In Weapons for a civilisation-destroying giant robot I asked about what weapons might be placed on a sixty-billion-ton fusion-powered snakebot 9.27 km long and 1.19 km in diameter, armoured with 224 metres of Boron-Carbide surfaced Tungsten-Depleted Uranium alloy armour. This question's predecessor: Defeating the Snakebot of Doom was shot down - and rightly so - by March Ho, who pointed out that its ground pressure was such that it'd sink into the bedrock like a rock in jelly.

So, now we have attempt 2, revised (by the alien adolescents before launch) to account for ground pressure and some other factors.

The Snakebot of Doom is 446 metres in diameter, with a body that is cylindrical for 7480m, and then tapers down to a point over a further 669m, the tail matching with a similarly shaped mouth. Its internals are made from a compound functionally similar to an AZ91D/SiC syntactic foam composite, with density of 0.97 g/cc, or 970 kg/m3. Its armour - which is 14 metres thick - is made from Tungsten-depleted Uranium alloy plates with a surface coating of Boron Carbide, and underlaid by an open energy-absorbing magnesium alloy foam.

The Snakebot of Doom weighs 1.486 billion metric tons with an effective density of 1271 kg/m3, has a maximum footprint of 3.34 square kilometres, and a ground pressure when on its belly of 4.3 MPa and when rolling in a hoop, a ground pressure of 13 MPa, on the order of the ground pressure of a woman running in stiletto heels. While these ground pressures are high for a vehicle, this is acceptable, as its purpose is to destroy infrastructure - even below ground - by rolling on it.

The snakebot is equipped with a multitude of sensors on its skin, including optical sensors from the far UV to the far IR, electromagnetic sensors, audio sensors (for what it matters given that it would most likely have to stop moving to hear anything) and radiological sensors. It also has broad-band radar and lidar capabilities. While these sensors are surface-mounted, they may be retracted for defensive purposes (and to protect them if the snakebot rolls), and replacements are available further beneath the armour in case of battle damage.

The snakebot is armed with 512 "small" railguns firing unguided steel 4.5x72mm flechettes at 5000 m/s, at 24 around rounds per second, 128 or so "medium" railguns dispersed over its outer armour, each firing a steel command-guided and optically-self-guided flechette about 18x288mm long at velocities of around 5000 m/s, at around two rounds per second.

It is also armed with six large railguns in its "mouth", only one of which is available for use at any time, the others being retained deeper beneath the mouth's armour as immediate-use backups, firing 144mm diameter, 2304mm long optically-self-guided munitions at a velocity of around 7000 metres per second, at about 40 rounds per minute. These munitions may be single depleted-uranium long-rod penetrators, or they may be capable of breaking up into hundreds of unguided steel sub munitions at some point prior to impact.

As a weapon of last resort, the Snakebot of Doom can launch up to sixteen scramjet-propelled ballistic missiles each containing a fusion warhead in the eighty-megaton range, with built-in ECM and anti-anti-missile defences (small command-guided railguns), before having to take around two weeks to build replacements.

Resupply of these munitions (except for the depleted uranium and atomic munitions, which would be used sparingly) would be by the expedient of the snakebot "eating" ferrous human infrastructure and processing it into more ammunition. To address a point made that guided munitions would be difficult to fabricate, these are being produced by nanoassemblers, and are not significantly more difficult for them to produce than an unguided projectile. The limiting factor is surface area and nanobot availability.

The snakebot is supported by a multitude of nanite-controlled birds which act as its spies. The controlled birds act naturally as far as possible, and each bird stays within its species' natural range. They will not attack and neither will they defend themselves from attack beyond those attacks or defences typically used by their species. However, they are able to observe the preparation of human defences and the Snakebot of Doom is able to act on this intelligence, if necessary by destroying the defended area with its stand-off railguns instead of simply flattening the area.

Prior to commencement of the attack, the snakebot's nanites have also tapped into the public internet, however, they cannot rapidly decrypt secure communications, not being equipped with quantum computers (unlike their military nanite brethren, which were not deployed on this mission).

