In space, do “shipping lanes” make sense?

Question

In settings with space travel we often see stories that rely on ships encountering each other, such as space piracy (which means you need to know where to wait in ambush), or distress signals that actually get answered by passing ships. Now on earth the idea of shipping lanes make sense because of currents and winds (not all paths across the ocean are equivalent), and we have similar factors with air traffic. But even if we didn't have these factors, in the grand scheme of things Earth's navigable airspace and waterways are pretty small.

Space, on the other hand, is big. When you're talking about traveling between planets (to say nothing of systems that are light-years apart), there are lots of ways to get there and, asteroid fields aside, vast swaths of big open space.

So is it realistic that common routes -- "shipping lanes", if you will -- would develop? If so, what factors would govern their placement? If my story depends on unplanned encounters between spaceships, what do I need to take into account to make that realistic?

As far as travel technology is concerned (e.g. FTL?), I haven't thought through the implementation yet. I am not thinking of fixtures like wormholes or B5's hyperspace lanes, where you have to follow a particular path, but if "shipping lanes" make sense for other reasons, I can imagine developing something like hyperspace lanes as a response. In other words, I'd like to do the "traffic study" before deciding how the ships work, and let the needs/patterns govern the implementation instead of the other way around.

Answer 1

This depends heavily on how ships travel faster than light in your universe.

Take Babylon 5: space travel is controlled by gates which allow you to enter and exit hyperspace. In this situation, space lanes are guaranteed. The gates will funnel space traffic into a few predictable patterns.

If you read the Extended Universe Star Wars it is very similar. You can enter hyperspace at any point but there are "hyperspace conduits" that you have to travel along. Planets on a crossroads are more important and are the center of shipping lanes.

Star Trek is the opposite. You can enter warp speed at any point in any direction. Here, there are no technological factors to influence shipping lanes.

So the first factor to consider is how your ships travel through space and take that into account.

Additionally, the earlier you are into space travel, the more likely shipping lanes are to form. When long distance ocean travel started, most ships couldn't travel directly to their destination, they were forced to make stops to resupply. Early space travel would likely be focused on traveling between a home planet and the most profitable locations. However, starbases and other minor planets could become resupply points, forcing shipping lanes to follow similar paths to stay alive.

Finally, there are economic forces to consider. The triangle trade sprang up due to market forces. Slaves from Africa to the Caribbean to grow cash crops. Cash crops to manufactories in America or Europe. Finally, manufactured goods to Africa to purchase more slaves, usually making a profit at each stop. In space, I would expect similar triangle shipping patterns to emerge based on market forces alone. Merchants would all travel the shortest path along the most profitable routes, sticking together for both safety and speed.

While technological forces need to be considered first and provide a strong indicator of what the shipping lanes will become and how rigid they are, over time I expect shipping lanes to emerge regardless.

Answer 2

I don't think it's unreasonable for shipping lanes to be established. There's a few reasons why shipping lanes become established on Earth:

• Currents

  As you've mentioned, the currents play a large part in why ships use shipping lanes. In space it's likely that gravity, spacial anomalies, radiation and other such things will lead to naturally safer and preferred routes.

• Quickest / most efficient route

  On Earth the quickest or most efficient route is often to follow the currents. In space, there might be a few different routes, but it wouldn't take a huge amount of traffic to establish a few favoured routes due to efficiency. Even in space there's economy of travel.

• Safety in numbers

  Another benefit to moving in a ship lane is protection from piracy. Pirates don't go for the ships in the lanes where there is a lot of them, they pick off the lone ships out of lane. They go for the easy targets, so by sticking together you're decreasing the chance of being pirated.

• Response times from authorities

  If authorities know where the majority of trade traffic is, they know where to focus their protection efforts. So if you stick with the majority of the traffic and do get into trouble then response times for help drop. The same is true on Earth or in space.

So as you see, shipping lanes would be established in space for pretty much the same reasons they're established on Earth.

Answer 3

An Argument for Space Shipping Lanes

We tend to think of space as very, very large and very, very empty. This isn't necessarily the case, as we see with Space Junk, the Oort Cloud, and other things. Given that there are things in space, you will need to take that into consideration when navigating.

