Alien Invasion!

[Urwumpe]

What is more likely: The aliens will arrive with extremely large generation ships, and will not be willed at all to turn around and fly home. So, they will fight to really the last man and last bullet. Technologically, they will rely on methods for causing high damage with minimal energy expense (all else is stupid), and will try to preserve their "alien" resources as much as possible, trying to take advantage of terrestrial resources as soon as possible.

So, a battle in space alone is unlikely. They will arrive quickly and will make landfall under saturation attacks as support. All that remains in space is rapid reserve, for controlling the orbits above us, most fighting will happen from quickly established forward control bases. They will concentrate on indications that show resources from space without needing to scan Earth for months - cities. Where we are, there must be something good.

They will not know about governments and countries. They will not care. when they arrive today, there was no sign about intelligent life on Earth when they departed. They will not be prepared about our own ways of warfare or our true numbers. But they will bring expectations from their own world - how they fight and how much civilization they would expect. Likely more than we expect of us today. So, they will arrive in higher numbers, enough for securing this planet with reasonable effort. Likely many troops of them will be perfectly green, maybe well-trained, but have no experience of combat by not having seen war for generations, while on the way for Earth.

---------- Post added at 10:23 PM ---------- Previous post was at 10:23 PM ----------

Yeah, but without modern infrastructure human population would collapse to perhaps 17. - 18. century levels posing much less threat.

Like in Afghanistan?

 

[T.Neo]

It seems unlikely there would be much resistance when most of the surviving humans would be busy growing enough food to survive upcoming winter/drought.

Yet "primitive" militias are able to fight effectively in sometimes scarce environments (i.e. afghanistan) while putting up with climatic changes and poor technological conditions.

Also remember that our resources may mean very little to them; Earth life may be of little or no nutritional value, or it may even be deadly poisonous to them. Water and mineral wealth are more plausible options, but they don't often exist under cities- look at Africa, South America etc.

I also wouldn't rule out humans capturing or copying alien technology (or at least using concepts gained from it in warfare).

 

[Andy44]

If they have a generation ship, than they need not be in a hurry to colonize. They'll just bomb us with asteroids and when the dust settles after a few years they'll just walk off the landing craft and start building their own cities. Any remaining humans will be living in caves and make good sport for alien hunting parties.

Only thing they'll have to really worry about are the sights of former nuclear powerplants and facilities, so they can map out regions of radioactive contamination to avoid and clean up later when they have the time.

Or they can make their new human slaves clean it up.

 

[T.Neo]

Or they can make their new human slaves clean it up.

Why bother with unruly, hungry slaves when unquestioning, efficient and semi-disposable droids can do the job ten times better?

 

[Ghostrider]

Like in Afghanistan?

There's a huge difference if we're considering the situation in Afghanistan: there, the Coalition forces must take a lot of effort in order to minimize collateral damage and look good on the PR front.

If the Coalition had the same goals as the hypotetical aliens and none of those concerns, the war there would be over in a week because instead of combined ground-air tactics they would employ massive bombardments using persistant nerve agents; they would poison all wells and firebomb every patch of cultivable land, until the whole place had been effectively depopulated.

Unlike us, they wouldn't have any rule to follow. Hell, I'd just EMP all of our advanced tech into the junkyard first, and then begin dropping gas and germ bombs from orbit. Maybe nuke out some big population centres, then proceed to annihilate the rural areas before even thinking of landing.

 

[Urwumpe]

If they have a generation ship, than they need not be in a hurry to colonize. They'll just bomb us with asteroids and when the dust settles after a few years they'll just walk off the landing craft and start building their own cities. Any remaining humans will be living in caves and make good sport for alien hunting parties.

Only if you have a perfect generation ship, that is a closed system. If you have resources that run out, for example spare parts or metals, you are not able to wait for indefinite time. You want to leave the generation ship as soon as possible and scavenge it as soon as you can, for taking over Earth.

Distant bombardments by asteroids are not optimal - they take a lot of time for preparation and you can use expendable parts of the generation ship for better and more precise effect.

 

[Andy44]

After spending dozens or even hundreds of years on a generation ship, what's another 10 years or so? And if they need supplies that bad, they can get hydrogen from our gas giants and water from Enceladus or Europa.

The thing about a generation ship is that it has to be a closed system because out in insterstellar space you're on your own for a very, very long time.

Worse, you really don't know what's awaiting you in your target star system, so you need to have the flexibility to take resources from a variety of sources, as well as lots of delta-V to spare. A fusion drive at the very least.

 

[T.Neo]

And if they need supplies that bad, they can get hydrogen from our gas giants and water from Enceladus or Europa.

Even if you have plenty of Dv and/or a highly advanced system, doing a transfer to Jupiter or Saturn isn't exactly a walk in the park...

 

[Andy44]

Like I said, they have time. And they have at least enough delta-V to reach stellar escape velocity.

