# How do I justify short-range engagements in space?

So, lately I have been developing a tabletop board-game, the subject of which is space battles. My intention for it is to be somewhat similar to Armada, but more realistic (e.g. tyranny of rocket equation, ships drift in the direction they were already going, etc.)

However, although I want it to be realistic, I don't want it to happen at the extreme ranges that most people say are probable with space combat. After all, I need this to fit on a table-top. I also really don't want to handwave it, as I'm trying for semi-hard science.

Given the following parameters, how do I justify short-range engagements?

• Energy shields exist, but they aren't Star Trek-level perfect. They work by absorbing all the energy of anything that hits them from the outside, storing it in capacitors. Once the capacitors are full, the shield goes down until the capacitors can be emptied. While the shields aren't infinitely powerful, they do have decent durability. After all, they have to protect the ship against interstellar gas and micrometeorites while the ships are moving.

• Anti-missile countermeasures are effective, but not 100% effective. For purposes of this question, let's set the optimum effectiveness at 98%, with a small decrease in effectiveness as the amount of incoming missiles increases.

• Power supply isn't a problem. For purposes of this question, they have something along the lines of a ZPM.

• Most ships have some ablative armor and anti-rad measures. As a result, hits that get through the shields work kind of like in Armada; very damaging, but not an insta-kill most of the time.

• How close range do you need? (For those of us not familiar with Armada) Oct 20, 2020 at 12:19
• I recommend reading the Vorkosigan Saga. The Young Miles omnibus deals with this issue a few times. Oct 20, 2020 at 20:07
• Star Trek shields fail more often than they hold, though... Oct 21, 2020 at 8:35
• It might be interesting to think about why/how weapon ranges might be limited in space combat, but for your game I suspect no one will care. In Warhammer 40k the range of typical guns is barely the length of 5 tanks. The same is true in other equivalent games. Most people to play them don't even notice this scale-compression and those who do rarely care.
– Dast
Oct 21, 2020 at 11:05
• Kind of irrespective of the question, but your energy shields sound like a very fun mechanic for a board game - you have to risk powering up your opponent in order to damage them, and if you are attacked, you suddenly have a bunch more resources to spend on getting around. Also encourages you to get into fights where you might otherwise be disadvantaged. I like it Oct 22, 2020 at 15:13

### Don't segment your battlefield into Cartesian space - then you can use a more "plot-friendly" scaling.

Deep Space is 3D, and 3D doesn't transform into table top well (How would you hold the pieces up in the air?). Because of this you're are already going to have to project your space 3D to 2D. You're already simplifying space combat significantly.

However, deep space projection is not the same as the space within a solar system or galaxy. 2 ships in different orbits around a body, currently a long way apart from each other will shortly be in closer contact with each other with zero movement. Moving between two positions specified by XYZ coordinates has a non-trivial cost to calculate, and more importantly is basically meaningless - your ships position isn't defined in XYZ - it's an orbital height and a parent body.

Your ship is "In orbit 1000km above Earth" or "In orbit 5AU from the sun". Not "X: 200, Y:150"

At a high level, your ships will be manoeuvring a few squares between systems, and then to a few key strategic orbit types within the systems, so use that as your game board. Divide it up at a high level: "outer solar system orbit"->"inner system orbit"->"high earth orbit"->"low earth orbit"->"on the planet". Two ships in the same orbital region can fight with each other.

Your board game map is something like this:

Detail view:

Trip between systems:

As much as I love a nice physically accurate board game - I don't want to break out the cosine table every round to calculate how my ships have advanced in their ecliptical orbits.

• Man this is starting to sound like Kerbal Combat Program. I like it
– Atog
Oct 20, 2020 at 13:38
• Most likely the best solution as it also lets you "fill" the board. Even if you, for example, flatten our solar system to just the plane (something you have to do anyway for a tabletop), and make planets comically sized, it would be still incredibly empty. Eg Earth+Moon might take 10 tiles because you want detailed battles there ... but then you would have another 100+ tiles for other parts of Earth orbit that would be completely empty and irrelevant. You can afford that in a PC game (you just don't go there, problem solved), but a tabletop game needs to be printed. Oct 21, 2020 at 7:18
• @JamesFaix s/he's specifically saying not to do Kerbal Combat Program. Oct 21, 2020 at 10:31
• Ahh yes, the board diagrams make that a lot clearer. Makes sense. I was imagining it being a more radial board. Perhaps with cells spread out along the lagrange points in each orbit
– Atog
Oct 21, 2020 at 10:47
• Excellent answer that addresses the OP’s problem rather than the question they asked. Only thing that would improve it would be tracking where in any orbit a ship is, though that might make things much more complex. Oct 23, 2020 at 5:40

Combat can be short-range if you change the goals of the fight: instead of it being about destroying the enemy ships, it's always about capture. Simply make it so that 99% of battles (missiles, lasers, shields, etc) are just fancy prelude into boarding the enemy ship. This way, battles focus on disabling the other ships while moving in closer and closer to eventually board.