While this does depend on how you get around space, current "non-warp" technology pays a lot of attention to the gravity of planets and other bodies. You use these for various maneuvers. Not to mention the cost of opposing gravity can be really high, so the low-energy travel routes may follow an Interplanetary Transport Network. Even if you do have the ability to directly oppose gravity, you may not always want to.

Assuming you have points of interest in space, and you care about gravity, there will be paths or approaches to planets that will be more populated than others. Space debris can quite literally blow a hole in your spaceship, so you need to be careful while navigating out there. Careful navigation and multiple people navigating means there will be safe and dangerous areas or approaches.

Answer 4

Slower than light or faster than light?

If you invoke some kind of magical FTL, then the nuances of that FTL will determine everything, and they can be tweaked to produce any results that you desire.

However, for relativistic slower-than-light interstellar planet that fits physics as we currently know it (e.g. engines spending limited fuel/energy to accelerate, and as much energy to decelerate), shipping lanes don't really make sense because:

• You don't stop in the middle as a trip with an intermediate stop takes exactly twice as much fuel and significantly more time as a trip without a stop;
• Interaction requires matching speed, not only position - if you're not willing to spend fuel to make an intercept, then you either fly past each other at ludicrous speed or get destroyed in a collision;
• Direct routes make practical sense - on land, you may want to follow roads and go through major towns on the way, so route from A to B will have travelers passing from C to D through A and B; in space the optimal route is a straight line between C and D without detours.
• the lane would be empty. Even if some ship would be destroyed en route, it would simply fly further with the same speed forever until it flies past (or into) the destination.
• as everything moves relative to each other, two ships going from A to B at different times will take different routes. Assuming slower-than-light travel times (years between stars, days or more between planets), if a faster ship leaves after a slower one, it may reach the destination before the slower one but it will never "meet" it, since they travel on different paths unless it intentionally went on an intercept trajectory and not to the destination.

Realistic physics don't really have unplanned encounters

Engines that can get you from Earth to Jupiter in weeks or from Earth to another planet in less than millenia are visible from far, far away, and also give up your exact location, direction and speed - i.e., source and destination. Any maneuvers require firing the engine - want to start moving? Throw out lots of matter or energy into space. Want to stop or steer? Same thing. Want to move with speeds that get you anywhere soon (as opposed to going from earth to a comet in 10 years) - throw out lots of energy once. I recall seeing calculations that if such a ship was moving between planets in Alpha Centauri, then we'd be able to track it with our current technology from Earth.

So no encounters can be really unplanned - a ship would know all the ships in the neighbourhood, and observe all their maneuvers long before they have any effect - i.e., if someone is changing their speed to meet with you, then you know that they have done that long before they actually meet with you. Before you launch, you'd have a database listing where exactly every ship currently is moving, even if they were launched decades ago. Furthermore, everyone else knows if any meetings occur, and where they go afterwards - if a ship gets intercepted, then everyone in multiple star systems know that and also know where both ships go afterwards.

Answer 5

TL;NR: Shipping lanes are needed if your ship can't reach traveling speed on its own.

As seen in many books, movies, TV shows and video games, shipping lanes especially make sense if your ship is not able to accelerate to the speed it needs to travel.

Some examples of "shipping lanes" in Science fiction that uses external Technology:

The Game Freelancer once established a big network of trading routes you need, to get fast around the planets of the systems.

In the Movie and TV Series Cowboy Bebop, they have also established a trading route network (similar to the Freelancer universe). There it is not possible to exit the lane at any point other than the start or the end of the lane. Also there are some side effects from the speed such as "ghost holograms" when you don´t exit the Route right way.

So if you have not developed a fast ship or good engines, you need a external force to shoot you in the direction of your choice.

---

This makes at least one vector fix if you look at a coordinate system. At the ecliptic plane it makes sense to establish routes to points of interests in a solar system. So the routes you build are mainly fixed in the horizontal but not in the vertical because of the movement of planets and objects you want to connect. A real travel lane could so be a complete plane in the solar system, the next lane would be layer further up or down.

