For Fun, the bomb dropped on Old Kentucky

[Liam's Ghost]

Touring The Stars: Old Kentucky informs us that the world was targeted by the only use of a Gigaton class nuclear warhead in history. Though the main text doesn't go into detail about the exact yield, the later scenario hook gives us a number of two hundred gigatons. I'm... almost certain that this was a typo. But for fun, I decided to roll with it and plug that yield into the generic nuclear weapon rules found in Interstellar Operations.

Please note a few things. First, I don't think the interstellar operations rules were meant to be used like this. Second, the rules don't clarify what happens if the blast height exceeds the altitude of the Atmospheric Interface (because the rules aren't intended to accommodate a weapon where that's a possibility). I'm assuming the blast stops once there's no significant atmosphere to push, but if you want, you could extend the blast radius the full sixty five space hexes. I'm not as clear on the secondary effects. The radiation and electromagnetic pulse might not care.

Third, you can talk about how a pure fusion weapon in an airburst wouldn't produce a lot of radiation or fallout, but the blast radius is so large, I don't think you can avoid fallout no matter how high in the atmosphere you detonate it. We're talking about a blast effect over a thousand kilometers across here.

Fourth. No, there is virtually no way to use this warhead in a game beyond "bomb falls, EVERYTHING dies."


Yield: 200 Gigatons (200,000 megatons or 200,000,000 kilotons)
Base Impact Damage: 40,000,000,000 (400,000,000 capital)
Critical Hit Chance: 4+
Crater Depth: 66
Blast Radius (ground): 14,620 hexes
Blast Radius (air): 19,444 hexes
Blast Height: Interface (high altitude row 5)
Damage Degredation (ground): 2,735,978
Damage Degredation (air): 2,051,983
Secondary Effect Radius (ground): 29,240 hexes
Secondary Effect Radius (air): 78,070 hexes
Secondary Effect Height: 2,342,100 meters (high altitude row 130)
Weapon Mass: 200 tons (according to the text. Using the mechanics in Interstellar operations, such a weapon would weigh 100,000 tons assuming tech level E)

[worktroll]

Technically, pure fusion devices cause massive & horrible neutron irradiation. Not only will that turn shielded humans into giant poached eggs, it's super-effective at causing things in the way to become radioactive via neutron capture & fission processes creating bulk radioactive isotopes.

Re weight - current estimates of Teller-Ulam style bombs come with a 'on the tin" efficiency topping out at, IIRC, 6.something MT/ton. So a 200-ton UT device would have no problems hitting a gigaton or two. But that's still two orders of magnitude low. I'll buy one of those magnitudes just because of the efficiency of going pure fusion with BT laser-initiation. For the second order, I'll postulate the Teller-Worktroll model - using smaller (1MT) scaled laser-pumped pure fusion bombs around a fusable core. Just replace the explosive lenses with H-bombs ...

W.

[Liam's Ghost]

The idea of using fusion bombs to trigger other fusion bombs amuses me.

I suspect the original intent was a two gigaton weapon. That would be one thousand tons by the IO mechanics, which I could easily see being handwaved to 200 tons.

The US claimed it could fit a thirty five megaton weapon in a four ton package back in the sixties, and we deployed a 25 megaton weapon that managed about five megatons per ton. Amusingly, neither of these can be replicated using interstellar operations rules, where the highest tech level nets you a 2 megaton per ton yield. It's almost like someone was trying to restrain the players' baser instincts.  :D

[worktroll]

Ah, the B-41, which inspired Slim Picken's ride in the movie O0

A true three-stage device, with added uranium tamper. To bump that two orders of magnitude ...well, when you care enough to send the very best ;)

[I am Belch II]

That's a big bomb.

[Grognard]

definite continent-killer nuke.
? but is it a planet-killer ?

[Liam's Ghost]

definite continent-killer nuke.
? but is it a planet-killer ?

Depends on how effectively the fallout can spread, whether the ozone layer fails, whether they get to see the sun anymore, that sort of thing. Either way, it's not an immediate kill, more of a slow death in the middle of the succession wars when there's no help to give.

[worktroll]

What was the population on OKt at the time?

Colony worlds are likely to have critical functions - spaceport, hospital, major storehouses for imports & exports, spare parts & repair for technology - concentrated, with population either huddled close on mining or inhospitable worlds, or spread out in more agrarian colonies. Either way, 200Tt of instant sunshine makes all that go away. Survivors are going to be dealing with absence of support & communications, potential lack of supplements, loss of shared transport infrastructure, and being split up into groups well below the numbers needed for long-term population survival.

[Maingunnery]

Now that is a decent nuke.  :)

[I am Belch II]

It's the Q-Bomb from Starship Troopers 3 movie.

