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Revisiting the “Tsar Bomba” nuclear test

Enlarge / The mushroom cloud from the Soviet detonation of “Tsar Bomba” on October 30, 1961, was so large that the photographers had a hard time capturing its full dimensions.

The detonation of the first nuclear bombs over Hiroshima and Nagasaki in August 1945 is seared into our collective memory, and the world has been haunted by the prospect of a devastating nuclear apocalypse ever since. Less well-known but equally significant from a nuclear arms race standpoint was the Soviet Union’s successful detonation of hydrogen “superbomb” in the wee hours of October 30, 1961.

Dubbed “Tsar Bomba” (loosely translated, “Emperor of Bombs”), it was the size of a small school bus—it wouldn’t even fit inside a bomber and had to be slung below the belly of the plane. The 60,000-pound (27 metric tons) test bomb’s explosive yield was 50 million tons (50 megatons) of TNT, although the design had a maximum explosive yield of 100 million tons (100 megatons).

The US had conducted the first successful test of a hydrogen bomb (codename: Ivy Mike) in 1954 and had been pondering the development of even more powerful hydrogen superbombs. But the Soviets’ successful test lent greater urgency to the matter. Ultimately, President John F. Kennedy opted for diplomacy, signing the Partial Nuclear Test Ban Treaty on October 7, 1963.

But US nuclear policy—and hence world history—might have turned out very differently, according to Alex Wellerstein, a historian of science at the Stevens Institute of Technology in New Jersey and author of Restricted Data: The History of Nuclear Secrecy in the United States, released earlier this year. He also maintains the NUKEMAP, an interactive tool that enables users to model the impact of various types of nuclear weapons on the geographical location of their choice. 

Wellerstein has analyzed recently declassified documents pertaining to the US response to Tsar Bomba during the Kennedy administration. He described his conclusions in a fascinating article recently published in the Bulletin of the Atomic Scientists, coinciding with the 60th anniversary of the test.

Wellerstein gives a particularly vivid description of the Tsar Bomba detonation in his introduction:

At 11:32 a.m., the bombardier released the weapon. As the bomb fell, an enormous parachute unfurled to slow its descent, giving the pilot time to retreat to a safe distance. A minute or so later, the bomb detonated. A cameraman watching from the island recalled:

A fire-red ball of enormous size rose and grew. It grew larger and larger, and when it reached enormous size, it went up. Behind it, like a funnel, the whole earth seemed to be drawn in. The sight was fantastic, unreal, and the fireball looked like some other planet. It was an unearthly spectacle!

The flash alone lasted more than a minute. The fireball expanded to nearly six miles in diameter—large enough to include the entire urban core of Washington or San Francisco, or all of midtown and downtown Manhattan. Over several minutes it rose and mushroomed into a massive cloud. Within ten minutes, it had reached a height of 42 miles and a diameter of some 60 miles. One civilian witness remarked that it was “as if the Earth was killed.”

According to Wellerstein, the US initially sought to minimize the significance of the Soviets’ success, officially dismissing it as a political publicity stunt with little to no technical or strategic importance. But the declassified files revealed that, behind the scenes, US officials took the matter very seriously indeed.

Physicist Edward Teller in particular strongly advocated in favor of developing two even more powerful hydrogen bombs, with yields of 1,000 and even 10,000 megatons, respectively. While much of Teller’s testimony at a secret meeting on the topic remains classified, Wellerstein found that many scientists who were present expressed shock at his proposal. Concerns about the practical use of such a massive weapon, particularly the widespread nuclear fallout, ultimately scuttled those plans.

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It was only last year that the Russian nuclear energy agency, Rosatom, declassified a 30-minute documentary about the development of Tsar Bomba, showing the detonation and subsequent massive mushroom cloud:

Last year, the Russian nuclear energy agency, Rosatom, released a 30-minute, formerly secret documentary video about the detonation of the world’s largest hydrogen bomb, dubbed “Tsar Bomba.”

While Wellerstein emphasizes that this was a carefully planned nuclear test, with relatively straightforward calculations about how far away the bombers and observation planes needed to be for safety, the pilots of those planes understandably felt some all-too-human trepidation. “There’s these great accounts from some of the pilots of observation planes who had to fly towards the cloud to get readings and things,” Wellerstein told Ars. “One of the guys said, ‘I did it. And it was the most terrifying event in my life.’ And the other guy said, ‘I’m sorry, I wimped out. I turned around, I couldn’t fly towards this monstrous mushroom cloud. I just couldn’t do it at the last minute.'”

Ars sat down with Wellerstein to learn more.

Ars Technica: The official US take after the Tsar Bomba detonation was that we were not especially concerned about it. But, in fact, you write that the US was very seriously considering developing a similar weapon. You reference a particular meeting in which Edward Teller actually shocked those in attendance with the type of weapon he was proposing.

Alex Wellerstein: I found the new information with regard to the US response to Tsar Bomba really interesting, because it contradicts what they said in public versus what was going on behind the scenes. A lot of the discussions about the Tsar Bomba in American writing essentially parrot then-President Kennedy’s line without realizing it: “Oh, these bombs are worthless. No, they can’t do it.” But it’s clear that there were people within the Kennedy administration who didn’t think it was as simple as that. We can be happy that those people didn’t win out.

There is always this temptation for big bombs. I found a memo by somebody at Sandia, talking about meeting with the military. He said that the military didn’t really know what they wanted these big bombs for, but they figured that if the Soviets thought they were a good idea, then the US should have one, too. It’s reminiscent of that line from Dr. Strangelove.

