A story about Space War and Space Politics in the solar system, you never heard of.

From a perspective, you may never be thought about.

Originally it was posted as an answer to a question of WorldBuilding site. Where a guy tried to imagine a realistic space combat based on the tech he thinks is realistic.
As with many of such attempts, A good answer can’t be given because strategy and tactics depend on small details, change one and it will eliminate a whole set of possible strategies and open a new one. Goals, specs of technologies, specs of space ships and all that – change 1% of it and the picture will change drastically. All that even without involving drastically different technologies, which we may imagine and which we may argue are in the realm of physics, and not only in the realm of physics but in the realm of our technologies in 10-20-30-50-100 years.

However, all those attempts aren’t a total waste of time, at least in some cases and may bring interesting results and I hope this is one of them.

There is not point to make TL;DR for it – it is just a possible picture of a possibility. And if you interested in future politics of solar system and have nothing against fusion engines for spaceships and maybe heard of the game Children of Death Earth, you may like it.

All that said the original question is here and it is also on the long side about details OP had in mind as important. The answer for that is all below, however it is a bit outdated as a strategy in scenarios, but space council and general concepts still holding.

We need more space thinking.


This is an interesting question. And it’s nice to see, person who takes it seriously.
The question is also hard to answer as well.
One of the reasons for that hardness is: even you have described your setup fairly detailed, it is not enough to answer the question without other assumptions.
The second reason is: any model of such interactions is waggle. Slight change of parameters may vastly change whole picture/results.
Game Eve-online is a good example of that.

Not so good

Which important topics are missing in your description?

  • First of all sizes of all ships, drones, projectiles.
  • The form also important. It affects the area of projections for crafts from different angles.
  • Detection very important topic in that situation. Some people think in therms of unlimited detection, some think opposite and it is a big topic by itself. I’m not sure which one is yours.
  • The effectiveness of laser weapon: power, beam divergence, impulse time.
  • Tracking ability for both types – laser and kinetic.
  • The maneuverability of ships. Yes, they have slow acceleration, but how fast they can change the direction of that acceleration.

To answer your question, someone has to have a model, with any details possible. Even in that case, it will be a very hard question, especially if there isn’t a big gap between tech levels. In the real world, you can see that in the discussions about – which army is stronger. Most tech is known, but the answer isn’t one sided.

I will make some assumptions, which are based on my knowledge, results of long discussions with other ppl about that subject, and good(or not so good) guesses.


  • Form – sphere
  • Size – from density 5m3 per ton
  • Detection – radar detection, IR, transition methods.
    detection is a hard topic, even if I personally do not agree with everything here, especially about the estimation of detection range, but definitely, a good place to check, also for other topics about possible ships etc. Also this question Stealth in Space: How realistic is it? have some good points, besides accepted answer. There is a battle between the tech and ability to trick that tech and people behind it.
    As in that part of your questions, all is about fleet vs fleet – I will address more for that situation, and a little bit about attacking moons.
    So assume fleets can see each other, quite well, at least at distances 5000-10000 km. Also, they have countermeasures for detection systems – for radars let say plasma clouds, works with IR as well; Thermonuclear engine plume towards to enemy – will also saturate some details. As distances are closer more details are defined.

Bad news
First of all, it’s a bad idea go to space war in first place, especially with such bad tech.
Second, bad idea to provoke someone when you nailed to space bodies. We are training for centuries in predictions of their movements. Especially in cases when they do not have an atmosphere.
You may trow kinetic weapon away, it sucks.(long story short, long story below)

  • Bad tech
    You consider slugs with speed 20 km/s and mass 40-10 kg as a possible weapon. Besides the fact fleets should travel with speeds more then that, to make planet traveling possible in reasonable time. Even if space is big, rocks are everywhere and would be sad to loose ships just because of them. Or they have protection, or active defense against them. They will have hard time to solve that with such small ships. But they have to find solution, specially for passenger ships. Even if Voyager isn’t destroyed, probability grow proportionally surface area of a craft.

Ok, back to your setting.
2 fleets noticed each other at distance 10000 km, what should they do.

First of all, they should be not a compact group.

