How does a spacecraft attempt an intercept course with a hostile one realistically (Part II)?

Question

Well, gentlemen. Here is Part II. We know what to do about the manoeuvre, but we need to know possible tactical options the two Task Groups would use.

Background

Now, as previously specified, we have the following statistics from Part I:

UNAPA (Main) Ships

• Antimatter-catalysed nuclear pulse propulsion (first generation) engines (primary engines); Gas Core nuclear thermal engines (fourth generation; Open Cycle version) (secondary engines)
• 132 km/s exhaust velocity (Primary Engines); 45 km/s (Secondary Engines)
• 180 kN of thrust (primary engines); 4,500 kN (secondary engines) x3
• 70 – 120 km/s of delta v
• 707 - 1200 tonnes of wet mass
• 331 - 706 tonnes of dry mass
• 0.02 Earth gees - 0.03 Earth gees of acceleration (primary engines); 1.2 - 2 Earth gees of acceleration (secondary engines)

Ganymedean (Main) Ships

• Helium 3-Deuterium ICF (second generation) engines (primary engines); Gas Core nuclear thermal engines (fourth generation; Open Cycle version) (secondary engines)
• 110 km/s exhaust velocity; (Primary Engines); 45 km/s (Secondary Engines)
• 195 kN of thrust (primary engines); 4,500 kN (secondary engines) x3
• 50 – 100 km/s of delta v
• 817 - 1400 tonnes of wet mass
• 482 - 740 tonnes of dry mass
• 0.014 - 0.024 Earth gees of acceleration (primary engines); 1 - 1.7 Earth gees of acceleration (secondary engines)

Drones (Both Sides)

• Gas Core Nuclear Thermal (Third Generation; Closed Cycle; Mini-version) engines (Main Stage); UDMH/N204 Chemical engines (Terminal Attack Stages)
• 23 km/s exhaust velocity (Main Stage); 3.3 km/s (Terminal Attack Stages)
• 460 kN of thrust x5 (Main Stage); 1,830 kN of thrust (Terminal Attack Stages; 1 per stage) x8
• 30 - 37 km/s of delta v
• 60 - 80 tonnes of wet mass
• 12 - 22 tonnes of dry mass
• 3 - 4 Earth gees of acceleration (Main Stage); 2.3 - 3.11 Earth Gees of Acceleration (per Terminal Attack Stage); 19 - 25 Earth Gees of Acceleration (combined Terminal Attack Stages)

The spacecraft all have kinetic weaponry to attack each other, with 2 ships in each task force also equipped with drones. The kinetic weapons are all with depleted uranium rounds of ammunition, each slug being 41 kilograms, each coilgun being between 150 to 332 km of maximum range, with an exit velocity of 20 km/s. Effective range for these weapons is 45 to 115 km. And this is just the range that these craft can use to get a targeting solution or lock on hostile craft, since in a general sense, the range is technically infinite.

Each of the coilguns has 41 kilogram slugs fired at a rate of 3 rounds per second, with the burst duration being 5 seconds and an accuracy (on average) between 0.01 metres position error per kilometre of distance to 0.9 metres position error per kilometre of distance for both sides, depending on how advanced their targeting systems are. The slugs are assisted by a 30 kilogram (wet mass) liquid-fueled LH2/LOX guidance stage to assist in staying on the target. ECM effectiveness is basically around a 50% - 72% effectiveness in the sense that they can disrupt communication systems and disrupt the targeting solution of a hostile craft. So, in the former this means that if you want to contact the departure point, or another craft, communications are going to be affected. In the latter, you can miss and in a few millennia, the depleted uranium round will hit the surface of another object in who-knows-how-many years.

A clarification: this does not imply spacecraft in this setting use kinetics entirely. Some law enforcement spacecraft use directed energy weapons (or DEWs for short) spacecraft to target specific parts of a hostile spacecraft, but are impractical for large scale military use in an offensive sense. Military-grade DEWs are basically anti-drone defences, and since the two Task Forces have Drone Carriers in this situation, those are included and there are spacecraft designed specifically for this purpose. Anti-drone DEWs have a wavelength of 3600 nanometres, and require a series of large mirrors, which are vulnerable in combat, thus forcing spacecraft to conceal them away from combat and remove a fraction of the concealment in combat, depending on how much power is needed to dispose of incoming missiles or drone swarms (in this case, the latter is the target). On average, though, the power requirements are too large to be made into practical offensive DEWs in this setting (for now, that is).

