In my world, humanity has turned to space as a source of resources. Of course, all that stuff has to be transported back somehow. On Earth, that is usually done with seafaring ships or rail vehicles.

Is there any reason someone would choose to transport solid materials via rail vehicles (i.e. vehicles, usually several joined units, connected to a fixed rail) instead of freely traveling ships?

  • 2
    $\begingroup$ If we think of a space elevator as a "space rail", then there are some definite advantages to it. $\endgroup$
    – Alexander
    Oct 11, 2018 at 6:32
  • 4
    $\begingroup$ I am not sure I understand: Are you asking about setting up rail-networks planetside or about setting up magical space rails between planets? $\endgroup$
    – dot_Sp0T
    Oct 11, 2018 at 6:34
  • $\begingroup$ Where in space are we talking about? And would this space-rail be a interconnected net like a real railway, or just one main trunk (i.e. space elevator)? $\endgroup$
    – bukwyrm
    Oct 11, 2018 at 9:23
  • $\begingroup$ It sounds obvious, but all the places you might want to interconnect in space are moving. You could have a railway on a non-earth body, but you can't have a railway between astral bodies. $\endgroup$
    – pjc50
    Oct 11, 2018 at 9:50
  • $\begingroup$ Railguns would make a lot of sense if you could build them. As in, a space elevator extended into space. Could use its rotary speed to accelerate vehicles to huge speeds cheaply. $\endgroup$
    – Nobody
    Oct 11, 2018 at 10:13

4 Answers 4


An interesting query!

I would posit that the answer is:


  1. Rail networks are great over continental distances: exactly the sort of transport web you say is in operation in your world.
  2. Rail networks require lots of moving pieces: switches, signals, sidings, multiple tracks to handle more than one train at a time.
  3. Rail networks require constant maintenance and direct access to every inch of the system for routine maintenance, emergency repairs, recovery of derailed vehicles and the like.

So much for planetside networks.

  1. Space is big. Very big. All the rail networks on Earth span about a million and a half km. The Moon is about 380,000km away. That's conceivable. But the distance to Ceres is something like 400 million km. That's not conceivable.
  2. Rail travel through space will be extremely slow in comparison to even a typical rocket. Consider that a rail network will necessitate vehicles having wheels of some kind. Just the friction of wheels spinning along will, I should think, cause the wheels to disintegrate, overheat and seize up or simply fall apart due to the great distance being traversed and no maintenance depots along the way.
  3. Flimsy rail. There being no earth to anchor or support the infrastructure, I think the motion of the vehicles would cause the track to bend and sway and rupture.
  4. Slow travel. Even a maglev kind of vehicle will be much slower than any kind of ordinary space vessel flying the same route.
  5. Gravity & rotation take their toll. Lastly, all the planets in the solar system are in constant motion around something else, and even the solar system itself is in motion. Even if you could anchor the track to the Earth, it won't line up with anything in space. The Moon moves at a different velocity, so a track anchored there as well would snap. Same goes for a track anchored to Earth and Ceres.

None of these things strike me as allowing for a viable rail network in space.

  • 6
    $\begingroup$ Related XKCD on joining two celestial bodies wiith a wire and travelling : what-if.xkcd.com/157 . Exactly all the problems on this answer are shown $\endgroup$
    – Goufalite
    Oct 11, 2018 at 6:30
  • 1
    $\begingroup$ I think the thing that makes rails in space most prohibiting is that distances between objects vary in time as planets and moons and asteroids are in constant motion. So any solid objects connecting two of these would snap and deform. But let's say someone invents an extendible space-rail, what happens when, say, Earth and Mars are on the opposing sides of their orbits and the sun is right between them? $\endgroup$ Oct 11, 2018 at 8:42
  • $\begingroup$ I agree that a rail network in space would be a difficult undertaking, but it definitively wouldn't be slow! A rocket needs reaction mass to propel itself ... this mass is sooner or later gone. Thus planing is needed as to when and how much to fire the rocket. If you'd have a rail (that's "rigid" enough) then you could (like a maglev train ...) accelerate on that for the first half of the journey and decelerate for the second half -- the rail would act as "reaction mass" and could also supply the energy needed to propel vehicles along it. $\endgroup$ Oct 11, 2018 at 10:42
  • $\begingroup$ @RealSubtle: Pfffttt... Space is 3D, just make it a curved extendable space rail (so curved it can reach over/under the Sun at maximum opposed eccentricities of Earth and Mars). I mean, the extending and reorienting space rail is already magic, so why not make it self-curving as well? $\endgroup$ Oct 11, 2018 at 11:10

Yes - in our Megastructure for our future Advanced Civilisation

enter image description here

A dyson swarm is a series of interconnected space habitats (or artificial satellites) that orbit a star, capturing its energy and utilising it to sustain a civilisation. Such a swarm is for an advanced civilisation, possibly using AI and self-replicating robots to create large structures.

It is easy to see that the creation of such a megastructure may require transport of raw materials in an orbital fashion without the constant use of rockets and propellant, for both its manufacture and maintenance.

Rockets could be problematic. If much material needs to be accelerated and decelerated using propellant, after such a massive amount of material is transported, the propellant gases and energy required would be enormous.

In contrast, an orbiting ring or cable (ie. Your Rail), could be used to transport goods and material using acceleration and deceleration of the material (ie. Your Train) with no expenditure of combustible gases. The ring would be on an orbital path, so there would be little to no lateral forces on it. The movement of people, food, construction material, and other items could be containerised and move along the rail between satellite habitats. Containers moving on a ring in opposing directions would prevent the rail from rotating.