Little illustration:

Of course the routes would be selected in different angles for every destination, but when you count the time the ship needs to travel, you will need to shoot in a direction where at that moment there is no planet or point of interest. Also the only points where one is likely to come across another ship are still the ports where the ships go in and out of the route. Maybe when the lane is highly populated you have some ships a few hours before you and behind you but an encounter at this scale of things would be lucky.

If the points of interest are fixed places in a system you of course would have also fixed lanes form one point to another.

Answer 6

Under the right set of circumstances, shipping "lanes" in interplanetary space might develop. Other than those specific circumstances, each trajectory will be fairly unique and stuff won't ever share trajectories unless one of the parties wants a close encounter.

Interplanetary Transportation Network

So what are the special circumstances?

Consider a very massive payload (say moving an entire asteroid). Reducing the energy it takes to move this object by even a little reduces the over all energy requirements by a tremendous amount.

The trajectory that requires the lowest amount of energy involves the use of the Interplanetary Transportation Network.

To use the ITN you must first "pay" the Hohmann Orbit Transfer cost to the nearest Lagrange point (Typically L1 or L2) and then a minimum amount of additional energy to tweak the trajectory as it passes through a succession of subsequent Lagrange points. Travel by this means will take a LLOOONNNGG time, so it won't be used by people or time sensitive goods. For moving large masses of goods this will be the preferred method of transport.

Lagrange Points

There are only a limited number of Lagrange points available (5 points for each significantly massed body). The most valuable of these Lagrange points will be those near the source, target, and the two gas giants (Jupiter and Saturn). The Lagrange points around Uranus & Neptune might be used if you plan to move bodies in their vicinity. Because of their limited number you might even see "congestion" at these locations for a thriving interplanetary civilization that's busy rearranging the solar system's minor bodies.

The shipping "lanes" will be those trajectories that link up the most widely used Lagrange points.

The Trojans and "Space Cities"

On the surface of the Earth, people tend to congregate at major transportation hubs. For instance major cities have arisen around good sea ports or the confluence of major rivers.

If your interplanetary civilization is busy moving minor bodies around, then at least some of them will pass though the Trojan Points / Asteroids. The Trojans occupy Jupiter's L4 & L5 Lagrange points.

This means you could plausibly develop "space cities" in the Trojan Asteroids and use them as a base of operations and resupply for the people rearranging the solar system.

Answer 7

While space is vast and infinite, mankind isn't.

Travel 'lanes' through space may include known protected areas that are safe to travel in and free of navigational hazards. Established lanes and routes may have incentives, such as a relay system that allows messages to go to either end of the route if assistance is required. Established routes may have toll fees or required travel checkpoints. An organized fleet system may require that all travel routes be registered in advance for planning and security purposes.

What do you have to hide by traveling away from the route, citizen? Traveling outside the lanes could have factors such as a need to avoid authority, ability to get to the destination faster by avoiding the lane, knowledge that the established route is unsafe or being forced to divert due to a hazard on the route. These are the people who are going to have random encounters in space.

Ships are very likely more than capable of traveling outside established routes, but it's akin to seeing an old pickup truck speeding off-road across the dusty plains and scrub brush instead of a simple commuter car traveling along the freeway.

Answer 8

The right constraint

Shipping lanes are not a result of a constraint of choice, but a constraint of resource. I could start a shipping company that takes a scenic route from A to B, but it will go bust because simple competition requires that I take the most efficient route I can, or someone else will undercut me.

Getting about cheaply

For the same reason, the most efficient route will be the most popular, and thus effectively a 'shipping lane'; gravitational effects give us the Interplanetary Transport Network [Wikipedia], essentially a cheap way to get around the solar system. In space, using these networks can slash your fuel costs because of the Tyranny Of The Rocket Equation [NASA].

Planets move

...and so the Interplanetary Transport Network is not a fixed map; it is continually shifting, and occasionally a new route or a sudden change in the optimal route will happen. Stars move much more slowly, so largely interstellar routes should be less likely to move. However, stars are also not much help for gravitational slingshots (precisely because they don't move very fast) so interstellar routes are pretty much straight lines anyway.

Answer 9

Whether shipping lanes will appear depends almost 100% on whether it is profitable to shipping companies to use shipping lanes. Shipping companies, due to their slim margins, are very dependent on profitability of their practice.

