Dynamics of system defense and other thoughts

[Hal]

This is a spinoff from Colonial battle squadrons: dreadnaughts or battle riders?

I thought I'd speparate this thread from the other because I hope it will become an ongoing discussion about specifics rather than about generalities. To that end, let us look at the dynamics of system defense...

What exactly do you think of when you hear the phrase "System defense"? What do you think is involved in defending any given star system as the commander of the fleet charged with defending a star system? Lets say for the sake of this discussion, that the strategic assessment board of your military has in their collective wisdom, determined that the most likely threat the star system will face, is an enemy raider fleet that masses no more than 200,000 dtons. The board has also determined that as the commanding officer of the system defense fleet, your defensive obligations include:

Refueling fleet that brings fuel from the gas giant to the main world

Refueling points - three gas worlds

Home world

an industrial complex in deep space

How would you defend these points of interest? What are the minium fleet dispostions you'd want at your disposal? What are the minimum sensor platforms you'd want in your control? What are the fleet dispositions you're prepared to make? By that, I mean, how many hulls or how many dtons of hull tonnage do you want overall? What strategy will you pursue? Will you split your defense up and back them up with "fortification weapons" or will you spend much of your resources in having 6 main fleets, plus 3 mobile reserves? How would YOU as the man on the spot spread your assets?

Now, you've taken the time to make your fleet material requests, your allocation of fleet assets in defense of your system. What are the weak points of your plan? How would you, if you were the enemy, attack YOUR planned defenses of the system?

Here are some potential tactics your enemy might use on you...

1) send in what appears to be a credible attack against one of your assets. Draw the defense into a directed response against the pending battle that is shaping up. JUMP just before conflict begins, or fight while you have the initial contact advantage, but jump before the enemy can bring overwhelming numbers against you. While the enemy is responding to your seeming main thrust, a secondary and smaller force is actually attacking a weaker point in their defense. Since the main elements are responding to the first feint, the secondary attack has more than likely isolated the force it is attacking for a longer protracted engagement.

2) Retain the entire fleet together just outside of sensor range of the defenders. Slowly maneuver inwards and concentrate on the smallest isolated fleet element - using what is known as an attempt at defeat in detail. If the enemy's forces are too thinly spread, it won't matter how much tonnage he has if you can bring a local numberial superiority to bear on that one point.

One thing that HIGH GUARD presents a problem with when discussing tactics is that it presumes that you will have all of your fleet together when you engage your enemy. Generally speaking, this tends not to be the case. Generally, you will have a forward element that comes in contact with his forward element. If your enemy can't run away (or refuses to), then your numerical superority can be brought to bear against him as your center and rearguard come into combat space. But if your enemy refuses to stick around for that battle - then what? Your forward element fights his forward element, and just when you're about to bring the rest of your advantages into play, he cowardly retreats by jumping away or accelerates with faster hulls (if he has them).

Then we have the other issue. Your fleet is split up, and element A is in battle against the enemy. If your fleet element B rushes to reach the scene of battle, it will have built up a massive velocity vector that will take them out of range of the ongoing battle after at best, two combat rounds before the supporting element B is out of range - must slow down, and return. That fleet element B might just as well not exist as far as fleet element A when fighting against the enemy. IF fleet element B takes time to arrive such that it can remain in the fight upon arrival, it has taken longer to arrive on the scene, and again, being as if it were of no value.

It would appear, that although there are certain advantages a defender might enjoy - there are certain headaches involved that makes defense of any given star system a MAJOR pain in the buttocks.

So, how would you counter these "raid" strategies?

I invite others to postulate a given star system for an ongoing example. In other words, how many planets in the star system, what their composition are (ie rocky, gas, etc), and then suggest a USP for the system so we can try to come up with a decent budget for that world. Then? Lets determine what that system needs to protect overall and how they'd go about it.

 

[robject]

Your suggestions sound to me simply like a number of interlocking engagements. But anyway...

So, strategies for a wargame. Off the top of my head:

(1) Protecting the mainworld against surface assault. (Is planetary assault even feasible?) Probably cheaper and more effective to salt the ground with a large number of very large meson guns, powered by the local grid.

(2) Protecting the mainworld against orbital bombardment. (Is this feasible?) This would require some sort of guerilla-style military presence in any asteroid belts in-system. The trick is to be able to neutralize any attempts to set up orbital bombardment "factories" (probably just special-purpose-built ships).

