Think about the Nostromo from Alien. A giant freight ship that transports iron ore (!) over many light years (passing several other systems) to Earth on a year long trip. I think most will agree that it makes nearly no sense at all. Iron is abundant on earth and even if not it is abundant on nearer bodies in system or nearby systems (I think).

I think this is true for most raw ores (except for plot device unobtainium) so there is no sense in this kind of mass transport between the systems.

Unobtainium that is only found in one or several systems aside, and scenarios aside in which FTL transport is zero cost and instant (or nearby) which goods make sense to be transported over vast distances in space? Are there some resources that make sense to be carried in giant transporters?

Examples I can think of:

Information : If you don't have FTL communications and information must travel with ships, it will be a very common good to transport. But it does not need big cargo rooms, so small ships (or even unmanned probes) are enough.

Very valuable (or important) manufactured goods, that cannot be produced at the destination. But if the destination (poor frontier colony) can't produce it, can they pay for it?

Art, special luxury food or other luxury goods for the rich.

And of course - people (who can pay for it).

So, no chance for our Han Solo like smuggler (except in this small niches) and no chance for our giant Nostromo like space hulks?


I agree that there is much intersection with the "duplicates". But I think the overwhelming mass of good answers is a very good information source. Perhaps the other two duplicates should link back in some way to here to provide additional and related answers?

It's hard to decide which answer to accept. I would accept several of them and share the points, but this is not possible. So I accept the most popular answer, despite getting good ideas from several other answers, too.

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    $\begingroup$ None of your examples work either. (depending on tech) Information can be transmitted at high speeds and lower power requirements using radio waves or lasers. Any "luxury" item will have to stand being in the cold vacuum of space, bombarded with radiation, for years unless you add shielding and heating. You,l need to stop it getting too hot as well during launch and landing because a lot of energy is released. Nano-fabrication tech will make actually sending anything, even people pointless. $\endgroup$ – Donald Hobson Jun 27 '16 at 13:01
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    $\begingroup$ The spice must flow! $\endgroup$ – Kys Jun 27 '16 at 13:36
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    $\begingroup$ Note that the Nostromo was towing a whole refinery, not just the iron ore. $\endgroup$ – Michael Schumacher Jun 27 '16 at 14:46
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    $\begingroup$ What is your tech? Is FTL travel possible? How much does it cost? How far are you going? Without some more detail about your world, the answer could range from "nothing" in the case of long, non-FTL travel worlds to "lots of stuff" in the case of fairly cheap FTL transportation. $\endgroup$ – ckersch Jun 27 '16 at 15:17
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    $\begingroup$ Don't forget that it's as impossible to get to other stars today as it was crossing the oceans 5000 years ago (or so). Which means, in the future, the answer might be anything! Today, we ship cotton grown in the US to China by freighter, where it is turned into t-shirts thanks to cheap labor, and those are then shipped back to the US (and around the world). Thanks to cheap labor in system A and cheap raw materials in system B, it may be desirable to ship anything interstellar distances! $\endgroup$ – Nick2253 Jun 28 '16 at 14:07

26 Answers 26


Things that are unique

Whether it's a mineral, a plant or an animal, the only place you know you can find it is <insert planet name here>. Well you have to import.

Alternatively, it is a manufactured good, produced by one company, and that company has only one manufacture. Likely they won't bother building a factory on another because there isn't a big enough market for it. But there are still people ready to import it. Or even alternativelier, you can find a similar product, but you want/need that exact one for reasons.

Things that are really, really valuable, like, a lot

Or more accurately, you can sell it at a high enough price that you can cover logistics cost, but not too high that nobody will buy it. Ties in with unique really, since anything unique tends to be really expensive as well.

If you have to import it from an exotic location and the shipping fees are ludicrous, it only adds to the intrinsic value bragging rights. Rich people typically only care about the price tag. Art is undoubtedly better when it traveled 42 parsecs.

Things that are kind of legal but not really

Maybe obtainium is extremely easy to find but extremely hard to acquire.

Reason number one would be paperwork. If it's regulated up the wazoo then maybe it's easier to acquire illegally. Or if you are up to no good, you don't want the paper trail.

Reason number two would be taxes. Maybe your corporation can bypass customs (legally or not), so that shipping fees plus import tax is cheaper than just buying it locally.

Or maybe you need it faster than the red tape will allow, so you have to turn to other sources.

At any rate, it's probably easier to covertly and illegally import things than covertly and illegally mass produce them.

Things that are actually people

People like to travel too. Though that depends if you count people as goods.

So to sum up, things extremely unique/niche or things extremely sublegal.

As for why giant transports, there's a reason we build ginormous boats to carry loads of containers, it's because the bigger the boat, the more cost effective. It helps bringing your revenue up and your shipping costs down.

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    $\begingroup$ faster than the red tape, LOL Even with near light speed ships your talking 10 years min. $\endgroup$ – Donald Hobson Jun 27 '16 at 16:27
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    $\begingroup$ @DonaldHobson you clearly haven't had to deal with the government at its best $\endgroup$ – Marshall Tigerus Jun 27 '16 at 18:59
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    $\begingroup$ @DonaldHobson As a real-life example, the waiting list for legal immigration in the US tends to hover around ten years, but if you're desperate, you can get in by riskier means... $\endgroup$ – phyrfox Jun 27 '16 at 19:46
  • $\begingroup$ Given the speeds involved, giant transports would probably not benefit from volumes of economy in the same way that ocean going vessels do. $\endgroup$ – wedstrom Jun 27 '16 at 20:43
  • $\begingroup$ @wedstrom This has nothing to do with speed. It has to do with fuel cost, crew pay, docking fees, and all the fixed costs that don't depend on how much stuff you are transporting. That exists regardless of the type of transportation. $\endgroup$ – AmiralPatate Jun 28 '16 at 7:38

Stars and star systems have a metallicity measure attached to them. Much to the despair of chemistry professionals, astrophysicists will call any element heavier than helium a metal - so we are not only talking about iron and gold here, we are also talking about carbon, nitrogen, oxygen etc.

Our galaxy is rich in astrophysics "metals" in the core, and in its main plane. In general, the further you move away from these, the less "metals" you have.

