High Explosive Alternatives to Nuclear Weapons

[Vrock_Summoner]

So, while this is related to a tabletop game I'll be running, it's primarily a scientific question, ergo why I'm posting it in this section.

In the source material the game is based on, antimatter (specifically positrons) has been weaponized to a large degree. The narrative purpose of this (as well as the in-universe reason for the heavy focus on its development) was clear, in allowing warheads with the output of small nuclear weapons to be dropped on or near parts of an evacuated city without rendering the whole area inhospitable due to lasting radiation or totally frying electronics throughout large sections of the city.

In altering parts of the setting of my game to bring them more in line with realistic and modern (if not necessarily practical) scientific constraints, I'd like to do away with this element of humanity mastering antimatter. On the other hand, that leaves the issue of filling the narrative shoes of those weapons. These antimatter weapons were designed under the specific constraint of "a nearly-indestructible target (conventional missiles and explosives typically having no effect whatsoever) at least the size of a skyscraper and potentially larger is probably in or near the outskirts of this city, assuming our primary line of defense fails, we need to blow it the hell up in a short time-frame without totally sabotaging our ability to deal with the next one of these targets."

So within that constraint, and with a fifteen year timeslot for development (ideally starting from the technological capacity of the year 2,000, but I can handwave it if you make more modern assumptions) what kinds of alternatives could we come up with? In this case, worry more about scientific and time-based plausibility than practicality - the nature of the threat is such that allowing any of these targets to reach their goal (a bit underground from the center of the city) will more or less trigger an extinction event for all life on the planet, so humanity isn't sparing many expenses.

Feel free to ask any additional questions about the scenario if necessary, but I'm pretty sure this covers all the prudent information and I didn't want to bog this down with irrelevant setting information since I care most about the science part.

[factotum]

There have been real-life conventional explosions that have come close to nuclear blasts in terms of size, you might want to start looking at those? I'm thinking of the Halifax Explosion of 1917 (estimated at around 2.9 kilotons), the Heligoland explosion of 1947 (deliberate attempt to destroy the island with high explosives, estimated at 3.2 kilotons) or the PEPCON disaster of 1988 (several separate explosions, of which the largest was estimated at a kiloton). You can actually see video footage of that last one taken from a nearby mountain, do a quick search on Youtube.

However, all of these were either explosions of large amounts of static material, or a ship's cargo going up. It would be difficult to see how you would deliver the required amounts of explosives if you wanted to set off an explosion like this in a mobile way, unless you were to deliberately crash something like a Saturn V onto your target--the Russian N-1 rocket that blew up on the launch pad gives an idea how potentially catastrophic something like that would be.

As for the only other option, which is creating significantly more powerful chemical explosives, it ain't going to happen. Any chemical combination that would yield significantly more explosive yield than the explosives we already know about would be too unstable to be usable, in the same way that pure nitroglycerin is more explosive than the dynamite you make from it, but will blow up if you hit it, or shake it, or tread too heavily on a floorboard vaguely near it, etc.

[Lord Torath]

The reason they call it a 5 mega-ton blast is because it's equivalent to 5 million tons of TNT. As Factotum says, there's really no way for a controllable chemical reaction to reach those levels of energy and still fit on the top of a rocket. Kinetic weapons (Thor strikes from orbit?) are a possible replacement.

[gomipile]

In the absence of N² mines, yeah, kinetic bombardment with telephone pole sized tungsten rods dropped from orbit sounds like your best bet.

There's no problem with tech levels, either. We've been capable of deploying orbital bombardment weapons like this for a long time. The technology to make them super effective and accurate has been in use by major militaries since the mid 80s. That is, GPS and solid state gyroscopes and accelerometers.

[factotum]

The "rods from the gods" aren't actually all that powerful, though, if you look into it. For instance, the tungsten rod that was planned to be used for that weighs about 9 tonnes (20 feet long by 1 foot wide), and when impacting at Mach 10 or thereabouts (it inevitably loses a lot of speed coming through the atmosphere) would hit with a kinetic energy equivalent to about 12 tonnes of TNT. You could quite easily create a conventional bomb that size, so the only reason for using the orbital bombardment approach is in situations where the enemy has significant enough air defences that the very high speed of the rod becomes important (since an anti-air missile ain't hitting a target travelling at mach 10 no matter how hard you wish it will).