Using this information, the Snakebot has been tasked to destroy all human infrastructure significantly more advanced than a shack or a tent, and to defend itself against counter-attack. Its target priority is to attack targets in the most militarily-capable areas first, prioritizing command and control and nuclear stockpiles.

It is not interested in exterminating humanity. Individual humans are of little interest to it unless they are counter-attacking with any effectiveness, at which point the snakebot will simply eliminate the threat in the most expeditious manner possible given its options. However, neither will it attempt to preserve the life of humans or any other species.

If damaged, the snakebot's controlling nanites will use whatever materials available within the machine's structure and in the environment to effect repairs. The snakebot took around ten years to build beneath the Antarctic ice-cap, and the time to repair damage can be expected to be roughly inversely proportional to the amount of damage - the more damage, the more nanites will be required to repair it, and conversely the slower the repairs will be. Relatively minor damage can be expected to take as little as a few hours, and major damage such as the total loss of one reactor can be expected to take many months to a year or more.

When the snakebot has destroyed all modern human infrastructure (i.e. anything more advanced than a shack or a tent), or it is incapacitated to the point where it cannot continue its mission at all without first effecting repairs, the snakebot and all the engineering nanites on earth, including those controlling birds, will self-destruct. Don't worry, the birds won't be significantly harmed by their controlling nanites, either while being controlled or when the nanites controlling them self-destruct.

Any nanites captured by humans will self-destruct, of course.

The question:

Given the entire military and civilian resources of the modern world (like we wouldn't unite to get rid of this thing) , how can the Snakebot of Doom be defeated, or are we destined to be reduced to living in crude lean-tos and tents until we can rebuild our civilisation?

Please remember that we're talking about the modern age. While the Snakebot of Doom has fusion reactors, We currently don't.

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    $\begingroup$ I liked the other one better. Simply disappeared into a molten mass of rock... $\endgroup$ Mar 3, 2016 at 4:10
  • $\begingroup$ This really did not change the situation at all.The question really is: Is its anti-missile/projectile defense infallible? Yes, then it's invincible. No, then it's just a matter of how many missiles/bombs/nukes/rail gun hits/rods of god/... we need to melt through the whatever-many-meters of armor the current version is supposed to have... $\endgroup$
    – fgysin
    Mar 3, 2016 at 13:24
  • $\begingroup$ Find the inventor a few years earlier an offer him a fortune if he would use is inventions of fusion energy, and incredibly complex self replicating namomachines to help humanity rather than making really huge really scary snake mecs. $\endgroup$ Mar 3, 2016 at 18:25
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    $\begingroup$ If the nano machines can build more of themselves and giant snake robots what makes you think they only built 1 giant snake robot? Food for thought. $\endgroup$ Mar 3, 2016 at 18:28
  • $\begingroup$ @sdrawkcabdear the fact that this nano machines will have an hard time just to build one giant snake robot. After all, they need raw material anyway $\endgroup$ Mar 3, 2016 at 21:43

10 Answers 10


Liquid Oxygen.

The foamed magnesium inside the snakebot is insanely flammable, so dousing the snakebot with tankerloads of LOX will make any open spark or flame ignite whatever is flammable. Depleted Uranium is also flammable, (indeed, when used as an APDSFS round in a tank it is "pyrophoric", in other words will spontaneously combust under the heat of friction and the presence of oxygen as it passes through the enemy tank).

Even dropping large tanks of LOX near the snakebot and allowing them to burst open and radically increase the amount of oxygen in the local environment, followed with hard impacts against the outer surface of the snakebot should start raging fires. (Since you have continually upgunned the snakebot I'll respond by having the US Navy shooting at the snakebot with their 64mJ railguns, under the cover of a rain of "Sunburn" mach five anti ship missiles and the usual hailstorm of conventional munitions). If the snakebot is ingesting the oxygen enriched air, then fires shold be induced within the magnesium interior structure as well.

USS Zumwalt


enter image description here

Tell the Earth Defense Squadron to bring marshmallows....

