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Old 05-07-2021, 01:10 PM   #1
Prince Charon
 
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Default [Space] Space Strategy: FTL Bottlenecks

A 'FTL Bottleneck' is any volume of space that you must pass through to go Faster Than Light (whether that means only for arriving, only for leaving, or both), which is also small enough to be controllable. How small that needs to be depends on your setting's tech assumptions.

Jump-points or some jump zones, wormholes, artificial 'jump-stations/gates,' and so on qualify as bottlenecks. An example from another role-playing game would be the pirate jump points in BattleTech, though the main 'jump points' don't count (those are just two convenient points just beyond the jump limit of a system, within the huge jump zones that surround it). The important part is that these are places where you can station a fleet or a defence station or similar, and thus have a chance at stopping a hostile force from invading your system, or blocking their retreat.

The specifics will generally depend on the setting, since you need a different strategy for points that you can only leave from (but can arrive in-system from anywhere) than for points that you only need to arrive in (but can escape into FTL from anywhere), and a different strategy for points that bottleneck you both ways. Likewise, you need a different strategy for settings where the jump-point only leads to one other system than for a setting where the same point connects to several other places, or to anywhere at all.

For example, in Irar, the Jewel in the British Crown (which inspired this thread, but this discussion works better here), the known form of FTL is wormhole travel. Each wormhole allows travel both ways, but only connects one system to one other system. Each system can have several wormholes, with the exact number varying by system. The wormholes are believed to be artificial, having been constructed by some ancient civilization tens of millions of years ago at the latest. Civilizations thus prefer to control both ends of wormholes leading to their home system and important other systems, where possible.

Mainly, this thread is to discuss settings with FTL bottlenecks, and how they are handled in the source material (if any), and how they have been or might be handled in-game.


Thoughts?
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Old 05-07-2021, 01:29 PM   #2
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Default Re: [Space] Space Strategy: FTL Bottlenecks

Jump points you have covered, wormholes are a natural variant of them.

You can hamper jump drives by not letting them jump near or way off large masses aka planets far off the way, so the defenders have enough time to prepare. Of course as long as la grange points donīt overrule this.

A way to make bottlenecks for warp drives is that even small bodies are a danger for there shields and therefor the only can fly along certain lanes from system to system.

Same goes for nebulas and other space weather which can make constant navigation roles necessary.

GURPS Space 3rd Ed, and allthough I donīt like it much Space 4th Ed. has some closer looks at this.
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Old 05-07-2021, 01:36 PM   #3
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Default Re: [Space] Space Strategy: FTL Bottlenecks

Quickly springing to mind is the Manticore Wormhole Junction, justification for the Star Kingdom of Manticore's ridiculous economic surplus and occasional strategic target.

Most Honorverse FTL travel is done in a largely unblockable manner - ships can go FTL anywhere outside a hyper limit from major masses, and emerge likewise. Intercept and combat in hyper is possible, but probably very unlikely against a force that is trying to avoid contact by taking less optimal paths. But hyper travel takes not insignificant time. Wormhole travel is instant over whatever distance the wormhole ends provide.

The junction is defended against an invasion force coming through it by massive battlestations closely placed around it. The junction is big by many settings' standards - a light-second across - but in setting almost all shipboard weapons have effective ranges longer than that. This was assisted by the wormhole having a detailed tonnage limitation mechanism so that you couldn't cram an entire sixth-of-a-cubic-lightsecond of warships through at once (Though that would be a bit less than it sounds like because the space drive forces a relatively large spacing between craft).


At least one Miles Vorkosigan book had a big focus on a jump point blockade battle. But I haven't read it in a while, so I don't remember all the details.


Settings that have had wargamers poke at them sometimes end up having specialized weapons designed to be launched through bottlenecks like this, usually to attempt to reduce bottleneck defenses before the less disposable fleet elements come through.