[Death by Lasers]

  200 gigatons :o  I guess I'm going to have to buy Touring the Stars: Old Kentucky to find out but apparently someone really, really, really didn't like that planet.  Once you get beyond the first couple of gigatons you are getting into the personnel vendetta region of nuclear yields. 

[Liam's Ghost]

You'd probably be disappointed. It doesn't do much more than destroy a windfarm and terrify people into scattering.

Though the rest of the book is a good read. Good for the lore.

[doulos05]

definite continent-killer nuke.
? but is it a planet-killer ?

The planet will be just fine. 200 gigatons isn't enough energy to overcome the gravitational energy of any habitable planet so it'll carry on orbiting it's primary just fine. Everything ON the planet on the other hand...

If there's any sort of atmosphere (left), it will trap the material. If it's a pure fusion bomb, all of that material will be irradiated. That's fallout. You're talking an mass extinction event. People on the other side of the planet can probably get away in dropships. Anybody staying on the planet will die.

[vidar]

I also wonder how much atmosphere would be lost.  You may have trouble breathing.

[Maingunnery]

I also wonder how much atmosphere would be lost.

Almost nothing.

[Liam's Ghost]

So it turns out that I was right, and the original intent was a two gigaton bomb rather than two hundred gigatons. I'll work up stats for it tomorrow.

[Cryhavok101]

Please note a few things. First, I don't think the interstellar operations rules were meant to be used like this. Second, the rules don't clarify what happens if the blast height exceeds the altitude of the Atmospheric Interface (because the rules aren't intended to accommodate a weapon where that's a possibility). I'm assuming the blast stops once there's no significant atmosphere to push, but if you want, you could extend the blast radius the full sixty five space hexes. I'm not as clear on the secondary effects. The radiation and electromagnetic pulse might not care.

As I understand it, the High Altitude map is just the space map that includes the 5 High Altitude hexes. When it says on the chart on page 177 of IO that "†For any heights of 18,000 meters or more, divide the result by 18,000, and round up; this is the number of High-Altitude Map hex rows instead." I would assume you just keep going past the interface how into the space portion of the high altitude map, as far as the blast takes you, even if that goes past the interface hex. At I guess I would think that would be realistic too, since the atmosphere gets progressively thinner the higher altitude you get.

You can also start applying the damage degradation modifier for vacuum once it passes the interface hex, from the chart on page 173 of IO.

[Liam's Ghost]

You need the atmosphere for the blast to be effective. The blast needs a medium to radiate through, otherwise it's just a bright flash. That's why nuclear weapons in space have to directly hit their targets to do anything, and they have to strike deep to have the best effect, without direct contact there's nothing to transmit the blast wave.

[Cryhavok101]

Ah okay, that makes sense.

[Liam's Ghost]

As promised, the 2 gigaton version.

Yield: 2 Gigatons (2,000 megatons or 2,000,000 kilotons)
Base Impact Damage: 400,000,000 (4,000,000 capital)
Critical Hit Chance: 4+
Crater Depth: 37
Blast Radius (ground): 3149 hexes
Blast Radius (air): 4188 hexes
Blast Height: Interface (high altitude row 5)
Damage Degradation (ground): 127,024
Damage Degradation (air): 95,268
Secondary Effect Radius (ground): 6298 hexes
Secondary Effect Radius (air): 8407 hexes
Secondary Effect Height: 252,210 meters (high altitude row 15)
Weapon Mass: 200 tons (according to the text. Using the mechanics in Interstellar operations, such a weapon would weigh 1000 tons assuming tech level E)

Of note, even though this version has only one percent of the yield of our previous 200 gigaton version, it has about fifteen percent of the effective radius and inflicts so much damage that anything within that radius is just as pulverized. The inverse square law is a harsh mistress, and illustrates nicely why modern armies tend to prefer saturating their targets with multiple lower yield weapons ("pancaking") rather than using single high yield weapons.

[ANS Kamas P81]

25Mt weapons existed on both sides, the well-named SS-18 for the Soviets carried 18, 20, and 25Mt single weapons or a ten-pack of MIRVs.  I suppose for something like Cheyenne mountain, you'd want a single big boom rather than a multiple strike; you gotta get deep in the mountain to take out the command facilities.  A big hole needs a big shovel, comrade, but I'm not sure a crater depth of 37 levels would have done enough...

[Korzon77]

"Okay Stanley, very funny. Now that you've finally proved that the neutron S missiles could really be created, can we get back to designing somethng a little less excessive."

(Or alternately).

"Gentlemen, trying to destroy technology accross the inner sphere seems, I dunno a bit--" Gets paper about the Old Kentucky bomb "--a very good idea. Yes. A very good idea, before someone starts wondering if they can build a bomb big enough to blow up a star."