One way to do this would be to limit a resource, for example ZPE reactors.

Say there are only a fixed amount of ZPE reactors in existence, and more can't be made for some reason. This makes anyone who blows up one a criminal of the highest sort. This way, battles and wars would be fought around possession of this limited yet extremely powerful resource.

• The Red Rising series uses this conceit, although in those works, the reasoning is couched in the structure of the society. Oct 20, 2020 at 20:58
• I wouldn't quote the Red Rising series. Too much handwaving and plotline errors. Oct 21, 2020 at 12:35
• A fixed amount is not necessary. A highly expensive reactor would lead to the same issue. If your side can only produce 1 reactor or 2 per year, and the same goes for the other side, then destruction is extremely wasteful. Oct 22, 2020 at 10:10

I'd go with powerful engines, heat management issues, and realistic plasma-based weapons.

Powerful engines

Your ability to hit something on the vast distances of space is your targeting capability divided by the agility of your target. Guided projectiles are expensive, unguided projectiles will easily miss if you shoot them from far enough and the enemy ship can change its velocity vector fast enough. Obviously the closer you are to them - the easier it is to score a hit. Ramp up your maneuvrability to reduce the distances at which your hit\miss chances tip in favor of hitting. This leaves lasers as long-range weapon which would suffer only from the diffraction and lightspeed lag, but their inefficiency ties in my next point.

Heat issues

The hardest thing to do in space is to stay cool. Ship produces a crapton of heat thanks to the laws of thermodynamic forbidding 100% efficiency, and this especially true for any kind of large guns like lasers and railguns. The least heat-producing weaponry, like various slug-throwers and autocannons is also coincidentally working best only at very close ranges (Sans missiles, sadly, but as I have said earlier - you can make them expensive).

Realistic plasma weaponry

Doesn't really work with the heat issues, but a realistic plasma gun would be a very short-ranged weapon due to the tendency of the plasma to expand and cool off rapidly. They'd be more like flamethrowers. But they'd be extremely powerful flamethrowers capable of vaporising your opponent, which will urge you to get close and personal with them. As an alternative, your engines can already perform this exact role if you'll point them in the direction of the enemy. Depending on their stats they can be lethal at distances up to kilometers.

One possible way to make space combat mostly happen at shorter ranges is to have all ships equipped with some sort of FTL-sensor. Let me give an example:

Ships are equipped with "Q-DAR" which is like radar, except it accesses quantum reality and can thus gather information about particles in local physical space (or similar technobabble). Practically speaking, a high-end Q-DAR system can map out all matter (including photons) in a spherical, 5-light-minute diameter bubble around the sensor instantly, ignoring usual lightspeed limitations that traditional radar has. This means that as long as the ship with the Q-DAR can move, they can't be hit by lightspeed weaponry like lasers and they can dodge kinetic rounds with ease. Even missiles would be seen from hundreds of millions of kilometers away giving plenty of time to prepare countermeasures.

Q-DAR means that ships have to get close enough so that they physical can't dodge so typical ship combat has two ships closing in on each other, wildly dodging, until they are so close that energy weapons and eventual kinetic weapons can't be dodged anymore.

If you want to get fancy and include stealth mechanics, maybe introduce an expensive "quantum fuzzer" which makes an area invisible to Q-DAR but also unable to use Q-DAR while "fuzzed".

• Yes, automated defences that can easily counter long range attacks but not shorter ones. Oct 20, 2020 at 12:21
• Radar works by measuring the time delay from the reflected waves. If Q-DAR is instantaneous, how can it measure distance? Oct 21, 2020 at 2:22
• @Aganju signal strength maybe? Four Q-DAR transceivers in a non-planar arrangement should do the trick (with a little computing power) Oct 21, 2020 at 2:34
• It measures quantum phase shift, obviously. Oct 21, 2020 at 10:32
• OP was looking for something "semi-hard science"
– craq
Oct 23, 2020 at 3:49
1. Anti-missile countermeasures are advanced to the stage that once a missile / torpedo is in space for any length of time it can be easily avoided / neutralised - the longer it spends in space, the more time the target has to counter it. Therefore the attacker must close to "Whites-of-their-eyes" distance so their shot spends a short enough time in space to stand any chance of defeating the countermeasures.

