Invading the Solar System

[Caiaphas]

Simply put, if you were going to invade the solar system specifically for the purposes of colonization, how would you go about it?

Force counts - Invaders:

150 independent battle groups consisting of 2 manned commander craft and 198 unmanned attack craft each
100000 light transports each carrying 5000 soldiers and all required equipment/weapons/rations/et cetera
50000 heavy transports each carrying a company of artillery, a company of heavy armored vehicles, and a battalion of light recon vehicles

[Steel]

This is a pretty ridiculous scenario.

You have given the invading force 500 million troops there.

My strategy will be to land in a dispersed pattern over the entire globe, each soldier with 14 bullets and orders to shoot civilians on sight. This will be sufficient to totally depopulate the earth.

If that sounds a bit silly, then I'll sit in orbit and throw tanks out the window until the earth is depopulated that way.

There is literally nothing that a civilization capable of bringing these forces could want with the planet, or be unable to clean up in weeks no matter how fucked it was.

[GrandMasterTerwynn]

Simply put, if you were going to invade the solar system specifically for the purposes of colonization, how would you go about it?

Force counts - Invaders:

150 independent battle groups consisting of 2 manned commander craft and 198 unmanned attack craft each
100000 light transports each carrying 5000 soldiers and all required equipment/weapons/rations/et cetera
50000 heavy transports each carrying a company of artillery, a company of heavy armored vehicles, and a battalion of light recon vehicles

Ugh, why bother landing troops on the planet when you can do this:

Take a big Near-Earth asteroid like 1866 Sisyphus. Drop it on Earth. Wait for dust to settle. Win.

This is the outcome of approximately 95% of the "aliens invade the present Solar System for whatever reason" scenarios, save for those where the invaders have either taken stupid pills, had their ships destroyed by Act of Plot, or are complete pacifists.

[Batman]

'Invade', not 'destroy'. The ground troops tell me that they're here to TAKE the planet in which case it's preferable to not damage the real estate too much.

[GrandMasterTerwynn]

'Invade', not 'destroy'. The ground troops tell me that they're here to TAKE the planet in which case it's preferable to not damage the real estate too much.:)

They're alien invaders. Their biochemistry is likely to be incompatible with ours. They'd might as well cause an mass-extinction and give their own ecology a leg-up. They can then mine our ruins for concrete and pre-processed metals without having to waste time shooting (and getting shot at by) the previous occupants.

[NettiWelho]

Start by landing a single vessel in capital of every country with nuclear capability, make it clear that absolute co-operation will ensure the survival of the inhabitants of the said country

begin a nuclear disarmament of the said country

if a government doesnt fall in line volunteraly, land a few million troops around the capital to emphasize the point, still no progress? kill the disagreeing leadership down the ladder till you get someone who realizes whats best for them

if a nuclear launch is attempted against anyone, intecept the nuke and track down those personally responsible

proceed to ensuring co-operation of non-nuclear countries with somewhat similiar procedures

if any really annoying/hard-to-work-with groups or regions are identified they are to be pacified according to the severity of the problem(this includes clearing a region of humans completely by genocide if more peaceful approaches are considered futile efforts)

hijack most of industrial capacity temporarily to build a tech-base to produce mass-fabricators/advanced factories -> autonomous mining/extraction vessels for the asteroid belt and gas giants, launch terraforming operation on mars and begin constructions of several quite large space installations

stay in control of humanity with benelovent-dictator approach for few generations, coaching unwanted things out of current society and generally prepare them for integration into the empire eventually to be released under semi-autonomous local(human) governance

[Caiaphas]

I should have mentioned this before--humanity is violently opposed to any negotiation whatsoever with these invaders, and has almost 1 billion soldiers available to them and the same numbers of attack craft, artillery, et cetera over, combining all of the resources of all of the various factions. If you think that's unrealistic, see the note at the bottom about the date.

Humans are much more well-armed--forgot to mention that.

Another thing I didn't add in--20 enormous colony ships sitting out in the Oort Cloud, 25 million colonists each.