From eLISA article

eLISA would be the first dedicated space-based gravitational wave detector. It aims to measure gravitational waves directly by using laser interferometry. The LISA concept has a constellation of three spacecraft, arranged in an equilateral triangle with million-kilometer arms (5 million km for classic LISA, 1 million km for eLISA) flying along an Earth-like heliocentric orbit. The distance between the satellites is precisely monitored to detect a passing gravitational wave.

So keeping distances 10000 km between, seems like not a big deal, from the technical point of view. Even with small crafts distance may be millions of km, with the working network between such crafts. Small craft may weight 1-2 mT or even less.

In case compact group, let it be D(defenders), A(attackers).
Group A moves with speed 50-100 km/s towards group D, in case the kinetic weapon is effective, both sides are the kinetic weapon by them self. And way much more efficient in therms delivering much more energy, because of their mass. Total time of engagement 200-100 sec (50-100km/s), after they detect each other. Best case scenario – they destroy each other completely. 100t payload with 40 kg warheads equals 2500 slugs from a single ship. They are more powerful (6-25 times), and it 4-8 times more by count, more than you may launch by the kinetic launcher, in the duration of the engagement. Engine plumes from group A toward group D detectors, which is high-temperature plasma, will make it harder to track these slugs.

Group A may miss group D, but they definitely will not miss moons, which D will defend. This is a bad scenario for D, and best solution to bring revenge to bases of A.

Ok, let say Group A decides to loose their advantage(speed) and slows down. Both detect each other 10000 km away. Both, because group D should intercept, it’s their only hope to defend their object (a planet, a station – whatever).

Dense group, relative speed 0, distance 10000km.
Drones will be handy in that situation. They consume 100kg reactive mass per second, with the first stage, and if it’s enough for 600 seconds of work, then speed at the end will be ca 30km/s, acceleration will grow from ca 30 m/c2 to ca 115 m/c2, distance covered ca 7500 km, total time to target 600+80 seconds, total mass 20 mT, which means 500 slugs equivalent(at least), there ca 10 drones per enemy ship, means 5000 slugs, which means 2.5 more then ships may launch with kinetic, in that time. As group A lost their advantage(speed), group D may do as countermeasure 2g and get 14km/s in that time, but that 1.5-2 times slower acceleration then they actually need.(not so simple but, may, and probably will, not work as well).

The Nice thing about drones as torpedoes.
The closer they are to target more speed they have and more maneuverability(angular velocity) they have, better they see an enemy.
Destroying them on close distances may make thing worse, not matter which cause – intended destruction, or defense system of group D.
Laser evaporating a ton in one minute? Not on such small ships. (evaporate with engine plumes may work actually, they trow half a ton per second with velocity 45 km/s of high-temperature plasma, but tracking the target will be difficult. But probably will not work, because of magnetic field which a drone may create, which he needs for its own engine)
Even if it will be evaporated – it’s still 20 ton of gas/plasma, still flying 30 km/s towards enemy ship. Yes, the impact will be less and distributed on the surface of the ship. How much consequences it will have – depends on the construction of the ship.
Drones maybe launched at once, one by one or in any order you might imagine, thus they are more flexible, as a tool of destruction.

Group D has some advantages, they may bring more armored shielding.
As you may know Bigelow Aerospace launched inflatable module for ISS. In some videos, they showed principles they use for micrometeorites protection. Multilayer protection(Whipple shield), where layers are at some distance from each other. The first layer destroys micrometeorite, making a dust from it, and a divergent beam of that dust collides with the second layer, but this time the impact is over a much larger surface. The first layer helps spread projectile, second withstand the impact. This principle will work with any high-speed projectile of any mass. So defense actually is possible, and not only Bigelow Aerospace style, but it comes with some mass and size. But that mass isn’t so big, like many may think.

Compact, close range combats – with such tech, are totally unrealistic.
You may agree or disagree with all(some) above, but definitely, a close combat situation has huge flaws. Many think about such combat like it is a tank battle, submarine battle, jet dog fights – it’s none of these.
Stop it, let it be more space like, let think more space style.

