# Interstellar Commerce **URL:** \ **Category:** Factual Questions\ **Created:** [December 11, 2017, 3:37pm UTC](https://boards.straightdope.com/t/interstellar-commerce/804202 "2017-12-11T15:37:03Z")\ **Posts on this page:** 20\ **Page:** 4
**Author:** ![septimus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/septimus/32/410_2.png) [@septimus](https://boards.straightdope.com/u/septimus)\ **Post date:** [December 12, 2017, 7:38am UTC](https://boards.straightdope.com/t/interstellar-commerce/804202/61 "2017-12-12T07:38:32Z")
> [@Sam\_Stone](#): > > Since I don’t think FTL is possible within physics as we understand it, I don’t think it will ever make much sense to transmit raw materials from one solar system to another. I don’t believe we have discovered any materials that would be worth the cost in energy to move across interstellar distances. > … > > The only goods that would make sense to transport would be things that are utterly unique, like an original artwork or a sample of an alien species. In my sci-fi epic, a super-race gobbles up entire planets using some virtually unlimited energy sources, perhaps fusion engines, or the local sun’s energy harvested directly. High-tech would permit replication of artwork with great precision, but abundant supplies of certain rare hard-to-synthesize elements (e.g. dysprosium, gold, U-235) might be almost essential to the technologies. If an essential element is missing from a planetary system, there would be difficulty mining other resources, let alone attempting “terraforming.” Living creatures would sometimes be shipped from one system to another but their cartage would be minuscule compared with the transport of machinery and materials. ---
**Author:** ![Paul\_in\_Qatar](https://avatars.discourse-cdn.com/v4/letter/p/ccd318/32.png) [@Paul\_in\_Qatar](https://boards.straightdope.com/u/Paul_in_Qatar)\ **Post date:** [December 12, 2017, 1:33pm UTC](https://boards.straightdope.com/t/interstellar-commerce/804202/62 "2017-12-12T13:33:30Z")
We could sail the freighter full of stuff to the farm world and then sell it for parts. (Power plant, metals, computers and so on.) I recall Abe Lincoln went down to New Orleans with a load of stuff, sold it and broke up the flatboat to sell the lumber. ---
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [December 12, 2017, 1:48pm UTC](https://boards.straightdope.com/t/interstellar-commerce/804202/63 "2017-12-12T13:48:13Z")
> [@Paul\_in\_Qatar](#): > > We could sail the freighter full of stuff to the farm world and then sell it for parts. (Power plant, metals, computers and so on.) I recall Abe Lincoln went down to New Orleans with a load of stuff, sold it and broke up the flatboat to sell the lumber. But he had a way to get home. ---
**Author:** ![eburacum45](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eburacum45/32/8690_2.png) [@eburacum45](https://boards.straightdope.com/u/eburacum45)\ **Post date:** [December 12, 2017, 1:49pm UTC](https://boards.straightdope.com/t/interstellar-commerce/804202/64 "2017-12-12T13:49:12Z")
> [@septimus](#): > > In my sci-fi epic, I’m planning to use [magnetic sails](https://en.wikipedia.org/wiki/Magnetic_sail) to address the deceleration problem. Won’t these work? (And my plan was [laser beamed propulsion](https://en.wikipedia.org/wiki/Laser_propulsion) for acceleration. Will this work?) A combination of the two would be best. The late Jordin Kare outlined a scheme to use lasers to accelerate vast numbers of tiny, lightweight sails made of metal foil, which are just smart enough to converge on the magnetic sail of a spaceship; this is known as the Sailbeam concept, and has the best prospects for acceleration of any system I’ve encountered yet. > **[Jordin Kare | Sailbeam](https://en.wikipedia.org/wiki/Jordin_Kare#Sailbeam)** > > Kare proposed the SailBeam Boosted Magsail in a report prepared for NASA's Institute for Advanced Concepts called "High-Acceleration Micro-Scale Laser Sails for Interstellar Propulsion". A key idea is that if vast numbers of tiny sails are used to accelerate rather than one enormous one, the same amount of mass can be brought to high speeds with a less complex optical system. Unlike particle-beam propulsion, in which the beam disperses as it travels, a stream of low-mass microsails is not li ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [December 12, 2017, 2:03pm UTC](https://boards.straightdope.com/t/interstellar-commerce/804202/65 "2017-12-12T14:03:15Z")