There is literally nothing that a civilization capable of bringing these forces could want with the planet, or be unable to clean up in weeks no matter how fucked it was.

Eh, I'm imagining this scenario as more a "our homeworld's screwed over, let's pack up everyone we can and bring them over here." Sort of a last-ditch effort, bringing every last resource they have. I'm trying to play down that imperialist conquerors idea for precisely that reason, though.

Take a big Near-Earth asteroid like 1866 Sisyphus. Drop it on Earth. Wait for dust to settle. Win.

Hadn't thought of that. I was just assuming that humanity had the ability to divert any asteroids like that or had already mined them out. I am setting this scenario in 2500, after all.

[RedImperator]

1. Destroy Earth's space assets.
2. Destroy Earth's ground-based anti-space weapons.
3. Destroy any concentrations of military assets before they can disperse, especially C3 assets.
4. Destroy the planet's industrial infrastructure, especially power generation and transportation.
5. Wait for planetary civilization to collapse. Land. Destroy pockets of organized resistance from orbit. Round up survivors into camps. Fleet remains in orbit to destroy targets of opportunity, local rebellions, possibly the camps.

Wait, let me guess--for your next contrivance, the invading fleet is incapable of effective orbital bombardment, forcing a contested landing.

[Steel]

Another thing I didn't add in--20 enormous colony ships sitting out in the Oort Cloud, 25 million colonists each.

Your 'enormous colony ships' only contain as many people as you have infantry in the invasion force.

I am setting this scenario in 2500, after all.

Why wouldn't you mention that to begin with. Normally that makes an enormous difference, although in this scenario it is still pretty irrelevant.

How the hell and why the hell is earth supposed to support a billion soldiers? Even 10% of the world in the armed forces is stretching belief.

Your invasion force is absurdly vast.

Even assuming a 'company' of tanks only has 10 tanks, that means you have 500,000 tanks. You can literally just sit in orbit and push the tanks out the door and destroy all the cities with trivial ease and practically no lasting damage to the environment.

[Caiaphas]

Damn. Hadn't thought of that.

[Junghalli]

Ugh, why bother landing troops on the planet when you can do this:

Take a big Near-Earth asteroid like 1866 Sisyphus. Drop it on Earth. Wait for dust to settle. Win.

This is the outcome of approximately 95% of the "aliens invade the present Solar System for whatever reason" scenarios, save for those where the invaders have either taken stupid pills, had their ships destroyed by Act of Plot, or are complete pacifists.

Well, you could suggest that they aren't dickish enough to immediately resort to effectively genocide (or at least a strategy that's going to cause way more human deaths than a conventional military take-over probably would).

Why bother with Earth at all? It is completely irrelevant.

Yeah, this. The OP already has them crossing over from another solar system and bringing hundreds of millions of people with them. If they can do that they should be able to just build giant space habitats and live in space, where there's nobody shooting at them. Given the time frame of the scenario you could have a war over the asteroid belt ... but unless humanity is doing crazy levels of resource consumption it should be rich enough they can spare some for 1/60th the world's present population of aliens. Unless one side in this scenario are total dickbags who are unwilling to live in peace with an alien race just as a matter of principle.

Eh, I'm imagining this scenario as more a "our homeworld's screwed over, let's pack up everyone we can and bring them over here."

That makes no sense in any realistic scenario. It would be much easier to build space habitats in their own solar system than to send huge numbers of colonists to a different one over a journey lasting years if not centuries to the tune of terajoules per kilogram.

I am setting this scenario in 2500, after all.

2500? By that time we might well have a partial Dyson Sphere around Sol and could just fry the aliens with our giant lasers. We have a star for a power plant and the entire solar system's resources while they're limited to whatever they brought with them on their few hundred thousand ships.

[Batman]

The aliens are obviously invading because Earth is the only planet with chocolate

[Swindle1984]

Simply put, if you were going to invade the solar system specifically for the purposes of colonization, how would you go about it?