Metal gradient in the Milky way

So if you are going to colonize the rim of the galaxy, and if the star system you are going to has only hydrogen and helium... It might be cheaper to bring your own shipments of the periodic table than to convert the local "non-metals" into heavier stuff. I believe it to be cheaper because usually most of the "metals" we are talking about here are formed in the core of stars when they go Nova. That may take more energy than a ship could provide.

Now the only piece of the puzzle left to solve is why someone would want to colonize a piece of the galaxy that has nothing valuable going for it. Well, maybe there is a wormhole there, or maybe it is an important passageway to somewhere else (i.e.: a star system right in the middle of two galactic arms). You may want to build a permanent station there. If all you can find there is H and He, it's a good idea to bring your own building material.

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    $\begingroup$ Sorry but rarer doesn't mean non existent, extracting carbon when its at parts per billion still makes sense if you can separate them. Plus if you have a bunch of helium hitting some more helium at 1% of the speed of light then that's enough energy for fusion and you'll get plenty of "metals" out. $\endgroup$ – Donald Hobson Jun 27 '16 at 16:32
  • $\begingroup$ @DonaldHobson I see your point, but my opinion about this is summarized in Bitoubi's answer. $\endgroup$ – The Square-Cube Law Jun 27 '16 at 16:52
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    $\begingroup$ Sometimes you might want to colonize a planet precisely because there is nothing there. That's the case in the Foundation series where Terminus is chosen as the capital of the Foundation because it has no valuable resources that would cause another group to invade it. $\endgroup$ – Rob Rose Aug 8 '17 at 5:50

Manufacturing equipment

Massive-scale manufacturing equipment would take too long for a colony to work to on its own.

20 years at sublight to get a massive orbital construction facility created by much more massive construction facilities in home system, or 50 years a small one yourself. Comparatively, may be cheaper due to pre-existing large-scale on homeworld.


Family heirlooms, crown jewels, things that have social value.

Damaging-to-extract minerals

Some highly uncommon minerals such as massive quantities of uranium and plutonium (mine in one system without life, strip-mining barren worlds, transport to planets with a lot of life where land is protected.)


Assuming some form of energy storage much more efficient than batteries is created, solar systems with no planets can have solar arrays that can blot out a sun in a dyson swarm without risking planets. Then energy is transported. If effectively unlimited storage, storage containers would be of assorted value based on how much energy is in them, and likely not in single containers for assorted market values (and so you don't have to combine everything in the swarm each time, just replace storage and from parts of swarm and continue.


Not just "those who can afford the trip" but those who are worth getting on the trip. Highly skilled doctors, architects, those of political value, etc. And they may actually be cargo if they're put into some kind of stasis for the duration of the trip.


Hey, manufacturing equipment and people rolled into one!

Military Equipment

Yea, you don't just send that stuff or the plans for that stuff flying around unmanned. And when you need an army 'now', just sending plans isn't good enough.


Not transporting people, transporting transportation devices. Delivering stargates if your story has that kind of thing, larger ships that destination can't produce, etc.

Specialty goods

It's patented and protected by encryption software or something and everyone relies on them. Gotta have actual manufacturer goods, and they don't have a plant on the target planet.

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    $\begingroup$ Expanding on what you bring up in "damaging-to-extract minerals," a galactic-scale civilization might strip-mine an entire planet as the first step of terraforming it. Then the entire planet can be devoted to life. $\endgroup$ – Rob Watts Jun 27 '16 at 17:14
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    $\begingroup$ @RobWatts Galactic scale civilization may may strip mine stars, or explode stars for resources, and that may not be healthy for system in many ways, and maybe 30ly nearby systems if this mining is supernovae style mining. $\endgroup$ – MolbOrg Jun 27 '16 at 21:21
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    $\begingroup$ "manufacturing equipment" is basically what Nostromo was doing - hauling an ore refinery structure. $\endgroup$ – Michał Jastrzębski May 12 '17 at 15:20
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    $\begingroup$ also, high profile prisoners could be another kind of human cargo. Be it as workers for dangerous, controlled industry off-world, or a dedicated prison planet. $\endgroup$ – Michał Jastrzębski May 12 '17 at 15:22

Maybe sometimes it is cheaper/easier to buy goods from another solar system that to actually produce it.

We can draw a parallel with our world, where for example Western countries could technically produce coffee in heated green houses, but it is more convenient to buy them from South countries and wait the goods to come in super tankers. Super tanker are expensive but it is still cost efficient to use them instead of producing coffee locally.

For the Nostromo, maybe it comes from a place where it is really cheap to produce iron ore (cheap workforce working to extract iron ore on a planet entirely made of iron ore for example...). Then for big bulks of iron ore it can be worth to pay the transport of the goods.


Almost nothing

In a strictly economic sense you're looking only at high value manufactured goods from specific regions. Consider the small wooden statues from Easter Island for example. These are reproduceable, but have no value unless they're original and historic.

Also as mentioned by AiX: Biological matter, probably in egg/seed form to minimise cost.

Unless you can justify moving entire historic buildings, like say, a pyramid, you're going to struggle to justify enormous bulk freighters. Han's style of small ship high speed runs are going to be the bulk of cargo.

So you want a giant bulk carrier

This is not impossible if you run it on economy of scale. First make haulage of small items by ordinary people cheap, really cheap, £0.50 for a letter cheap. You'll also need to make moving people equivalently cheap, people need to be moving around to want things from home and to want to send things to people far away.

Now, when someone posts something to a family member far away, that letter goes to a planetary hub, then to a sector hub. Between high population sectors you get your big bulk mail carriers.

Sentimental value is what can drive your bulk freight, not commercial value.


A simple way to allow bulk transport would be to include 2 factors in your universe.

1: make it cheap to get to space, think some kind of antigravity drive which can get things to orbit for little more than the potential energy difference. No big expensive rockets. It can be very slow if you need an excuse to include big expensive rockets for military stuff etc

2: I gather that your universe allows FTL. Make the cost of FTL high and flat rate. Whether the thing entering FTL is the smallest engine with the smallest hull or a supertanker with an FTL engine bolted to the side, make ftl cost the same. The same quantity of unobtanium crystals get burned up or similar.