(3) Hmmm....

 

[far-trader]

What exactly do you think of when you hear the phrase "System defense"?

Hmm, good question. The answer, and the tough thing about replying is it's different for every star system. And different in many of the rules systems too. And even different depending on your interpretation of some of the rules.

Unlike an idea about the makeup of Imperial forces (generally TL14-15 and J4 M6) each star system will have very different parameters to address under System Defense.

What type of invading force (if any) is likely? A system far from any border is unlikely to need a major force. It's concern may be with a hostile neighbour or pesky pirates and a simple patrol squadron will be enough. Another system with no tactical value right on the border may not need much either as they'll be ignored in any war.

What is the system's resource level? TL chiefly will tell. High enough and you'll have Deep Meson Sites where needed as the primary System Defense. Low TL and you'll be lucky to have ships that can run to get help. Presuming of course you even have a shipyard.

Lets say for the sake of this discussion...

We, well I, would need more information

What TL? What's my budget? You mention "fortification weapons" which sounds like ground based defenses coming out of the defense fleet allocation and under it's command. Is there where one would find (if appropriate TL) Deep Meson Sites? How long do I need to hold before IN forces arrive to relieve us? Or is this an IN fleet assigned as the System Defense?

But anyway, with just what you have outlined...

First I'd use my contacts in government to form a second threat assessment committee and make sure they came back with an inflated number so I can have a bigger budget

Something on the order of 300Ktons of enemy raiding fleet. OK, had to try

1 - Refueling fleet that brings fuel from the gas giant to the main world.

So the world has no local fuel source? First order of business is a strategic reserve of fuel on planet to handle loss of the tankers and/or blockading of the world and/or gas giants. The tanker fleet would be simple big slow tankers and an SDB escort. Purification can take place on world. This way any captured tankers would at best provide unrefined fuel. I'd have them rigged to blow if taken too. Tankers would be streamlined so they can make the skimming and landing to offload while the escort maintains a high-guard. There would be a constant tanker train sufficient to replace all used fuel without tapping the reserve. The train would however be somewhat random in which gas-giant was being skimmed, no point in making it easy for the enemy by only using one.

And some of the tankers would be Q-ships, a fact widely know and publicized, just not exactly how many or where in the trains. So any raiding fleet has to contend with the possibility that it's big fat tanker target could in fact be a heavy SDB ready to open a giant can of whoop-ass.

2 - Refueling points - three gas worlds.

In addition to the potential Q-tanker(s) and the tanker train SDBs either on high-guard or enroute I'd ring them with "fortification defenses". These would be as secret as possible. Sleeper bases probably, built deep in local small satellites. Staffed by rotating low-berth crews they'd only go active in the case of clear threats and while passive would have very limited contact. Once active their roles may vary. Some might open fire immediately to help out the tankers and SDBs. Some might lie quiet to harrass enemy tankers later once the main raider fleet has moved on to other areas. You'd probably sign up for a full term of duty and there'd be no visits between reassignment. Reassignment would be by very stealthy craft, probably as a part of the Q-tanker's mission. Low tech these bases would probably have missiles, high tech they'd be meson cannons.

Any other forces would be dependant on the strategic value of the gas giants. Not ours, we've taken care of that with our Homeworld strategic reserves of fuel. I mean the value to the enemy. If they need an insystem refuel point then we may make it harder for them to secure it by having a small fleet at each. I'd also have the gas giants mined so if you don't know the safe and changing skimming profile you might just hit a big boom while deep in the gravity well. This would also discourage pirates from hanging about and allow enforcing a no-free-fuel rule to maintain the starport monopoly on selling fuel. Anyone wanting to skim would have to pay an overwatch fee (Cr100 per ton of fuel) to guide you down the right skimming profile and defray the costs of the "rescue" fleet that's there in case you get into trouble while skimming.

3 - Homeworld.

This is our primary concern. It's where we live and have our starport/shipyard after all. So this is where our main fleet is deployed. As well as a heavy fortification element, both deep site and orbital.

4 - An industrial complex in deep space.

How "deep" is deep? I'd keep it close to the Homeworld for a lot of reasons not defense related. I'm guessing the reason it's (presumably) not close to the Homeworld is resource driven.

OK, this is our seconday concern then. It's probably not that strategic to the enemy raiding fleet, at least not in any short term concern. Still we'll have a good defense fleet here and some fortification. Depending on the nature of the thing the defense fleet may be more of a tactical cover for withdrawl/evacuation of the complex and sensitive material if threatened.

