You Might Want to Know: ICBMs Arriving - VII. What Happens When The Warheads Get Where They Are Going
V. What Happens When the Warheads Get Where They Are Going
Finally, from a technical point of view anyway, there’s the question of what the warheads of Intercontinental Ballistic Missiles will do when get to wherever they are going, and detonate.
This is hard to get one’s mind around. Many of us seem to have given up trying. Or else we let ourselves be satisfied with numbers, abstractions. Understandable, I guess. It’s tough stuff.
When it comes to blast yield, nuclear weapons come in many sizes of unimaginably huge. In 1969, the lowest yielding ICBM warhead we had, the W59, yielded one megaton, the blast equivalent of one million tons of TNT.
Can you picture a million tons of TNT sitting out in a field somewhere? I can’t.
That’s just one million tons. In the 70’s and 80’s, the largest yielding warhead we had on our ICBMs was the W53 on our Titan II missiles. The W53 yielded the equivalent of nine million tons of TNT. We’d installed eighteen Titan IIs in silos around my home town of Tucson. And around two other towns in our country.
Unfortunately, by that time, the Soviets had a warhead that yielded the equivalent of twenty million tons. We were pretty sure about that. We’d known for sure, since 1961, that nuclear warheads could be made to yield as much as you wanted, no limit. That was the year the Soviets dropped a three-stage hydrogen bomb at their island test site up near the Arctic Circle that yielded the equivalent of fifty million tons of TNT. Some said fifty-seven million. The original plan had been for it to yield one hundred million tons. I won’t ask us to try to imagine that.
To give us some chance of getting our minds around what would actually happen when an ICBM gets where it is going, let’s look at a warhead that yields only one million tons, one megaton. We’ll also ignore the part of the yield that would linger longest and be the most unpredictable and be likely eventually to kill as many people as were killed by the detonation itself, as it seems to have done in Hiroshima—namely the ionizing radiation that is released promptly at the time of detonation and later in fallout. We’ll ignore this.
Nuclear weapons produce fireballs of different sizes, depending on the yield. The fireball of a nuclear weapons is the area in which the heat produced is so intense that everything inside the fireball is obliterated. “Obliterated” means “erased,” not just “destroyed” but “obliterated.” “Vaporized,” it is sometimes said. The fireball of a one-megaton warhead, detonated on the ground, would cover over four square miles. Detonated in the air the fireball would cover two and a half square miles.
At the center of a nuclear detonation, the heat is hotter than at the center of the sun, if you can imagine that. At the edges of the fireball the heat is not as great but still enough to obliterate what’s inside the fireball.
Beyond the fireball, heat may still be the most broadly damaging effect, especially if the detonation has taken place in the air rather than on the ground. A one-megaton bomb exploded on the ground could cause third-degree burns—the worst kind—over an area of about three hundred square miles. Exploded in the air, as the Hiroshima and Nagasaki bombs were made to do, it would cause third-degree burns over an area approaching four hundred square miles.
And start fires, of course, wherever there was something that could burn.
Giving the yield of nuclear weapons in terms of tons of TNT is misleading. TNT doesn’t give you either the kind of heat we’ve been talking about or the ionizing radiation we’re not talking about. People might be killed by the quick blast of ionizing radiation the detonation produced—the “prompt radiation”—for several miles out from ground zero. But if you were closer to ground zero, the heat or blast would have killed you already.
But, as I say, as is often done in these discussions, we’ll leave out the ionizing radiation.
Then would come the fires that had been started by the heat with probably no one to come put them out and nothing to put them out with. The fires might join into one big fire and become a kind of tornado of fire called a firestorm, as they had done in Hiroshima. Firestorms burn up all the oxygen and suffocate people who might be in underground shelters. Regular incendiary bombs could generate firestorms too. We’d shown we could do that in Germany and Japan, even before we dropped Little Boy on Hiroshima.
Titan IIs nine-megaton W53, detonated in the air, would produce heat that could cause third degree burns over an area of almost three thousand square miles. The Soviets’ twenty-megaton warheads exploded at altitude could cause third degree burns over an area of almost six thousand square miles.
The estimated accuracy of the Minuteman II ICBM was tiny, like two football fields. That’s important. The closer the better, needless to say. The closer you get, the less yield you need to get good results, the results you are hoping for.
In 1970, on the way to getting to the one thousand ICBMs Secretary McNamara had said we needed, we started to replace all the Minuteman I and II ICBMs with our new Minuteman IIIs. The Minuteman III would undoubtedly have a new warhead.
Because of the Minuteman III’s greater accuracy, we might be able to put a warhead on it that yielded less than a megaton. Maybe only twenty or thirty Hiroshimas.
There we are. Now what? I wish I knew.
[If you want to see the predicted effects of nuclear weapons with different yields on particular map areas—of, say, Washington, D.C. or your home town—take a look at Alex Wellerstein’s remarkable interactive online NukeMap. On NukeMap, you can “detonate” bombs in different map areas, not actual places, of course. Abstract representations again, but striking. Some photographs of what an actual Hiroshima was like in August 1945 can be seen here.]
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