If each interstellar journey costs 10 million credits whether you're transporting 20 kg's of hard drives or 2 million tons of cargo you're going to build your ships big and if getting to orbit is cheap enough you can afford to ship lower value items.

With these adjustments you can transport almost anything of reasonably high value.


There is something others have failed to mention so far. Common goods not readily accessible by colonies.

Starting colonies, or even somewhat developed ones are bound to lack the industry for producing a massive amount of goods and technologies.

The amount of logistics needed to develop most modern technologies is immense. For a modern smartphone you need a number of mining industries to extract numerous metals from the earth, you need a chain of specialized industries to develop the components en-mass, from batteries to transistors to screens to wrappings. You need industries for inks, speakers, glues and a bunch of other elements. you even need industries to develop software and apps.

A colony ranging from small to medium sized is bound to lack some industries that are essential for the manufacture of many modern technologies, as such, they either have to import the resources or the finished product.

Given this need to import stuff even when lacking a single component, it's probable that colonies will import the finished product until they are capable of building the entire chain of manufacture.

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    $\begingroup$ Ah but your assuming modern manufacturing and interstellar travel. We might have some sort of nano assembler by then. Also the chain of manufacture is the cheapest way to make lots of something on a small scale. It could be scaled down a lot. $\endgroup$ – Donald Hobson Jun 27 '16 at 16:23
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    $\begingroup$ Even if nano assemblers are used to assemble components, I'd bet it would be a pretty expensive way to manufacture bigger goods. Things like rockets (and even cars) are bound to be hard to make in a colony. And that's not even considering the resources needed for the manufacture of goods. You don't need just a mine, you need a series of different mining operations each focused on a specific resource. I think Cameron's Avatar does a good job at this, they are a pretty small mining colony, as such they import most machinery. $\endgroup$ – Miguel Bartelsman Jun 27 '16 at 16:59
  • $\begingroup$ Automotive production is almost done by robots, there no technical reasons to not replace humans with robots in production. It's may be more like statecraft, then 192x technologies, as you think. Machines production is more energy, resources and knowledge (something like programs but for production). $\endgroup$ – MolbOrg Jun 27 '16 at 21:34

One of the biggest motivators of interstellar transportation and shipping would be war. In a multi-solar system conflict where many planets are struggling to survive, the planets on the front lines would be unable to manufacture and maintain the weapons, ammunition, defenses, and soldiers that they would need.

This scenario has a lot of parallels to World War Two. Before America had entered the war, England was struggling to meet the bare necessities required to keep on fighting. England was so desperate for things like fuel, guns, and rubber that it was willing to look past the money and put itself into debt. On the American side, despite thousands of ships getting sunk by U-boats, the trade was lucrative enough to keep people coming.

War causes desperation, and in a multi-star conflict there would be a huge amount of trade with things that would usually not be worth shipping that far.

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    $\begingroup$ Any star ship going near the speed of light could throw some junk out the air lock and obliterate an enemy planet. $\endgroup$ – Donald Hobson Jun 28 '16 at 18:03


It makes sense to transport energy in enormous giant GIANT transporters.

Some tasks have a need for lots of energy. For example disassembling a star, or moving a planet as can be seen in this example.

There are other tasks, which may need lots of energy, too. For example just for living if you have a big, I mean really BIG, human population, or for supplying a big big big AI for solving some universe problems (even if it's a quantum computer and a very efficient one - it may need lots of energy).

If they were stuck with some possible thermonuclear reactions and can't burn everything in an efficient way, by time or mass of the reactor. It might be the case some reactions are just slow by nature and it needs time and energy to find good efficient solutions for them. Stars are not efficient actually (hm except supernova's), so we can't just copy them, we have to invent something. Stars are not efficient in terms of total mass required for their existence vs power flow they are producing.

Building an FTL drive may require lots of energy. Not to produce the parts of it, or for the fuel supply, but to pump it with energy up to a level where it begins to work. See Alcubierre drive, energy requirement for a reference.

Some mass of construction of a reactor, where such reaction will be placed, even if it is 10kg per 1GW of power, it may be a lot of mass and volume of such mass for a reactor with star-like power productions. The best I can imagine at the moment is 1t per 1GW, mass/power ratio. Such a ratio (if possible) would allow us 10 times more energy generation, with materials we already have in our system, than our sun produces. It may (or may not) be a better ratio on a larger scale, in giant giant reactors, but still: it will be a lot of mass.

As a result

  • fuel they burn, and constructions where they burn it
  • mass needed to build such constructions. Carbon for example, for the enormous large scale of energy production - it needs lot of it.

As a note

I'm not sure what my definition of enormously large and enormous power production is. When I talk about disassembling planets, on my scale it's just an industrial task. Although even that task needs enough energy. Probably this is enormous big for me: Laniakea Supercluster. Yes, definitely enormous big. Quasar - not bad, not bad, I like it.

How big?

One day of work for our sun is something like cub 70X70X70 km of a liquid He3+D mix. Stars are good sources of such isotopes, so it makes sense (maybe) to transport them from stars.

So if we need to increase our energy production by 0.1% of the Sun's energy, we may consider to send and receive 7x7x7 km shipment each day. (It may be solved another way, so it's valid for way much more energy bursts).

Or we may send such ships to setup another system for energy productions and ship building. If we will be able to build just one FTL ship (which do not need rails) with our non-FTL capabilities, the entire galaxy will be ours, in less than 2000 years(humanity may grow fast enough to require all energy produced by all stars in a galaxy, if a possibility for the grow is given).


Behind that are some calculations, involving possible human population grows etc.
But up to 1,000 light years, there are easier, non-FTL ways, to transport energy. But for farther distances, FTL transporting of energy will be very handy, if that's possible. And if the engine needs much energy just to start functioning, maybe it will be the exact time when we, if we can afford some, get one of these.


So there are some reasons to transport some forms of mass. It's true even if you are able to transmute elements efficiently, and true if you can't. So if you look at that Fe transport like description of transporting X-type construction material, and no unobtanium, just regular matter (Carbon for example), it might make sense, but not because of the labor costs, not because it's cheaper, easier, whatever, but because you have to, because there is no other way to get as much as you need in that system.

