All costs are situational, so this isn't a particularly impactful critique. I'm sorry, but I'm not sure the number of situations where killing a 100,000 civilians, potentially your own civilians, to kill a 1,000 enemy forces is the right move is a particularly large category. Accounting for other costs is optional. Not accounting for relevant costs, or accounting for them badly, is also stupid and self destructive.
Say Poland got occupied by the space Nazis, and the free polish space force had to come in an liberate Poland. Option 1 is general nuking to clear out the space Nazis, killing 30% of the polish civilian population, about 12 million civilians, in the preparatory bombardment, then only lose 30k troops. Or, you don't use more limited, less indiscriminate means, lose 10x as many soldiers of 300k or so, but civilian casualties are closer to France in WWII, around 1%, or about 400k casualties. Is each polish soldier worth 42 polish civilians?
Is the above consideration something the Polish high command can simply "decide" to take into account or not?
Say it was space America liberating you from the space Nazis: are you going to feel indifferent between a space America willing to sacrifice 40 poles per American life, vs a space America willing to sacrifice 1 American life to save 40 Poles? Would you suggest that choice would have no impact on your opinion of the new masters/liberators?
In that scenario you have already went with the assumption that the enemy opposition is not fighting very hard for whatever reason, because "France in WW2" represents a tired, distracted army that's undersupplied and isn't into making fortified urban stronghold in the way of the enemy. Combined with the implied assumption that the attacking side can, politically and militarily, afford to lose 300k soldiers
and still win, seems like this scenario is yet again a case of simply overwhelming force that can afford a considerable malus due to the sheer advantage it already carries.
OTOH, if the invasion force has barely 300k soldiers in total, obviously if they would lose that much, they haven't won, they got bled out fighting on the ground with lacking FIRES, and the place is not liberated anyway.
On the third mutant hand, this being a liberation, possibility opens up to functional enough local recruitment and support, so a meaningful part of that number can be local conscripts\guerillas.
From my quote: "I'm not sure of very many situations where that occurs." That is the important part, my critique of your point, not my restatement of your point.
The math is fairly simple: in a random distribution, the position of any one shell is independent of the prior one: this is a measure of the spread within the limit of the ships accuracy, not some purposeful grid pattern. Any one shot covers roughly 1/250th of the area. Lets assume it down to a 1/250th chance to hit on any one shot, in case with my complexity I made a mistake, just to illustrate the math.
So, the first shot had a 1/250th chance of scoring a kill. Or, another way, everyone has a 99.6% chance of surviving.
What's the chance of killing someone on the second shot? Well, they're independent, so its still 1/250. People thus had a 99.6% chance of surviving the first shot, and a 99.6% chance of surviving the second. Or, we could write that as 0.996^(2), or 99.2%. Statistically this suggest, out of 500, 498 survive the first shot, 496 survive the second, etcetera. 100 shots, .996^100=66.97% survive, or 334.
Its possible though I made an error there though, redoing my math gives a different order of magnitude.
Law of large numbers, which this is, of course still applies - if you do it in practice, chances are you will get a pretty nice spread pattern. Sure, with bad luck 20% or 40% or so may even survive, but we didn't calculate for larger wounded\neutralized effect radius, so even if some were not dead, the survivors would be a mess of confused, wounded and shellshocked survivors, instead of a remotely effective fighting force, so the friendly ground forces who called orbital support could mop them up easily anyway.
Huh, its almost as if extra range might, cost more? Perhaps? But no, you've already proven this is an absurd general assumption! Surely your not reversing yourself here!
Again, depending on the fight profile, it may bring little to no extra cost.
Eh, Sats might be cheaper. Satellites are likely to be expensive for many of the same reasons ground based precision weapons are: they're highly complex machines that need to work in tough situations under exacting standards: a kinetic round has to be guided to be worthwhile, as I think we've established: the ranges are too great for plausible ballistic accuracy under most reasonable assumptions.
Are they really? Doing a basic calc, if you achieve 0.5 MOA accuracy from 300km height, not that crazy for even modern ballistics, you get a 43 meter deviation. Considering the delays and reentry effects probably degrading that further, kinetic kill rounds and hitting moving targets is out. However, cluster munitions, HE against large area targets and nukes are still in.
Though due to cost of a nuke giving it a more capable delivery vehicle may be worthwhile at little relative cost. Leaving HE and cluster munitions. Of course we won't be talking of sniping tanks and bunkers with few shots like modern artillery can do with good fire correction, it would be more along the lines of abovementioned WW2 cruiser, if not worse - "i want those 10 kilometers of frontline hit from the orbit". Reminds me of Rogue Trader, which does have rule for this, and the scatter for orbital macrobattery bombardment even on a perfectly aimed hit covers an area of 10 square kilometers, and on bad one scatter can go up to low double digit kilometers. Precision weapon this isn't, but no one can deny the military utility of such fire support.
As for sat costs, there is nothing magical that means unmanned space hardware has to be super complex and expensive. Once weight and dimension limits become lax, they will have the solution of "when in doubt, slap on more steel and lead protection". And in a scenario where you are casually transporting whole armies across planets, obviously lift costs have gotten quite reasonable.
A 50 kg planetary Excalibur round cost roughly $50,000 dollars, an equivalent to $1 million dollars per ton. Falcon Heavy based on the
first sketchy source I could find suggests Falcon Heavy is already under $1,000 per kg to LEO, so delivery cost would thus be roughly $1 million per ton. So, cheaper transport costs to "free", assuming space Excalibur would be the same per unit cost as planetary Excalibur is a 50% cost saving. Which is nice, but 1) not plausible, and 2) not as much as one would hope for.