(or longer but still relatively close)

1. Targeting computers require that the target be within a close enough distance that the speed of light is not a factor, i.e. when it's firing the missile, the target is still in the same place that the attacker detects it at, and it hasn't moved in the time it takes light to get from there to here.

(or)

1. Armour is so advanced that single-shots are useless, only a continuous burst of projectiles (or a continuous burn from a laser beam or something) has any chance of breaking through. But to do this you need to get close to keep your weapon trained on the target as it fires.
• Adding to your first point: suppose lasers are able to detonate the missiles early, but not damage ships (thus providing anti-missile countermeasures) - at closer ranges, the missile may be close enough even when prematurely detonated to either cause damage, or to cause sensor-whiteout and obscure the following missiles, which then get through. Oct 21, 2020 at 12:42

Take a cue from history

I don't want it to happen at the extreme ranges that most people say are probable with space combat.

Do some research on the development of the F4 during the Vietnam War. At the time, the F4 was not even equipped with guns as all the top-thinkers thought combat would be at a distance at hypersonic speeds only requiring missiles. That proved to be catastrophic. That's the short version. Dig a little deeper and you'll have a historical model as to why your space combat isn't as distant as the experts predicted. You could even add this as part of the backstory.

• my suggestion to anyone is - try to avoid derive space tactics and battles from airforce. There are some misleading similarities, like 3d actions, but differences are to was and too significant. Oct 23, 2020 at 1:08
• Certainly wasn't saying look at air force fighting tactics, but rather the difference between what planners confidently thought (long-range only engagements) and reality, then project that dynamic into the story. Oct 23, 2020 at 3:20
• as planners part sure it is good advise - future, even close one 5-10 years does not necessarily comply with our fantasy about it, business is an everyday demonstration of that. It was just for those which may think that it may be a good idea to expand on your advice, seen too many of those. As to the answer itself, the guy asks for a recipe about space combat and as a guy who thought about possible tactics myself, I would say it isn't that easy and thinking requires good coincidences and partners to brainstorm and is heavily dependant on which technologies are at hand. OP won't make it. Oct 23, 2020 at 9:02

# Nanite Scanning Cloud

Each ship (or fleet) disperses a cloud of nanites at the start of the battle. Maybe earlier. Maybe constantly if feasible in terms of cost and materials.

The nanites scan for attacks and transmit data back to the fleet. This isn't much help against most energy weapons; unless you allow instant data transmission via something like quantum pairing the nanites information is going to travel at the speed of light just like the attack. But against missiles or really any attack that moves slower than c, this gives the ships time to react. Redirect shields, launch counter-measures, or even dodge. And the further away the attacks started, the more time and more data the defenders have to deal with them.

Of course, since both sides use this (presumably with different encryption and frequencies), just disabling the nanites leaves you just as blind. So while it is a possibility, it is not used as frequently. You could also say that the nanites transmit a constant ping, so neutralizing them (or destroying them with an energy weapon) alerts the other side to your position and intent.

The end result is that the closer you are when you attack, the less chance the opponents have to defend and the more effective your attacks.

To get combat at short ranges you need the technology to favor the defense.

Guns: The projectiles can be detected in flight. Shoot from long range and the target simply evades. While you can use a scattershot approach to ensure hits this means only a tiny percentage of your shots hit and the shields/armor are good enough that that isn't going to cut it.

Plasma: It's charged, it repels itself, it's a short range weapon by it's very nature.

Missiles: Easy pickings for countermissiles--a countermissile is smaller and more nimble. (It just doesn't have the range or the boom.) This means either very large volleys (impractical in most cases) or close range shots with sprint birds.

Lasers: You already mentioned ablative armor. At long range a laser can't deliver enough power to burn through the ablative layer because the inherent inaccuracy in the weapon mounts causes the aiming point to move a bit. (Try going outside at night and aim a laser pointer at a precise target 100' away and have somebody near that target observe how it wiggles around. Sci-Fi generally assumes weapon mounts with insane accuracy. Aiming systems which can hold a point at great ranges are slow moving.)

Anti-gravity wells.

