Credible Earth Invasion Scenario - your take? Get an Oscar!

[Homdax]

So we have seen it many times over. A movie (latest may have been The Avengers) with some kind of Earth invasion plot.

Several Earth invasion plots sucks. If not all.
In most movies I immediately recall, for some reason the aliens think it is a good idea to secure Manhattan. First. Why?

I do remember Independence Day as maybe having a more intelligent approach, but maybe those aliens only had greater numbers and could take Manhattan and downtown Seattle together with Kairo and Moscow and a bunch of other city centers. But still, why the city centers. How come downtown is so attractive to invasion forces?

Maybe I am on the wrong track, maybe making downtown's go splodey has a desired psychological effect from the invaders perspective, and they get to shoot out as many humans as possible in fewer blows?

I hereby name you Strategic Commander of an Earth Invasion force. Type down your strategic plan (or Oscar winning plot).
You "could" use HW related tech as reference. Njummie.

[Norsehound]

Wiping out population centers means less population for the earth to utilize to resist the invasion. Cities represent a center where people can organize and coordinate. Cities also have stockpiles of manpower, supplies, and useable resources. Wiping them out puts humankind on the run without shelter and scavenging for whatever they can find.

On the other hand, allowing a civilization population to exists means exploiting the human weakness of sheltering and caring for civilians. Making them a liability could hamper the effectiveness of a resistance. And leaving them alive and unsuspecting makes it easier to catch a whole population off-guard instead of forcing them to go underground and making it harder for them to root out.

In order to make a full plan on how to take the earth the conditions and objectives need to be clarified. Are we after the population or the planet itself? Do our plans call for the survival of humankind or are they inconsequential to our objectives? Are we there to enslave the people and plant the flag? Take their women back with us to our home planet? Detonate the earth to form a radiation source for our space fleet? Take their water?

I think part of the problem with invasion scenarios is that they are contrived for dramatic effect. The end up being a cliche take over the world or circumstances mean they can't use the most effective approach to an invasion. There are some invasion scenarios that do work, like the Daleks in "Dalek Invasion of Earth", which I recall started with a plague to wipe out most of the population. What was left became slaves or robo-men. The resistance was laughable in effectiveness and it was only the appearance of the Doctor and their companions that turned the tide. The Cybermen in 'Invasion' had the situation pretty well bottled up by infiltrating an earth industry and seeding devices to incapacitate the population while they started the early phase of their operations. Again the Doctor to foil it, largely because he had a heads up on the invasion before it began and knew where to go to kill it.

The Decepticon wold domination plan failed to take into account how organized the humans were and how effective their task-force was, and the presumption that their strongest opposition- the autobots- were already neutralized.

[Guilliman]

Genetically engineered super virus that wipes out humanity, land, extract resources and off to next planet.

[overmind2000]

Makes for a rather low pyrotechnics film though - which as far as I can see is what most alien invasion films are about
A virus based film could easily be very mystery focused - secret agents hunting down the creator of the super virus; scientists trying to develop cures; some hero who makes the cure with a dysfunctional family racing to cross a virus panicked nation as he tries to make it home both in time for his daughters birthday and to save the earth.
It could go easily the cheesy path or the heavy serious one - either way it would be one with very limited alien appearances - end and beginning most likely (beginning if cheesy - end if serious).

A sequel could then be surviving human resistance - either using biosuits and isolation to avoid infection or with natural/developed immunities to the virus. Fighting or at least surviving in an invaded world

That said I could see that being a method avoided by alien invaders - some law/rule that they follow which bans the use of genetic/virus warfare similar to treaties that we use in our own wars. Granted this is one that they follow and not us, but it at least, if presented in the film, gives a credible reason why they haven't simply used that method (since for pure resource extraction its the best approach).

That would bring things back to other options to consider; you've got the traditional might of arms that a warlike invader might use; or political whereby invaders focus upon creating another world war scenario or similar pressures to have humanity weaken/cripple itself. Downside is both are rather wasteful on resources and run the risk of damaging the prize (nothing fights harder than a cornered creature and a cornered faction would easily use high powered weapons if they've nothing to use - nukes or similar high damage weapons).

[Homdax]

Bio warfare banned from this thread. I wanz splodeys.

[Norsehound]

If you put something like an airborne, hyper-infectious virus into the atmosphere to kill off the entire population then you've poisoned the world with a biological agent that can just as likely turn against the invaders. Especially if adaptability was included to make it several steps ahead of the bio-specialists of Earth who are trying to find a cure.

If mineral resource is all you're after why not just blow away the atmosphere? Gets rid of the corrosive agents and eliminates weather. Just scrape off the surface and get at the stuff you need.

If the population is what you're after I would strategize some way to take advantage of the human psyche. Perhaps capture a few samples from across the globe, create a psychological profile. Plant agents in media outlets to slowly indoctrinate the people, then hit them with the appropriate triggers. Many will willingly enter your invasion transports, perhaps even dragging the few stone-age people who don't watch television or have no internet access. The uncultured barbarians who havent' been exposed could be wiped out, captured by those you've programmed, or both.