Force counts - Invaders:

150 independent battle groups consisting of 2 manned commander craft and 198 unmanned attack craft each
100000 light transports each carrying 5000 soldiers and all required equipment/weapons/rations/et cetera
50000 heavy transports each carrying a company of artillery, a company of heavy armored vehicles, and a battalion of light recon vehicles

Ugh, why bother landing troops on the planet when you can do this:

Take a big Near-Earth asteroid like 1866 Sisyphus. Drop it on Earth. Wait for dust to settle. Win.

This is the outcome of approximately 95% of the "aliens invade the present Solar System for whatever reason" scenarios, save for those where the invaders have either taken stupid pills, had their ships destroyed by Act of Plot, or are complete pacifists.

In Footfall, they only resorted to a big rock after nukes, conventional weapons, and small rocks/flying crowbars/Rods From God failed to get us to roll over and surrender (literally).

We beat them on the ground because their military was ineffectual and made entirely of amateurs who hadn't experienced combat before, and we beat them in space because the Soviets blew their wad with a shitload of nukes to chase the aliens out of orbit and then the Americans launched an improvised Project Orion nuclear-propelled battleship. It was so poorly made (rushed from design to construction due to the invasion) and damaged in battle that it actually couldn't return to Earth without the assistance of the aliens once they had surrendered.

Which makes me wonder, if they used nuclear detonations to propel the ship (and set off bomb-pumped x-ray and gamma ray lasers), did they use directed bursts for more efficient propulsion? And if so, why not weaponize them into Casaba-Howitzers? Much simpler directed-energy weapon than an x-ray or gamma ray laser, and no need for two nuclear warheads (one to power the laser, another to set off the pump bomb since conventional explosives would detonate too slowly and allow the laser to vibrate off-target.).

[Peptuck]

Why bother with Earth at all? It is completely irrelevant.

Yeah, this. The OP already has them crossing over from another solar system and bringing hundreds of millions of people with them. If they can do that they should be able to just build giant space habitats and live in space, where there's nobody shooting at them. Given the time frame of the scenario you could have a war over the asteroid belt ... but unless humanity is doing crazy levels of resource consumption it should be rich enough they can spare some for 1/60th the world's present population of aliens. Unless one side in this scenario are total dickbags who are unwilling to live in peace with an alien race just as a matter of principle.

A more interesting scenario might be the aliens arriving in Sol and initially coexisting peacefully alongside humanity in exchange for resources, and then have the conflict erupt some time later between different factions of human/alien blocs.

Because as it stands, this scenario is straightforward if its a military conflict off the bat - its only a question of whether the aliens are genocidal or whether they're compassionate enough to try to mitigate damage.

[Lusankya]

Why bother with Earth at all? It is completely irrelevant.

I don't know. Maybe some crazy Martian religious people flew planes into a couple of their biggest space stations, and now the aliens are pissed and want to invade Vietnam to stop the Alpha Centaurian Communists.

Maybe the aliens just like planets.

Maybe they want to convert everybody into space-Jews.

Maybe they need a supply depot in a non-binary star system in the area, but all these crazy monkeys keep on flouting their carefully-crafted space pollution laws, and they're crazy Singaporean aliens who get cross at you if you litter.

Maybe they were annoyed because people on message boards kept on responding to the question, "How would you perform task X with resources Y, J and C?" with crap like, "Well, I'm too stupid unimaginative to think of a reason why they'd undertake task X in the first place," or, "Maybe instead of task X, they can just commit genocide!" and wanted to shove sense up the arse of some stupid nerds.

[GrandMasterTerwynn]

Ugh, why bother landing troops on the planet when you can do this:

Take a big Near-Earth asteroid like 1866 Sisyphus. Drop it on Earth. Wait for dust to settle. Win.

This is the outcome of approximately 95% of the "aliens invade the present Solar System for whatever reason" scenarios, save for those where the invaders have either taken stupid pills, had their ships destroyed by Act of Plot, or are complete pacifists.