All your (capital?) ships are equipped with a kind of "anti-gravity well" generator, that pushes all inbound matter slowly away from their course, kind of like opposite gravity. Like gravity, this force would be only weak, so that attacks from long distances will almost always be deflected successfully, while attacks from closer distances would hit.

### Pirates vs Merchant Ships.

Make your game about pirates fighting against merchant ships, possibly in a cyberpunk dystopia where everyone (including the pirates) are working for megacorporations. Why are things happening at a close range? Because the pirates pretended to be normal merchant ships and snuck up close to their prey before revealing their true colors. That way, they can more easily board their targets and make off with loot, as well as making it more difficult for their prey to just fire their engines and run away.

Long ranged attacks take a long time to arrive, they are predictable. The shield has plenty of time to adjust to maximize absorption at the point of impact and negate any attack from far away.

Likewise, anti-missile countermeasures are only 98% effective at short range, but at long range you have a far longer amount of time to build shrapnel fields in the direction of the missile, and since missiles have limited fuel and thus limited maneuverability it's pointless to even try because it's guaranteed the missile will run out of fuel and be checkmated by the CWS.

Worst comes to worst, if the ship has to rely on its physical armor it can always orientate itself to reduce damage. The ship can be rotated and offset automatically so long as there is enough time. If an attack comes from far away the ship simply rotates so that the projectile does not penetrate, it deflects, or misses altogether.

You could also take ques from real world politics. The US and Russia both had ICBMs with nukes, yet they decided to slug it out in proxy wars in SEA and the middle east. Why? Because you need to use appropriate force, and as soon as you start lobbing nukes so does the other side. In space everyone can target everyone at any time. You always have lines of fire, and it's incredibly easy to throw thousands or millions of superweapons at your foes. But, you can't do that because they would do the same right back at you.

Space is big and predictable. If you make your missiles pretty dumb so they move in roughly a straight line and at limited speed then they can always be avoided at long ranges. Alternatively you should provide a way to disarm guided missiles you see coming from far away (maybe lasers, maybe decoy flares). In either case the long range missiles/projectiles will require some response, but the response should be an easy action to completely nullify the attack. The only time you can't nullify them completely is when you're busy defending from other ships in close range because now you need to defend from 2 enemies at once.

Bit of a selfish plug, but I was designing Space Chess which has these gunships that shoot projectiles in a straight line. In my play tests, the projectiles haven't ever hit any ship because you can simply move out of the way... Worse, because my map is a sphere and projectiles can orbit around, the shooting ship has to eventually spend an action point to move out of the way too.

A worldbuilding shift could amplify the weaknesses of long-range missile and laser weapons:

## This area of space is blanketed in a thick nebula, composed of charged antimatter particles.

There may be too many scientific liberties needed to create a backstory for how this came to be, but if it can form, we could (perhaps) see the following effects:

Starships are generally safe from the effects of the nebula due to their energy shields.

Planetary atmospheres tend to protect those planets from stray nebula particles, but over very long time scales the effects of atmospheric annihilation could accumulate.

Nebula particles interacting with planetary atmospheres (or any other matter in the solar system) will emit a lot of radiation, interfering with unshielded electronics, including automated guidance systems. It also makes long-range detection of ships difficult.

Long-range missiles and torpedos are too small to carry an energy shield generator, so they cannot survive for long before sustaining excessive damage from stray nebula particles.

Laser beams cannot maintain coherence over long distances due to the charged particles interfering with them.

The simple answer seems to be that hitting targets is hard when they are a long way away. For non-guided weapons this is sufficient. At hundreds of miles distance the target will appear as a dot to your firing systems and you'll need extreme accuracy from the weapon tracking systems to hit that dot with any sort of beam or projectile.

This relates to the angular diameter formula: α = 2arctan(radius/Distance)

The angular diameter is the range of angles through which a fired shot will impact at some point on the target circle. Half of that angle is the required tolerance for your aiming mechanism in order to hit the target reliably.

Let's plug in some numbers. Assume we're firing on a vessel about the size of a naval cruiser - around 160m length - at 100 km distance. To hit reliably at that distance we our fire control systems to have an accuracy in the range of arctan(0.08 / 100) = 0.046 degrees - about 2.75 arc minutes. Not too bad for a stationary, spherical target and assuming you don't mind where you hit.

Now try to make that shot while both of you are moving, you're both trying to dodge incoming fire and so on. Now not only do you need very accurate weapon mounts, they need to track fast without losing that accuracy.