> [@JRDelirious](#): > > Right, if you have a product of one specific planetary or system ecology (that you can’t really reproduce or transplant efficiently, this is key), that is itself essential to the interstellar civilization to function, by either permitting interstellar travel itself or allowing the lifespans needed to function in galactic-spread culture, then that becomes Commodity Supreme. > > But even there we have the issue with RL science lapping the fiction: for us of the world of 2017, it seems like the makeup of any material substance, given enough time and effort, be can be analytically determined down to each atom and then more of it assembled synthetically, and that the same can be done for what are the processes by which it does its work. So in Space Opera we are often forced to say that there is this X or Y thing that somehow can’t be efficiently synthesized, or gene-sequenced, or hothouse-grown, or put through the matter replicator, and has only one known source (or very few) and that’s why it’s so valuable. Agreed - anything that can be manufactured\* is not worth shipping, unless shipping is super cheap. \*by which I also exclude intangible things like ideas and provenances (e.g. an antique Lassiter laser pistol from Earth-That-Was) - you can make another one, but you can’t make another genuine original. ---
**Author:** ![eburacum45](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eburacum45/32/8690_2.png) [@eburacum45](https://boards.straightdope.com/u/eburacum45)\ **Post date:** [December 12, 2017, 2:18pm UTC](https://boards.straightdope.com/t/interstellar-commerce/804202/66 "2017-12-12T14:18:52Z")
> [@septimus](#): > > Living creatures would sometimes be shipped from one system to another but their cartage would be minuscule compared with the transport of machinery and materials. I think it would be the other way round. Living creatures need a life support system to survive, so you can’t just ship them by themselves. At the very least you need to freeze them, and ensure hey can be revived without damage- which might not be possible. Even frozen, you need to ship the freezer infrastructure and a power source as well. However machinery and other physical commodities can be shipped as blueprints, as _information_, and assembled on site. If you can ship living creatures as DNA, then do so, but you would need some pretty advanced biological technology to grow the creatures at the other end. ---
**Author:** ![Tibby](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tibby/32/17030_2.png) [@Tibby](https://boards.straightdope.com/u/Tibby)\ **Post date:** [December 12, 2017, 2:53pm UTC](https://boards.straightdope.com/t/interstellar-commerce/804202/67 "2017-12-12T14:53:14Z")
Maybe the desination of space freighters won’t be to other planets, but to other types of cosmic real estate, like neuton stars/pulsars to harness the ulta-high cosmic rays as an energy source. However, even if possible, I imagine the freighters would have to be unmanned. It would probably be more cost-effective to move the civilization close (but, not too close) to the pulsar and tap into the energy at a safe distance. Perhaps this is the way to reach Type III civilization status. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [December 12, 2017, 3:58pm UTC](https://boards.straightdope.com/t/interstellar-commerce/804202/68 "2017-12-12T15:58:24Z")
> [@Claude\_Remains](#): > > Not sure if my Ambien is kicking in or GQ has gone straight down the toilet.😕 Actually the problem is the Q isn’t properly a GQ question. Many of the answers are as factual as possible given that we’re discussing alternate futures. This is more properly an IMHO thread. Offset by the fact that GQ has the best audience for actual science and for hard SF. ---
**Author:** ![Stranger\_On\_A\_Train](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)\ **Post date:** [December 12, 2017, 11:14pm UTC](https://boards.straightdope.com/t/interstellar-commerce/804202/69 "2017-12-12T23:14:34Z")
> [@septimus](#): > > Certain elements (e.g. gold, U-235, rare earths) might still be important for an advanced technology, yet extremely rare in some stellar systems. These might be mined on systems where plentiful, and then sent on to other systems where needed. If a star system were resource-poor (e.g. around a Population II star with low metallicity) it would be a poor candidate for settlement or industry in general. Given the enormous energies to transport materials between star systems in any useful timeframe for planning, even if we assume that to be hundreds or thousands of years, it just isn’t sensible to engage in any kind of ‘trade’. Markets are predicated on the notion of feedback governing supply and demand, but with a latency of many centuries or millennia, the concept of market feedback just doesn’t work, particlarly when the specific need for a particular material may well be obsoleted by advances in technology or changes in society. Those thousands of years for transportation is more than an order of magnitude longer than industrial society has existed to date and could hardly be expected to be static pver that period. > [@septimus](#): > > In my sci-fi epic, I’m planning to use [magnetic sails](https://en.wikipedia.org/wiki/Magnetic_sail) to address the deceleration problem. Won’t these work? (And my plan was [laser beamed propulsion](https://en.wikipedia.org/wiki/Laser_propulsion) for acceleration. Will this work?) Magnetic sails require magnetic fields to operate upon. The magnetic field generated by