So in OP's example, it's not a problem of what they are transporting, but a problem of the scale they operate at - it's not big enough to be viable. But as these ideas were mostly formed in 60-70's and earlier, it might be forgiven for old stuff - harm has already been done and what we may hope for, more good was done too.


Cheaper production in a nearby system, if the production of one FTL drive will cost something like Jupiter's mass of energy, even if future operation will cost no energy - do you really think transporting some goods will be worth it to use FTL for when there are tasks for the civilization as a whole to solve? Transporting people is one of them. I like that part of AmiralPatate's answer.


Chthonian planet - an interesting type of planets (very close to sun orbiting gas giants). There have to be lots of unusual isotopes, made by neutron flux from the star.


You should also look at the other side of the equation. The cost of import is so high because of limiting factor of "energy". If you had unlimited energy then even iron becomes a viable import. Of course, if you had unlimited energy, then we could just "poof" more iron into existence but....

So lets assume you have unlimited energy, and a short supply of something. Importing would make sense.

Given a method of travel that takes "normal" amounts of energy (like hyperspace or subspace) imports of raw materials becomes viable again.

Lastly, fuel may make sense. Think KSP and bringing back karbonite. Sure it takes a lot of the mined fuel to get the extra fuel back, and that's just in the same solar system, but that small amount of extra fuel is way more powerful then "normal" fuel.

  • $\begingroup$ Except that other planets are not covered in super energetic fuels that we can't make. An exception would be a planet made of antimatter. $\endgroup$ – Donald Hobson Jun 28 '16 at 18:05
  • $\begingroup$ Right, kinda, but what about a planet that has a fuel that is 20% more "energetic" then what we can make. It may be worth wile to import that fuel. But yes essentially, until you overcome "energy" your going to have a hard time importing "normal"things. $\endgroup$ – coteyr Jun 28 '16 at 20:50

Anything can make sense - it depends on the situation.

For example, although Earth as plenty of iron in its crust, you still have to dig it out of there in a reasonably unpleasant manner. If you have a very overpopulated planet and need every inch for agriculture and housing, there's limited scope for creating a huge hole just to dig up iron. The difference between whether you will go for the hole or the planetary transport depends then on the cost. If transporting stuff by bulk is cheap (as in, staff costs are next to nothing, ship costs are a single sunk cost, fuel is cheap once you push it in the right direction etc), then it can be cheaper to mine asteroids and ship the refined material back home.

Its the same argument for shipping shoes to the local store - is it cheaper to make them in Vietnam and transport them to your local Walmart rather than make them in a local factory? You bet - otherwise they'd be made in the local factory.

For iron this might not be quite so clearcut, but for rare earth minerals the costs can make sense, particularly for minerals that are required in quantity but not available on Earth (think platinum for example). In such a case it might be cheaper to dump a huge amount of asteroid into an automated refinery and by the time it reaches earth, all the rock is chucked away and you have a ship full of refined precious metal. Of course, you then have the problem of having a huge amount of precious stuff that would be cheap if allowed onto the market at once (think diamonds that should be cheap but are currently kept expensive by the traders hoarding them)


Assuming your universe doesn't enjoy bulk artificial transmutation technology, then rare but useful elements would have to be mined, refined, and transported.

The relative abundance of elements, as well as the cosmogenic processes by which they are created, are both well known:

Nucleosynthetic sources

No matter where you are in the universe, precious heavy metals are scarce. Our solar system happens to enjoy the relatively rich and diverse effluence of ancient supernovae, but to produce tons of the scarcest metals we have to search for veins and refine megatons of ore. If you're stuck in an interstellar region far from supernova detritus you simply will not find those elements and will have to import them.

  • $\begingroup$ Similarly, new supernovae may be valuable places to mine due to plentiful radioactive isotopes and maybe even ultra-heavy elements that have already decayed everywhere else. $\endgroup$ – praosylen Mar 4 '17 at 19:57

In order to 'make sense' you need to look at the whole universe that they create, not just a small portion. In these universes, they usually have some technology that overcomes the some of the problems of travelling long distances. You already excluded FTL technology in your question, but you need to realize that FTL is a feature of the Alien world, as the nearest System is more than 4 light years from Earth, and they make a multi-system trip in a year or so. These types of technologies distort what 'makes sense' as they greatly reduce the cost if you don't consider that technology. If you look at the development of Canals and Railroads you can see how it might make economical sense to send resources that were gathered from further away rather than those that are closer. There can be similar analogs made for intersystem vs intrasystem travel. Traveling withing a system it difficult and hazardous because of the orbital mechanics of all the interacting bodies. Travelling between systems may be very simple, and cheap, because there is nothing to interfere with you, and once you are at speed, you don't need to spend fuel to maneuver. Inside of a system, you must spend quite a bit of fuel to maneuver and to get your orbits right. You can kind of understand this by looking at travel near a big city. I live 20 miles from my office, which is on the outskirts of a big city. It takes me about 30 minutes to travel to work. There are people that live 6 miles from the office, but in the city, and it takes them the same amount of time, because of traffic, to travel to the office. I could be given a series of tasks in the city that will only have me traveling a few miles but eat up much more time than one would expect, given the distance traveled. Orbiting withing a system is kind of like that, sometimes you have to travel quite far to make a small relative change to your destination.

The market is a weird thing, and there is a lot of information encoded in the price. On the micro level, there are plenty of things in our current economy that don't appear to make sense, but they would fully make sense to one who fully understood all the factors involved. Check out this story (http://www.wsj.com/articles/SB10001424052702303277704579344852685727292), there is a significant portion of steel being supplied to US producers by China, and India. About as far away as you can get on this earth. There are many economical reasons why this is being done, but you cannot neglect this point. It is really happening. Reality frequently has things that don't make sense on the surface and require further study or pondering to understand. I would avoid building a world where everything is as it would seem it should be. Those types of worlds feel artificial, and readers, viewers, or human batteries plugged into a virtual-reality simulation will reject these types of worlds.