 

[Sky Captain]

Also real world insurgencies often depend on outside supply of weapons and combat gear to successfully fight. In such post apocalyptic situation with most of human industry and manufacturing capability gone there would be very limited supplies of weapons and ammo

 

[T.Neo]

Also real world insurgencies often depend on outside supply of weapons and combat gear to successfully fight. In such post apocalyptic situation with most of human industry and manufacturing capability gone there would be very limited supplies of weapons and ammo

Ah, so there are afghan factories producing ammunition and supplies?

Don't get me wrong, ammunition and suchlike will no longer be produced after the attack, but sizable amounts of supplies etc should still exist.

EDIT:
Lest we not forget alien technology... the ergonomics of it will certainly differ from human devices, but I wouldn't see why some tinkering and/or modification of it would make it usable by humans.

 

[Urwumpe]

Like I said, they have time. And they have at least enough delta-V to reach stellar escape velocity.

They have time - but can you build a building with modern technology that lasts for all eternity? if you have the magical eternal generation ship, yes. But if you use realistic endurances, having a generation ship that can be fixed from on-board spares for 300 years is already an futuristic achievement. Our current spacecraft hardly survive 10 years without breaking down completely.

Building a completely closed system is not possible according to thermodynamics (entropy), you will have an ending of your generation ship. And this will likely come when the destination is reached and the ship has done it's job. It makes no sense to design it to last artificially longer so you can attempt bombing the planet into submission - how should you know what awaits you? If the target planet develops space combat ships after you departed, you are a huge fragile target when you arrive.

And that is maybe a nice plot device for sci-fi writers (motherships which are sensible to human computer malware), but militarily, it is stupid:
All forms of strategy, are the reduction of the bad surprises to the minimum. You don't go "Hey, maybe they will punish us to dust for such a plan, but it could be fun.", you will want to choose the strategy that offers you the lowest number of assumptions on the capability of the enemy.

Especially if your enemy has 300 years (or more) for changing his character.

 

[Andy44]

Well, I was thinking that an alien generation ship's occupants would be surprised to find a sentient species here, or any life at all for that matter. So far the galaxy seems like a very lonely place. So why pack all sorts of weapons, when the nuclear fuel is so precious?

 

[Urwumpe]

Well, I was thinking that an alien generation ship's occupants would be surprised to find a sentient species here, or any life at all for that matter. So far the galaxy seems like a very lonely place. So why pack all sorts of weapons, when the nuclear fuel is so precious?

Depends on what you know about the target planet. If it is showing signs of life (like Ozone), you maybe have to expect at least primitive life.

But look how we would have appeared 300 years ago - 1709. Our fictive invaders wouldn't even pick up our first radio signals until they are 120 light years to us.

If we would go, based on that knowledge of our own past, we would take serious weapons with us - as much as for the alternative: The ability of returning home instead of committing suicide in space. And maybe the invaders can't return home. How many countries of today did exist 600 years ago? When we would have send a fictive generation ship out in 1409, it would very likely return to a new unknown world. With a large number of fugitives, that won't be welcome.

 

[Andy44]

When we would have send a fictive generation ship out in 1409, it would very likely return to a new unknown world. With a large number of fugitives, that won't be welcome.

Ha, imagine a bunch of people showing up whose entire society was spent aboard a small-city-sized vessel starting in 1409! They would be a very strange bunch of humans indeed. After so many generations they would even resemble 1409'rs anymore, they would be some wierd tribe. Probably worshipping their own vehicle powerplant or something.

 

[Urwumpe]

Ha, imagine a bunch of people showing up whose entire society was spent aboard a small-city-sized vessel starting in 1409! They would be a very strange bunch of humans indeed. After so many generations they would even resemble 1409'rs anymore, they would be some wierd tribe. Probably worshipping their own vehicle powerplant or something.

Yeah. And thinking about their homeplanet as the prize for their hardships along the journey...

 

[Linguofreak]

There's a huge difference if we're considering the situation in Afghanistan: there, the Coalition forces must take a lot of effort in order to minimize collateral damage and look good on the PR front.

If the Coalition had the same goals as the hypotetical aliens and none of those concerns, the war there would be over in a week because instead of combined ground-air tactics they would employ massive bombardments using persistant nerve agents; they would poison all wells and firebomb every patch of cultivable land, until the whole place had been effectively depopulated.

Unlike us, they wouldn't have any rule to follow. Hell, I'd just EMP all of our advanced tech into the junkyard first, and then begin dropping gas and germ bombs from orbit. Maybe nuke out some big population centres, then proceed to annihilate the rural areas before even thinking of landing.

Also, the coalition forces in Afghanistan are vulnerable to the same chemical agents as their opponents, and so the use of chemical weapons, especially persistent agents, could really backfire, especially if they used persistent agents and had the goal of capturing the territory for their own use.