[overmind2000]

Bio warfare banned from this thread. I wanz splodeys.

Does this mean we can't use a biologically engineered army of cloned warriors to invade with? Even if we make them all very splodey upon death?

[Coey]

Turn off the Internet, watch humanity tear itself apart, job done.

[Homdax]

Hmmm, fair point. Cloned warriors allowed.

I just hate the push-button scenarios. Its no phun. Even if the Space Marines eventually had to come up with a virus thingie against the Tyranids.

Coey, I had a life pre-Internet. Hard to fathom, but, indeed it was there. It involved carpenting, stoneworks, dating and having sex.

[Misiok]

1 Learn the human language. Spy on the human network. Get a brief history lesson on humanity to know their capabilities and strategies.

1.5 Drop a ton of EMP's on planet to kill electronics.

2 Bombard/glass/nuke strategic centers that will

a - invoke terror in humanity (showcase of power)
b - destroy all resolve in humanity (show what the invaders are capable of)
c - blow up the biggest population centres
d - from spy network know where silos are and blow them up too

2.3 - Keep jamming all known human forms of communication. Even if they are impossible to use anymore (cause' of explodeys and emp's) or too old, because just in case.

2.5 (if allowed, in late stages of its evolution it is very explodey, and when done with its mission it sends an explodey signal. Then again, if allowed it doesn't require any more from the invaders as it'll do its job of killing native life and mining resources for us without interference like in C&C games because we should by now break all humanity's electroncis and spirits) Seed tiberium-like substance to take all the sexy minerals from earth into easily harvestable form.

2.5.5 Get immunity shots against all human diseases, teach troops/program robots about Earth's native life, planet's cycles and so on. Program technology to self destroy by either explosions or other means making it unsalvagable and usable by natives (learned from spy network)

3 (if 2.5 not allowed) Make landfall into an either secluded continent that's not technologically advanced or is warring with itself. (like Australia or Africa)

4a Start localized invasion warfare, blitzkrieg style. Get a proper hold on conquered terrains, make false peace treaties with desperate and terrified nations (that are still powerful, if they are at all). When we subdue our first continent and is in 100% ours, start bigger scale invasion warfare, with methodical sweeping advances. Take few humans for experiments, try to find use for them in our empire. Turn them into Stroggs maybe if they're not good for anything (and if they are, turn them into Strogg anyway if we're using living armies).

Alternatively or not, do both actually, hiding the first from worlds view.

4b Promise humanity a future, tell them a fake story about how desperate we were and how we had no other choice to land. Promise to share technology, share useless technology. Make more face alliances/treaties, promise space colonization with human centric colonists.

4b.1 Abduct said colonists for usage in empire/modification/whatever.

5 If 'negotiations' fail, continue with sweepin advances until planet is ours.

6 Profit. Mine the planet until it's barren rock, or liking how it can sustain life, turn it into a garden world (with dead bodies as fertilizer) and assimilate into empire, without humans on it.

[Fixer]

Throw adequate number of rocks at Earth to reduce human population causing only comparatively short term ecological damage. Since you can move interstellar distances this should not be too hard.

Watch devastation.

Come in offering 'humanitarian aid' years later while surviving remnants of mankind are at the end of the nuclear winter and are starting to recover.
Maintain control of technology, organise survivor camps, give broken remnants of species comparative luxury and their undying thanks.
Use humanity as effective slave labour in rebuilding the ecosystem with imported seeds, xenoforming the world for your benefit in the guise of rebuilding Earth for humanity. Use political media to vilify dissenters.

Mass Sterilisation of human race.
Move in to new beach front property.

[Kirjava]

I'm alarmed at how blase everyone is being about not preventing attractive, bickering young couples with a history of sexual tension from meeting. This should be the first point of order once the attack has begun. Also, the whackier of the human scientists, whose crackpot theories have been ignored for years but will now be turned to by a desperate President at the last hour should be targeted as a priority.

[Carl]

Whilst you've soprt of baned this with you no bio weapon thingy, i'd go with the solution used in the babylon 5 crusade episode "Memmory of War".

An entire world, billions of people, dead in 3 days. They never saw it coming, they never worked out how or why or even who. To quote their final message "we do not understand, we do not understand". Defintly one of sci-fi's greatest high octane nightmare fuel moments.

As others have said, if your objective dosen't benefit from keeping the cities and human population alive, just kill them. For that attacking their cities directly makes sense. It wipes out the vast majority of their population in one go. Take out the military along the way and the remenants are allready dead, they just haven't been killed yet.

[TDATL]

1. Show up in a suitably impressive manner.
2. Say you are God (or a representative of.)
3. Order all to submit to you.
4. Watch Chaos.

Objective = Amusement in a boring galaxy

Success.

[SquidDNA]

I rather liked the approach taken in "The Arrival" (see also: A Deepness in the Sky.) Think about it-- it takes decades and centuries to travel between the stars. There's not really any rush to conquer when you get there. Infiltrate, build up your power, and in the case it's ever necessary to reveal your presence, mankind will be powerless to do anything about it because you will own it.