-------

Overall the best way to "play" this may be as you suggest. Stat a star system and rule set, pick requirements vs threat and go from there.

 

[robject]

Dan muses:

So the world has no local fuel source?

Hey, isn't it cheaper to re-route a couple of comets into orbit around the mainworld? Voila, fuel reserves. I suspect any self-respecting mainworld will have done this long ago for industrial purposes anyway... (hey, as long as we're just guessing).

 

[far-trader]

Might make sense. I wonder what the navigation and other hazards might be? And just how hard would it be to actually grab a comet and settle it into a nice handy, safe, stable orbit?

 

[Andrew Boulton]

Originally posted by far-trader:
And just how hard would it be to actually grab a comet and settle it into a nice handy, safe, stable orbit?

With fusion and thruster plates, pretty easy.

 

[mike wightman]

A couple of questions, or five:

what is the TL of the system?

what is the TL of the attacking force?

are the High Guard rules the model for ship combat?

is the attacking fleet allowed to have used drop tanks to jump into the system?

near-c rocks, yes or no?

 

[far-trader]

Originally posted by Andrew Boulton:
</font><blockquote>quote:</font><hr />Originally posted by far-trader:
And just how hard would it be to actually grab a comet and settle it into a nice handy, safe, stable orbit?

With fusion and thruster plates, pretty easy. </font>[/QUOTE]Hmm, I'm not so sure. If the comet is a solid body maybe but if it's a collection of small (relatively) bodies, or a fractured and unstable body it's gonna require more than just landing a fusion reactor and thruster plate on it.

Then once it starts to enter the habitable zone (ya know, where the mainworld orbits) or sooner it'll start to boil off and there goes your anchor for your engines (at least for some vectors) as well as your fuel (eventually).

Even if you do manage to get it into orbit, or more probably at a lagrange point, it'll keep boiling away. So you lose fuel, need to keep constantly adjusting it's position, and the boiling off is probably going to be a hazard for navigation near it. And the body itself will be increasingly unstable as more boils away.

I think cometary refuelling is best done in deep space where it's still frozen solid.

Of course I'm really just looking for a good reason why every homeworld doesn't already have this setup

 

[Border Reiver]

Just a little thought on near c rocks and system defence. I have them made redundant at TL A with the introduction of repulsor technology.

A passive early warning system alerts COACC of approaching near c object and batteries of orbital repulsors fire up excluding all inbound traffic until the all clear.

The firing solution would be simple, trajectory and speed known and rocks don't make evasive manoeuvres. Even if they slow the intruder down for more violent countermeasures it is still a successful defence.

 

[travlar]

If the planet has enough resources, then a cruiser and a handful of supporting ships at each place would probably do a good job. Mines in the GGs would be good, but only if the enemy fleet needs to refuel.

 

[flykiller]

so many assumptions ....

not sure it's possible to "mine" a gas giant effectively. with reasonable sensor and guidance rules the number of mines required would be very large and constitute a prohibitive expense all by themselves. and surely any mine that can see and identify an enemy ship can be seen itself and then must suffer numerous anti-missile defense actions. and if it survives, and if it hits, will a conventional warhead bring down the target? if it's a nuke, does it overcome the nuclear damper screen and detonate?

mining a gas giant seems ineffective.

 

[Ptah]

First, everything that far trader said in his first post makes sense to me.

Second, I'd also suggest mining the gas giants but have always wondering about effectiveness myself. flykiller brings up some good points:

Originally posted by flykiller:
not sure it's possible to "mine" a gas giant effectively. with reasonable sensor and guidance rules the number of mines required would be very large and constitute a prohibitive expense all by themselves. and surely any mine that can see and identify an enemy ship can be seen itself and then must suffer numerous anti-missile defense actions. and if it survives, and if it hits, will a conventional warhead bring down the target? if it's a nuke, does it overcome the nuclear damper screen and detonate?

I'm not sure where i come out on mines but some "pro-mine" considerations.
A gas gaint is a small area to defend compared to normal ship-to-ship comabt ranges so I think mines (i.e., missiles) could be very effective.

(a) Detection
To make them hard to detect have them operate only by passive sensors. It should be easy for a passive sensor to pick up the wake/atmospheric disturbance created by a skimming fuel ship. Each mine could have it's own sensor and/or sensor platforms could be embedded in the gas giant. In normal operation the mines and/or platform emit no signals. If they detect a skimming operation AND the proper recognition code is not broadcast by the skimming ship, the mines go active/recieve a signal, and hone in on the target.