How can it be in a more realistic way

  • First of all prepare for future war, make more flying engines aka drones
    Thermonuclear engines have great potential for in solar system travel. Theoretical ISP is about 0.1c. And because engines are useful, any way you will build them in big quantities for other tasks too, so not many reasons to constrain yourself by not making drones too.
  • Build the network
    Because distances between nodes may be 5kk kilometers (1/30 a.e.) – thus for a 1 cubic a.u. it needs roughly speaking 27000 units. (we build cars in millions)
    The Network will be useful for civilians, for scientists, for the military – as navigation, as data transmission, as instruments to observe the solar system, as job creation – everyone will be happy to have the Network. To cover everything up to Jupiter, you need 15kk such nodes. Up to Saturn 113kk nodes.
  • Hide
    After you successfully made everyone happy about the Network, place some of your war drones as part of that network. Hiding 10’000-100’000 of dual purpose crafts will be not so difficult. They all have engines, they all do some maneuvering, they all have some high tech equipment. Actually, they all may be capable target ships, planets etc. Let say in case of a distress code from civilian ship – in some cases you may send them nodes – as tug, as transmitter (let say they have broken their own transmitter, but node have one at least because it’s part of its job), maybe some capsules for lost cosmonauts, for searching them, for to transport them, for energy supply for their suits, etc etc. And if military will be not interested in such network, civilians definitely are.
  • Do not hide
    Actually, there is no need to hide the fact that drones may be used as some sort of weapon. The reason for that is – Everything they need for the military task, they do need for everyday tasks.
    So it is just a question of may or may not you aim them, and control them.
  • Place as much civilian and scientific equipment as possible.
    More high tech equipment it will be aboard, the greater impact it will have on a target. More fragile it is, easier it is to disperse it before impact, to cover maneuver trajectories of a target. Higher costs of equipment, higher is the compensations and more profits in no war time.
  • Share network
    As you can’t prevent having some hidden options – so safe to assume who builds drones those has full control on that node. As they are not so much useful in small quantities, no reasons to make separate networks for an outer solar system, thereby they are part of a global network and everyone who participates get benefits proportionally of their shares, and nodes aka drones, which are such shares and are the Wealth.
  • Make more fun of it – Sell/Buy everything
    Sell launch codes, sell data access, sell rescue services, sell observation data, sell protection, sell maintenance.
  • Even more fun
    As usual make politics around that, your vote is proportional to your global network shares, at that moment. So buy vote access keys before you vote.

Back to war, go wild, burn your money.

As you decide to go war.

  • first of all make sure you have enough shares for such action
  • more importantly, make sure that your surveillance, didn’t fail and data they have collected may convince at least half of shareholders, and better be no doubt about that and be sure it will convince at least 80 percent of them, be on safe side of that reality.
  • claiming space bodies in space for exclusive use, definitely is a crime, so don’t worry attacking moons, they all know what that means, they all guilty.
  • even if you do not have to worry about the legitimacy of your actions, be nice and get approval for your actions, placing your data about the violation in the network. Also it will be a warning, for these who claims moon ownership, and they may correct their behavior. All will appreciate your respect, and probably you will not waste your valuable shares to solve that problem.
  • If they are dummy enough and keep violate the law – use friendly parts of network (those who validated your decision), launch your missiles/nodes/shares/drones. As many as you need to eliminate their claims.
  • record all your efforts, and losses of your assets. As result of conduction legitimate actions they should be covered.
  • if you think there is law violation, but your estimation shows they will be not covered in reasonable time from law-abiding actions and from that source – then probably it isn’t law violation.
  • if you still think, it is a violation of the law, you may consult or buy services from groups who are better and more efficient in such actions. If they think they can’t get profit from that, then definitely there is no law violation. Chill out it’s your daemons.
  • Be sure your actions are validated by all of your citizens.
  • As citizen, be sure that all actions of your group with other groups are valid. Because if not, your group will be punished as a whole, and nobody will care about you as individual. So think about your future, and have order in your house right now. If you doubt, if you see it’s impossible – move to other more reasonable group, or move these who disagrees in new house, make sure to divide your common wealth, if you do not, it may have bad consequences for your group. Divorce until you agree as group on subjects, which may impact your personal live literally.
  • be smart, do not trow all your assets in war, because you will loose your vote in network council. Even if all costs will be covered in shares and commodities, it needs time to restore your shares, as well as your vote in Network Council, but percentage of your voice may be less, just because others took your place. It’s will be your punishment, because you haven’t solved that all in more civilized way.
  • you may participate in law enforcement which are validated in Network Council, you get your costs covered as usual. It will help you manage your shares/drones, have more control over maintenance costs, utilize old shares. Also it helps to get participation from other groups, who also accept that rule, establish relations in case you need their help. But it’s also nice way to utilize old drones and get twice of their cost. But be sure who you have as friends, or you know, you will be punished, this or another way. Safer to participate on network council approved actions.