[halfeye]

My first thought is that you are wrong about anti-matter detonations being radiation free, they won't be, there will be radiation all over the place, just like from nuclear fusion. What there won't be, is left over warhead, such as you get with nuclear fission.

Black hole bombs likewise, all that energy comes out as radiation, heat, light, x-rays, gammas, alphas, betas etc.

[Strigon]

The "rods from the gods" aren't actually all that powerful, though, if you look into it. For instance, the tungsten rod that was planned to be used for that weighs about 9 tonnes (20 feet long by 1 foot wide), and when impacting at Mach 10 or thereabouts (it inevitably loses a lot of speed coming through the atmosphere) would hit with a kinetic energy equivalent to about 12 tonnes of TNT. You could quite easily create a conventional bomb that size, so the only reason for using the orbital bombardment approach is in situations where the enemy has significant enough air defences that the very high speed of the rod becomes important (since an anti-air missile ain't hitting a target travelling at mach 10 no matter how hard you wish it will).

There are a lot of advantages, though; the first is the fact that the rods are a lot more dense, meaning you need a much smaller fairing for the size of the explosive. Also, if you go for a steep enough trajectory, you could easily have a small terminal stage to overcome much of the atmospheric drag; moving at mach 10, it would take ~30 seconds or so to hit the ground from the upper edge of the atmosphere, and most of that would be in the last five seconds. Having a powerful booster working against the atmosphere for five seconds is very doable, and would be a massive improvement. It's actually even better than that, since it would be going faster at first, so the burn time would be even shorter.

If you make it very accurate, it's also a lot more precise; it will never detonate early, and it projects its force very efficiently into whatever it hits.

Depending on how much hand-waving you're willing to do, a series of massive orbital installations that fire railguns could work, too. An osmium core coated with tungsten would increase its density by a bit, increasing its impact velocity even further. If you don't think they'll be used very often, you could easily scale them up as big as you like, within reason, while having a corresponding increase in damage dealt.

Then, if you're really going crazy, invent a stable super-heavy element; some of them are predicted to have densities almost twice as great as osmium, which is more than enough for almost any purpose you could imagine.

This weapon, however, would be simultaneously:
1) Very, very expensive. It could be cut down quite a lot by having only one, and waiting for an appropriate time to strike, but we're still talking about a military space station. Rough figures talk of the ISS costing $150 billion. This price would probably double or triple, at least, to build the weapons and defenses it would need - because, honestly, why would you build something like that if it's as fragile as the ISS? All in all, we're talking the entire US military budget for a year going into this one weapon. Chances are it's not going to be just one country building this, which means a lot of red tape for using it. Plus there's the costs of maintaining it, which I can't possibly predict, but would probably be even more costly in the long run.

2) A huge target. Having a weapon like that is equivalent to having a nuclear arsenal in terms of the power it grants you. Naturally, any nation that could possibly fund such a weapon could also have nukes without any issue, but the nice thing about nuclear weapons is that you don't have all your eggs in one basket. Crippling a country's nuclear capabilities quickly is next to impossible. Taking down a giant space station is not.

3) A massive responsibility. This is a weapon that could strike anywhere on Earth, with the power of a nuclear bomb, possibly without being detected and definitely without being intercepted. Any warning you would have would be even less than for an ICBM, which means you could remove any target, at all, with complete impunity. At least once.

4) Ridiculous. This is a Star Wars or Ace Combat type superweapon, that's very cool, very powerful, and very impractical. Having something like this in a setting lends it an air of heroic myths or legends, no matter how plausible you make it seem. This can be good or bad, depending on the tone you choose.


So, if you're looking for things that are physically possible, and you're willing to hand wave away political or economical issues, a number of Rods From the Gods style installations will serve your needs quite well. If not, then your conventional weapons means are very limited. Probably best to just make something up that incorporates Fluorine; it's a nasty enough substance that, as long as you don't have any actual chemists in your audience, people should be willing to accept it as a ridiculous yield high explosive.