Now lets consider their exact situation. Why would someone ship iron ore across several systems when it could be had, in great quantities, in your own system? Because it is cheaper. Why would it be cheaper then? You could gain some answers just by looking at what happens here. Iron mining is unsightly, Strip mining is an efficient method, but leaves surface of the world scarred. Perhaps they are strip mining worlds that are marginally habitable, thus reducing the cost of sustaining a mining crew, but aren't really useful for colonization. Metallic asteroids do seem to be plentiful in our system, but what is the cost of mining them. There are challenges, low G, no atmosphere, no radiation shielding, no ability to grow food onsite, that would make a mining colony on a marginally habitable world more attractive than an asteroid. Another factor to consider is the concentration of resources, depending on the demand, mining a series of asteroids could be much more expensive then setting up a mining base upon a marginally habitable world.

  • $\begingroup$ Except that the energy and time required for interstellar transport are enormous and that even "marginally habitable" worlds would be very rare. (If we define marginally habitable as a world with suitable temperature and pressure without toxic chemicals so humans need only wear an air mask. $\endgroup$ – Donald Hobson Jun 28 '16 at 20:12
  • $\begingroup$ FTL is not excluded by OP. Buying steel in china, makes total sense as it is cheaper, some reasons are clear too. But we as earth are self sufficient, we do not export anything from other star system, I do not mean someone suggest to us something to buy, but as perfect example of self sufficient inhabited star system, which is totally possible. Countries are not, but whole system yes. $\endgroup$ – MolbOrg Jun 28 '16 at 20:55
  • $\begingroup$ @MolbOrg This is exactly what I am saying. Iron ore is being transported across the systems because it is cheaper than getting the closer ore. Just like the situation with China. $\endgroup$ – Mike Vonn Jun 29 '16 at 13:07
  • $\begingroup$ @Mauser I understand, and probably may tie other facts here, like china was biggest consumer of steel not so long ago, weakening their currency, as russians got such advantage too, established world goods flow system and to on. I do not support that cheap price simplification in interstellar trade. There are lot of reasons for me to think the way I think about that. I'm not working in production, but I watch lot lot of information about it, historical perspective to todays tech. I do not deny need or possibility of interstellar transporting, FTL or not. U may wish to look at my answers. $\endgroup$ – MolbOrg Jun 29 '16 at 17:33
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    $\begingroup$ @Mauser I spared some symbols because of comment limits, I meant half of my answers on WB are about this topic how can it be in space. They representing different parts of one model, better or not - but they do. Being space capable means some changes in tech productions and our approaches. Ideally no humans involved, upload program take product. I'm not missing, I blame storytellers for doing that. I understand why they do that(knowledge, time, 1960, 1970, readers, publishers, I wish a story etcetc). But we are free, why we should do same? But, I see u point of talking about in context of uni. $\endgroup$ – MolbOrg Jun 30 '16 at 16:10

Goods you can't get locally.

In your particular example, it's possible (although unlikely) that the Nostromo was transporting iron ore because there isn't any left in the solar system, so humanity, the bulk of which is still living there, needs to get it from somewhere else. Now the idea that by that point in the future humanity's used up all the iron ore in the solar system (and there's a lot of it) is pretty absurd, although the idea of running out of accessible supplies on Earth is not quite so far-fetched, and certainly there are other commodities which are scarcer which could hit this point.

Depending on your interstellar transportation technology of course, you might find that although you do have plentiful iron ore still in your own solar system it's actually easier to get it from another one. Such as, perhaps you have a system based on jump gates, and your local jump gate is conveniently placed for your colony but it's a heck of a long trek to get to the iron ore and for some reason you can't build a gate there as well (maybe you can only have one gate per star for some reason). But there's another system with a gate that's near the iron ore there, and it works out a lot cheaper to use the gates to get to their mines because aside from the gates maybe your propulsion tech isn't much better than our kind of rocketry.

Of course, there's an argument as to why you'd have any of these transports having people on board, but that would depend if your setting has computers capable of flying and navigating safely and reliably across interstellar journeys. If you need people on board, the cost presumably goes up a lot as they need life support, living space, entertainment, salaries and the ship has to not accelerate at a rate that turns them into a pulp.

But the only reason anybody ever ships anything anywhere is because it turns out to be profitable to do so. That's not likely to change in an interstellar society, you just need to figure out why it's profitable.


Drugs legal or otherwise.

Delicate biological goods which are impossible to cultivate away from their home ecosystems.

People with specific training or skills.

Goods which require lots of labor. (Shipped from where labor is cheap to where labor is expensive)

Manufactured goods that one group has perfected and nobody else can quite get right. (Swiss watches a century ago, Italian sports cars today)

Manufactured goods or raw materials the production of which causes pollution which the buyers would like to externalize to other cultures. (Rare earth minerals from china)

High tech goods shipped from higher tech cultures to lower tech cultures.


We can take some lessons from modern trade here too, that I think are too often left out of this conversation.

The original idea of what one country would export versus import came down to comparative advantage - it's covered in any intro-level undergraduate macroeconomics course. Simple models went something like: I have cheaper labor and you have cheaper capital, so I produce more labor-intensive goods and you produce more capital-intensive goods, and we trade.

Huge problem though - the real world obviously doesn't work this way. The US had cars from the US... and cars from Germany, and from Italy, Japan, Korea, and so on. Why in the world do we do that?

I won't delve into the economics too much, but one of the early solutions came down to the love of variety. This was, incidentally, the area Paul Krugman's work won a Nobel in. We don't want just our cars, we want your cars too.

So people in one solar system might pine for the finished goods from another solar system, just because they want exotic variety. But, is this feasible over interstellar distances? I think it's easy to get hung up on "nope" based on what we know now. But personally I think if people in the future are still what we would recognize as "people" that they'll be finding a way to ship this stuff, at least for those wealthy enough to afford it.