War compensations

  • Nobody cares, how much imaginable profits you have lost because of someone’s law violations. You guilty because you didn’t spot that earlier, and didn’t share that information earlier with network council.
  • If you do inform network council about law violation, but nobody cares, most likely you are too selfish so you will be punished for that selfishness, this or another way, not because of the will of others, but because of your actions.
  • Law enforcing procedures should be covered, from sources where this law violation was, in a legitimate way. If it can’t be done, there is no law violation.

As those who spotted a violation of the law and lost some shares in the process bringing the order, you should be compensated for that efforts, but it is not unconditional compensation from all others. It should be compensated from sources where you spotted law violation, in a legitimate way.
If some one claims moons as their property, make sure there is a better use for more people with better profit. If not, probably it is better used now as it is, so it is legit already at that moment. It may be changed in future if new use will be found, which is better. So if you claim something about moons, be prepared to accommodate changes, when times come. So better do not consider it as your own possession, at any given time.

So if you launch an attack to that moon, as the only asset of that group, you will be compensated only from that moon sources, if you use it in a non-law violating way. You may settle some complexes, which will not violate the law, and cover your losses, let say twice, you have spent on eliminating law violation. Actually, it’s not important how much, until most groups which have an interest in that resource, agrees that you do good.

Let say moons are the main asset of group D, and they begin nonlegitimate actions against group A. Let say attacking your ships.
Such things will be seen from many nodes, at least you may prove for many groups that action had a place. Who was the first, who was the last – unclear, but it was – yes it was.
If some one had destroyed others property – he have to prove legitimacy of his actions, for all who may be interested in that actions. You do not have to prove or disclose how important was that spy on that ship. You get the right to destroy similar property. Congrats you got new asset, keep it, use it or sell it, exchange it. Similar by ppl on board, or by mass – simpler that similarity is, better for all – depends how you declared that asset for that travel.

  • better declare all you assets
    So all hidden piracy bases which are not declared in network council, they do not exist, they are outside network council law, outside their space volume too, because if they do inside space volume they will be spotted without exceptions. Anyone may do with them anything he wish or can.
  • keep connection with network.
    Keep connected with the network and better have all certified equipment for close range monitoring or buy service from those who have such.
    It may be small drones flying around your ship, which are produced by well-known technologies which anyone may check and validate, produced on manufacture under collective management, which may be audited. Such devices not necessary should be too sophisticated, rapid development etc. They should be trusted sources of information, trusted as much as it possible. They will help to prove who opened fire first, and stage of destruction in result. Shot them and you are guilty. Any drone may be taken for to be disassembled to check it, no reason/permission required, just pay its cost. Cheat with production of them, those who are guilty will have big big problems. Constant random check is obligation of all who uses them. (cryptography and money approach)
    They may use your connection links, or their own, have engines or not. They are not part of your ship, they are witnesses of things which may take place near you. Nodes are witnesses on more global scale.(any way they do monitoring of everything for navigation purposes, and scientific purposes etc etc)
  • buy insurance for destruction of unidentified maneuvering objects with relative velocities more then 200 km/s, 15kk km around your current position. Agitate others for that, more people participate, cheaper it is. Also, it will give you enough time to buy more support for yourself if it’s needed.

Node/drone/share as warfare

The network is superior power, what it can do as a weapon.

Nodes are multipurpose units. They do orbit around the Sun, and have no purpose to bring them back and forth(to the planets, to the stations). As commodity, you may buy and sell them, without needs to physically move it. So you may use them there where you need them. That fact releases you from worry about their mass, rocket equations, fuel supply. They also do not need to be fast at acceleration, until you fast enough to buy you a time, it’s ok for you. As result nodes may be more efficient in terms of their delta-v. So you have a wide spectrum of possibilities, around which you may build your tactics. Years of accelerations and devastating impact on 0.1c for space bodies(e ratio wet/dry), or faster response.