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    $\begingroup$ Also: you cannot stop the liquid to hit the snake also if you hit the oxygen tank, so all the snake weapons are basically useless. Nice idea $\endgroup$ Mar 3, 2016 at 15:49
  • $\begingroup$ The interior is sealed - you'd have to crack open the armour - at least ten metres of it - to get any gas inside, let alone enough to make it burn. Uranium is only pyrophoric when finely divided, not in it's bulk form. Apart from that, it won't really care much about a fire. It can roll like anyone else if necessary to extinguish one. besides, how do you know what's inside it? You could speculate from its size and mass, but it might be something else. $\endgroup$
    – Monty Wild
    Mar 3, 2016 at 23:18
  • $\begingroup$ You stipulated what is inside, and f course if the snakebite is consuming materials to create more ammunition, then it is not sealed from the outside environment. $\endgroup$
    – Thucydides
    Mar 4, 2016 at 1:12
  • $\begingroup$ @MontyWild I suppose some tankers of Fluoroantimonic acid can do the job. $\endgroup$ Mar 4, 2016 at 9:01
  • $\begingroup$ @Thucydides, you mean, the snakebot is not sealed the way our bodies are not sealed? We eat things, and technically what we eat remains outside until absorbed, and what is not absorbed has never been "inside" at all. The snakebot works the same way. $\endgroup$
    – Monty Wild
    Mar 6, 2016 at 23:41

You might just want to write off one continent, say South America.

This is clearly not optimal, but would seem to work pretty well in terms of preserving the rest of the planet.

You have not specified just how fast the SOD moves, and even suggested that it will move most quickly when rolling itself along like a giant hoop. Let's take 100 mph as a starting point. You have also suggested that the SOD destroys buildings by rolling over them. This limits its destructive footprint to a track no more than 446 meters wide - call it 1/3 mile. Then it will take about 1200 days, or nearly 3.4 years, to cleanse an area of 1 million square miles. South America has an area of about 7 million square miles, and a worst-case time of about 24 years to scour the entire continent clean. During this time, teams of combat engineers will be building sacrificial structures in the cleared areas, requiring a repeat visit. Done properly, the SOD can be led by the nose, around and around the devastated region, condemned to a never-ending mission of futility. Applying a bit of analysis to determine the SOD's targeting priorities, I suggest that the SOD can actually be confined to a much smaller area, effectively tracing out a repetitive loop.

The actual resources required will actually be smaller than you might think, since it's not necessary to produce urban concentrations of structures. A few large, flimsy (that is, cheap) widely-spaced structures will do the job as long as there are no alternatives nearby.

And, of course, these sacrificial structures will make excellent testbeds for the latest ideas in booby traps.

  • $\begingroup$ It won't start with south America, it'll probably start with the White House in Washington DC with a large railgun submunition round by surprise if at all possible, and then reduce the continental US. Remember, it's prioritising command & control and nuclear stockpiles in the most militarily capable areas first. There's time after the militaries of the world are reduced to flatten the rest of the world's infrastructure. $\endgroup$
    – Monty Wild
    Mar 3, 2016 at 23:00
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    $\begingroup$ @MontyWild - Then obviously is starts with 16 nukes in North America. 2 weeks later, another 16 in Europe and Russia. In both cases it uses staggered launches to produce TOT (time on target) delivery. Being a snake form doesn't seem to affect things much - the nukes do all the work. $\endgroup$ Mar 3, 2016 at 23:09
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    $\begingroup$ Maybe not all sixteen nukes. Perhaps ten to twelve. It'll keep a reserve for emergencies. $\endgroup$
    – Monty Wild
    Mar 3, 2016 at 23:17
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    $\begingroup$ Boot 'em, don't piss on them. $\endgroup$ Mar 3, 2016 at 23:22
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    $\begingroup$ Good idea to write off one continent. Pity it's going to be North America. $\endgroup$
    – a4android
    Jul 25, 2016 at 9:02

It is worth noting that any “guidance” feature I can immediately think of that would be feasibly mountable in the railgun rounds isn’t going to functionally work, given their collosal momentum in their given direction, and the fact that they are most likely surrounded not by a shroud of air but rather rapidly expanding plasma.

Feasably, as noted by fgysin ‘s answer, this really just depends on how ‘hax’ the interception accuracy on the railgun batteries are, and whether it can reconfigure where on its body they are located in a pinch (because, all things considered, you only have roughly half of them available at any given angle, since half the snake roughly ground facing and is circular).