[Akranadas]

Depends how patient your alien invading force is and what type of technology they have access to. Simply going in all guns blazing is good in theroy, but you're invasion force will eventually get bogged down into a war of attrition as the humans decide to focus on guerrilla warfare rather than using their weapons in the open. You want to invade earth as slow as possible and as quietly as possible, you want to destabilise the governments one by one, humans by their nature are extremely individualist and tend to group with those of a certain background or common cause. What you don't want is to unite humanity as a whole, that would prove counter productive to your battle, due to your lack of ability to transport troops to the ground, keep them feed and armed while fighting a potential armed force numbering in the billions.

Attacking key cities is also less of a good strategy, this provides humanity with fuel for their fight as every major city in the human population is seen as a beacon of humanities rise to power over the Earth, likewise goes for monuments of their achievements.

A patient invasion force is the one I would be commanding, instead of sending whole hosts of my alien soldiers to fight the humans on a planet I have no knowledge of or even understand I would observe them for the first few months, learning what I can about the planet and the humans that infest it. The most valuable point in humanities claim to the Earth is its lack of understanding and control over the environment, humans attempt to predict and control the weather but in the end it is them who is at the mercy of what they call; mother nature.
This is where I would strike first and slowly whittle away at humanity, what I would do is send advance task forces to the polar regions of Earth, the most uninhabited regions of their planet and from there I would deploy hidden equipment designed to slowly increase the melting of the polar ice caps. The plan is simple, abuse the humans knowledge of "global warming" and slowly increase the sea levels of the Earth. The would slowly destabilise the coastal regions of Earth major nations, as many of these nations have their most populated cities located along the shores of their islands, this in turn would generate a large number of refugees attempting to flee the rising sea levels, and in so causing a massive humanitarian crisis for the more wealthy Earth nations to handle. This off course would happen over a decade or so as not to alarm the human population into investigating and potentially discovering our plot.

Phase two would being by reducing Earth communications by slowly removing their orbital artificial satellites through exposure to increased radiation, this must be done at a slow rate as to ensure that humanity doesn't suspect outside intervention such as them sending scouts to see why all of a sudden a large number of satellites has disappeared. Once a sufficient number of satellites are down, enough to keep some form of communication open but low enough to ensure that communication becomes slow and time consuming process we begin phase three. We send a small task force to hit a key Earth target, not a major city but a more isolated area as to not drawn the attention of Earth's combined military, No the target would be a nation of limited appeal to Earth's global perception, in this case; North Korea. By striking this nation and removing it from the map, we generate a sense unease among the surviving nations as suddenly one of their most unfavoured states goes silent. Eventually they will send a force to investigate and by that time, we will be gone and will strike a another small nation, removing it from the Earth, we will continue to do so until the unease has reached a peak among the human nations, then Phase four begins.

Phase Four is where we sow mistrust among the nations of Earth before they attempt to unify under one banner, make contact with a key nation state (undecided but they must be a major military power) and broker a 'deal' with this nation, they will announce our arrival and their unified cooperation to the rest of the world, and in doing so we will announce that due to their cooperation and solely their cooperation they will be spared death. This will sow discontent as nations begin to mistrust each other, we will continue this tactic; picking rivals with deep history and siding with one nation over the other, and announcing they will be destroyed shortly. Hopefully this will result in nations engaging in conflict as to weed out the traitors among their race, and war will erupt across the Earth; the exchange of nuclear weapons is inevitable, but better for them to use it against themselves then use.

After the nations are at war, their resolve all but gone we reveal our true fighting force by moving against the remaining key Earth military outposts, paying particular attention of Earth Airfields as they will be humanities primary means of transporting and evacuation of civilians. After these targets are remove, we isolate cities and remove them from Earth one by One, concentrating our fire power on them. Humans will attempt to pull use into there way of battle, either through guerrilla warfare or by attempting to combine their ground forces to fight us conventionally. The idea is to ignore these tactics, and continue destroying large population centres as quickly as possible, we do not want to engage humans on the battlefield, even though we can win; we want them to have to continually reposition and stretch their supplies to the limits, as their weapons of war run on fuels we can bleed them dry.

The conquest of Earth will take decades, but we're here for the long hull; there will still be resistance possible 50 years from the first battle but as we slowly remove known population centres and disrupt their normal way of life they will slowly begin to crumble. Some may beg for peace or surrender, but peace was never our intention.

[Starfisher]

Throw adequate number of rocks at Earth to reduce human population causing only comparatively short term ecological damage. Since you can move interstellar distances this should not be too hard.

Watch devastation.

Come in offering 'humanitarian aid' years later while surviving remnants of mankind are at the end of the nuclear winter and are starting to recover.
Maintain control of technology, organise survivor camps, give broken remnants of species comparative luxury and their undying thanks.
Use humanity as effective slave labour in rebuilding the ecosystem with imported seeds, xenoforming the world for your benefit in the guise of rebuilding Earth for humanity. Use political media to vilify dissenters.