  • Note about thermonuclear engines
    Theoretical ISP for TE is about 0.1c=30000 km/s
    First, you need to figure out how to build them, or thermonuclear reactor in general. Trust is made by leaking plasma from that reactor. Then you figure out how to do that leaking more efficient, more straight from the back of your ship.
    Second, you have to figure out how to make more trust with the same energy (which is the energy of thermonuclear reaction), and this is done by lowering ISP of the engine. Long story short, it can be done by injecting a way much lower temperature plasma, or gases(which will be converted to plasma after mixing with hot thermonuclear plasma). There are some papers about that in the network, not highly scientific, but reasonably enough, based on old thermonuclear lab reactors.
    So the ability to have lower ISP, as you have 23km/s, is an improvement.
  • Second note
    Very cool thing about lowering ISP and fusion rocket engine is this: you may use anything for reactive mass. Any material in space, in trash can, wreck, parts of your ship, space rocks – anything may be converted to plasma with help of plasma from thermonuclear reactor. As you may operate with plasma, their chemical properties are not important, except ionization energy and nuclear mass, so you may need to be able to adjust your engine on the fly, but there is also no problems in doing that which is bigger than reactor itself.
  • assume that mass of a node is similar to a drone mass of 100 ton, energy 5 GW per engine, 5 engines – same parameters as in question except ISP. ISP may vary from 0.1c and below. Wet/Dry ratio is ca 4, and with ISP below 0.1c . Reactive mass also can be some equipment installed on that node, robot arm crashes telescopes, another engines etc and put small chunks in to working engine dispenser camera.
  • engines are tubes pretty long ca 100 meters, 2-2.5 meters in diameter, consisting out of rings with spaces between them, which are kept in place with carbon sticks and carbon duct tape. Made from CNT. Working material temperature ca 2000K, power 5GW.

Different distances, if produced power is the same, needs different ISP, if someone will be faster in therms of time. So you may place nodes 60 a.e. away with higher ISP and get them back faster then those placed at 10 a.e. but with a lower ISP. (many are familiar with that because of travel to Mars discussions) (constant acceleration vs short and powerful burst) Also velocity of those nodes, which were further away will be higher then of those at closer distance. This is nice because if you can predict target position(moons as example), it makes sense to place your drone further from the potentially target. It also may mean lower probability of detection, destruction etc, however not in network council space, but you may keep some stuff outside that space.

  • improve you ships, use same material which is used to build coils in reactor (I assume long carbon nanotubes) for tethers, call tug service (or have your own) that will make your travel faster and you may use them as warfare, and you may take as much of those engines/tugs as you have money for(buy or rent). So it will be not just dead payload you have in case of engagement, but useful payload which spends your time and saves your reactive mass, or if you have lot of reactive mass, saves fuel.

One ship traveler
So you took let say 50 engines, because you can, and you think it will be a bad trip, but you badly need to Jupiter, because you will not pay for shipping and gathering of He3, you wish to extract it by yourself with your own equipment. You belong to group A.
Group D will stop you, some of their ships have spotted you nearby(let say 100kk km), because their group paid for detection around 100kk km for each ship, and he takes a decided to intercept you, and for some reasons he decided not to use shares (low ranking member of group D, or whatever)
As a member of group A, you have some KOS list, but paid for information around 15kk km, it means from 110 nearby nodes, so you got a warning after mD(member of group D) entered into that zone.
You are a smart guy, saving money on information access, and spending them on buying/renting more as usual engines.
After you got the information you have different choices/opportunities and which one to choose may depend on the situation.

  • mD was stupid and burned almost everything, got 30km/s on intercept course (you may estimate that by paying for information about trajectory parameters of that vessel, and you was smart to hide your capability, you accelerate as an average vessel). You have 5 days plus before interception may occur. You decided to not disclose your capabilities at the moment, and contacted your military, it took 5 hours, they decided to use nodes. There is at least 110 nodes in sphere 15kk km around the member of group D, which may be chosen for the attack. You choose 10 to approach target closer, to have a better picture, and choose 10 another from far distances to launch an actual attack, which will be ended in less than 40000 seconds. So you have at least 10 times to try to destroy D-ship, and at least 100 missiles like nodes.