Well, you could suggest that they aren't dickish enough to immediately resort to effectively genocide (or at least a strategy that's going to cause way more human deaths than a conventional military take-over probably would).

Anyone dickish enough to colonize a system that already has a broadcasting civilization inhabiting it is probably going to be dickish enough to want to render the previous occupants incapable of causing trouble for the invaders. And the quickest way to do it is to make the prior occupants dead.

But, if one feels squeamish about killing every human at once, one could simply drop rocks on every power plant and industrial center they could find. That way, apart from the few million people who will perish directly from the assault; one could say that the rest will die from the famines, disease outbreaks, and civil war that'd result from the immediate (forced) collapse of technological civilization. This can go on until there's a remnant population of humans incapable of reaching higher than the Iron Age. And if they try . . . well, there's plenty more rocks to drop on them.

[Simon_Jester]

Which makes me wonder, if they used nuclear detonations to propel the ship (and set off bomb-pumped x-ray and gamma ray lasers), did they use directed bursts for more efficient propulsion? And if so, why not weaponize them into Casaba-Howitzers? Much simpler directed-energy weapon than an x-ray or gamma ray laser, and no need for two nuclear warheads (one to power the laser, another to set off the pump bomb since conventional explosives would detonate too slowly and allow the laser to vibrate off-target.).

Hmm. I don't know. I speculate (am not at all sure) that the authors (Pournelle in particular) couldn't tell all they knew about Casaba Howitzer at the time; it may have been classified.

But that is only speculation.

Anyone dickish enough to colonize a system that already has a broadcasting civilization inhabiting it is probably going to be dickish enough to want to render the previous occupants incapable of causing trouble for the invaders.

It's possible that they didn't discover the existing civilization until it was too late to abort or redirect. Consider if they had a several hundred year trip, so their scouting probe didn't have any radio signals to pick up, and didn't look closely enough at Earth to pick out humanity. It looks good, so they launch the colonists. 3/4 into the trip, they realize people actually live there, but it is too late to change course now.

If they didn't expect to face civilized opposition, why so many weapons?

[Formless]

If they didn't expect to face civilized opposition, why so many weapons?

Maybe they manufactured them along the way? Or shortly after getting here, once they realized they needed them? They are colonists, after all, in order to accomplish their task they need to bring with them the means of production, which could be trivially re-purposed for manufacturing arms (even if those arms are re-fits/modifications of otherwise non-military equipment-- this could even be used as an excuse for a sci-fi author arming them with exotic stuff like mechs!).

Also, certain technologies can already serve double duty as both weapons and non-weapons, particularly:

• Orion drives
• Lasers
• Mass drivers
• Mining equipment
• Terraforming equipment
• Construction equipment
• Demolition equipment
• Other engine technologies of sufficient thrust
• Power beaming stations (presumably, with the right modifications)
• Particle accelerators (if their technology uses exotic fuels like anti-matter, which may also be useful as weapons; again, presumably would require proper modifications)
• Probes
• Nano-tech (though see Mike's objections)
• Bio-tech (though see Mike's objections)
• Chemicals
• The Deflector Dish (yes, you heard me. Star Trek actually got this right: if your ship flies at relativistic speeds it will need something to protect itself from incoming radiation, and one method of doing that is to shoot the radiation with radiation. The rest of pretty self explanatory)
• Other technologies we aren't yet aware of (the "unknown unknowns" that you always have to consider when dealing with alien civilizations, including things even they might be unaware of, like pollution)
• etc.

That's just to name a few. In fact, a sufficiently peaceful (amongst themselves, anyway) civilization may even prefer to wage war with otherwise improvised weapons, rather than dump resources into a specialized military industrial complex.

[Formless]

Ghetto edit: another thought that occurs to me is that maybe this isn't the first time this kind of thing has happened (running into a civilization that started colonizing space while they were en-rout) and they make sure to arm every colonization effort just in case they need to protect their investment. Or maybe the weapons are for dealing with their own internal factions and/or are used by the alien's equivalent of the police.