the Milky Way galaxy is very weak in our neighborhood, so in order for magnetic drag to be effective your starship would have to be moving relatively slow to begin with. Ditto for light pressure or electrostatic drag. While beamed propulsion removes the mass limitation of the Tsiolkovsky rocket equation over interstellar distances would require many gigawatts per gram on top of the large inefficiencies in high energy lasers or masers. Beamed power or propulsion offers interesting opportunities for powering nanosatellites or spacecraft in planetary orbit or flock formations but I am highly doubtful of it ever being practical for interstellar propulsion. > [@MrDibble](#): > > One thing that might be a valuable commodity _for one trip_ - one end of a traversable wormhole. Of course, if you can make a traversable wormhole and accelerate it up to relativistic speeds, or two conjugate womeholes between distant stars, you have a practical time machine and the entire notion of markets being based on cause and effect is out the window. Stranger ---
**Author:** ![TimeWinder](https://avatars.discourse-cdn.com/v4/letter/t/bcef8e/32.png) [@TimeWinder](https://boards.straightdope.com/u/TimeWinder)\ **Post date:** [December 12, 2017, 11:29pm UTC](https://boards.straightdope.com/t/interstellar-commerce/804202/70 "2017-12-12T23:29:57Z")
> [@Voyager](#): > > And all planetary ecologies look like a single state on Earth, or even a single county. Ice planets, jungle planets, desert planets and farm planets drive me bonkers. Also jobs/races: Warrior planets, farmer planets, science planets… ---
**Author:** ![Tibby](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tibby/32/17030_2.png) [@Tibby](https://boards.straightdope.com/u/Tibby)\ **Post date:** [December 13, 2017, 12:25am UTC](https://boards.straightdope.com/t/interstellar-commerce/804202/71 "2017-12-13T00:25:34Z")
> [@MrDibble](#): > > Drugs. The answer is drugs. > \ You may be on to something here: drugs (the therapeutic kind), specifically those derived from natural sources (pharmacognosy), may be one of the best “freights” to justify the cost of interstellar/galactic commerce. Harvest plants, microbes, etc. from nitrogen-based alien biospheres and either transport them back to Earth for study (of course, our species may no longer exist when the spaceship door opens upon return, Earth having been taken over by the new apex species—sentient sea cucumbers), or isolate the secondary metabolites on board, run clinical trials on space guinea pigs and space convicts, use mass spectrometry to map the structure of medically beneficial compounds, then beam the blueprints back to Earth for synthesis and distribution to the masses. I await the best stool softener the Universe has to offer. ---
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [December 13, 2017, 2:24am UTC](https://boards.straightdope.com/t/interstellar-commerce/804202/72 "2017-12-13T02:24:14Z")
> [@Tibby or Not Tibby](#): > > (of course, our species may no longer exist when the spaceship door opens upon return, Earth having been taken over by the new apex species—sentient sea cucumbers) I, for one, welcome our new echinoderm masters. ---
**Author:** ![MrDibble](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mrdibble/32/114_2.png) [@MrDibble](https://boards.straightdope.com/u/MrDibble)\ **Post date:** [December 13, 2017, 5:48am UTC](https://boards.straightdope.com/t/interstellar-commerce/804202/73 "2017-12-13T05:48:13Z")
> [@Stranger\_On\_A\_Train](#): > > Of course, if you can make a traversable wormhole and accelerate it up to relativistic speeds, or two conjugate womeholes between distant stars, you have a practical time machine and the entire notion of markets being based on cause and effect is out the window. I’m thinking there’s some reason you can’t go (too) relativistic while carrying the wormhole (it’d evaporate, or something) so really slow freight is the only way to get that end anywhere. ---
**Author:** ![Stranger\_On\_A\_Train](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)\ **Post date:** [December 13, 2017, 7:01am UTC](https://boards.straightdope.com/t/interstellar-commerce/804202/74 "2017-12-13T07:01:17Z")
> [@MrDibble](#): > > I’m thinking there’s some reason you can’t go (too) relativistic while carrying the wormhole (it’d evaporate, or something) so really slow freight is the only way to get that end anywhere. No, there is no reason that it would’t be possible to move a traversable wormhole terminus, and regardless, it represents a non-continuous (or at least non-trivial) connection that can create temporal loops even without invoking relativistic contraction. Stranger ---