With this in mind, you can decide how effective each of these are (in hindsight, they're all kinda just brute force methods, really, you should combine them with more rigid overall strategies):

Saturation (least feasible, AKA distract and bash)

Plain and simple, shoot enough things that you lower the ammo supply enough that it has to be picky with its targets, also hopefully inflict some minor damage and get it to retract its sensors. Then do some pattern bombardment with ICBMs. Bonus points for trying to disable the smaller rail systems with smaller arms fire to slow down the intercept rate (e.g. .50 cals, Autocannons etc.)

Primary con for this one is that any force that large outside of a dedicated air assault would most likely be spotted ahead of time by birds and would then eat a 80 MT warhead. Whoops.

Blind and Bash

Sort of works like the saturation method, except a lot less threatening. In this instance, you pretty much just have your aircraft with powerful radar systems just beam active all over your snake, functionally covering it in radio noise. This approach also involves shelling it with flare shells/munitions all around and covering the thing is smoke with a similar method. Don’t forget heavy audio shrouding and some suicide vehicles just blasting out gamma radiation.

Oh yeah, then pattern bombardment with nukes.

Bonus points for having some dude playing guitar on the back of a truck with megaphones, and having one of your gamma sources on the truck. Also bonus points for adding a transmitting radio telescope to the mix.

Primary con is pretty much the same as the first one. But really, once the snake is blind, you’re mostly good to go to town on it. Actually, just covering it in smoke might be sufficient. Radar doesn’t go too well through it and lidar well, really much either. But the other approach is much cooler. There’s arguably a more efficient way to do this one.

Just wait until its like, in a 500-600 deep body of water and just go to town with your nuclear arsenal.

Seawater works better here.

Edit: Dangit, you beat me to it while I was doing the writeup. Well, you do the deep water scenario here, but it could arguably work at shallower distances.

See, seawater has the nasty habit of pretty much hard blocking all of your snakes detection systems with only like, 20 m of depth. Has the bonus of making the shockwave potentally a lot more ruinious on your megasnek as well. Oh yeah, also railguns don’t work too well when they’re submerged, for a few reasons (conductive medium between the rails means you can’t build up as much potential charge, and y’know, shooting through water sucks), and rearing its head up out of the water probably ain’t going to give it enough shooty to intercept enough of your warheads. Not that it should really know they’re there.

Not saying it’d be impossible to avoid, given our snake has magical bird spies that wouldn’t feasibly be able to communicate with it in this instance anyway (at least, not fast enough to communicate about the ICBM launches). Digging itself deeper might feasibly work if it finds out in time and the terrain permits, probably would work better than the "shoot down the mach 25 icbm warheads with the few railguns it can bring to bear".

There’s a kinda obvious con in that well, you just covered a huge swathe of water in a pretty much yet unprecedented amount of nuclear fallout. Snake is possibly dead, but good job pretty much ruining a potentially huge part of our biosphere. Also, giant nuclear tsunamis, huge amount of nuclear fallout into the superstream, earthquakes etc. But they’re kind of shared between all the methods.

Snake has also had at-least 20 years to think about this however, so it's probably going to try the smart thing and pretty much cover any distance it travels underwater via the north polar cap, which slows it down, but leaves it near undetectable until it emerges on land, where it's safe.

Also, getting all nations to agree to such heavy nuclear bombardment is somewhat questionable. Also applies to all answers. After this, it just comes down to whether the firepower is enough to disable/destroy, and I don't specifically know that.

Other method.

While the snake is on its military destroying spree, find and hire a huge number of graphic designers (ideally some of which are the type that are extremely proficient at physically drawing technical documents, just in case snake decides to do some EMPing everywhere, or y’know, power goes out during later phases), give them the tools, and make a codex of advancing human technology (from basic stuff to maybe early digital age computing equipment, including stuff like mining and refinery equipment and whatnot) in physical books form.

Books aren’t exactly more complex than a tent, but if the snake calls bullshit, just make it in single pages. Anyway, print off dozens of copies and distribute them across the globe.