These aliens on the other hand, may not be so vulnerable to what we would consider nerve agents, and may very well even consider them benign. What if Sarin was actually nutritious for them? (A lot of chemical agents are called "gasses" but are actually liquids at room temperature and deployed as mists. Sarin is one of them). Or if they farted hydrogen cyanide? Or if mustard "gas" was part of a popular skin lotion? These are just given as examples, I'm not sure what, if any role they could play in alien biology, but the point is that any number of compounds that we would consider chemical warfare agents could be a natural, even necessary part of their biology, or the biology of some creature on their home world. Of course, this could work both ways, and there could be alot about us that they'd find toxic. (And, also, for either species to use chemical weapons against the other, they'd have to know each other's biology to know what would be effective)

Germ bombs probably wouldn't work unless they could get samples of our own germs. Their bacteria would fairly likely find our body environment toxic (heck, there are a lot of our own diseases that can only survive in certain Earth creatures, let alone aliens), and genetic incompatibility would probably prevent their viruses from reproducing. They might not even use nucleic acids as genetic material, and even if they did, they might use different types of nucleic acid, and even if they did use the same DNA and RNA that we do, their cells might "read" things in an entirely different manner, so that any viruses that tried going cross-species wouldn't get copied right.

---------- Post added at 03:45 AM ---------- Previous post was at 03:33 AM ----------

Ah, so there are afghan factories producing ammunition and supplies?

No. There are (for instance) Iranian factories producing ammo and supplies. And there are smugglers hauling ammo and supplies. And in fact, I wouldn't be surprised if weapons from Western factories aren't reaching them over the black market.

This is one of the big reasons we lost Vietnam: We didn't know if we really wanted to fight or not. We were willing to go in there and start shooting, but we weren't willing to risk broadening the conflict enough to make any real effort to cutting off the enemy's supplies.

Unless we're being invaded because we're a proxy for some other group of aliens, we won't have outside help.

 

[Andy44]

Actually the Afghans and Pakistanis make their own Kalashnikov rifles, as these were designed to be made by any competent machinist. But other stuff they get from elsewhere.

 

[JamesG]

There are prenty of Human weapons to last small population of resistance fighters several generations. Unless the alien bodyform of is completely alien, then their weapons would be adaptable to human use.

You are presuming that the alien biology or technology doesn't allow hybernation or suspended animation. If they can put all the passengers on ice, or grow them from tiny seeds, etc. then they can pack millions into a fairly small ship.

You'd think that they would have sent a scout ship first. You wouldn't want to send your wagons west without making sure that the indians can't kick your ass first.

There are plenty of KE bomb materials floating around our solar system. Most of which would only need a gentle nudge and a basic terminal guidance pack on the back to be highly effective city killers.

I still like the engineered sterility virus the best. Fiendishly clever and subtle yet highly effective.

 

[Sky Captain]

From Atomic Rockets regarding orbitla fire support.
http://www.projectrho.com/rocket/rocket3as.html

Planetary Assault: Close Fire Support & Utilizing Recon Drones

With good enough targeting information transmitted from recon drones through a computerized system, space warships could help kill even individual vehicles or even individual enemy soldiers from orbit when possible. Such would not be their primary mission, and initially the warships would attack more valuable targets. But afterwards, a warship would still have practically unlimited ammo for its electrically-powered beam weapons running off nuclear reactors. Using a hundred-thousand-ton warship to kill a couple enemy soldiers riding around in a truck might superficially seem wasteful, but there is next to no marginal cost in the preceding scenario.
Consider a warship orbiting at 200-km low-orbit altitude for final fire support. A little like a terrestrial sniper can shoot an enemy from 0.5-km away, some beam weapons on the warship could be designed to hit precise locations on the ground below, with potential accuracy of within a meter. If there was a single person or handful of people on the warship manually trying to search for targets, aim, and fire the weapons, it would be a slow process. Yet, if there are a large number of robotic recon drones searching for enemy vehicles and soldiers, transmitting their precise coordinates, a computerized fire control system on the warship could shoot thousands of designated targets per hour, continuing for hours or days if necessary. Given the firepower and capabilities possible with one space warship, imagine what a fleet of thousands of such warships (or more) could do against a planet.
Space warships would initially destroy all targets they could see from space, but, for foreseeable technology, orbital surveillance might not find every last target. Deploying air and ground versions of robotic recon drones could help give further targeting information. For example, if a golf ball-sized robotic drone with a miniature jet engine flies up to the window of a building and sees enemy soldiers inside, it can transmit a signal causing the warship's computers to fry the area within a 50-meter radius with a lethal radiation beam a fraction of a second later ... potentially very effective yet still with less collateral damage than just nuking the whole city.
The preceding could be done before sending in regular armies or occupation forces in order to drastically reduce ground combat casualties, although use of expendable robots and/or telepresence whenever possible might make human or sapient casualties beyond non-sapient robots be low anyway.

Well, I guess if they have roughly similar capabilities like mentioned above any insurgency could be quickly eradicated. Even if they have only one ship it could still provide cover for their landing zone making any air or ground attack against their forces impossible. And aliens don`t have to wory about collateral damage they cold just fry the whole area where insurgent`s are known to operate thus eliminating the threat completely.