Mass Sterilisation of human race.
Move in to new beach front property.

Hard to argue with this approach. Except instead of leaving anything alive, just drop a big enough rock fast enough that nothing survives. Wait a few years for the surface to cool back down, begin mining operations.

It's hard to imagine an invasion scenario where you actually want living things left on the surface. Either you want the resources of the planet, in which case even having an atmosphere is probably optional and there's no reason to get into a fight when you can just scrub the thin scum of life off the planet's crust, or you want to do something with the humans, in which case an invasion is probably the least effective mechanism to achieve your aims. You don't invade at all - you just show up, offer some technological crumbs and set up Scientology some religion to control us and done, no splosions necessary.

So I guess you really have to choose between "invasion", which means there's nothing left alive after about ten minutes, or "something else", in which case the possibilities are endless.

[roflmao]

This: http://www.youtube.com/watch?v=dgU8qVHhD-c

And yeah, it all depends on the objectives. If neither eco nor population matter, just nuke the planet. If both matter, some sort of psychological terror sounds fun (albeit implausible). And of course the virus.

The thing about Avengers is:

Spoiler

Loki didn't want to just destroy earth. He wanted to rule earth, so it pretty much necessitated keeping the earth relatively intact. What do you do in this scenario?

[Nurizeko]

So we have seen it many times over. A movie (latest may have been The Avengers) with some kind of Earth invasion plot.

Several Earth invasion plots sucks. If not all.
In most movies I immediately recall, for some reason the aliens think it is a good idea to secure Manhattan. First. Why?

I do remember Independence Day as maybe having a more intelligent approach, but maybe those aliens only had greater numbers and could take Manhattan and downtown Seattle together with Kairo and Moscow and a bunch of other city centers. But still, why the city centers. How come downtown is so attractive to invasion forces?

Maybe I am on the wrong track, maybe making downtown's go splodey has a desired psychological effect from the invaders perspective, and they get to shoot out as many humans as possible in fewer blows?

I hereby name you Strategic Commander of an Earth Invasion force. Type down your strategic plan (or Oscar winning plot).
You "could" use HW related tech as reference. Njummie.

Kill all humans?

Create a threat of menace in the countryside/wilderness that drives people into the cities, wipe out telecommunications and stuff if I can, keep up this campaign as long as is intended, and when the time is right saturate bomb the cities, and leave ground-forces as clean-up. Obviously humans are kill on sight, with orders to pursue and eliminate with prejudice. Have a side intelligence operation designed to infiltrate human survivors, or make collaborators to rat out the rebelling humans, and once they serve their purpose wipe them out to.

After that campaign if any humans remain it's probably too late, might keep a few for a zoo or something.

If I just want their planet rather than its habitability I'll just opt for the rock throwing scenario.


Enslave all humans?

I would begin by undermining financial institutions, creating a state of weak panicked economy. Advanced forces would also after the economic unbalancing strike at the power grid and telecommunications.

Leave long enough for both to cause enough chaos then strike at the military. Assuming I'm more advanced I'm betting as a foreign invading force I have more self-sustaining capabilities than a regular human military which relies on the resources (financial, material, etc) of the host country.

Aside from killing the military off I'd try and minimise other human casualties as A) slave labour and B) humanity is less likely to field an effective guerilla operation if it is too busy huddling together in it's big cities looking after each other. Plus more people in a crowded location = more chaos.

Lastly as the minimum civilian casualties will assist in, I will open negotiations with humanity for what I want from them/Earth, and otherwise keep my occupation fairly distant so as not to feel like I am impeding on their every day lives, allow them to feel 'free' but close enough that once in a while when they're not doing their own thing and look over their shoulders I am there with my shit.

[Yoshi]

Given the tech required to cross interstellar distances in a reasonable manner. This would be my approach if you didn't need humans but still wanted habitation.

1.
While on approach to Earth you conduct visual imaging scans of the planet locating everything you possible can of value. The closer you get the easier it is to see potential targets, Cities, Military bases, ect ect. All the while listening in on our broadcasts to pan out information that grants more knowledge of 'who we are' and how we think.

2. Once in Earth Orbit, first strike will not be on the Cities, First strike will be precision orbital strikes on every single Military Base located from earlier information gathering. This is of course unlikely to be all of them and things like Submersed subs will no doubt escape these initial strikes but you will be able to hit a majority of equipment and other valued assets. This is also when you start taking out Telecom devices in orbit which would help hamper communications to some extent even though it wouldn't completely eliminate them.

3. Second Strike would involve orbital strikes on major population centers. It will have been followed up relatively quickly after the initial military strike. Where some people have no doubt left the cities already but mass panick from the military strikes will have created obscene amounts of congestion so its unlikely that a significant amount of people have made it out by this point.

4. Begin landing, being smart aliens you will have taken precautions against foreign bacteria and viruses. Best landing zone sites will be wide flat exposed areas, such as the Great Plains in the United States, this is where the alien centralized hub gets set up, ooooooh we're going hollywood here.....not really.