Edit:

My first thought is that you are wrong about anti-matter detonations being radiation free, they won't be, there will be radiation all over the place, just like from nuclear fusion. What there won't be, is left over warhead, such as you get with nuclear fission.

Black hole bombs likewise, all that energy comes out as radiation, heat, light, x-rays, gammas, alphas, betas etc.

Yeah, but there isn't any fallout, which is what I think the main concern was. Sure, you have a nasty burst, but a decent distance will mitigate the risk nicely. Not like a nuclear blast, where there's radioactive material left about getting blown for potentially hundreds of miles, polluting the area for years and years.

[Lvl 2 Expert]

Similar to the rods from above you could have railguns. Similar (very loosely speaking) to why electric engines are faster up to speed and need less gears than internal combustion engines, magnetic guns could fire projectiles much faster than explosive powered guns. It'd still require a lot of energy, but there is less of an upper limit, so you can pack a lot of kinetic energy into a single projectile if you're using the kind of cannon that would fit on a decent warship. There are two main drawbacks: one it that any part of the projectile not made of ferromagnetic material, like most explosives, would be dead weight for the launch, so the fastest projectiles are metal only. The second is that these bullets can travel so fast that there is an area behind the horizon you can't properly fire at, because the projectiles are dropping down to earth slower than the earth curves away beneath the projectiles. And adjusting the speed means lowering the impact.

Steam engines have sort of similar properties in this regard as electric ones do by the way, so if it sounds cooler I'm sure you could make big steam guns build on the same principles as those steam catapults that launch planes off aircraft carriers.

Both of these options work best if there's a massive power source nearby, a nuclear reactor for instance would be ideal.

[halfeye]

Yeah, but there isn't any fallout, which is what I think the main concern was. Sure, you have a nasty burst, but a decent distance will mitigate the risk nicely. Not like a nuclear blast, where there's radioactive material left about getting blown for potentially hundreds of miles, polluting the area for years and years.

There's not so much, but there's not none. Ionizing radiation causes radio-activity in previously inert substances. Height above the ground matters, if all that's irradiated is air, nothing much will come of it, but irradiated dirt can be quite nasty.

[gomipile]

The "rods from the gods" aren't actually all that powerful, though, if you look into it. For instance, the tungsten rod that was planned to be used for that weighs about 9 tonnes (20 feet long by 1 foot wide), and when impacting at Mach 10 or thereabouts (it inevitably loses a lot of speed coming through the atmosphere) would hit with a kinetic energy equivalent to about 12 tonnes of TNT. You could quite easily create a conventional bomb that size, so the only reason for using the orbital bombardment approach is in situations where the enemy has significant enough air defences that the very high speed of the rod becomes important (since an anti-air missile ain't hitting a target travelling at mach 10 no matter how hard you wish it will).

What you do get is high energy density, though. It's the same reason the frozen chickens hit harder than thawed chickens, despite identical energies, only even worse.

If you can hit the kaiju (which is similar-to-but-legally-distinct-from an Angel) directly with the 12 tonne equivalent rod, that energy is concentrated on less than a basketball hoop's area. A 12 tonne conventional weapon, on the other hand, will deliver much, much less energy per square meter.

....Wait, I just realized the OP's campaign might be able to get away with giant shaped charges. Basically massively scaled up anti-tank rounds. I guess they could be delivered as giant smart bombs or on massive missiles. They'd still be fairly inefficient in that they wouldn't deliver the full energy content to the target, but a very high energy density could be delivered to a small area on the target, at the expense of a very heavy, carefully designed payload.

[Maximum77]

Antimatter weapons. Gamma ray burst weapons

[Strigon]

There's not so much, but there's not none. Ionizing radiation causes radio-activity in previously inert substances. Height above the ground matters, if all that's irradiated is air, nothing much will come of it, but irradiated dirt can be quite nasty.

Fair play, but it still doesn't really spread. You wouldn't have to evacuate nearby towns, for instance.