If you need more time, use the dummy structure/escaping plane/chase the space station method to buy yourself more time.

Once the snake kills itself, use your new codices to develop societal equipment and mechanical equipment again at an unprecedented rate, use your extremely high technological base to build your country’s population, and restabilise world order. Bonus points if no one else thought of this and you can come out even better than you were before the snake invaded.

Blamo, steam/diesel punk setting where humanity is searching for knowledge documents that hold the key to the digital age they were in only a few generations ago. Really, given that the snake isn’t really just burning everything, all the library resources collected by humanity over the ages would still be there, you’d just need the starting farming equipment so you can self-sufficient enough that society can start searching and expanding its manufacturing and tech base.

Okay, that's a little out of the scope of the question there, but it's a reasonable method for coming out on top after snake encounter.

Also off topic a little, but why not use nanobot spies in ordinary people as well if they can function well in birds. You already can have them in birds, so why not chicken, total global saturation (well not really) of nanobot spies (after they're eaten).


The biggest hole in the Snakebot's defences is that they are all open-air weapons. If you can catch the thing while it's traversing the deep sea floor, you could use nuclear depth charges and pound it into rubble before it could stick enough of its body up above the surface to defend and counter-attack.

Of course, it would only spend a lot of time on the deep sea floor if it was trying to be sneaky, probably on its way from Antarctica to its first target (probably Washington DC to decapitate the US government, unless it reckons that another country is more militarily capable). Once it began its attack, it would likely cross open water via shallow sea routes so that it could more readily defend against an attack at those times. Still, there may be times when it can't do that for whatever reason. It may be possible to force it into bypassing a logical safe sea route by the expedient of mining it or its approaches, forcing it to stand off and traverse the sea by a deeper route.

A mistake that a lot of the people posting answers to this question seem to have made is assuming that Big = Dumb. This thing is as smart as a whole army of humans, and it has spies everywhere, flapping around being birds and watching everything that birds can see, as well as tapped into the internet and broadcast communications. Whatever you do to defeat it will have to either beat its reaction time, which is pretty good under most circumstances, or be unanticipated by enough of the committee of nanobots that run the snakebot that the rest dismiss the possibility as too unlikely to worry about given its current operational constraints.

Also, it isn't advertising that it has bugged the world's birds. The birds will behave naturally as far as practical, they might just spend a bit more time looking at humans than they previously did more than ten years ago when the nanobots began to bug them. What humans really pay serious attention to what a bird looks at if the bird doesn't bother them and doesn't act unnaturally? Since the nanites self-destruct harmlessly if a human examines a bird closely enough, it is unlikely that they'll be discovered.

Hence, the best chance of destroying the snakebot after it has begun its attack is to force it via nuclear land/sea mines in shallow areas such as the Bering Straits to traverse deep ocean such as the North Pacific, then to depth-charge it, given that it must raise an extremity above water to counter-attack.


Since the snake points to the military base, all we need to do is:

  1. Prepare a bait with some nukes along the path of the snake
  2. Move all the ships (and submarines) which had nuclear weapon at the extreme range of its weapon
  3. Wait for the snake to be near (or over) the nukes

At this point detonate the nukes, than fire the weapon from the ships and finally after 20 minutes fire the weapon from the submarines.

Since the first wave of nuke probably will do some damages (after all they are at nearly point blank range), the other two waves probably are sufficient to destroy it or to make so much damages that then you can simply destroy it with conventional weapons.

Also, since the snake is probably slow, it probably be vulnerable to kinetic weapons, like the impact of objects (tungsten rods ? Lead/Mercury rods ?) dropped from very high altitude, outside the range of its point defense.

Aside the problems noted by Thucydides in his answer, you still have some pretty basic problems.

Where to get all the depleted uranium (and all the other materials) you need ?
Earth as probably some tens of million tons of uranium totally, you are speaking at least of hundreds of million tons. And most of it is extracted (at a rate of about 50.000 tons/year) in country like Canada, USA and Russia and Australia, which I am pretty sure will note that all their uranium disappeared.
Given the density of Uranium, if your nanites could match the current production of uranium, you are producing just about 2600 m3/year. Given a 14 meters thickness, also if only half is uranium, you still have that a section of the armor of 1 meter length is about 18990 m3, so you need about 7 years to extract the material to build 1 meter of the snake. And no, you cannot produce it by fusion, since also stellar core stop it's fusion process when it produce iron and the heavier elements are produced by a supernova.