**Author:** ![eburacum45](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eburacum45/32/8690_2.png) [@eburacum45](https://boards.straightdope.com/u/eburacum45)\ **Post date:** [December 13, 2017, 2:02pm UTC](https://boards.straightdope.com/t/interstellar-commerce/804202/75 "2017-12-13T14:02:38Z")
> [@Stranger\_On\_A\_Train](#): > > Magnetic sails require magnetic fields to operate upon. The magnetic field generated by the Milky Way galaxy is very weak in our neighborhood, so in order for magnetic drag to be effective your starship would have to be moving relatively slow to begin with. None of this is relevant. Magnetic brakes as a concept were developed as a result of investigations into the characteristics of Robert Bussard’s magnetic ramscoop. It turns out that a gigantic scoop large enough to collect interstellar material for use as fuel and propellant would exret a braking force on the ship as it captured the interstellar medium; this means that a ramscoop would be no use as an accelerating device, but it could be very useful as a _decelerating_ device (i.e. a brake). And it would, in fact, work better the fast the ship was travelling- i.e. it would become less efficient as the ship slowed down and eventually stop working long before the ship stopped. A paper that discusses the magbrake concept, among other ideas > **[Magsails\_320Zubrin.pdf](https://www.orionsarm.com/fm_store/Magsails_320Zubrin.pdf)** > > 3.50 MB > [@](#): > > Beamed power or propulsion offers interesting opportunities for powering nanosatellites or spacecraft in planetary orbit or flock formations but I am highly doubtful of it ever being practical for interstellar propulsion. I doubt that rocketry alone will ever get us to the stars - beamed propulsion using mass particles may be the only feasible option. Yes, the efficiencies are very large, but they occur in the launch systems and don’t affect the mass fraction of the ship. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [December 13, 2017, 5:03pm UTC](https://boards.straightdope.com/t/interstellar-commerce/804202/76 "2017-12-13T17:03:11Z")
A ramscoop can actually be useful even for propulsion, but only to a point. I did the calculations once, and assuming an efficient fusion drive and a perfectly-inelastic collection system, a ramscoop ship’s top speed would be 0.12c . You can increase that further with an elastic collection system, or if you can somehow convert the hydrogen to energy with a greater efficiency than fusion. Or, even without that, you can cruise at a little under top speed for a while to fill up a fuel tank, and then turn off the scoop and burn the fuel you’ve stored up to get you up to a higher speed. ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [December 13, 2017, 5:23pm UTC](https://boards.straightdope.com/t/interstellar-commerce/804202/77 "2017-12-13T17:23:15Z")
> [@Chronos](#): > > A ramscoop can actually be useful even for propulsion, but only to a point. I did the calculations once, and assuming an efficient fusion drive and a perfectly-inelastic collection system, a ramscoop ship’s top speed would be 0.12c . Atomic Rockets [agrees with that figure](http://www.projectrho.com/public_html/rocket/slowerlight.php#id--Go_Fast--Bussard_Ramjet--Ramjet_Problems). ---
**Author:** ![sbunny8](https://avatars.discourse-cdn.com/v4/letter/s/c77e96/32.png) [@sbunny8](https://boards.straightdope.com/u/sbunny8)\ **Post date:** [December 13, 2017, 7:38pm UTC](https://boards.straightdope.com/t/interstellar-commerce/804202/78 "2017-12-13T19:38:50Z")
I know the OP said we won’t count people, but those people going to new colonies will need to take lots of stuff with them at the beginning. emergency food supplies medicine hand tools, looms, sewing machines, razor blades farm animals (preferably females plus a good supply of frozen sperm). Even if the colonies don’t have anything to send back, there’s lots of money to be paid by the colonists who are shipping out and want to have supplies when they get there. So, what do they do with the empty freighter? Sending it back empty seems like a waste, but it might be worth it if the cost of sending an empty ship is less than the cost of building another ship back on Earth. Two alternatives come to mind: Dismantle the ship at the destination planet, use the parts to build other useful things like a machine shop and a electrical power plant. Or, fill up the ship with local handcrafts made by the colonists, to be sold back on Earth to people who would like to have a trinket on their shelf that came from another planet. ---
**Author:** ![Stranger\_On\_A\_Train](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)\ **Post date:** [December 13, 2017, 8:04pm UTC](https://boards.straightdope.com/t/interstellar-commerce/804202/79 "2017-12-13T20:04:05Z")
> [@eburacum45](#): > > None of this is relevant. Magnetic brakes as a concept were developed as a result of investigations into the characteristics of Robert Bussard’s magnetic ramscoop. It turns out that a gigantic scoop large enough to collect interstellar material for use as fuel and propellant would exret a braking force on the ship as it captured the interstellar medium; this means that a ramscoop would be no use as an accelerating device, but it could be very useful as a _decelerating_ device (i.e. a brake). And it would, in fact, work better