Or you could have realistic weapon mounts that work just fine hitting targets with a margin of error measured in degrees.

Missiles will suffer for a different but equivalent reason. Tracking a moving target takes fuel, and you can't carry a crazy amount of delta-V along with you. In order to hit the target you'll need to make a lot of precise vector changes over the flight time of the missile and the target is going to be doing everything it can to throw your guidance system off, including shining broad-beam ECM across all of your sensors. It's hard to hit what you can't see... unless you're coming from close enough that they don't have time to saturate your sensor array, or would have to put out massive ECM fans that would blind their own guided munitions at the same time.

So close up is the only way to play the game that has any chance of success. Load the port cannons and prepare to come about!

• I think this is the right answer but I think you've underestimated how hard it could be to calculate where to fire the laser at a ship that is far away. If the ships in question are capable of building up any kind of speed, then you really have to think of relativity in terms of calculating where the target is likely to be when the laser beam reaches it, and at long distances, the lead time can be significant. If I'm not mistaken the targeting computer would have to resolve 10 dimensional geodesics in a predictive manner to give you a chance to hit at high speeds and distances. Oct 23, 2020 at 7:03
• @ToddWilcox Oh, I agree. That's why I only mentioned a stationary target. Predicting the future position of a moving target is reasonably simple if they are under zero or constant acceleration, but I don't expect a ship in battle to move predictably. Even if you can get a firing solution that's good enough, aiming your weapons to that prediction isn't going to be simple over long ranges, or high relative motion. Close up and small relative velocity is the only way to really improve the odds. Oct 24, 2020 at 15:51

## Lasers (and other beam-based weapons)

Laser beams cause damage by heating a single point of the ship's hull, so their efficiency can be lowered a lot by simply moving or rotating a bit so the hotspot never stays in one place. When the attacker is close, they can adjust their beam with the target's movement to keep it on point. But when the distance is so large that light-lag becomes a problem, they won't be able to react fast enough.

## Kinetic weapons (dumb, solid projectiles)

Can be detected and dodged on long distances, as long as they aren't fired with near-relativistic speed. When they are, then accuracy might be a problem.

## Guided projectiles (torpedoes)

Can be detected even more easily, because they generate emission. They can be shot down with point-defense weapons. The further away they get detected, the more time your point-defense weapons will have to lock on to them and destroy them. So the efficiency of point-defense increases a lot in long-range engagements.

## Plasma weapons

Dissipate on long ranges, so they are a short-range weapon in any case.

## Bottom line

A long-range space engagement is a long and tedious battle of attrition decided by who first runs out of fuel and ammo. If you want to decide a battle quickly, you have to get up close and personal. Your lasers can cut through the hull even when the enemy tries to get away. Your gauss cannons actually hit. Your torpedoes hit before their point-defense guns can lock on to them. Your plasma projectiles do maximum damage.

But so do theirs.

• You could have energy weapons with a fast decreasing efficiency, i.e. their damage could be reduced by the square of the distance, making them very good at short range but pretty useless at medium-long range

• For missiles, you may make the efficiency of your anti-missile countermeasure dependant of how long it takes the missile to reach the target (i.e, if you fire at 2km from target, a missile could reach it in 3.6 seconds, if you fire from 1000km away it would take 30 minutes). You can use square or cube of this time in your equations to make the countermeasure efficiency increase rapidly with distance

Alternatively, you may introduce a second type of shields using a very different technology (lets call it "super-shield", with specific features:

• This super-shield is nearly indestructible and can last a very long time (making any attempt to attack the ship impossible)
• This technology however can easily be jammed at short range, making possible to attack a ship only if you come close enough to jam its super-shield (which will by side effect jam your own super-shield, forcing both the ships to use the "capacitor energy shields" you describe in your question

Or your ships could have some cloaking devices making it almost impossible to target them unless you're very close.

For short range space battles, check out "The Lost Fleet" book series by Jack Campbell. That series depicts space battles almost like cavalry charges. A short space of time while 2 ships are moving past each other within 100km at very high speed. This makes manouvers and strategy more important than raw firepower.

Alternatively, the use of common countermeasures accessible to everyone would be a thematic option to make long range combat less effective. See Countermeasure drones or other ECM could acheive this. This would make long range combat more of a quick formality prior to an actual combat phase. See Peter F Hamiltons Nights Dawn Triligy. The use of radiation and nuclear drone countermeasures make long range combat pretty much a formality of who has more drones.

Hope this helps