  • $\begingroup$ you have to do deeper then that. I may imagine painting worth of shipping, peoples may be insane sometimes and will go with everything they have to make things happening. Do auto manufacturers build they production lines in countries where they with to sell - yes, they do. How many sales have it to be - lot, but not even millions of sales, 10000-50000 is enough. Woow question is, how they can do it, are that production lines unique? No, they don't, they send drawings etc etc and peoples there, in place, build that line for them. Just send drawings for your variety and it will be build in place $\endgroup$ – MolbOrg Jun 28 '16 at 14:53

Think about it...you have a freighter, that has FTL capabilities, and you want to make a lot of money. Depending on how FTL works in your world, is a smaller or larger ship more efficient, or is size not a factor (I think this would be more likely the case). Ship size would really only affect a ships sub-light maneuvering capabilities. Additionally, ships will have some sort of nuclear reactors or something similar to minimize the fuel requirements and have as few crew members as possible.

So assuming you have a ship already in space, not requiring much in the way of supplies or fuel, with FTL capabilites, why wouldn't it be as large a ship as possible, completely dedicated to ripping apart rocks, planets, etc., in order to maximize the profit from each trip;i.e an FTL capable Nostromo.

This makes jump costs known and any freight charge, for any freight, that exceeds that cost is profit. So basically, anything you can make a profit on qualifies as "worth it".

  • $\begingroup$ for big scale of thinking we go $\endgroup$ – MolbOrg Jun 28 '16 at 20:41

Water ice

If you are going to colonize planets, you will need lots of water, and apparently water is not so common around the solar system.

Gases, or other elements only available in trace amounts.

Gases only found in trace amounts in Earth's close neighborhood could be extremely valuable. NASA already has plans to harvest Helium-3 from a moon base in the future. Given the appropriate technology, a near-endless source could be extracted from gas giants around the galaxy.

  • 1
    $\begingroup$ Water is't such a big problem, up some reasonable limit. Abundance Oxygen is 3th with his 1%, after H(75%) and He(23%). That's why in Expanse(tvseries) this water crisis looks so funny. Isotopes, that is more likely. $\endgroup$ – MolbOrg Jun 27 '16 at 21:15
  • $\begingroup$ If want this to work then you must have used up every scrap of He3 to import it. You must be able to fuse He3 but not any other element. Send the rockets at <1% light speed if you don't want to use most of the He3 as fuel. (long transit times so not only that you cant fuse H1 or get other energy source, you must also think 100's of years ahead so tech stagnation situation.) $\endgroup$ – Donald Hobson Jun 28 '16 at 18:12
  • $\begingroup$ The fuel argument is becoming more and more moot. Electric propulsion is here right now, and only requires a small nuclear reactor as fuel. space.com/26713-impossible-space-engine-nasa-test.html $\endgroup$ – Drunken Code Monkey Jun 28 '16 at 18:40

Just going to take this a few directions that I haven't seen yet:

The beings importing the goods are completely out of the goods otherwise

This is a sidestep to "X is unique". Maybe Iron was plentiful, but it all got used up. The populace in question has resorted to recycling, but they still need an infusion of pure Iron due to imperfect recovery. Asteroid mining makes up the difference.

Moving around space is ridiculously easy

If solar sails make fuel costs cheap, and robots do all the hard stuff, why not? Which leads into:

Automation is cheap enough, and the item is non-perishable

If you have robots, who do not sleep, or get bored, or age flying the ships, and the item doesn't go bad, why not? Once you get a bunch going, you will have this chain of income coming in after a long initial wait.

The product in question is incredibly important, and any ends justify the need

See: Space 2001, The Omega Men comic series, (maybe) Avatar, and any other work of fiction where unobtanium prevents some catastrophic event from happening.

In which information is the product, and the density of information is not transmittable

There is a saying in IT that a honda full of hard-drives barrelling down the highway has much more bandwidth than broadband. What would you do if you found what amounted to the alien Library of Congress, with incredibly dense DNA encoded information in reams of shelves of buildings of information? It would take forever to beam it with radio waves, it's lossy, and there is no fiber-optics in space. Chances are, the best way to get the info to whoever needs it is to ship it to them, or ship them to it.


I'm not saying that tourist would be shipped this way, but if there are colonies that are also tourist destinations, they will likely need regular and large supply drops. Tourism has supported dictatorships and countries that ordinarily have nothing to export; don't disregard human curiosity.

  • $\begingroup$ good balanced answer. Although you may consider to think about how much it have to be to for all got used up. It's true and totally possible, but just how big. $\endgroup$ – MolbOrg Jun 30 '16 at 16:18

Your thinking is limited by our current knowledge. If we use the logic presented then the same can be applied to our recent history. (And current market economics) Any goods that are abundant in the new planet but can't be found on earth will become high value and can be transported. Our history shows that raw materials will be shipped in quantity (Think cotton, spices etc in the past) and manufactured here. This supposes that we will find materials in space of high value to us, (superconductors etc) which are not available on earth or the solar system.

  • $\begingroup$ Interesting point. There is a finite amount of material in our solar system and while iron may never be needed in large enough quantities to warrant bringing it from other star systems, I can think of some other things that might. If humans begin to undertake larger projects (massive city sized computer complexes, large populations on other planets, etc), or the population continues expanding at high rates, raw materials may need to be brought in. $\endgroup$ – matt_Vera Jun 27 '16 at 23:32
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    $\begingroup$ You can't just find superconductors just like that. $\endgroup$ – King of Snakes Jun 28 '16 at 4:07
  • $\begingroup$ But what if Iron stores are depleted on the home world or can't be found in large enough supplies to complete massive star ships, space stations, etc. Iron then becomes a very valuable commodity. $\endgroup$ – Steve Mangiameli Jun 28 '16 at 16:44

Seeds, and other biological derivatives.

Minerals and ores are likely to be found anywhere, mined off of other planets or asteroids or the like - and perhaps elements to make up whatever alloys or compounds are needed for manufacturing, or living. After all, elements from the periodic table are unlikely to change if they're found on an asteroid or a new planet.

However, biological elements are probably going to continue to be a limiting factor. The places they can be obtained are limited, dependent on a lot of other limiting factors, and they will be in high demand (because they're limited) and thus quite valuable.