Many settings have the FTL bottlenecks be artificial gateways. Often built by some kind of precursors and impossible to reproduce in the modern age.
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Old 05-07-2021, 01:42 PM   #4
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Default Re: [Space] Space Strategy: FTL Bottlenecks

Something I forgot to mention in the OP that applies to most or all such settings: Communication and Sensors. If you can send messages through the bottleneck, or see what's on the other side, that's going to allow options that you don't have if you have to use couriers, and don't know who's coming through until they arrive.
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Old 05-07-2021, 01:55 PM   #5
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Default Re: [Space] Space Strategy: FTL Bottlenecks

Another consideration is if it's possible to rapidly shut down the bottleneck - by damaging/destroying it, disconnecting it from its power source, physically blocking it (like the Iris system in Stargate), etc. Particularly if this shut down is readily reversible, this gives whoever controls the bottleneck a great deal of power over who can travel through it... and particularly if it's slow (or impossible) to bring back up, this can be the basis for attacks on it. In a case like that, with a two-way wormhole or similar, unless one side completely dominates the other, you'll require cooperation between the two for both sides to stay open. These can make them a decent option for the location of an embassy, or even an outright military base.
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Old 05-07-2021, 01:55 PM   #6
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Default Re: [Space] Space Strategy: FTL Bottlenecks

A relative of this is limited jump geography, where you can't actually directly block the jump lines, but from any given system you can only directly get to a limited number of other systems, and between jumps you have to do something that is susceptible to harassment or interdiction.
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Old 05-07-2021, 03:17 PM   #7
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Default Re: [Space] Space Strategy: FTL Bottlenecks

Quote:
Originally Posted by Anthony View Post
A relative of this is limited jump geography, where you can't actually directly block the jump lines, but from any given system you can only directly get to a limited number of other systems, and between jumps you have to do something that is susceptible to harassment or interdiction.
Sometimes softened to technically you can get to a lot more destinations, but it's very unsafe to jump to a destination that you don't have extensive survey data for. Making it possible to bypass the expected bottleneck locations but only for the desperate or highly prepared.

EDIT: Though in both games and stories this generally has the flaw of being too all-or-nothing. If the main characters try it and it doesn't work it's a presumed TPK...
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Old 05-07-2021, 04:16 PM   #8
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Default Re: [Space] Space Strategy: FTL Bottlenecks

I've mentioned my idea "Sundivers" before. In order to get enough power to travel FTL you have to plot a course for a sun, skimming right on the edge of its corona. The more massive the sun, the farther you can jump. And you have to get the course and approach speed right or you'll jump into interstellar space. This creates a jump drive that still allows for interstellar chases.

Fun fact, in Marvel comics, the Solar System is actually an interstellar choke point. The Skrulls and the Kree would fight over it because peculiar local conditions mean you could go very far very fast if you left from there, making it a strategically important location.
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Old 05-07-2021, 04:49 PM   #9
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Default Re: [Space] Space Strategy: FTL Bottlenecks

In his Hub series James H. Schmitz has FTL that can be blocked by forcefields. So most hub worlds have networks of fields that mean ships have to drop out of ftl a safe distance away. Empty systems and early colony planets are much more open. One story centers on a transit station in a empty area that is where several major trade routes cross where there is a hyperspace part of the station for ships to transship cargo without having to leave hyperspace and a normal part with a hotel.

Last edited by dcarson; 05-08-2021 at 02:57 PM.
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Old 05-07-2021, 05:19 PM   #10
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Default Re: [Space] Space Strategy: FTL Bottlenecks

Another possibility is that calculating jumps is just really hard. like mind-bogglingly computer-intensive. Think like a building-sized bank of computers working for years to plot a single new jump course intensity.

So, interstellar pilots rely on what are basically maps. They stick to well-charted routes. They don't strictly *have* to, but if you don't, you're effectively stranded in the middle of deep space. The odds of randomly jumping back in are literally astronomical. Everybody's working from the same set of maps, so everybody is going on the same routes. Therefore, choke points.

An army could gain substantial advantage by using a new route, but once the data is captured, it's done. And once the route is used, it's at least known that *somebody* has it.
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