In actuality, space Excalibur is likely to actually be more expensive per kg and heavier than planetary Excalibur: with longer ranges at higher speeds, finer maneuverability is needed to preserve accuracy. It needs some ability to course correct in space, thin atmosphere, and thick atmosphere. It needs to not burn up in the atmosphere. Conventional heat shields seem to be in the 5-20% of rentry mass range, so that alone might grow the weapon weight by 10 or so kg. Getting through atmosphere fast you want something like 10 tons/meter. A current Excalibur only has roughly 2.7 tons/meter. So you would also likely want some mixture of more weight and narrow round to get through the atmosphere with good speed, which is going to increase cost.
Sticking a ceramic shield in front of the shell is always an option, and not a very expensive one.
It doesn't need to maneuver in space unless it's a round meant against space stations or for use on atmosphereless planets. Fired against a habitable planet, it can do the course correcting after it is in atmosphere already and it also happens to get slowed down closer to terminal velocity (which in Earth conditions is considerably lower than the muzzle velocity). It would be
expected for a military to know whether the planet they are invading has an atmosphere and what is it made out of, and load their transports with equipment and ordnance appropriate to that specific atmosphere...
There is no need for very expensive universal rounds.
I would go with assuming the lift costs to be negligible, because we are discussing it in the context of a bloody planetary invasion. If you are bringing along not just a few mechanized divisions, but whole armies measured in millions, few hundred thousands at very minimum, we are talking of megatons of transport capacity. If you can provide that in the first place, imagine the "weight premium" that would have to be applied to tanks, and even things as simple as supplies. One "weight saving", paratrooper style light armored vehicle will already weight about 20 tons. You would need at very minimum bring low tens of thousands of those for even an easy planetary invasion. Each of them weights as much as several hundred of those shells, and probably needs again as much at least in fuel, ammo, parts.
A single MBT goes into the territory of tens of thousands of artillery shells sized munitions logistics wise.
And unlike with orbital bombardment munitions, you will also need some kind of landers or dropships to actually bring them down, which will also have their own weight, and their fuel would also have weight and so on.
This is the logic indicating that invading forces would generally be encouraged to do a lot of their work with orbital fire support as possible. Losing one platoon of 4 tanks is logistically worse than spending a thousands or two of light precision munitions delivered from orbit to prevent that loss in terms of the invading force's mass budget.
So, a tactical orbiting weapons platform might have a 100 rounds for roughly 10 tons of weight at $250,000 per round, in line with a Javelin, for a total ammo cost of $25 million dollars, and when a Gripen costs $30 million flyaway, $4 million per ton, if the vehicle had overall dry weight of 10 tons, that would be roughly $40 million for the vehicle, total cost roughly $65 million. Current, still quite high, transport costs boosts this overall cost to $85 million, a roughly 30% increase.
The thing is that Gripen doesn't run on air and shoot bad words.
Let's even say our SpaceGripen is an aerospace fighter and doesn't need a massive specialized dropship to safely bring it down to the ground.
Or its not, but then it has to piggyback on the dropships you use to land tanks or even more oversize cargo, and it will take a whole lot of space in one of those.
Still, it will need fuel for the whole campaign (few tons for every single flight if its jet or rocket based, if its some fancy nuclear powered aerospace fighter, it may run on whatever locally sourced reaction mass but probably will weight far more than 10 tons), parts for the whole campaign, and to actually fight, you will need to bring munitions for it... As this is a serious war, probably not 500$ dumb bombs, but at least 100,000$ a piece guided missiles, and all of these things will also have their own weight.
Its my impression we are already approaching, if not already, at a point where for many of the tasks we've discussed in this thread, space launch cost would already not be the driving cost concern.
This is especially true when nukes are involved: direct cost estimates are extremely hard to find, but the US current costs seems to be in the $20 million per warhead range for a roughly 200 kg weapon, a per ton cost of $100 million dollars per ton. At such a price point, nuclear weapons transport cost would be just 1% construction costs even at current high costs.
The tech involved has such high innate costs that I'm not sure relatively cheap transport costs will actually make "cheap" orbital platforms. As you mention earlier, ground SAM systems can cost $50 million each, and a space system is likely to be more demanding than current SAMs, not less, and have a higher cost point. Your OSM (Orbit to Surface missile) platform could quite likely cost $100 million, with transport costs being relatively minor proportion, outside of cheap lift being necessary for the logistical operation of such a craft, such as the ability to refuel and re-arm at relatively non-crippling costs. It might not super matter if your $5 million dollar a ton SAM costs $100,000 a ton to deliver. It does matter if the 10 tons of $1,000 a ton rocket fuel you need to deliver every week to maintain maneuverability cost $100,000 per ton.
Again, you are running with the assumption that despite space lift costs being cheap, even cheap sats have to still be loaded with insane electronics because space, which isn't even true for modern "economy sats"
with prices well below a million USD. SAMs are expensive due to the sensors they need to detect aircraft who don't want to be detected. A platform meant to whack a certain specific spot on a planet with a JDAM like missile does not need those.
If you want orbital air superiority platform, sure, it may cost that much, even more, but that's a different kind of a weapon.
Also, you are bringing up a... small scale warfare problem with the support platforms needing to spend a lot of time and fuel maneuvering to change orbits and provide support in various places.
Sure, if you had only one or two, that would be a huge pain.
However, that's less of a problem the larger the invasion gets. Once you have hundreds of those spread over lots of different orbits, there is little need to move them at all, because each time the ground forces call for support, statistically at least one of them will be in the right spot in no more than a few minutes.