Priority construction gets put on defensive emplacements and turrets, with a big emphasis on underground systems to shield and hide most defensive emplacements when not in use. Even exposed Defensive emplacements are still armored and able to take punishment.

5. Deploy a wide expanding ground based sensor net, of sentries and other recon devices to supplement Orbital Survelliance of the area. Anything comes within 200 Kilometers of the base that is unwanted gets pulverized by ground emplacements and other devices. This distance is increased by twenty times for vehicles both ground and air based. Distance would be varied somewhat to prevent accurate pinpointing of the killing zones. Orbital hits would be utilized in conjunction with planetary based forces. Any mobilization spotted from Orbit or airborne recon runs would be subject to an immediate orbital hit.

6. Wait for the inevitable human counterattack, due to position away from most high density population centers high yield strikes would be expected. Orbital Ships would be on constant alert and would destroy any Missile launched before it left initial Boost Phase rendering strategic nuclear response completely impossible(Especially given that many nuclear sites have no doubt already been hit in the initial attack.).

7. Patiently wait until the majority of counter attacks have been delt with before beginning to expand outward. Dont bother seeking out and killing humans, merely kill the ones that get to close. This coupled with demoralizing punishment delt from the sky will eventually lead to a loss of resistance because the survivors will start to fear anyone that speaks of resistance when the aliens have shown they really only give a shit when you come and bother them as well as gather in large numbers. Humans will begin ostracizing these aggressive fight to the death people in lieue of more immediate and long term survival of just staying out of the Aliens way.

Not to mention initial landing zones in exposed open areas destroys most aspects of guerrilla warfare as any assault is forced to move in the open where it is easily seen and dealt with. Coupled with Thermal imaging from space among other sensory techs as well as simply listening for broadcasts and triangulating their location for a hit demolishes most ideas of effective and coordinated resistance. Nuclear munitions can't be smuggled in close enough proximity to guarantee effectiveness.


Humans would no doubt live on, but they would never repel the invaders or ever be able to deal damage to make Earth not worth the time. Command of low orbit with the kind of technology an invading force would have gives an unparalleled tactical advantage much in the same way that Air Power gives an enormous advantage over simply Ground Power. You have unmatched visual clarity as well as being in the perfect location to demolish any nuclear launches before they became a threat.

Humans would eventually regress to more tribal based society as technology slowly faded away for them, even if this specifically would take a great deal of time. The Aliens just crossed interstellar space they aren't in a great hurry.

[BlackOmne]

WHAT'S WRONG WITH YOU PEOPLE?! You're giving the blueprints of our destruction to the aliens (they're reading this at the moment)!! j/k!

Seriously, there are some interesting ideas here.

[Shraa Elohim]

Hmmm, I'd try to convince the entire population of Earth to move to somewhere nice and centralised. With my Super Technology I'd convince them that most of the world is overrun with some kind of extraterrestrial phenomenon (I dunno, worms a la Dune) and that we're the Interstellar Pest Control or something. Offer them a choice between massive human casualties as we take them out from orbit or suggest the world migrates to somewhere like North America. Promise them ample food supplies and interesting (but harmless) technological tidbits to keep them pacified and loyal. Then, once they've all gone to North America, start giving them supplies for a few years to make people feel that this is genuine.

Then pull the plug on it, and lock down the continent so that once you realise you're colonising/mining etc, they can't get any nukes off. Meanwhile they're collapsing with massive food riots and ethnic tensions of 7 billion people on one continent ripping themselves apart. Let them thin their numbers and, if needs be, drop and EMP to speed things up. And if things still haven't sorted out, and humans try some trans-oceanic crusade to recapture their homes on Eurasia... Well, then the real fun begins.

[Croaxleigh]

This is assuming human-like aliens, or aliens with the technology to appear human at the very least.

Step 1) Infiltrate. Establish sleeper agents in major countries around the world, implant deep-cover spies, the works.
Step 2) Begin a campaign of terror. We're not talking World Trade Center attacks or blowing up of major cities... more things like setting off major explosions in Small Town America and other places that nobody would expect. The goal is to show people that nobody is safe, regardless of how secluded they are.
Step 3) Create a "Big Bad" to claim credit for the attacks. Bonus points if he doesn't really exist; it'll keep the legitimate governments running around on a wild goose chase.
Step 4) Continue escalating the attacks, especially in border regions that are highly disputed. World tensions rise, and the governments of the world are powerless to actually stop things.
Step 5) Gradually advance a few of the infiltrated agents, putting them in a position where they can be effective against the "terrorists." The goal is to make them heroes, and make them instrumental in finally putting an end to the reign of terror.
Step 6) Let them ride their heroism all the way to the White House and other seats of government. Establish more of your agents in cabinet positions, etc., until you have a significant level of influence in the governments of the world's major countries.
Step 7) "First Contact."

By the time the actual invading force arrives, the agents you have in place will have effectively convinced large portions of the population that you're a benevolent race. You'll share some SCIENCE! as a good faith measure beforehand to help sell this image, and direct military action against you prior to the invasion will be prevented by the agents you've placed in charge of the world's governments. When your sudden and inevitable betrayal comes, those agents will be the ones who formally "surrender" to the invading force.