[gomipile]

Fair play, but it still doesn't really spread. You wouldn't have to evacuate nearby towns, for instance.

It depends what's near the blast. For example, the underwater Bikini Atoll tests were much, much worse than the air bursts, because they activated the metal ions in the seawater.

[Vrock_Summoner]

Antimatter weapons. Gamma ray burst weapons

The whole thread is about getting away from those because I consider them contextually entirely implausible.

If you can hit the kaiju (which is similar-to-but-legally-distinct-from an Angel)

Not entirely sure the formalities are necessary.

directly with the 12 tonne equivalent rod, that energy is concentrated on less than a basketball hoop's area. A 12 tonne conventional weapon, on the other hand, will deliver much, much less energy per square meter.

Very interesting data. The effectiveness in this case is mostly dependent on whether it can pierce the ATF and still have both the leftover momentum and structural integrity to skewer the target. Explosive weapons were considered effective in that there's no loss in additional energy going from eroding the outer defensive barrier to damaging the target within, so I'm not sure if that issue would resurface for a kinetic weapon of this type. (Like, if the bomb has to expend fifty percent of its explosive energy eroding the ATF, then the target still takes half the energy from the attack in burns, whereas if the "rod of god" expends half its momentum piercing the outer shell, I get the impression it would end up with a lot less than half the piercing effectiveness leftover, not that I'm a scientist or anything.) There wouldn't be nearly enough time for thermal energy displacement to have any meaningful effect on the hit, but maybe some kind of well-timed directed energy weapon fired just before impact, like an electrolaser...?

Edit: I may have completely misunderstood the concept behind a kinetic weapon of this scale.

....Wait, I just realized the OP's campaign might be able to get away with giant shaped charges. Basically massively scaled up anti-tank rounds. I guess they could be delivered as giant smart bombs or on massive missiles. They'd still be fairly inefficient in that they wouldn't deliver the full energy content to the target, but a very high energy density could be delivered to a small area on the target, at the expense of a very heavy, carefully designed payload.

Perhaps!

Similar to the rods from above you could have railguns. Similar (very loosely speaking) to why electric engines are faster up to speed and need less gears than internal combustion engines, magnetic guns could fire projectiles much faster than explosive powered guns. It'd still require a lot of energy, but there is less of an upper limit, so you can pack a lot of kinetic energy into a single projectile if you're using the kind of cannon that would fit on a decent warship. There are two main drawbacks: one it that any part of the projectile not made of ferromagnetic material, like most explosives, would be dead weight for the launch, so the fastest projectiles are metal only. The second is that these bullets can travel so fast that there is an area behind the horizon you can't properly fire at, because the projectiles are dropping down to earth slower than the earth curves away beneath the projectiles. And adjusting the speed means lowering the impact.

Steam engines have sort of similar properties in this regard as electric ones do by the way, so if it sounds cooler I'm sure you could make big steam guns build on the same principles as those steam catapults that launch planes off aircraft carriers.

Both of these options work best if there's a massive power source nearby, a nuclear reactor for instance would be ideal.

Given the resources being dedicated to this, nuclear power is definitely on the table.

There are a lot of advantages, though; the first is the fact that the rods are a lot more dense, meaning you need a much smaller fairing for the size of the explosive. Also, if you go for a steep enough trajectory, you could easily have a small terminal stage to overcome much of the atmospheric drag; moving at mach 10, it would take ~30 seconds or so to hit the ground from the upper edge of the atmosphere, and most of that would be in the last five seconds. Having a powerful booster working against the atmosphere for five seconds is very doable, and would be a massive improvement. It's actually even better than that, since it would be going faster at first, so the burn time would be even shorter.

If you make it very accurate, it's also a lot more precise; it will never detonate early, and it projects its force very efficiently into whatever it hits.

Some very good suggestions!

Depending on how much hand-waving you're willing to do, a series of massive orbital installations that fire railguns could work, too. An osmium core coated with tungsten would increase its density by a bit, increasing its impact velocity even further. If you don't think they'll be used very often, you could easily scale them up as big as you like, within reason, while having a corresponding increase in damage dealt.