In addition, the sensors of the spacecraft used in the manoeuvre (and throughout both wars in general) will be addressed in Part III. :/

UNAPA Task Force Composition

• 12 Space Dominance Vehicles (SDVs); 2 being Drone Carriers (100 - 120 drones each) and 8 Space Offence Vehicles (SOVs), 4 Space Defence Vehicles (SDeVs)
• 3 Space Control Vehicles (SCVs) with 3 battalions each SDV with a complement of Transatmospheric Vehicles (TAVs) and/or Transatmospheric Pods (TAPs), the former for regular armed forces and latter for rapid deployment Espatiers and SpecOps units.

Ganymedean Attacking Task Force Composition

• 6 Space Dominance Vehicles (SDVs); 2 being Drone Carriers (100 - 120 drones each) and 2 Space Offence Vehicles (SOVs), 2 Space Defence Vehicles (SDeVs)

Defences on UNAPA Task Force Target

• 1 Orbital Defence Platform (ODPs; anti-spacecraft/missile satellite network server(s))
• 8 - 12 SDVs ( 4 - 6 SOVs, 2 - 4 SDeVs, 2 Drone Carriers)
• 32 - 45 Orbital Guard Vehicles (OGVs)*

UNAPA Objective: Launch a ground assault on the moons of Europa, Ganymede, Callisto and Io.

Ganymedite Objective: Prevent the UNAPA ground assault by either destroying them or forcing them to turn back (by this, I refer to return to the point of origin via gravitational slingshot).

Soft Detection Time: 1.2 Days Post-Departure

Hard Detection Time: 4.4 (Brachistochone Transfer)- 87 Days (Hohmann Transfer) Post-Departure

Identification Time: 6.8 (Brachistochone Transfer) 97 Days (Hohmann Transfer) Post-Departure

Target Lock Time: 8.4 - 10.4 (Brachistochone Transfer) ~100 Days(Hohmann Transfer; Depends on positions of both objects at the time of departure) Post-Departure (Arrival)

Oh and for those of you unaware of the characteristics of Ganymede or Carpo, 2 links, coming up! Ganymede link there and Carpo link there.

In addition: the x[insert number of engines here] is an engine cluster, and only applies to secondary engines of main craft and drone engines.

Asterisk #1 = Law Enforcement Only; To be used to minimise civilian casualties, if any.

Question

Now, for a quote/sneak peek from the story:

“Option #1 would be to launch the drones at a precise point along our approach before the battle, and when we engage, strike the UNAPA Task Force from behind as we conduct a return trajectory to Ganymede, use the drones to inflict heavy casualties and then finish them off [by attacking from behind]. Option #2 would be to fire our coilguns at a precise point similar to option #1 and use the slugs as “mines” and then launch the drones around a similar precise point, and use them as an advance. This will limit their capability to manoeuvre and (if the drones are lucky) will leave the Task Force in tatters [Assuming a 95% chance of success]. Option #3 will involve approaching from behind Carpo, as depicted in Option #1, but the option is also a risky one. In the second option, depending on our distance, our computer systems may not give a firing solution in an efficient manner, and the drones may be stopped in their tracks by enemy SDeVs in most options [referring to Options 1 and 2].”

— Commander Dmitri Vladimirnovich Kalinin, Explaining the Available Options for attack prior to the Battle of Carpo

With this in mind and the background information, which of the tactical options available to the Ganymedean Task Force shown in the quote/sneak peek could they use when the initial setup and actual battle occur?

NOTE: The following provides a Reddit link to the scenario itself: UNAPA vs Outer Solar System Perspectives Part I. The answers to the travel time and Delta V needed for the manoeuvre are all here in the Reddit version of the previous part: Delta V Requirements and Travel Time to Carpo Using Both Brachistochrone and Hohmann transfers

Answer 1

We need more space thinking.