• If the technology has limited topology (such as gate networks), shipping lanes will be natural.
• If the cost of traveling extra distance is low, then it is more likely you will see shipping lanes to simplify navigation (it simply doesn't cost all that much per benefit).
• If the benefit of shipping lanes is very high, such as if the need to do rescues occurs often, or the cargo is too valuable to be "lost in space."
• If the odds of being raided are high, shipping lanes are more likely (flocking like herd animals).
• If the ruling society wants to keep tabs on shipping for tax reasons, they may mandate shipping lanes (possibly by installing checkpoints, which would act a lot like gates, except enforced by society rather than the physics of travel).
• Shipping lanes are more likely to form in the mid-range of timescales. On the low timescales, adventurers would dominate, and they do whatever they please. On large timescales, the number of shipping lanes could get so large that they look more like a fluid than a network. In the middle ground, you would see more stranded shapes that look like shipping lanes.

Answer 10

In short, you can define lanes on stellar maps, for the primary reason that there will always be an "easiest" way to get from A to B, which will be followed by every ship that is trying to go from A to B. However, it will probably be impractical to mark them with beacons or the like as we mark shipping channels with bouys.

The difference, in space travel, is that A and B are rarely situated in the same points in space at any two points in time. For interplanetary transit, the most efficient yet direct path is a "Hohman Transfer Orbit", basically transitioning from planetary to solar orbit along a path and at a velocity that will cause you to move between planetary orbits and be "caught" by the planet you're heading to. Even then, that orbital path depends 100% on the time you depart one planet for the other, and therefore the relative position and travel of the planets, determining the point at which you depart one and arrive at the other.

In interstellar sublight travel, it's pretty much the same; the stars are rotating around the galaxy at terrific speed, but that means so are we, so we can head nearly directly toward the other star, maybe a fraction of a degree inside to make sure we're not chasing it around the galactic hub (and to make sure we can enter into orbit around the star and not plunge right into it when we get there). These paths will be a little more static relative to the galaxy itself, and therefore ships will have to be vigilant to check for people coming the other way, but "Big Space Theory" will dominate; similar to Big Sky Theory in air travel, space will never be as densely populated with transportation traffic as the roads on the ground, so all in all the odds of a mid-air collision in "uncontrolled" regions of interplanetary or interstellar space will be fairly low.

Answer 11

According to this answer to another question an Alcubierre drive would need to have a channel setup far in advance. So with such a technology, you'd need to have a network on established lanes just to be able to go faster than light. Outside the lanes you would not be able to go FTL at all, which for far-away destinations means that you could not reach the destination in your lifetime. Even if this should turn out to be false in our universe (well, we don't even know yet if the Alcubierre drive actually can work in our universe at all!), you still can claim it as requirement in your invented universe.

Similar considerations are true when using wormholes for travel: The wormholes naturally would be such points where you would encounter many other ships.

When travelling normally in interstellar space, you'd likely want to reach your destination in a straight line, in order to not waste fuel for course corrections. This again would mean preferred routed, which just would be the straight line between both points. This is also true for moving targets, since this would just mean the lane also moves over time.

Things get more complex in the solar system (or other stellar systems) because of the gravity. Here a single lane would be less likely; however for ships with similar engines, the optimal energy path at any given time would also be the same, and it could be calculated long in advance, so e.g. pirates would know exactly where to go.

Answer 12

I think due to sheer size, you can't have lanes unless you have bottlenecks. In worlds similar to the ones found in the Vorkosigan series, you have "shipping lanes" because you travel using wormholes between star-systems. You will see trading posts and major "cross-roads" around those wormholes.

Answer 13

In a hard science milieu, there is only one real consideration among spacecraft in contention with each other: orbital superiority.

Spacecraft within a star system that are available to contend with each other will be in one of only two states:

• In orbit around a point of interest.
• In a transfer orbit that takes them from one point of interest to another.

Points of interest are generally planets, planetoids, moons, asteroids, comets, Lagrange points (maybe a space station at a Lagrange point), or wormholes if your settings allows them. Importantly, these points will always be in an orbit of their own around something larger (planet, main star(s).)