Then, if you're really going crazy, invent a stable super-heavy element; some of them are predicted to have densities almost twice as great as osmium, which is more than enough for almost any purpose you could imagine.

The first one seems plausible with a fifteen year development time in mind, I'll consider it. Definitely gonna try not to introduce hypothetical elements.

This weapon, however, would be simultaneously:
1) Very, very expensive. It could be cut down quite a lot by having only one, and waiting for an appropriate time to strike, but we're still talking about a military space station. Rough figures talk of the ISS costing $150 billion. This price would probably double or triple, at least, to build the weapons and defenses it would need - because, honestly, why would you build something like that if it's as fragile as the ISS? All in all, we're talking the entire US military budget for a year going into this one weapon. Chances are it's not going to be just one country building this, which means a lot of red tape for using it. Plus there's the costs of maintaining it, which I can't possibly predict, but would probably be even more costly in the long run.

A multinational construction project introducing red tape that prevents it from being used most of the time is actually helpful from a narrative perspective, in this case.

2) A huge target. Having a weapon like that is equivalent to having a nuclear arsenal in terms of the power it grants you. Naturally, any nation that could possibly fund such a weapon could also have nukes without any issue, but the nice thing about nuclear weapons is that you don't have all your eggs in one basket. Crippling a country's nuclear capabilities quickly is next to impossible. Taking down a giant space station is not.

Certainly a risk to be accounted for, if a target tries to exploit it, and leaves the risk of internal sabotage as well. Most countries probably aren't terribly likely to shoot off humanity's hand while their own lives are at stake, but stranger things have happened.

3) A massive responsibility. This is a weapon that could strike anywhere on Earth, with the power of a nuclear bomb, possibly without being detected and definitely without being intercepted. Any warning you would have would be even less than for an ICBM, which means you could remove any target, at all, with complete impunity. At least once.

Multi-national internal control, which means more red tape and tension. Exciting!

4) Ridiculous. This is a Star Wars or Ace Combat type superweapon, that's very cool, very powerful, and very impractical. Having something like this in a setting lends it an air of heroic myths or legends, no matter how plausible you make it seem. This can be good or bad, depending on the tone you choose.

This is unfortunate, but not unexpected. It's an incredibly specific set of circumstances, so some incredibly specific, somewhat over-the-top weapons are liable to result, which does shift the tone somewhat.

So, if you're looking for things that are physically possible, and you're willing to hand wave away political or economical issues, a number of Rods From the Gods style installations will serve your needs quite well. If not, then your conventional weapons means are very limited. Probably best to just make something up that incorporates Fluorine; it's a nasty enough substance that, as long as you don't have any actual chemists in your audience, people should be willing to accept it as a ridiculous yield high explosive.

Political and economic issues are far from nonexistent, but also not what they would be in real life context, since at this point the U.N. has gained directive power over most of the world's major nations and converted them to an overall war prep economy largely to deal with this future threat.

As far as BSing something with fluorine, maybe, but I'd like to hedge as close to "how humanity might actually respond" as possible that doesn't result in them imploding or not having any real defensive measures to begin with.

[Cazero]

Nuclear fusion bombs.
Radioactivity comes from splitting large atoms and by definition fusion doesn't do that. (I have no idea about what is supposed to happen to the EMP.)

[factotum]

Nuclear fusion bombs.
Radioactivity comes from splitting large atoms and by definition fusion doesn't do that. (I have no idea about what is supposed to happen to the EMP.)

Radioactive elements can be formed by the process of neutron capture, though, and a fusion explosion still generates a lot of free neutrons which can irradiate surrounding soils and get blasted into the atmosphere as fallout.

[halfeye]

Nuclear fusion bombs.
Radioactivity comes from splitting large atoms and by definition fusion doesn't do that. (I have no idea about what is supposed to happen to the EMP.)

Those are hydrogen bombs, and the trigger is always (thus far, new tech like very high powered lasers might make alternatives possible in the future) a fission bomb of non-trivial size, which produce fallout of their own.