[Junghalli]

One motivation for an alien invasion I personally find relatively plausible is some sort of "White Man's Burden" type deal. If we assume a borderline effective-postscarcity civilization taking over a place like Earth might cost relatively little in blood and treasure (with sufficiently advanced technology concievably it could be done by a single adventurer), and I could easily see an advanced race coming to think of itself as having a duty to help other less advanced ones, even against their will if they're too stupid to appreciate the benefits of higher civilization (or at least that's the way the aliens would think of it). This does have the advantage of nicely getting around the whole "lol drop rocks until everyone dies" answer, as aliens on such a mission would obviously probably want to avoid mass deaths of the people they're invading to "help" in the first place.

OK, it's a bit of a stretch but honestly it makes a lot more sense than aliens invading Earth for liebensraum.

The OP just says "invade the solar system specifically for the purposes of colonization". It does not say "colonize Earth".

Plus I really get the impression he's using this to get feedback for his fiction in which case IMHO it sounds like it could use some constructive criticism.

[Caiaphas]

Plus I really get the impression he's using this to get feedback for his fiction in which case IMHO it sounds like it could use some constructive criticism.

Damn. I thought I was being sneaky about this.

[Junghalli]

Damn. I thought I was being sneaky about this.

I've done it too, I know the signs.

[Star Wars 888]

Gee, are some of you really like this? Would you really order your men to shoot civilians on sight? Really?

BTW, the OP doesn't specify how powerful and advanced the ships are, how well trained your crew is, etc.

[sirocco]

One motivation for an alien invasion I personally find relatively plausible is some sort of "White Man's Burden" type deal. If we assume a borderline effective-postscarcity civilization taking over a place like Earth might cost relatively little in blood and treasure (with sufficiently advanced technology concievably it could be done by a single adventurer), and I could easily see an advanced race coming to think of itself as having a duty to help other less advanced ones, even against their will if they're too stupid to appreciate the benefits of higher civilization (or at least that's the way the aliens would think of it). This does have the advantage of nicely getting around the whole "lol drop rocks until everyone dies" answer, as aliens on such a mission would obviously probably want to avoid mass deaths of the people they're invading to "help" in the first place.

OK, it's a bit of a stretch but honestly it makes a lot more sense than aliens invading Earth for liebensraum.

And what about a race of explorers that departed their homeworld centuries ago. They weren't that good with birth control and spacecraft maintenance and now their technology is maybe no longer up to the task of sustaining them. They happened to cross our corner of the galaxy and discover that Earth is suitable for them too, well except the fact that there is already a 6-billion-people civilization on it. They think that the planet is not big enough for both of us and since we are pre-deep-space-travel race of monkeys polluting our own habitat, they should be the one to inherit Earth.

As to why they can't just build space habitats or put their population into cryo-sleep, let's say that all the smart guys were shot down by the crazy militaries that want to colonize Earth. So good enough?

[Temujin]

Which makes me wonder, if they used nuclear detonations to propel the ship (and set off bomb-pumped x-ray and gamma ray lasers), did they use directed bursts for more efficient propulsion? And if so, why not weaponize them into Casaba-Howitzers? Much simpler directed-energy weapon than an x-ray or gamma ray laser, and no need for two nuclear warheads (one to power the laser, another to set off the pump bomb since conventional explosives would detonate too slowly and allow the laser to vibrate off-target.).

Hmm. I don't know. I speculate (am not at all sure) that the authors (Pournelle in particular) couldn't tell all they knew about Casaba Howitzer at the time; it may have been classified.

But that is only speculation.

It's been years since I read the novel, but IIRC they didn't have time to weaponize them into Casaba-Howitzers; they just assembled them for use with possible minor modifications. As for the gamma ray lasers, I believe they were said to be mounted near the pusher plate and utilized some of the energy from the propulsion bombs.

That's supposed to be the design, unfortunately I couldn't find a bigger picture. But if you can read it, the gamma ray lasers are mounted in the right location near the base.