Build it in Antarctica
Antarctica is isolated (not really) and has nothing more that water. So you have at least two more problems: how your nanites will spread and how do you hide that you are building some really big mining factory ? Also, Antarctica, while isolated, is not really abandoned and I have no doubt that such a activity will be hidden for so much time. Basically your snake will probably be destroyed long before it could be operative.

Wrong starting point
From the Antarctica you have three choices as first target: South America, South Africa and Australia, each of them are a good terrain for defense and you need to go swimming to reach everyone of them. Since the only realistic starting point is South America (it is the nearest to Antarctica), the snake has to handle the Andes, which make the snake really vulnerable and the attack simpler: also with all the snake's weapons there are still the mountains to make a shield. Also, how a such massive thing can ascend from the ocean floor once it left Antarctica ?

The snake will run out of ammunition
At this firing rate, you fire about 4*10^9 kg of ammunition in one minute, and the snake need to replace it rebuilding it. So it must consume the equivalent material every minute or shutdown some (if not most) of its weapon. Not considering the problem to move all the ammunition inside the snake.

It is still too heavy
While 13 MPa can be the max pressure, as I seems to understand just 4.3 MPa can be way too much if "the German WWII Maus tank had a ground pressure of merely 0.14MPa, and it quickly sank into the ground during its field trials" like reported from March Ho in his answer. And while you are in the range of pressure of a woman running in stiletto heels, you must consider the ground: on asphalt it is true that you don't sank, but on a softer ground you sank very fast.
And you have the problem to move on ice: it harder than grass ground and somewhat softer that asphalt, but melt under pressure (the basic principle of the ice skates)

  • $\begingroup$ i dont really think it would want to constantly fire all of its weapons at full auto, constantly. the idea of using nuclear mines to incapacitate the snake might still work, but it would still be mostly immune to missiles afterwords, so shooting it wont be that much more effective. $\endgroup$ Mar 3, 2016 at 16:47
  • $\begingroup$ @DuncanUrquhart True, but in a combat situation, you probably fire way more than one minute, considering that it should be really simple to make the snake fire to dummy target. The nuclear mine have the only objective of incapacitate the point defense of the snake, with the added bonus of a powerful EMP that can effectively blind it to the next attacks. Once you pearce the armour, the snake is done. $\endgroup$ Mar 3, 2016 at 20:57
  • $\begingroup$ Beneath the Antarctic ice is land full of minerals. The snakebot doesn't autofire much, it aims, so it wouldn't expend nearly as much ammunition as it could if it just opened up indiscriminately. All that firepower is to prevent time-on-target point-defence saturation. And yes, it's heavy - it's intended to rip up the ground and smash any buried installations. Finally, if you bury nukes in its path, and any birds saw you do it, kiss any chance of that ploy working good-bye - it'll flatten the area with heavy sub-munition railgun rounds or even a nuke rather than go anywhere near it. $\endgroup$
    – Monty Wild
    Mar 3, 2016 at 23:11
  • $\begingroup$ @MontyWild Yes, but it is nowhere near to what (and how much) it is needed to build the snake. The main resources are coal and iron ore inshore, oil and gas offshore. The weight is the weak point, IMHO. None of the material you use can withstand such massive structure. And the bugged birds aren't everywhere all the time $\endgroup$ Mar 4, 2016 at 8:45
  • $\begingroup$ @Gianluca, I think you're right about the weight and the bugged birds. $\endgroup$
    – a4android
    Jul 25, 2016 at 9:05

EMP from over the horizon and blind it,

The EMP blast from a nuke can extend beyond the horizon ( the snake can't intercept it because the earth is in the way). The EMP might not penetrate the meters of armor, but who cares.

It will fry the electronics near the surface, which are all the sensors. The snake will be blind and unable to intercept missiles or spot its opponents to shoot them. Then just nuke/bomb it into oblivion. As an added plus it will fry all the nanobots in the area to stop/ slow the repair process.