[Mando Knight]

(I have no idea about what is supposed to happen to the EMP.)

The EMP is just the product of the unparalleled burst of raw energy caused by a nuclear explosion. A "pure" fusion weapon (as well as an antimatter-based weapon) would cause an EMP just as easily as existing fission-triggered hydrogen bombs.

[zlefin]

you say the target is nigh-indestructible. what are these targets? do they have other active or passive defenses?
when faced with something very tough, often the use of things like high powered drills at point blank can work, if there's no active defenses to deal with.

if humanity is faced with an extinction level threat, accepting the loss of a city seems like a perfectly acceptable outcome; evne the loss of a loto of cities, evne if they aren't yet evacuated. so just use the nukes.

[druid91]

Some variant of the Cassaba Howitzer? It's still nuclear, but it's a focused beam rather than spewing the blast out every which way. Supposedly the Cassaba Howitzer would focus 50 percent of the blast energy on the singular target, the nuclear spear itself would move at an appreciable fraction of the speed of light on a spot not much wider than 0.4 meters. Less efficient IN atmosphere than it is in space but still not ineffective.


In any case, there are a number of fun ideas Here. Though it's a site about writing semi-hard science fiction.

[Vrock_Summoner]

Some variant of the Cassaba Howitzer? It's still nuclear, but it's a focused beam rather than spewing the blast out every which way. Supposedly the Cassaba Howitzer would focus 50 percent of the blast energy on the singular target, the nuclear spear itself would move at an appreciable fraction of the speed of light on a spot not much wider than 0.4 meters. Less efficient IN atmosphere than it is in space but still not ineffective.


In any case, there are a number of fun ideas Here. Though it's a site about writing semi-hard science fiction.

Nice! Thanks so much for the recommendations!

you say the target is nigh-indestructible. what are these targets? do they have other active or passive defenses?

Angels from the Neon Genesis Evangelion series. Their bodies are often fairly durable as well, but the main thing making them near-indestructible to conventional arms is the AT Field, which is hard to describe to someone not familiar with the material but roughly translates to a self-replenishing ambient force field. This ranges in strength from "can be blasted through by the small nuke equivalent and still inflict massive damage to the target" to "yeah we just dropped several on it and it seems okay" to "is that thing incinerating everything around it as it goes or is that just me."

Each target might have a variety of offensive weapons which are nearly impossible to predict in advance. Examples from the series include multiple instances of prehensile melee weapons capable of slicing through buildings, energy cannons able to level city blocks or more, one that dropped itself from orbit to basically become a city-leveling kinetic bomb, a directed-energy beam that passed through a skyscraper that was being used as cover without pausing and left the thing melting behind it, not to mention more esoteric abilities like crying super-corrosive acid, infecting and fusing with machinery and people, and pulling everything within its radius on the ground into a pocket universe. Long story short, preparing for specific offensive abilities is probably a losing game.

if humanity is faced with an extinction level threat, accepting the loss of a city seems like a perfectly acceptable outcome; evne the loss of a loto of cities, evne if they aren't yet evacuated. so just use the nukes.

The thing the Angels are after is underground, very difficult to move, and the city exists pretty much entirely to support the infrastructure dedicated to the immediate defense of that objective. They'll nuke it in favor of the ultimate alternative (indeed, the underground bunker they built around the objective is almost certainly already set up with a nuclear self destruct system as a last resort), but it's in their best interests to be able to maintain their investments on its defense since they'll have to deal with more than one of these things.

Especially since the so-called primary line of defense is here, as well as most of the equipment and materials for maintenance thereof. Those being the clones of the first Angel which were lobotimized, clad in restrictive plates, switched to artificial power, and piloted by fourteen year olds with mental issues (it makes sense in context), all so humanity could at least have something on its side with an AT Field as well to weaken the Angels' Fields at close range through destructive interference. This show is wack, yo.