Nice thing about such situation is – if member of group D retreats, stuff you have launched isn’t wasted. Nodes will go for higher ISP, slow down in 10-20 a.e. somewhere else, year or two later, and will do same thing they did earlier. Maintenance will send them fuel in eco mode with higher ISP – and after few years nodes will be capable of any future strikes and can be used as usual in before of that time. On new location they also may be even more valuable, because of scientific data. So this launch themselves may cost you nothing actually, and if you smart enough you may even make profit on that, even sell that attack for someone else – which will continue it. (sell/buy make fun)

base ISP 230km/s, energy 5 GW per engine, 5 engines base ISP 230km/s, energy 5 GW per engine, 5 engines

If launch profile was good, we may have more mass with higher velocity, but at least we will have 25 ton. If it was launched from 5kk km with ISP 139km/s (1/1.65 of base) it will have speed 190 km/s and acceleration 90 m/s2(or more, overloaded, for a short time).
So it above zero possibility that some of 10 nodes will intercept the target.

  • close combat situation, ship vs node/drone/share/missile
    Actually, with that 25-ton node mass, there isn’t much left from that node after the acceleration and initial 100-t mass, what is left – 5 engines, some fuel, some reactive mass, some targeting equipment, communications.
    First of all, it can divide at least into 5 pieces – engines.
    Engines may be overloaded – so it may make even more acceleration if needed, for a short period of time. The overload may be used to explode those engines in a controllable manner – from evaporating engine to just crash it in few smaller chunks. This also means control over dispersion cone, we may choose in a wide range, from meters to kilometers per second, how fast will grow that debris bubble. And everything can be done very very fast, milliseconds or less (fully depends on engine injector capability).

Probably we will divide node before it reaches a destructive range of energy weapon. And guide them from each other. Our goal is to make some attack angle before we reach the target, also it may help in case if target begins to maneuver, will make probability for an interception a bit better.
And there almost everything depends on defense against high-velocity targets, energy weapon reach, tracking speed, etc. If slugs with delta max 4km/s, speed 20 km, mass at impact 10kg, from distance 100 km have a chance, then good.
Overload engine, let plasma leak from all places, from both trust ports and from sides. It will form some plasma bubble, some plasma cone towards the enemy ship and his sensors. This plasma bubble may be big. For enemy sensors(IR, radars) it will be a hard time to tell exact position of the engine. Energy weapon is useless above sensors range, it also useless if no lock on target is acquired.
As we defined radars range as 1000 km, so dangerous zone will begin at that distance. So enemy ship has 5.26 seconds, to eliminate targets, 5 ton each, from one direction but different angles.

ship-D may launch slugs, even more then 3 per second, just drop them all with 0 speed, if it hits the engine, he will loose its ability to maneuver and will break into tiny pieces. But in that case, it enough to detect 200-400 meters before impact and blow the engine with proper parameters which maximize the ability to hit the ship.
But the problem is – engine on low ISP mode trows ca 20 kg mass with velocity 23 km/s (and ca 210 km/s relative to enemy) and because of that it is a good close combat weapon. Overload engine in 5 times, trow 100kg reactive mass per second with relative velocity 210 km/s (slowing down with 450m/c2) towards enemy ship and slug problems. It will wipe all small kinetic countermeasures, slugs included. And you may vary ISP to make half tonne wall upfront, it will evaporate anything without strong magnetic fields, making plasma from it, which moves to enemy ship faster then engine. It will hit ship, make it more contrast target, overload engine again, last spurt last tiny correction, evaporate engine just 10-30ms before touchdown it will smash all over the ship surface, or do not evaporate, it will make 3m input hole and 50m output hole. But better evaporate, it will smash ship more evenly, so it may stay one piece, which means more reactive mass to sell to scavengers.

I bet, in such circumstances, all 25 tons may be smashed into that ship, or maybe just only one engine, and another 4 may be sold for future use.

There are much more of those scenarios, outside smashing each other in close combat

They depend on how well you predicted reactions of people. Which capabilities they have. This is tech vs tech and people vs people.


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