹³ J. If 1000 tons of materials appear and collide at that velocity you will have 10x the energy released if the cargo impacts something. If the mothership is much more massive than the cargo you could use that for energy generation too. The weapons potential would be significant. Diving into the black hole would give you much higher velocity.
You need to consider what velocities a ship has after leaving "hyperspace". Making a 180 rotation around the milky way from the sun would mean the ship is traveling 220 km/s in the opposite direction from surrounding stars, likely 440 km/s collision. Adjusting to the local velocity ads a lot of energy and might require reaction mass.

We could attach a 1 ton ram in front of the mother ship and make it look like a viking prow made of regolith. Then we place the cargo bay in the front of the mother ship but behind the ram. When we dive into a neutron star the ram will impact the surface at 1.5 x 10⁸ m/s (not adjusted for relativity) The ram gives the 2 x 10¹⁷ J energy we needed but the cargo bay can also pick up 1000 tons of neutron star surface material before jumping through hyperspace. The plasma remains of the mothership arrives at the target destination flying at 1 x 10⁸ m/s and carrying a kiloton of highly unstable neutronium. The neutronium would fission instantly.

In deep space you have better heat sinks than on earth. A warm ocean (perhaps under Chandra) could boil liquid nitrogen to drive a turbine. The mothership could crash into a deep camber and melt/boil a large volume of ice. The heavy metals from the neutron star and mothership plasma would eventually settle and could be collected. Free neutrons could produce more deuterium.

 

[Noisy Rhysling]

You missed my point. The "Food" issue on a robot ship is zero. The fuel is already in the calculations, you don't need to add it twice.

 

[GTOM]

You missed my point. The "Food" issue on a robot ship is zero. The fuel is already in the calculations, you don't need to add it twice.

The untrust factor is bigger, they don't like to give hypertechnology to AIs.

 

[Noisy Rhysling]

The untrust factor is bigger, they don't like to give hypertechnology to AIs.

Yeah, that's today. Tomorrow is always what we don't expect it to be.