Good

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.
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.
• Form also important. It affects 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 big topic by itself. I'm not sure which one is yours.
• Effectiveness of laser weapon: power, beam divergence, impulse time.
• Tracking ability for for both types - laser and kinetic.
• Maneuverability of ships. Yes they have slow acceleration, but how fast they can change direction of that acceleration.

To answer your question, someone have to have model, with any details possible. Even in that case it will be very hard question, specially if there is't big gap between tech levels. In real world you can see that on examples: which army is stronger. Most tech is known, but answer is't much clear.

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

Assumptions

• Form - sphere
• Size - from density 5m3 per tonne
• Detection - radar detection, IR, transition methods.
  detection is hard topic, even if I personally do not agree with everything here, specially about estimation of detection range, but definitely good place to checkout, also for another 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 is'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 technical point of view. Even with small crafts distance may be millions of km, with 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 kinetic weapon is effective, both sides are 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 single ship. They are more powerful (6-25 times), and it 4-8 times more by count, more than you may launch by kinetic launcher, in duration of engagement. Engine plumes from group A toward group D detectors, which is high temperature plasma, will make it more 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 slow down. Both detects each other 10000 km away. Both, because group D should intercept, it's their once hope.

Dense group, relative speed 0, distance 10000km.
Drones will be handy in that situation. They consume 100kg reactive mass per second, with 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 lower acceleration then they actually need.(not so simple but, may, and probably will, not work as well).

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 20 tonne in one minute? Not on such small ships. (evaporate with engine plumes may work actually, they trow half tonne per second with velocity 45 km/s high temperature plasma, but tracking will be difficult. But probably will not work, because of magnetic field of drone, which he needs for his own engine)
Even if it will be evaporated - it's still 20 tonne of gas, still flying 30 km/s towards enemy ship. Yes impact will be lower, and distributed on surface of the ship. How much consequences it will have - depends.
Drones maybe launched at once, or in any scheme, so they are more flexible, as a tool of destruction.

Group D have 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, where layers are at some distance from each other. First layer destroys micrometeorite, making dist from it, and divergent beam of that dust, which collides with second layer, but this time on much bigger surface. First layer helps spread projectile, second withstand the impact. This principle will work with any high speed, any mass etc. So defense actually is possible, and not only Bigelow Aerospace style, but it comes with some mass and size. But that mass is't so big, like many think.

Compact, close range combats - with such tech, are total unrealistic.
You may agree or disagree with all(some) above, but definitely, such 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 such.
Stop it, let it be more space like, let think more space style.

How can it be in more realistic way

• First of all prepare for future war, make more flying engines aka drones
  Thermonuclear engines have great potential in solar system travel. Theoretical ISP is somewhere about 0.1c. As engines are useful, anyway you will build them in big quantities for other tasks too, so not much reasons to constrain yourself by not making drones too.
• Build network
  Because distances between nodes may be 5kk kilometers (1/30 a.e.) - so for 1 cubic a.e. needs roughly speaking 27000 units. (we build cars in millions)
  Network will be useful for civilians, for scientists, for military - as navigation, as data transmission, as instruments to observe solar system, as job creation - every one 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 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 some 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 its part of job it do), maybe some capsules for lost cosmonauts, for searching them, for 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 that drones may be used as some sort of weapon. Everything they need for military task, they 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, greater impact it will be. More fragile it is, easier it to disperse before impact, to cover maneuver trajectories of your enemy. Higher costs of equipment, more are compensations, more profits in no war time.
• Share network
  As you can't prevent having some hidden options - so safe to assume who builds have full control on that node. As they are not so much useful in small quantities, no reasons to make separate networks for outer solar system, thereby they are part of global network, and everyone who participates get benefits proportionally 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, did't failed 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 in the network. Also it will be 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 is't law violation.
• if you still think, it is law violation, you may consult or buy services from groups who are better and more efficient in such actions. If they think no 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 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 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 did'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, 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 u 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 someones law violations. You guilty because you didn't spot that earlier, and didn't share that information earlier with network council.

• If you do informed 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 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 better use for more people with better profit. If not, probably it is better use now as it is, so it is legit already at that moment. It may be changed in future, if new usage will be found, which is better. So if you claims something about moons, be prepared to accommodate changes, when times come. So better do not consider it as your only possession, at any given time.