the fast the ship was travelling- i.e. it would become less efficient as the ship slowed down and eventually stop working long before the ship stopped. > A paper that discusses the magbrake concept, among other ideas > [http://www.orionsarm.com/fm\_store/Magsails\_320Zubrin.pdf](http://www.orionsarm.com/fm_store/Magsails_320Zubrin.pdf) Aside from a number of subtle errors and assumptions in that paper (and the incorrect assertion that “the operational magsail is based on technology expected to be available within the next decade”) you’ll note that the performance is based upon moving at relativistic speeds (and incidentally is not corrected for relativistic effects); in reality, getting a spacecraft of any significant mass up to even 0.01_c_ would take such an enormous amount of energy which makes it unlikely to ever be workable for commerce or colonization, and you can see that the performance of a magnetic (or a more practicable electrostatic) device drops exponentially as the vehicle speed drops to a small fraction of _c_. Even if you can accelerate the vehicle to a speed where this would be useful, decelerating from the remaining few percent of _c_ to interplanetary speeds using rocket propulsion is still problematic as the amount of propellant required will dwarf the mass of the payload by many orders of magnitude for any foreseeable propulsion technology. > [@eburacum45](#): > > I doubt that rocketry alone will ever get us to the stars - beamed propulsion using mass particles may be the only feasible option. Yes, the efficiencies are very large, but they occur in the launch systems and don’t affect the mass fraction of the ship. Agreed that thermal rockets of any flavor–[POST=16494836]even powered by nuclear fusion[/POST]–are unlikely to be useful for interstellar travel. However, even setting aside the inefficiencies of the directed power system, the basic problem is one of basic scale; to power a spacecraft of even a few kilograms to 0.1_c_ would require greater than the current world energy power generation for several months. Of course, you would do this using a solar orbiting emitter and collected solar energy, but the size and scale of such a device would qualify as a megastructure of vast proportions with thousands of hectares of solar collection area, millions of hectares of thermal radiators to get rid of waste heat, and a microwave emitter the size of a football field, or high energy laser with an enormous lasing cavity (presumably some kind of tunable free electron laser). This scales proportionally for a spacecraft large enough to carry actually useful payload mass, and even if all other issues of power generation and throughput could be addressed the heat rejection problem becomes prohibitive. I think we’ll need some kind of fundamental breakthrough in propulsion physics before it is viable to send even small autonomous spacecraft to other stars in anything less than millennial timeframes, and without traversable wormholes or some kind of hypothetical superluminal propulsion, the notion of sending people or engaging in commerce in on interstellar scales is just not plausible. > [@Chronos](#): > > A ramscoop can actually be useful even for propulsion, but only to a point. I did the calculations once, and assuming an efficient fusion drive and a perfectly-inelastic collection system, a ramscoop ship’s top speed would be 0.12c . You can increase that further with an elastic collection system, or if you can somehow convert the hydrogen to energy with a greater efficiency than fusion. Or, even without that, you can cruise at a little under top speed for a while to fill up a fuel tank, and then turn off the scoop and burn the fuel you’ve stored up to get you up to a higher speed. The problem–or at least, one of many—with an interstellar ramjet is that it has to be accelerated to at least a few percent of _c_ just to start working, and thus we come back to the same problem of achieving even those speeds without some science-fictional method of propulsion. This is notwithstanding making p-p fusion in a ramjet viable; even at small fractions of the _c_ the length of the “chamber” would be huge, the incidental gamma radiation would be lethal without massive shielding, and in everything but the P-P I branch there is a significant loss of energy to neutrinos which is not useful for propulsion. Stranger ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [December 13, 2017, 8:17pm UTC](https://boards.straightdope.com/t/interstellar-commerce/804202/80 "2017-12-13T20:17:49Z")
What we need is to invent the [cosmogonic drive](https://books.google.com/books?id=1p8eyKrFtu0C&pg=PA220&lpg=PA220&dq=cosmogonic+machine&source=bl&ots=YkDwWb_jRJ&sig=KxCjbghUvAJ1RqLjJDqvBBsxfgg&hl=en&sa=X&ved=0ahUKEwiPie225ofYAhVK44MKHZbyBuUQ6AEILDAB#v=onepage&q=cosmogonic%20machine&f=false). [Previous page](https://boards.straightdope.com/t/interstellar-commerce/804202.md?page=3) [Next page](https://boards.straightdope.com/t/interstellar-commerce/804202.md?page=5)