So, people want (for example) bread. Wheat bread, finely ground white flour bread. They might not be willing to pay the prices for loaves of bread to be shipped, unless they're really, really rich, and even bags of flour or grain are likely to be too expensive, too much spoilage in transit, to be economic to ship around - but some corporation or other ships wheat seeds, and sets up a farm/hydroponics/whatever, and starts growing wheat to be processed locally, and the price per loaf drops to something hefty but not unreasonable, because people would want that constancy of foods from home, or exoticism of foods discovered from other planets. Or their familiar vegetables and pantry staples.

And herbs and spices are a whole new level of good tradables - they would be in very high demand (a small amount brings familiar flavors), and pretty low bulk - either as seeds or finished products. It's one of the reasons spices were so prized for trade goods historically - when this situation was more or less fact, each civilization was self sufficient and travel was long, costly, and unreliable - so luxury goods were shipped, not so much raw materials.

Beyond foodstuffs, many plants are used for other things - cloth or fiber (cotton, linen, hemp), dyes, medicines, drugs (both medicinal and recreational) the many uses of plant matter (paper, wood for fuel or building, cardboard, charcoal), chemicals used in manufacturing processes or plants used for environmental effects (ornamental, or to crowd out other plants, or to provide some resource). Sending the finished products might be possible, depending on supply, demand, and price - but sending the means for each colony to make their own independently (seeds, manufacturing tools and equipment, etc) would likely be cost-efficient and sustainable enough to make it economic to ship initial loads, replacements for crop failures, occasional followup loads of seeds to increase diversity, and so on.

So it need not be a one-time cargo, either. Many of the products people use interfere with the plant's reproduction (wheat that goes to bread does not go to the next wheat crop, many vegetables are picked and consumed before the seeds finish maturing). Even with a concerted effort to make the populations of plants on each world self-propagating, periodic infusions of new diversity from fresh seeds, or replacing generations lost after crop failures, would probably be quite welcome and very valuable in their own right.

A load of mixed seeds would be pretty valuable, in high demand, and still give enough yield for the space they take for the end results to be valuable but not out of reach for people to actually buy. Even if the long shipping, imperfect storage, etc leads to some amount of loss or spoilage, some seeds would be unexpectedly valuable (from crop failures, or a newly discovered use) to make up for it.

Animals and their products would also be in high demand. Again, shipping adults would likely be too much expense for too little return, too much lost in transit, too messy. Only the really rich could afford such. But shipping genetic material for cloning, or for in-vitro fertilization, might make the end products reasonably profitable. Somebody pays the really high price for a ships-load silk from earth, somebody pays the same price for carefully preserved silkworm eggs (or spiders eggs, for spider silk instead) - and the silk they produce locally is a very popular and more affordable luxury item. So the local herds (sheep, cows, horses, the whatever from colony x and the whatsits from colony 3a) might have to be shipped over for high prices and lots of loss to begin with, depending on the tech levels involved (though maybe even cloned beasts might be enough to start a herd, if only to the second generation), but they could be supplemented with new genetic material from in-vitro fertilization within a reasonable level of technology.

Manufacturing equipment is probably also going to be popular - raw materials can be found, sure, but tools (and further back, the tools to make the tools) are going to be something that's a lot easier and cheaper for a central, specialized manufacturing place to make in bulk than individual colonies. The price for making everything themselves from scratch is effort, especially when a colony is just starting out and having to do everything for themselves. The price of shipping would offset by the production capability, the further back along the process you go - so a shipment of tractors, gets paid for in how much more can be produced with them than without them doing everything by hand - the pieces to make a tractor factory, gets paid out in every tractor and everything every tractor made can produce. The less that can be shipped, and the greater its impact, the more likely it would be cost-effective. And, there would be a continuing trade in repair parts and upgrades.

It might take a while for the colony to be able to product enough of their own whatevers to pay off the equipment (with a colony credit line, or 'company store' levels of human plotting) - but for the colony to exist, they had to think something was there worth investing in, yah? And they're going to be paying off the shipping cost with stuff they think will be worth it - ten years' (or whatever) cost for shipping, but it would take fifty years without it - so forty years to make up the difference in the price.

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    $\begingroup$ Given the advances in gene editing and synthesis expect the DNA to be synthesized where required. This also lets you design foods that are much better than the original. $\endgroup$ – Donald Hobson Jun 28 '16 at 16:14
  • $\begingroup$ @DonaldHobson - Maybe, but that would only produce maybe a few variations in the DNA without a lot of extra work. I suspect that genetic diversity would be a very good thing, especially when trying to adapt something to a very new environment - mono-cultures are vulnerable. And it's probably easier to ship out a bulk of seeds than re-sequence the DNA (or even pre-scan and store) for a few thousand variations. I expect cloned or modified food will have its place on the sliding scale of availability, price, and demand - but I'd expect grown food and bred animals to still have a place as well. $\endgroup$ – Megha Jun 29 '16 at 12:35

I suggest something smaller, and infinitely Lighter. The distances and times needed for these transactions provide for an ever growing difference between Homeworld and colonies, each trip spanning generations, more or less. I suggest that Ideas - sheer human (or other) ingenuity would be the ideal cargo. Why carry a cargo hold of weapons when just the blueprints and theory would do? Trade for the colonies' latest gizmos and potions, but only the Idea of them. The commerce of intellectual property is abundant on Earth now, Imagine if your systems diverged as expected, a network of idea trading could be economical to run, and profitable to each world.

  • $\begingroup$ Excellent. I glad someone mention that. $\endgroup$ – MolbOrg Jun 28 '16 at 20:58

What different about different solar systems? The are going to have different laws. Different laws about what can be done with intellectual property. Different laws about what kind of GMO organisms they allow. Different laws about whether or not technology that produces a lot of radiation is allowed.

The legal tension of a product that was produced in galaxy A by an organism that isn't legal in galaxy B, could make for an interesting plot.

New colonies with low populations can profit a lot from having high value items that can only be effectively produced at scale to them. A classic example are computer chips.


Scarcity (also called paucity) is the fundamental economic problem of having seemingly unlimited human wants in a world of limited resources. It states that society has insufficient productive resources to fulfill all human wants and needs.