So if you launch attack to moon, as only asset of that group, you will be compensated only from that moon sources, if you use it in non law violating way. You may settle some complexes, which will not violate law, and cover your losses, let say twice, you have spend on eliminating law violation. Actually it's not important how much, until most groups which have 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 first, who was 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 exists, 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 connection with 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 disassemble, without any reasons, just pay it cost. Cheat with production of them, those who is guilty, 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.

Node is multipurpose units, which orbiting around system, without need to bring it back and forth. 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 how much is their mass. They also do not need to be fast in acceleration, until you fast enough to buy you a time, it's ok for you. As result nodes may be more efficient in therms of delta velocity. So you have more wide spectrum of possibilities, where 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 on 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 same energy (which is energy of thermonuclear reaction), and this is done by lowering ISP of engine. Long story shorter, it can be done by injecting way much lower temperature plasma, or gases(which will be converted to plasma after mixing with hot thermonuclear plasma). There is some papers about that in network, not highly scientific, but reasonably enough, based on old thermonuclear lab reactors.
  So ability to have lower ISP, as you have 23km/s, is improvement.

• Second note
  Very cool thing about lowering ISP is this: you may use anything for that. 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 fly, but there is also no problems bigger then reactor itself.

• assume that mass of node is like drone mass 100 tonne, 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, consists 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 lower ISP. (many are familiar with that because of travel to mars discussions)
Also velocity of those node which was farther 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 farther from 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 much as you have money for(buy or rent). So it will be not just dead payload you have in case, 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 He3, you wish extract it by your own equipment. You belongs to group A.
Group D will stop you, some ship spotted you nearby(let say 100kk km), because their group paid for detection around 100kk km for each ship, and he decided to intercept you, and for some reasons he decided not to use shares (low ranking member of group D, or whatever)
As 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 warning after mD entered in 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 opportunity's, which 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 average vessel). You have 5 days plus before interception may occur. You decided to not disclose your capability at the moment, and contacted your military, it took 5 hour, they decided to use nodes. There is at least 110 nodes in sphere 15kk km around member of group D, which may be chosen for attack. You choose 10 to approach target closer, to have better picture, and choose 10 another from far distances to launch actual attack, which will be ended in less then 40000 seconds. So you have at least 10 times to try to destroy D-ship, and at least 100 missile like nodes.

Nice thing about such situation is - if member of group D retreats, stuff you have launched is'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. 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

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/c²(or more, overloaded, for 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 node mass isn't much left from that node - 5 engines, some fuel, some reactive mass, some targeting equipment, communications.
  First of all, it can divide at least in 5 pieces - engines.
  Engines may be overloaded - so it may be even more acceleration if needed, for sort period of time. Also may be user to explode in controllable manner - from evaporating engine to just crash it in few smaller chunks. This also means control over dispersion cone, we may choose in 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 injector capability).

Probably we will divide node before it reaches a destructive range of energy weapon. And guide them from each other, our goal 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 enemy ship and his sensors. This plasma bubble may be big. For enemy sensors(IR, radars) it will be hard time to tell exact position of engine. Energy weapon is useless above sensors range, it also useless if no lock on target.
As we defined radars for 1000 km range, 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 is much more scenarios, outside smashing each other in close combat

They depend on how well you predicted reactions of people, which are their current possibility's. This is tech vs tech and people vs people.

The answer is limited by size, but I hope it will help to improve global view on that subject.

Answer 2

There are a few assumptions you need to keep in mind when thinking about combat in space:

There is no stealth in space; with few exceptions you will be able to see everything the other side does

There is no terrain in space (at least not the way we are used to thinking about it)

Kinetic energy weapons will go until they run into something

With no stealth in space, you will be able to see the enemy ships boosting literally months in advance of your encounter (given the transit times between Earth and the Gas giant planets, you could conceivably see them coming years ahead of time). Even if the enemy force moves into an orbit around Jupiter and passes behind the planet from where you are currently, you know the size, mass and engine power of the ships from observing them, so even if they make a boost behind the planet, you can calculate a "cone" where they will emerge with a reasonable degree of accuracy.