[BlackOmne]

If purpose is: take earth's mineral resources
Use the large 'rock throwing' idea mentioned by Starfisher or Nurizeko above. While waiting on Earth to cool, mine the rest of the solar system.

If purpose is: to use Earth's biosphere for bio resources or to live on it without those pesky humans
Secretly drop nanites on the planet in several locations. Program the nanites to secretly and quietly spread across the planet in small numbers and to 'infect' every human on earth, a few to each human. The nanites are programmed to sginal their infected status (via some inconspicuous signal) and to remain dormant until every human on the planet is infected. Once all humans (or at least 99.999% o fthem) are infected, turn the nanites on to rapidly reproduce and kill their hosts through either disintegration/disassembly or conversion to a carbon block (for easy collection of resource) - the human race is made extinct within a matter seconds or minutes. Build and shield the nanites in a such a way that accidental means of deactivation (eg, a human getting an x-ray or MRI) durinng their dormancy period are avoided.

[Langy]

What if the purpose is to enslave humanity?

[BlackOmne]

Why enslave humans? As playthings? I would think that an alien race capable of travelling interstellar distances would be capable of building robots to act as slaves. If you want the humans as either playthings or food sources, you could program the nanites to only destroy the higher functions of the human brain, leaving either a human that easily submits to instruction or a human that is vegetable enough to collect and put into storage until ready to eat.

[Carl]

@Black: there's actually an intresting anwser to that, but i guess i better get writing for that scenario .

[TDATL]

For the lulz or the evulz are the most probable reasons Earth would be invaded.

There is nothing on earth that is unique outside of it's life. Attacking the earth would potentially destroy the only thing special about it.

Everything else is available in HUGE amounts throughout the galaxy. People often think our water is somehow special. It isn't. Water is two hydrogen and an oxygen. Hydrogen is the single most abundant element in the universe. Oxygen is the third most abundant element in the universe. A little spark and you have instant water.

[BlackOmne]

Another violent reason to keep humans alive (and perhaps not brainless) would be as hosts for an intelligent alien symbiote (eg, like the Goa'uld in Stargate).

[Carl]

I'm still writing but just want to add:

@TDATL: If your an oxygen breathig lifeform, (or rather earth like atmosphere breathing), their are certian things which whilst avalibile in space, are more easilly or more safely aquirabblle on a planet. If you have the technology to easilly haul the stuff to orbit at minimal cost to yourself that saftey and conviniance may well represent a sufficent gain to be worth the hassel of taking out the local populance. Obviouslly not relevant to what i'm writing about at the moment, but still worth noting.

[Yoshi]

There is nothing on earth that is unique outside of it's life. Attacking the earth would potentially destroy the only thing special about it.

Colonization is a feasible reason to invade the earth if the Aliens utilize an atmosphere like ours. As then its simply a matter of convenience, World suitable for them right along their exploration paths. Far simpler to colonize an already suitable world than it is to completely Terraform an unsuitable planet.
Yes their might be LOTS of other earth like planets to colonize but they A. Might not run across them all the time, and B. Even if they do they would still most likely take ours simply because it is here, in their path and available for use once the natives are dealt with.

Our own species is a big example of how 'superior' forces often don't give a shit about the current indigenous population of an area when moving in.

[Nanaki]

Some information tidbits:
Resource-wise, Earth has little* to offer any sapient species with the means to reach it from other starsystems. The rest of the solar system has magnitudes more resources, and do not involve a costly invasion plan on utilizing them.

*The only resource that can be found on Earth and not anywhere else in the Solar System would be Fossil Fuels, and even that may be questionable, since Mars, depending on weither it harbored life or not in a previous era, might also have deposits of fossil fuels. Why do you think scientists are so hellbent on trying to figure out weither Mars has life? Possibility for oil on Mars = Suddenly the space industry has trillions of dollars to spend on getting there and exploiting it.

*Also, 'life' may be something offered, but that opens an entirely different can of worms.

Colonization is a feasible reason to invade the earth if the Aliens utilize an atmosphere like ours. As then its simply a matter of convenience, World suitable for them right along their exploration paths. Far simpler to colonize an already suitable world than it is to completely Terraform an unsuitable planet.

Actually, I would say that Earth's existing 'contamination' of life would be a massive problem even if the invading aliens had very similar biology to us. Your talking about them colonizing a world with thousands of different pathogens their immune systems have never encountered before. Considering the amount of technology it takes to just cross interstellar distances, it would probably be far less risky/costly to terraform an uninhabitable rock without that pre-existing biology than it is to adapt your entire species to that biology.

[Yoshi]

Actually, I would say that Earth's existing 'contamination' of life would be a massive problem even if the invading aliens had very similar biology to us. Your talking about them colonizing a world with thousands of different pathogens their immune systems have never encountered before.