Also, transfer orbits can be composed of multiple different stages (think of a deep space probe sling-shotting around the sun). As a side note, transfer orbits (as their name indicates) are themselves orbits around points of interest. What makes them transfer orbits is that the orbit is temporarily around a point of interest that is neither the starting point nor the destination.

So, essentially all spacecraft are in orbit at all times. Now, like in the movie "Gravity", if your orbit intersects with another craft's orbit at the correct time, you will meet... generally in an event that lies on the spectrum between collision and rendezvous.

Based on the fact that orbits must be planned ahead, often over long periods of time (think weeks and months), the opportunity for two craft to meet in a particular orbit depends on how navigational communication is done in this setting. Is there a system "flight control" that manages all craft? Do you file your "flight plan" with control ahead of time? Is it an uncontrolled system where you happen to have many crafts attempting the same transfer around the same time? Meetings could happen, and perhaps even unplanned meetings.

The only remaining problem is the such meetings will almost invariable happen at enormous speed differences. Does this provide the opportunities you seek?

Answer 14

I understand that the answer is already accepted but: albucierre drive lanes.

Albucierre drives create a kind of fold in space you can ride and achieve FTL without really going FTL. A disadvantage (besides needing more negative mass than there is observable positive mass in the universe) is that you lose the negative mass while traveling.

The solution: send a slower-than-light ship that creates a lane of negative mass, allowing ships afterwards to have an easy time traveling along the lane. The creation of such a lane takes years of travel time and the generation of the negative mass (assuming its possible) is probably going to take some time too. So a star lane is going to be pretty important, but if you really need to you can use more expensive travel off-lane... Unless you chose to make that so expensive its not an option.

Answer 15

This depends on what level of travel the "shipping lanes" are at, if it's at an interstellar level, then possibly depending on the type of FTL travel; any type of stargate or wormhole style, such as in Babylon 5, or the Human Reach series works well for this. However on an interplanetary level, there really is no such thing, as spacecraft will, again depending of the drive, have to plot a new route each journey, as their destination is continuous moving and they themselves are moving around various celestial bodies. Of course if you take into account things like Hohmann Transfer Orbits and ships trajectories, this means while you do not have shipping lanes you have predictable routes that a ship will travel; some paths are more fuel efficient then others

A good site for further reading on this topic would be the Atomic Rockets website created by Winchell Chung

Answer 16

Flight paths

This is analogous to flight paths in airspace. Aircraft follow defined flight paths for several reasons.

1. To facilitate air traffic control.
2. To avoid collisions. A light speed collision would be messy and impossible to avoid.
3. To follow the shortest distance between two points.
4. To allow refueling stops.

The more crowded space gets the more important shipping lanes would become. I would imagine the space around major planets would be tightly regulated. The space between stars would need to be monitored to avoid collisions.

Answer 17

Shipping lanes make sense in most scenarios.

Take the example of ocean travel, for instance. A sea is (mostly) very empty, and a ship that's taking one particular route may just as well take another. But even then, shipping routes exist. This is due to a variety of reasons:

Efficiency: Most ships prefer to take the route that will be the most economical, to conserve fuel and labour costs. The most efficient routes thus become established lanes.

Security: A well-travelled lane is less likely to be raided or blockaded, as an efficient route is a resource most nations guard jealously: it is why large navies exist with the very purpose of safeguarding trade routes. Thus, vessels will naturally want to take thos routes.

Safety: The sea is fraught with dangers like rocks, storms and maelstroms. A trade route is mostly established in such a way that it passes through areas where these dangers do not or are unlikely to occur. Thus, ships will want to use these routes, as there is a guarantee of no unexpected surprises.

These same reasons can be applied to space as well. With the ever-present dangers of ion clouds, asteroid fields, solar storms, pirates and raiders, it is natural for traders to stick to relatively clear routes. Once these become recognized trade routes, governments will probably employ resources for their protection, because trade is an integral part of the economy. Indeed, companies might spring up whose very purpose is to manage and safeguard these routes, charging heavy duties in exchange.

But if there is need for secrecy and speed, there will always be a black market for unregulated couriers and merchants, who, instead of sticking to safer, but time-consuming routes, carry their wares through open space. Dangerous, but also very much paying...