KE weapons do not slow down, or suffer from ballistic trajectories unless you deliberately fire inside the gravity well of a planet, so the idea of a coilgun having a "range" is a non starter. The limitation of drones and missiles is the amount of deltaV they have, which determines how dramatically they can change their trajectories, followed by the amount of fuel or reaction mass they have (since running out of remass means the weapon is now on a ballistic trajectory and will continue on its present orbit until it impacts something.

So tactically, you might consider launching weapons at as long a range as practical. One light second is a good rule of thumb because realistically, most ships will not be able to move very far or make much of a change in deltaV inside of a second (this is the practical limit for laser weapons, especially high powered Ravening Beams of Death [RBoDs]). A very fast rocket or coilgun round could cover the distance in a matter of hours (one light second is just under the distance from the Earth to the Moon, and the "New Horizons" spacecraft covered that distance in @ 9 hours).

A burst of coilgun rounds and incoming missiles sill cause the opposition to make a burn to avoid the incoming rounds, deploy their defensive weaponry or both. This potentially puts them out of their optimum orbits and causes them to start using fuel, reaction mass and weapons before they are ready. For a smaller force, this could be quite critical.

For the incoming Earth fleet, launching their coilgun attack before entering Jovian orbit provides a means of "flanking" the enemy fleet, the coilgun rounds will have to be dealt with and the Earth Fleet could time their orbit to appear from behind Jupiter just as the coilgun rounds are arriving on their trajectories. The Jovian fleet will be sandwiched between incoming rounds from two different directions.

Rick Robinson's Rocketpunk Manifesto site discusses space warfare at length, although the assumptions being used there are generally massive Laserstars capable of mounting RBoDs and firing beams capable of vaporizing targets at a range of one light second, backed by Kinetic Stars mounting batteries of missiles and coil guns to deliver kinetic weapons in vast numbers to counter or disrupt the RBoD. The other assumption is the fleet will deploy in a "constellation" of ships, drones and sensors up to a light second in diameter in order to provide maximum coverage, dispersion of ships and a detailed 3D view of the enemy. See: http://www.rocketpunk-manifesto.com/search?q=space+warfare, as well as Atomic Rockets: http://www.projectrho.com/public_html/rocket/spacewarintro.php

Answer 3

There is already a very detailed answer. I would just like to add that perhaps it helps to zoom out a bit, before we drill into the actual battle with all the numbers and tactics.

All battles in history share some generic categories, and i do not see why a space combat will not:

Guerrilla: Weaker side uses strike and return, pointing at long term wearing down the stronger enemy with lower own losses. Frontal assault is out of choice, at least for some time. The only effective strategy when the defender is stronger. Countermeasures are based on pure strength and deception, like often strong patrols, traps, feint 'weakened'.

Direct frontal attack: Used when attacker is significantly stronger and expected to provide a quick and cheap resolution. If the defender is expected to get reinforced, this tactic usage becomes even more attractive. If the defender is indeed much weaker there are really few countering options. Deception is the only tool of the defender, by misleading, sabotage, make diversions and the such. Try to buy time or somehow inflict some heavy damage, either on critical equipment or even at morale level. The defender also may look that weak, but been actually considerably stronger for the conflict. This is again deception.

Opportunity driven: Both sides do not wish to fully engage. There can be small skirmishes up to the point where no noticeable risk is taken. This is preferable when both sides are close to equal strength, including attacker/defender ratios. Both forces keep maneuvering until one side make a significant mistake; then the other side fully attacks to exploit that mistake. Because otherwise you simply attack without the disadvantage the opposite force raises for itself. It is also possible the mistake to grow gradually. An non significant skirmish results a small mistake, the small mistakes brings forth a large mistake and so on. Still the same. Deception is still in dominance here as mistakes will most likely be reasoned out of false assumptions.

Unique tactic: At some point at some battle, a new tactic was introduced now and then, successfully altering future strategies forever. This new tactic was more or less violating the "standards" up to the time. The Athenians (before Thermopylae) won Persians at Marathon using frontal assault despite been 1 for 10 and without archers or cavalry. Because they encircle them, breaking morale. From then on, most generals in history pay at least basic attention to the sides.