(b) Hitting
Compared to normal design parameters (deep space encounters), the distance to target is short meaning defensive measures may not have time to operate effectively or at all. In addition, the missile may just put itself in the path of the skimmer-I assume there is no real evasive action possible in a skimming operation. If the missile can damage the fuel scoops mission accomplished.

(c) Placement
Maybe part of the defense is they are also palced at different orbits (within the gas giant clouds of course) whihc may also change. The local forces have a map of the mine field and know what orbital corridors are free of mines and when. Just another added difficulty for defenders.

(d) more on detection
A gas giant mine I would envision as basically a missile with an anti-grav/contra-grav drive for simple station keeping. By that I mean orbital distance not necessary longitude and latitude, I'd imagine they would drift with the wind. The power plant will basically be idle until needed so any energy signature should be lost in the immense background signals coming from the gas giant. This would make mines very hard to detect.

(e)tactics
You will certainly want to mix up when and how your mines attack. If they all go at once the enemy will just send in cheap "drone" ships to draw their fire. There also may be room for a mine sweeper ship design, basically an anti-missile escort for the fuel skimmers.

(f) potential consequences
Mines may require constant replenishment as the gas giant environment is very unforgiving. God forbid a mine malfunction and strike a friendly ship. More durable mines left over from previous conlficts could pose a major hazard to wild system refueling. Of course your mine field is useless if the enemy can get your "map" and/or break or steal your recognition codes.

 

[RandyT0001]

A few thoughts:

Rough Surface Area (at 1 bar pressure)
Jupiter = 64.24 trillion sq km
Saturn = 45.24 trillion sq km
Uranus = 8.17 trillion sq km
Neptune = 7.54 trillion sq km

So one mine per 1000 sq km means
Jupiter needs 64.24 billion mines
Saturn needs 45.24 billion mines
Uranus needs 8.17 billion mines
Neptune needs 7.54 billion mines

Let's say each mine is cheap and has the same cost as a missile (Cr 5,000)
Jupiter costs Cr 321.2 trillion
Saturn costs Cr 226.2 trillion
Uranus costs Cr 40.85 trillion
Neptune costs Cr 37.7 trillion

Lets average the cost of these four to get an estimated cost for mining a 'typical' gas giant.
Cost to 'mine' a 'typical' gas giant probably averages to about Cr 156.5 trillion.

So in order to mine the three (undefined sized) gas giants in the system would cost about Cr 470 trillion. That's about the same cost as ten 75k dton Atlantic class heavy cruisers or 26 (inefficient) 50k dton Empress Troyhune planetoid monitors. I know one can design more efficient defense monitors than the Empress Troyhune with more capable spinal mounts and one might be able to purchase perhaps 50 such monitors for the price of mining the gas giants.

IMO, mining the gas giants is cost inefficient for system defense.

 

[dm_dracos]

Just my two cents on the defense side, for the deep space industrial complex (and maybe im just a blood thirsty pirate wanna be) but what about sprinkling the area with small (under 5dt.) rock/meteorite/ect with a small computer control and a nice big thruster packs, and use them as unmanned attackers, use a tightbeam laser to activate them, and give them main targeting info. and let them go hunting (got the idea from the newer thomahawk cruise missiles that loiter an area looking for targets of oppertunity.
But could also be used for the defense of the gas giants, within reason)
Dracos

 

[Hal]

So that I don't "influence" the discussion with my own biases, I would like for someone to create the following and submit it for discussion:

1 Star System
1 Class G or K main sequence star
3 or 4 gas giants
Variable number of other worlds

Additional needs: Randomly assign current orbital locations for worlds in their orbits. The way this is done is to treat each planet's current location as being X degrees off the Zero directional (Due east on the map). Thus, a planet that is due north would be considered to be 90 degrees. A planet that was at a 45 degree slope towards 7/8 O'clock would be treated as 225 degrees and so on. The idea here is to get an general picture of where the planets are in relation to each other at the time the "snapshot" of the solar system was made.

The deep space installation is kept in a region where the manufacturing processes will not "taint" the world (we postulated that they were ecologically oriented which is why they don't permit onworld refueling - they do however, have such resources available in the event of a seige or what have you. Think of the Alaskan oil reserves that we don't touch in the USA or the Carribean oil reserves we don't use by law). As for the main world itself? Treat as near earth habitable with a "rich" trade classification and has a population rating of say... 9?