[zlefin]

makes more sense knowing the show, I'm familiar with it; of course shows generally don't aim to have thoroughly accurate science on their side :P
I'm not sure the particulars of the defenses, in terms of say how much energy would be involved in breaking through it, affects of highly localized vs more broad-based explosives, how it detects what is and isn't a threat (finding a way to sneak stuff past a shield is always very handy), actual durability of the underlying body.

realistically there'd be a wide of variety of weapons made to try to probe answers to those questions; and iirc you won't be able to find answers to those well enough from the source material, aside from the general principle of conventional weapons not working well.

EMP isn't too big of a threat to such a city, as due to its nature, they could afford to harden everything in it vs EMPs. EMP hardening is routine in some more sensitive military applications. given the importance they can also afford a fair bit of radiation, as they just need to keep people able to live for a reasonable amount of time (possible while constantly using NBC suits); and they can also accept if people working there can only stay half a year total or somesuch before dying (not sure on radiation sickness details). and of course they can have tons of radiation shielding and aerial scrubbers throughout the whole place to help keep stuff from getting too bad.

[Plus one]

The kinetic gravity striker could be fired from further away with an engine attached. Who says the planet it's in orbit of is earth. In space things can often end up going ridiculously fast. If it's metal then the rail gun aspect could help electrically charge it and add heat. A laser to cut through the atmosphere...
Conventional explosives will destroy the terrain under it and leave it in a hole and short of it flying more will keep it there. An easy target. Lava or a small tactical nuke might be used.
Factory's use lasers to cut metal. I'm sure high end military can do far higher output if required. If it doesn't injure it then NASA is experimenting with using them to launch spacecraft. Get it going towards the sun and keep firing? Nobody will object much to a nuke being detonated in space.

[Strigon]

The kinetic gravity striker could be fired from further away with an engine attached. Who says the planet it's in orbit of is earth. In space things can often end up going ridiculously fast. If it's metal then the rail gun aspect could help electrically charge it and add heat. A laser to cut through the atmosphere...

The thing is that, no matter how fast an object is going, it can only punch through so much atmosphere; I believe the limit is an amount of air (or any substance) equal to its mass. This is, of course, complicated by things like aerodynamic effects and gravity, but the point is that past a certain initial velocity, any extra speed will only dump more energy into the surrounding air; and we're trying to minimize collateral damage.
The trick isn't so much to get it going fast, as to keep it going fast.

Factory's use lasers to cut metal. I'm sure high end military can do far higher output if required. If it doesn't injure it then NASA is experimenting with using them to launch spacecraft. Get it going towards the sun and keep firing?

The military's been trying to use them for a long time, with very few practical results. Factories can use them because they deal with very controlled environments, and they can stick the laser practically on top of the thing they're slicing. That's almost the exact opposite of most military engagements.

Nobody will object much to a nuke being detonated in space.

Oh yes they would.

[factotum]

Oh yes they would.

And even if they didn't object to *that*, they'd definitely object to the process necessary to actually get the nuke up there in the first place--e.g. transport a large quantity of radioactive material up in a rocket, which have been known to explode and scatter their contents across a large area.

[Tyndmyr]

The kinetic gravity striker could be fired from further away with an engine attached. Who says the planet it's in orbit of is earth. In space things can often end up going ridiculously fast. If it's metal then the rail gun aspect could help electrically charge it and add heat. A laser to cut through the atmosphere...
Conventional explosives will destroy the terrain under it and leave it in a hole and short of it flying more will keep it there. An easy target. Lava or a small tactical nuke might be used.
Factory's use lasers to cut metal. I'm sure high end military can do far higher output if required. If it doesn't injure it then NASA is experimenting with using them to launch spacecraft. Get it going towards the sun and keep firing? Nobody will object much to a nuke being detonated in space.

Distance isn't a big issue, really. I mean, yeah, you COULD boost it out of earth orbit, but...why? If you wanna fire it at earth, that's a ton of extra lift costs, and ultimately, you still have to deal with atmo regardless of how fast it's going. Also, further away complicates targeting.

You're better off using that thrust to lift up more or larger rods, and sticking to earth orbit.

Edit: Also, yes, people would definitely object to nukes in space.

Also, Also, Lava is...probably not a reasonable substitute? Makes for a cool supervillain lair, but it doesn't actually have all that much boom.