The notion of scarcity is that there is never enough (of something) to satisfy all conceivable human wants, even at advanced states of human technology. Scarcity involves making a sacrifice—giving something up, or making a tradeoff—in order to obtain more of the scarce resource that is wanted. (https://en.wikipedia.org/wiki/Scarcity)

There are plenty of cases for large-scale transport of resources between systems, even if those resources are readily available locally. Since utilization of a resource has opportunity cost associated with it, society will tend to allocate resources (over time) to whatever production it feels is most desirable. A good example of this is the current trend of farmers parceling off their acreage to sell to homebuilders and developers, since the land is more valuable for housing than it is for crop and livestock production in populated areas.

Consider this... lets say that Earth is the galactic seat of our intergalactic society and also boasts as the origin of our species. It has a huge population, making land extremely scarce. It becomes a city-planet covered in high-rise ultra-luxury housing, and living on Earth is considered very prestigious. The price of real estate skyrockets, and eventually only the wealthy and influential can afford to live on Earth. High property values and associated taxes drive even the middle-class out to neighboring settlements, where they become impoverished due to lack of opportunity.

Resources we take for granted have now become expensive and difficult to obtain, and mining companies find it more profitable to sell their land for windfall profits under pressure from increased environmental regulation, "not in my backyard" policies, and exorbitant labor costs. Those production facilities left are under massive demand, and the price of commodities are driven through the stratosphere (literally).

Some industrious firm then finds it profitable to mine nearby planets and asteroids for those resources, and for a time, also starts reaping huge profits from the venture by selling (comparatively) cheap ore back on Earth. The Earth mining companies, flush with cash due to lack of competition and high demand, start buying mining rights to nearby space objects to protect their oligopoly.

Now you have a scenario where, while the resources themselves are abundant, they are otherwise allocated. At the same time, large-scale building projects have slowed due to the considerable political red-tape and overcrowding situations, where every single construction project requires displacing existing residents and having designs approved for both engineering and aesthetic purposes, requiring multiple rounds of revisions from fickle political organizations before demolition and groundbreaking can occur. Projects stretch out a decade or more, with many of the resources being sourced elsewhere (construction workers or robot maintenance techs can't afford to live on Earth).

Johnny Entrepreneur (maybe a former high-level mining company employee with a lot of knowledge and a lot more contacts) says, "Hey, I've got a cheap off-world labor source and access to all the steel you need. Sign a contract with me, give me 50,000,000 credits, and I'll guarantee on-time shipments at a great price starting in 7 years when you are ready to start building. If you don't want my steel, I can always sell it to your competitor." The builder, with his source of cheap materials, now has a competitive advantage and starts outbidding his competitors one after another. Those competitors in turn start sourcing their materials that way too, creating a demand for extraterrestrial steel imports.

Meanwhile, Johnny Entrepreneur uses a small part of his contract advance to purchase some derelict military vessel from a defunct establishment, retrofits it to carry cargo, and rounds up some desperate and impoverished former Earth residents, offering them free land on some distant planet, provides for the immediate needs of them, their spouses, and children, and the employees get the promise of a big paycheck when the contract is fulfilled.

The terrestrial mining companies, now facing a much cheaper source of supply, find it more profitable to finally sell the remaining mines to developers, and just like that, steel (or more accurately, iron ore), becomes one of the scarcest resources on Earth despite the fact that it is one of the most abundant things on the planet. The terrestrial mining companies' war chests are opened to develop and build the biggest, most efficient ore freighters in the galaxy so they can supplant the comparatively small start-up mining companies, and several years later the Nostromo leaves space dock.

Anything... absolutely anything will be transported across distances provided that someone can make a small profit off of producing and transporting it, and it can be delivered within acceptable timeframes. If you don't believe me, take a look at the current industry for transporting things like hay long distances, when it can be readily grown locally. Paying 5,000 monetary units for a truckload of hay makes a lot of sense when that same 10 acres can support 30,000 monetary unites worth of horses, or it can be sold to a real-estate developer for 25,000 monetary units per acre. Iron ore would be no different in a galactic society where land on Earth is at a massive premium.

  • $\begingroup$ Good example of problems, which are born because Geocentric model thinking. Moon contains metal enough to cover entry earth with 6km tick layer, mercury contains for 20km layer. Most matter we use contains in solar system in quantities exceeding capabilities(not the wishes, but physical capabilities) to consume it, being in borders of our planet. Plain Physical limit for wishes on the planet. $\endgroup$ – MolbOrg Jun 28 '16 at 21:16

Lots of good answers here and I won't repeat them, but one thing everyone has missed - putting the incentive on export rather than import.

Or to put it another way -- is there anything that you'd be so desperate to get out of your neighborhood that you'd be willing to physically export it to another star system?

Consider toxic waste. If society is generating something toxic enough, they might find that the only way of disposing it would be to put it on a ship an send it as far away as possible.

  • $\begingroup$ Good start point, thinking what they send back in exchange. You can better then toxic waste, toxic waste is just laziness and cost of energy, one ftl travel may be enough to purify entry earth. But if someone just pleased to have trash hill - move everything to moon, so it may be observed in process of romantic dinner on evening. $\endgroup$ – MolbOrg Jun 28 '16 at 21:27

High tech items that only advanced civilizations can produce such as:

  1. Advanced materials such as carbon nanotubes and exotic isotopes
  2. Nanobots
  3. Advanced weapons (lasers, force shields etc)
  4. Advanced manufactured goods - antigrav engines, teleportation devices, advanced computer technology, FTL drives
  5. Medical technology
  6. Exotic foods, art, and luxury goods that the members of the advanced civilizations can amuse themselves with.
  • $\begingroup$ Why so much trust in that advanced civilization, to buy strategic important stuff. Lessons of trojan horse are lost in well of time? We do not trust so much even humans. But if they are so good and trustworthy, why they do not get us that tech to research and produce in house? As we see on example of SpaceX in house production have advantages, and cost savings. $\endgroup$ – MolbOrg Jun 28 '16 at 21:21
  • $\begingroup$ Luxury goods are always good, as is contraband. All the rest depend on the cost of transport against what the market is prepared to pay. $\endgroup$ – Wayne Watson May 13 '17 at 8:33

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