That should get things rolling <g>. Interesting analysis of the issues involved in mining. Might I suggest that rather than dismiss the tactics of mining - that you reconsider what advantages mining does give the defender? For example, suppose you as the defender decide that you don't need to mine the ENTIRE world, but just a given section of it - leaving a corridor for skimming purposes. What you've just done there is made it so that certain portions of the world are rendered as "hostile terrain". For those of you who are wargamers - that is like securing a flank of your army with an impassible or nearly impassible swamp. So, limited mining might actually be advantageous. The problem there however, is that even civlian data of ships trying to skim FREE hydrogen, will be useful to invaders in that they can know where your minefield is. And - as is the case with minefields, these "missiles" could be considered an obstacle that can be cleared with specialized mine sweepers. Best part of that strategy? The enemy NOW has to create mine sweepers. Now, in HIGH GUARD terms, what would a minefield attack look like? Would it look like an ordinary missile attack? If so, then minesweepers are hardly neccessary - mines are no different than ordinary missiles and can be countered by the same methods as missiles (ie laser defense and/or sandcasters and/or armor).

As for forming a secondary threat assessment committe - I propose we nominate that man to become a politician, BOY does he think like one

 

[RandyT0001]

Ok, let's say you want to mine only 10% of the three gas giants' surface at a (assumed) cost of about Cr 47 trillion. That much money only buys one Atlantic class heavy cruiser or two Empress Troyhune monitors, not much defense there. How else could you spend that much money and defend the system.

How about deep meson sites? There are no examples of the cost of such a site that I'm aware of in Classic Traveller (which is what I have). Therefore I use Andrew's Highguard Shipyard utility to design a 'ship' to use as a cost basis for such a meson site.

</font><blockquote>code:</font><hr /><pre style="font-size:x-small; font-family: monospace;">Ship: Deep Meson Bubble
Class: Deep Meson Bubble
Type: Deep Meson Bubble
Architect: TylersTools
Tech Level: 15

USP
Mb-K500DJ3-009900-000T0-0 MCr 7,407.850 12 KTons
Bat Bear 1 Crew: 257
Bat 1 TL: 15

Cargo: 135.500 Frozen Watch Fuel: 1,560.000 EP: 1,560.000
Agility: 0 Marines: 127
Backups: 1 x Model/9fib Computer 1 x Bridge 1 x Factor 9
Nuclear Damper 1 x Factor 9 Meson Screen

Architects Fee: MCr 74.079 Cost in Quantity: MCr 5,926.280</pre>[/QUOTE]It is a sphere so the meson gun can fire in any direction. The cost of the hull is retained to simulate for the construction cost in a deep site. There is a company of troopers with enough cargo space for several armored vehicles to protect the surface mounted sensors above and the deep site itself. There are defensive backups. The size of the site does not adjust the to hit DM based on size. On worlds where geothermal taps can provide power it may be somewhat smaller overall and less prone to detection since it would not have a fusion reactor to radiate. The cost is about BCr 6 each. Probably a standard design.

So dividing the Cr 47 trillion by the BCr 6 for each deep meson site means that you can buy about 7800 (plus some change). Let's put one quarter on them on the mainworld and one quarter in the moons around each of the three gas giants. That would be 1950 deep meson sites each. Let's say the mainworld is the largest one normally possible from system generation at 16,000 km in diameter. That world has a surface area of about 407 million square km. That ends up being one deep meson site per (roughly) 209,000 sq km. That's about the size of Belarus (Romania is a little too big and Syria is a little too small) or between Kansas and Nebraska in size. (If you put half of the sites on the same mainworld then each meson site covers an area about the size of Kentucky or Iceland of about 104,000 sq km.)

Having about 1900 meson guns on the mainworld and around each of the major refueling gas giants would probably do quick destruction on the 200,000 dton 'raiding' fleet.

So once again 'mining' the gas giants is cost ineffective IMO.

Hal, you need to specify a Credit amount for building the defenses. If you specify an amount in the tens of trillions of credits (in order to get enough mines around the gas giants to really be effective, IMO) then one could use those same funds to buy a large number (100's to 1000's) of very effective system monitors to defend the system from the 200,000 dton of 'raiders'. If you make the funds small, say about BCr 10, then there is no way (IMO) to buy enough mines to seed around the gas giants to be really effective nor a deterent.