Possibly, though at this point we could get into an endless debate over it. Since their is the very real possibility that most pathogens wouldn't be compatible with their physiology even if it was similar to our own. As there are many diseases that cannot cross species barriers normally. Or their physiology may be different enough that while they breath oxygen they do still need to set about introducing their own plants/animals on a new world due to not being able to consume our food and such.
Just multiple possibilities that can go either way in such a scenario.

[Starfisher]

Why do you think scientists are so hellbent on trying to figure out weither Mars has life? Possibility for oil on Mars = Suddenly the space industry has trillions of dollars to spend on getting there and exploiting it.

You are joking, right? Heh.

[Dooks Dizzo]

Resource-wise, Earth has little* to offer any sapient species with the means to reach it from other starsystems

This.

Want water? There's a moon around Jupiter that is made of almost nothing but. Heavy metals? Asteroid belt. Near limitless energy? Pick any star, build large solar panels. And you'll have trouble convincing me that any race capaple of intersteller travel can't cook up a few life forms to play god with if they so chose.

The only one I've ever really liked the idea of was a pacifist race in need of a couple million murderous bastards to fight a war for them. And even then, that's just unadulterated macho bullshit.

I think an alien race showing up and stip mining the moon down to dust while totally ignoring the people of earth and then leaving us to suck it would be pretty hilarious and possibly even original.

[Croaxleigh]

"Tell me... what is it that they're doing?"
"It appears that they're strip-mining the moon, Mr. President."
"As a first stage of invasion?"
"No, I'm pretty sure that they're just here for the moon. We tried to make contact, and they told us, um... they told us to 'suck it.'"

[Starfisher]

I think an alien race showing up and stip mining the moon down to dust while totally ignoring the people of earth and then leaving us to suck it would be pretty hilarious and possibly even original.

After playing Homeworld (the whole "angel moon" thing), I had an idea for a story where a race shows up and then proceeds to drag the moon out of orbit and into some sort of portal. They completely ignore all communications, and are apparently as unaware of various failed attempts to stop them as we would be if a bunch of ants got mad we were digging up the tree they lived under. The tidal/gravitational forces involved cause massive devastation on Earth, and then they just leave. Meanwhile, the Earth is left only with sun tides, and the coastal ecology changes dramatically as a result.

For some reason, the idea that nice round white moons were a premium item in the universe struck a Hitchhiker's Guide note in my head.

[Carl]

If all your intrested in is water and heavy metals, then yeah sure, there's tons of the stuff in the solar system. But if it's life anything like our own there are several compunds that are in reletivlly short supply in the solar system. There's still avalibile, but not to the degree anything else is. For life anything like our own it's a damm site safer and simpler just to set down and get it here where there's a nice safe atmosphere and a mistake means a trip to the doctor, not explosive decompresion for you and perhaps your work collegues.

Basiclly do a bit of research into what a colony at one of the langrange points would need shipped from earth and then tally that against whats avalibile in the solar system. Mostly it's agriculturual compounds, trace elements our and other earth life needs, and water. Water is reletivlly easilly avalibile. The rest. Not so much. Certianlly titan for example has most of it, and i'm sure there are various asteroids and other bodies that contain this or that. But earth is a one stop shop, plus if they';re like us, a damm sight safer.

@Dook: If the race is telepathic them being pacafist isn't unbeliviable at all. But conscripting just humanity probably is a bit dumb .

EDIT: Also don't make assumptions about tech levels. Fushion drives + eithier generational length closed cycle enviroments or cryogenics will get you across interstellar space. It dosen't automaticlly follow that they'd vastly outnumber and outgun us TBH. Fushion drives might sound really impressive. And to a degree they are. But if they're just using a high efficency vershion of currentlly researched methods, teir tech base might only be baby steps ahead of our own instead of great leaps and strides.

[Elerium]

Also I have a nagging feeling the governments and militaries of the Earth would have already contemplated all of the suggestions above if not more should an alien race try to do something fishy. If we can think of "EMP's from space" to "satellites plinking out due to a suspicious increased radiation activity" then I bet this has already been discussed with other nations at some point.
Aliens if they're going the silent route will also eventually botch up with their covert ops- you could rely on human clones that are indoctrinated but this like all plans could prove too risky- if you mess it up leaving enough evidence of alien interaction (clear visual sightings and recordings, a dead body/left equipment is the worst) mankind will soon be shaking hands and forming curious groups up with each other I bet.

So.. maybe human clones trained and conditioned (no defection goddamn it) to slip in high positions of power and then hit them with an invasion (EMP, false communications and all) plus ultimately if they can't rat out the traitors who are leading them into the dragon's maw mankind is screwed?

Then again, you could drop planetoid in their ocean. Big waves! Har! Har! Har!

[Nanaki]

You are joking, right? Heh.

Yes. It is a joke about the obsessive nature of scientists when it comes to life on Mars.

----------

If all your intrested in is water and heavy metals, then yeah sure, there's tons of the stuff in the solar system. But if it's life anything like our own there are several compunds that are in reletivlly short supply in the solar system. There's still avalibile, but not to the degree anything else is. For life anything like our own it's a damm site safer and simpler just to set down and get it here where there's a nice safe atmosphere and a mistake means a trip to the doctor, not explosive decompresion for you and perhaps your work collegues.