If you want to be careful do it with three surface skimming nukes. One emp at 80 miles out to take down the nanobot probe birds that might spot the next one. The second at 30 miles to blind the snake and a third to kill it.

It is possible to shield electronics from EMP but doing it well requires wrapping them in solid layers of conductors to create a faraday cage. The really hard part is protecting sensors (cameras, missile guidance systems, gps) which have to be on the outside.

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    $\begingroup$ The nanobots (which run the snakebot and have secretly hijacked the birds) aren't electronic, they use rod logic, and are EMP-immune. There are lots of backups for EMP-sensitive sensors, which can be deployed pretty rapidly. Nice try, though. The third nuke would be killed before detonation. $\endgroup$
    – Monty Wild
    Mar 3, 2016 at 23:14
  • $\begingroup$ Why not run the entire snake on rod logic if you have it? It also would be possible to plant a nuclear mine in its path. $\endgroup$ Mar 3, 2016 at 23:43
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    $\begingroup$ The whole snakebot is run by its maintenance/construction nanobots, which use rod logic. As I mentioned in a previous comment, planting a nuclear mine will only work if no bugged birds (most of them after ten years of infiltration) see you do it and if its radiological sensors don't detect it. Otherwise, the snakebot will stand off and use its other weapons to destroy the area. $\endgroup$
    – Monty Wild
    Mar 4, 2016 at 0:29

1) Nuclear land mines. Yes, it's spies will tell them where they are but it has no weapons that can dig them out unless it's just about on top of them--but at that point an observer pushes the button. Knowing where they are they don't pose an actual threat but they can contain it if you emplace a ring of them around it.

2) Now that you have it pinned you call in NASA. Grab a whole bunch of nukes and head for the asteroid belt. You want a very solid asteroid (stony iron or something more metallic if you can find it) probably something around half a mile across although just how big depends on exactly how tough the snake is.

Build a base dug into one side of the asteroid, gently lob nukes around to the far side and push the button. Do it right and you can get something like 10% of the bomb's energy into motion--your asteroid will move. Take the asteroid well inside Earth's orbit, approach from as close to the sun as you can. Line up on the snake, the crew will bail at at the point where their rocket can push them 4000 miles before the impact.

The snake's spies don't operate in space, such a rock is basically undetectable by modern technology and you didn't specify any super telescopes--the snake won't see the rock until it touches the atmosphere and there won't be anything it can do about it at that point. It's defenses are formidable but they can't stop the huge energy of the rock.

The rock I'm using isn't big enough to actually smash the whole snake because a rock of that size would be pretty bad for humanity (It would rival the dinosaur killer.) However, it will cut the snake in two and the parts will be devastated--the snake can be finished off with nukes.

  • $\begingroup$ If the Anti-Snakebot asteriod impactor rivals the KT dinosaur killer its velocity will be of the order of 50 km/sec, so how long will it take to travel from the asteroid belt? Because that's how the Snakebot has to sit in the target zone. Pity if it moved. Also it will take time for the NASA mission to get the asteroid in the first place. Mmmm. $\endgroup$
    – a4android
    Jul 25, 2016 at 8:56
  • $\begingroup$ @a4android That's why you contain him with nuclear land mines. $\endgroup$ Apr 18, 2017 at 23:39
  • $\begingroup$ Allowing for the distane from earth to the asteroid belt ranges between 1,2 to 2.3 Astronomical units (AU). Assuming a two AU killer asteroid moving at 50 km/s, means it will take 72 days to arrive. Add another 72 days for the NASA asteroid deflection team to get out there. That's a minimum time of 144 days to contain the Snakebot. Bring on your artillery & nuclear land mines answer. Although if you had to destroy a Snakebot of Doom a killer asteroid is the way to do it. Doubt if it would be practical (sadly). My estimates are very optimistic. $\endgroup$
    – a4android
    Apr 19, 2017 at 7:53

An approach so different I decided to make it a separate post:

Contain the snake with nuclear mines as in my other post. Now, gather the world's supply of artillery. The snake can stop at best 13,000 shells/second (and in practice I don't think it will get 100% accuracy.) The massed artillery of the world can lob more shells than that. Now, conventional artillery isn't going to do a lot to the snake but all we need is to knock back it's defenses. Observation posts can locate the guns, start mixing in nuclear shells. Some will no doubt get picked off but some will get through and each round that gets through takes down a gun. Each gun that you take out makes the rest easier targets.