Over time, it may indeed be possible for the rails themselves to become ideal, habitable areas.

Rails could overlap too, to create a three dimensional ring structure, like this: enter image description here

Such a structure could actually harness completely the energy of a star, and provide for a complex internodal network of intersecting railcars and trains, without the constant unsustainable use of expendable propellent.

If you create a story in such a setting, I would definitely read it!



A simple way is that rail vehicles don't need to have engines or thrusters or actual people on them. Rather than having a space shuttle that needs all that extra room, a rail vehicle only needs to have 1 compartment dedicated to control, and if you want to be more advance, you could remove even that.

The way I envision it isn't so much a Railway vehicle, but morel like shipping containers that can be attached to a rail. The rail uses electromagnets to accelerate the container, launching it along a set path to another station further along (No rails inbetween, only at the start and end) . All the controls and power is used on the rails, and fine tuning the path and amount of acceleration. The railway vehicle as you call it simple carries goods from 1 place to another. It doesn't contain anything except what the goods inside need. (Think of it like a shipping container in space rather than a train).

Basically, it makes mass travel and goods delivery cheap. If you want to transport people, you just need to make room for oxygen, food and waste storage, no room for fuel, thrusters and a control system. If you want to deliver steel, then you might just put them into the container right away. If you want to deliver more, you might even link them together and send them in one go.

Of course, there is technically a huge margin for error on an interplanetary and higher scale, which you would add thrusters, fuel and a control system but its effectively removing all the extra fuel you need for acceleration and deceleration.

I remove the rail in the middle because its space. Space is huge and you will travel in a straight line if nothing disturbs you. Chances are, everything that can disturb you will be tracked and monitored and factored into the equations. So to save on materials, you remove the middle, and focus on the start and the end.

  • 1
    $\begingroup$ The idea of flinging shipping containers through space is interesting. But how does this answer the question? OP specifies that rail vehicles, for the purpose of the query are vehicles, usually several joined units, connected to a fixed rail, instead of freely traveling ships. Removing the rails rather defeats the purpose of have rail based transport. $\endgroup$
    – elemtilas
    Oct 11, 2018 at 5:46
  • $\begingroup$ @elemtilas I guess if you want to nitpick rail vehicles as having wheels and must be in contact with a physical medium at all time then sure it doesn't count. Neither would a maglev train. I'm proposing space trains. Its like a train, but for space. $\endgroup$
    – Shadowzee
    Oct 11, 2018 at 6:08
  • 4
    $\begingroup$ This proposal is a railgun at best. By the OP's requirements, it should be "connected to a fixed rail", which is not the case here for the majority of the journey (and note that a maglev is connected to a fixed rail, despite not touching it - in your proposal, there is no rail). $\endgroup$
    – Surpriser
    Oct 11, 2018 at 7:50
  • $\begingroup$ @Shadowzee - it wasn't my intention to nitpick so much as to point out what I think is a basic flaw in the premise, which is, there're no actual rails. $\endgroup$
    – elemtilas
    Oct 11, 2018 at 16:01
  • $\begingroup$ @Surpriser What if I shoot it with a rail attached to it? That way its connected to a rail that is fixed to it? You might picture it like a railgun, but I imaging a ring of rails floating around the planet with many launching and arriving zones. After all this is a planet wide railway, designed to accommodate interplanetary traffic. $\endgroup$
    – Shadowzee
    Oct 11, 2018 at 22:41


Consider the reason for having rail networks on earth: We could certainly try to push wagons of goods overland without any fixed tracks below them (and to a certain extent, people did that), but this would be incredibly cumbersome at best and infeasible at its worst, due to all the obstructions and friction with the ground.

Rails provide a smooth, continuous surface which minimizes the effort needed to move objects along them (we have roads instead of driving cross-country for the same reason).

In space, there is no friction and there are virtually no obstructions. Once you have put something on a certain trajectory, it will follow that course inevitably, affected only by gravity until you take deliberate measures to change the course, e.g. using thrusters.

Rails are completely unneccessary in that setting.

This does not even touch upon the engineering difficulties (impossibilities?) posed by such a construction. See elemtilas' answer for some examples.

Yes, for transportation from/to orbit

This concept is called a Space elevator. The basic idea is a cable that is anchored to the ground at one end and extends beyond geostationary orbit. The outer end is held up by centrifugal force, which also keeps the cable under tension. Climbers (which correspond to trains, if we see the cable as some sort of rail) can ascend or descend along the cable, gaining/losing horizontal speed along the way.

However, this only works for getting stuff in orbit around the body it is anchored to, not as a connection between different bodies.

Daniel Jour mentioned in a comment that you could also let go of the cable at an altitude higher than geostationary orbit, which could provide additional speed high enough to swing to another body without extra propulsion. Even then, most of the journey would be traveled away from any anchoring rails.

  • $\begingroup$ If you let go of a space elevator at a higher altitude than geostationary orbit (for an earth based) then you can of course leave earth orbit and "swing" yourself towards other bodies. $\endgroup$ Oct 11, 2018 at 10:56
  • $\begingroup$ True, I have edited my answer accordingly. $\endgroup$
    – Surpriser
    Oct 11, 2018 at 11:31

Not the answer you're looking for? Browse other questions tagged .