Unfortunately, it is not that simple. As I said earlier, there is the whole 'Earth pathogen' issue, and then there is the whole issue of dealing with the natives in the first place. When you put everything together, the risks and expenses on mining hydrocarbons (I am presuming this is what you are talking about?) on Titan and other places is tiny compared to the risks and expenses of mining them on Earth.

EDIT: Also don't make assumptions about tech levels. Fushion drives + eithier generational length closed cycle enviroments or cryogenics will get you across interstellar space. It dosen't automaticlly follow that they'd vastly outnumber and outgun us TBH. Fushion drives might sound really impressive. And to a degree they are. But if they're just using a high efficency vershion of currentlly researched methods, teir tech base might only be baby steps ahead of our own instead of great leaps and strides.

All of those things are extremely high tech, we as humanity wont see any of that stuff for at least until 2050, or even 2100. Also, 'high efficiency version of currently researched methods' does not discount the fact that currently we have a hard time generating net-positive energy from fusion reactors. Nevermind generating it on a commercial and reliable scale. Trillions of dollars are going into fusion yet we are moving at snails pace regarding research and development. The first net-postive reactor will not even achieve first plasma until 2019, and thats assuming it even works. Assuming it does work, we would need to build an additional prototype for commercially viable reactors, and construction of that will not even start until 2024.

Also, it does not even discount on how insanely expensive it would be to ride to another solar system using that technology, and the rewards from doing so would be completely unprofitable. Building all of that to visit another solar system would be akin to modern-day Earth building a manned rocket to Pluto. Sure, it is -technically- possible, but the chances of something going horribly wrong along the way are far too high to be acceptable, and even if it was somehow done, what would be the purpose of it? You would need so much mass for reaction mass you would have very little space for much else.

[Moe]

Is anyone from the "earth has minerals and water!" crew planning on elaborating how the invading aliens are going to move the tons and tons of minerals and water out of this gravity well? The amount of energy required for that is ludicrously high.

[Akranadas]

Easy Moe: Space Magic

[Dooks Dizzo]

"Tell me... what is it that they're doing?"
"It appears that they're strip-mining the moon, Mr. President."
"As a first stage of invasion?"
"No, I'm pretty sure that they're just here for the moon. We tried to make contact, and they told us, um... they told us to 'suck it.'"

I would see that movie.

[Pyro Paul]

The primary reason any invading force would first target large population centers is primarly because large population centers tend to be located on key transit hubs and any attack on these locations would cripple logistics to a large degree. As a prime example, look at St. Louis Missouri which serves as the major railroad hub for crossing the Mississippi River. You take that out you effectively cut the nation in half logistically.

There is also the fact that many Utility services are centered rather close or in these Urban centers. Quiet a few Power, Communications, and Server hubs for networked computers are with-in city limits...

Lastly, Aliens wouldn't know any better...
our cultures could be vastly diffrent...

remember, there was a time when a major military installation was a city as it was the only place with Walls...

[Akranadas]

Still doesn't explain why they want to invade our planet in the first place. Space is full of resources.

[Lautaro]

I don't find credible an invasion of an advanced sentient race (i doubt we have something they could need)... but an invasion from a non sentient race, I think it makes more sense.

For example, a gargantuan creature that travels space and every time it finds a suitable planet starts releasing spores that infest the planet and twist their inhabitants and finally consume the planet (like a fly putting larvas in a corpse). I think that the spores could turn humans into servants so they tend to other spores that turn into actual spawns of the "leviathan" (so the movie could be an "aliens meet zombies" film).

(Hi, I'm new in the forum but I watch it from a long time ago)

[SquidDNA]

Something else from "A Deepness in the Sky".. Spacefaring cultures need planetside industrial support to stay viable. This may have been purely to motivate the plot, but it's an interesting point.

[Dooks Dizzo]

Well as far as first posts go, I am quite happy with yours! Welcome aboard, and I want to state for the record that I welcome our new alien zombie fly larve overlords.

[Norsehound]

After playing Homeworld (the whole "angel moon" thing), I had an idea for a story where a race shows up and then proceeds to drag the moon out of orbit and into some sort of portal. They completely ignore all communications, and are apparently as unaware of various failed attempts to stop them as we would be if a bunch of ants got mad we were digging up the tree they lived under. The tidal/gravitational forces involved cause massive devastation on Earth, and then they just leave. Meanwhile, the Earth is left only with sun tides, and the coastal ecology changes dramatically as a result.

For some reason, the idea that nice round white moons were a premium item in the universe struck a Hitchhiker's Guide note in my head.

Kind of reminds me of the Lovecraftian notion of alien beings: They are so far above us that they don't even notice us at all.

[Lautaro]

Yeah it was one of my game ideas to make if I win the lottery (half LOL half tears)... that and the "Homeworld meets Mass Effect meets Master of Orion" game of my dreams.