YMMV

 

[flykiller]

thank you mr. tyler for attaching some hard numbers to my vague meanderings.

yes, one could partially mine a gas giant - after all the primary function of mining is to create fear and uncertainty, not absolute denial of use - but even mining 1/3 of one gas giant seems to be an exercise in budget busting.

speaking of finances, let's consider that aspect. expecting 100,000 dtons incoming, we follow fartrader's shrewd suggestion to pad our estimates and manage to get 150,000 dtons for defense - but that 150,000 dtons of defense can't cover all five in-system points of interest without risking being overwhelmed individually in the face of a united attacking force. so here we have the defender spending 150% as much as the attacker, and he still can't cover all his bases. presumably the defender will put 75,000 dtons at the homeworld and 75,000 dtons at the industrial facility, leaving the enemy fleet free to refuel at any gas giant and move on to a better target. multiply this by a half-dozen other systems expecting this same attacking force to pay them a visit, and you have serious defense resources being pinned down by a single 100,000 dton task force.

 

[Hal]

This is why I like posing "classroom" like questions

It gets people thinking, and also poses questions to answers that don't examine everything.

I've noted the propensity for using TL 15 planetary defense schemes, so I'm going to be mean and point out that many of the 3rd Imperium worlds are at a lower tech level. Somewhere along the way, I should sort my excel database on Tech levels and present a general "average" tech and suggest that as a baseline tech for the detailed model of star system defense.

As for a budget? Man or man, if I get started on setting budgets, there are going to be people hurling darts and barbs my way

I did some digging in Pocket Empires and found an interesting detail. There is a game mechanic for determining military budgets that doesn't use the 2 to 3% budget levels that used to be popular at TML. I'll see if I can dig that up and see what that suggests. In the meantime? Here is what I suggest:

Create what you consider to be an "Ideal" budget requirement. Since many of our weapon systems seem to be built by the lowest bidder, perhaps we can find the "Greatest" defense scheme, "comfortable" defense scheme, "No frills" defense scheme, and "what, you want all this for how much?" defense scheme.

The idea here is to look at what goes on with any given planetary defense. Thus far Gentlemen, I'm beginning to wonder if the battle rider concept of using planetary defense replenishments is a viable idea after all. If it is exceedingly difficult to defend a star system, then any reduction in hull numbers would be resisted by the local authorities when some Imperial Admiral says "By authority of the Iridium throne, I hearby request replenishment of 4 battle rider hulls".

The idea of massive meson gun emplacements look good. At Tech level 11, these emplacements (which I alluded to as fortification weapons) would become increasingly more likely. But sadly, their range is limited and unless placed in a hull, are less than mobile. So, lets see what you the "Defenders" want, versus what later inspection of Pocket Empires says you'll get

 

[Hal]

One thing that occurs to me as a result of this discussion is that if spreading one's forces amongst 5 separate defense points is difficult - then perhaps any serious defense of a system has to prioritize their disposition and forego being able to cover them all. Something to ponder...

 

[far-trader]

Whoa whoa whoa there everybody. Who says you need 1 mine per 1000km square? I mean where are you getting that as a reasonable figure Randy? Certainly given your numbers mines are useless. The real world tells us other wise in many applications. And besides the idea just offers too many adventure hooks (see Ptah's great post on the previous page that details much of what I imagined but didn't spell out).

If you're modeling them after missiles (which seems the easiest) then that should probably be the effective range for seeding the field too. Either that or a much cheaper simpler mine that just sits there waiting to go boom in proximity or contact. Both lead to about the same numbers in my opinion. YM does V

It's late so by all means check my math, I very well may have goofed.

Using 6G missiles covering 60,000km radius in a single turn seems plenty. But lets err on the side of saturation and cut that to a 6,000km fast strike range so there's no chance to counter them. In round numbers that's one mine per 10 billion square km with some overlap. So I only need about MCr3.212 to seed Jupiter with 6424 mines for an effective deterrent. Heck I'll go ahead and multiply that by 10 to really make them thick and for less than the cost of a pair of space fighters the gas giant is a very dangerous place to go flying. And it's not going to take over a century for 1000 ships to lay them (your 64.24 billion mines at a rate of 1 mine layed per minute). It can be done in just two weeks with only 3 ships at the same rate of 1 mine per minute. Much more doable.

Yes? No? Maybe?