When you manage to clear the defenses from an area you bring in the big booms with the specific objective of carving a hole in the snake. Once you have managed to cut through the armor you aim your nuclear missiles inside the snake. That super-tough armor will contain the blast nicely--it will devastate the snake. While it's unlikely to finish it off it will make it easy to get another through.

Given the nannite nature of the snake it's probably impossible to truly kill but you can keep destroying any attempt to rebuild.

  • 1
    $\begingroup$ This is a distinct improvement on the killer asteroid plan. $\endgroup$
    – a4android
    Jul 25, 2016 at 8:58

In my opinion this really did not change the situation at all compared to the first questions.

The question really is: Is its anti-missile/projectile defense infallible?

  • Yes, then it's invincible.
  • No, then it's just a matter of how many missiles/bombs/nukes/rail gun hits/rods of god/... we need to melt through the whatever-many-meters of armor the current version is supposed to have... And trust me we have enough of them stored on the planet (and can probably produce them faster than we can fire them at this thing...).
  • $\begingroup$ However, it is not suggested that unobtanium is being used. The mechanical shock and radiation pulse, not to mention EMP, are likely to do bad things to the internal mechanisms and electronics. You don't have to melt a tank to stop it for instance - just blowing its tracks off works fine. That's not to say the SOD has tracks, but the principle is the same. $\endgroup$ Mar 4, 2016 at 1:05
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    $\begingroup$ Of course, it'll probably be even easier... It's just that so far this seemed like one of those primary school my-monster-vs-your-monster contests "No, but you know, my monster also has anti-nuke railguns! -- Oh, in that case, my monster...". $\endgroup$
    – fgysin
    Mar 7, 2016 at 6:59

Simple; hack the nanites.

Quote OP: "Prior to commencement of the attack, the snakebot's nanites have also tapped into the public internet, however, they cannot rapidly decrypt secure communications, not being equipped with quantum computers (unlike their military nanite brethren, which were not deployed on this mission).

Using this information, the Snakebot has been tasked to destroy all human infrastructure significantly more advanced than a shack or a tent, and to defend itself against counter-attack. Its target priority is to attack targets in the most militarily-capable areas first, prioritizing command and control and nuclear stockpiles."

If it can't rapidly decrypt secure communications, that means it can't quickly fend off a hack attempt, and that means it's possible to hack it. Granted, it will be difficult; this thing has advanced technology. However, the fact that it can interpret Internet code means it can be targeted or otherwise affected by viruses.

Since this thing is actively trying to break into and decrypt information in secure channels, its effectively attacking government software, and this will be recognized and reacted to As Fast As Possible. It shouldn't take long to connect the dots ("Mr. President! A giant snakebot is rolling toward the White House! Mr. President, our computer experts report a massive cyberattack! We have no idea what-wait, did you say giant snakebot?") and figure out a solution.

They don't even need to hack it; we just need two groups of coders, one to block and deter the snakebot's cyberattacks, the other to reconfigure the software so when it does break through, instead of the valuable information it wants, it gets cleverly designed clickbait absolutely loaded with malware. In other words, instead of finding water, it'll set off a bomb.

The viruses thus "absorbed" into the snakebot should allow the techies to do one or more of the following options:

  1. Gain access to the snakebot's software

  2. Gain "feedback" from the snakebot, allowing the techies to analyze its destructive capability, discover its mission, and know its location at all times

  3. Cause the snakebot to blow itself up, overload its circuitry, or become confused on what its mission is (or how to fulfill it)-basically, alter and/or break the code

  4. Change the snakebot's mission

If that doesn't work, this thing has nukes; a well-timed shot or well-placed bomb could blow up a Snakebot nuke and by extension, blow up the snakebot. An EMP could work as well, I'm not sure (you didn't account for nukes in the OP).


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