Enlarge / Image from recently declassified footage of the Tsar Bomba at an undisclosed location in the 1960s.

Ars Technica: We must not allow a Tsar Bomba gap!

Alex Wellerstein: Exactly. The parody of Edward Teller is that he’s a person who liked big bombs for the sake of it. Apparently that’s not a parody, because he actually thought that the weapons that we had, as big as they were—he thought we should have made much larger ones. It’s hard to know what he thought the application would be. By their own calculations, you could not deliver this from a bomber. If you take the yield-to-weight ratios and apply them to a 10,000 megaton bomb, you’ll end up with something that weighs the same as the space shuttle.

So it’s not a deliverable weapon that you’re going to just use. It’s clumsy. There was some concern that the Soviets might figure out how to put it on a missile. But what’s the point when you could have a thousand Minuteman missiles with one megaton on each? There were jokes that you didn’t really need to deliver a weapon at that size. You could just bury it in your backyard. Then the real effect would be the amount of fallout you’re injecting into the global atmosphere. It would be a doomsday device, like Dr. Strangelove.

I don’t know how seriously that was taken internally. The Eisenhower Air Force essentially turned down weapons like this and said, “We really don’t think there’s an application for this.” It’s a sign that the scientists didn’t make a very compelling case. My pet theory is that the weapons scientists did see this as a doomsday device, a last-ditch deterrent. That’s really at odds with how the Air Force thought about nuclear weapons. The Air Force thought about winning nuclear wars; a suicide bomb was not how they conceptualized their role. It was not the practical nuclear arsenal that they wanted. So it did come down essentially to an efficiency question, though it’s clear there was propaganda value to these big bombs.

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Enlarge / The Tsar Bomba was the largest hydrogen bomb ever detonated.

Ars Technica: The propaganda value seems to be why the Soviets developed Tsar Bomba—that, and deterrence. 

Alex Wellerstein: What should a nuclear arsenal actually be? Are we getting the security proportionate to what we’re spending and deploying? And are the risks worth all of that,? If your focus is on making bigger bombs just for the sake of making bigger bombs, the only argument you could make for that is deterrence, which is partially about logic and partially about terror. The French translation of deterrence is essentially dissuasion. The Russian translation is terrorization. They’re both right. It’s about scaring you so that you don’t do something that would be illogical.

If you’re terrified by gigantic bombs, no matter how inefficient they are, then maybe they serve their point if they don’t get used. That being said, an arms race just for its own sake comes with its own costs and risks. Deterrence is not necessarily going to always succeed. If it fails, how bad do you want it to be? You want it to be bad enough that the deterrence in theory won’t fail, but you also don’t really need overkill where you’re edging towards total human extinction. This is the balance that was getting worked out in the ’50s and ’60s—and it’s still frankly being worked out today.

Enlarge / Total destruction radius, superimposed on Paris. Red circle = total destruction (radius 35 kilometers), yellow circle = fireball (radius 3.5 kilometers).

Ars Technica: You mentioned in your article that there are lessons to be learned from the Tsar Bomba test and its aftermath that are still relevant today. 

Alex Wellerstein: We’re in the middle of a very odd arms race at the moment. There are big debates about whether it’s better to have small weapons that you could potentially imagine using, versus very large weapons that would be so terrible that you wouldn’t be tempted to use them—and your adversary would hopefully also be trying to avoid using them. The biggest shift that’s happened over the last couple of decades is that the US has invested a lot in anti-ballistic missile technology. That has either genuinely spooked the Russians and the Chinese, or it’s allowed their military industrial complexes to push for a lot of money. They have similar dynamics as we do. It doesn’t matter if they actually think it will be effective or not.

The result is that both the Chinese and the Russians are developing fairly untested high-technology deterrence options, which include things like hypersonic warheads, or drone-torpedoes—the kind of stuff that you would imagine they would do because they fear that their second strike capability is being affected by anti-ballistic missile technology. The US response to that is, maybe we should have some hypersonics also. It’s another arms race for its own sake.

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Enlarge / A comparison of the “superbombs” developed or conceived by US and Soviet nuclear scientists
Alex Wellerstein

When I look at the Tsar Bomba episode, I see what could have been a pointless arms race that was fortunately averted through the use of a treaty. Of course, treaties don’t stop competition, but they do change the domains in which it plays out. When I look at the current arms race—if you think you’re going to somehow win the arms race by making more or weirder weapons, that’s just going to keep the cycle going. You’re all going to spend a lot of money, and many of these technologies, especially when they’re new and unusual, incur risks, some of which you can’t even predict.

Hypersonics do dramatically reduce the reaction times. But then you get into situations where miscommunication or false alarms become much more risky. Nuclear war is a bad idea for everybody. If we’re looking for stability and not superiority, we want to encourage technological developments that lean in that direction. Hypersonics don’t lean in that direction. Anti-ballistic missile systems don’t lean in that direction. What we need is not to build more ridiculous weapons just because the other guy tested one but to actually come up with a plan for stabilizing things. This is a field where innovation and creativity can be a very negative thing.

Ars Technica: It seems like there was a brief period in the wake of the Tsar Bomba detonation test where the world was kind of balanced on a knife-edge with regard to which direction the governments would take on nuclear policy. Are we getting close to a similar knife-edge today?

Alex Wellerstein: The path they took in the 1960s was still a very dangerous path. They still had thousands of weapons deployed. A megaton bomb will still ruin your day, especially when there’s 10,000 of them. It wasn’t until very late at the end of the Cold War that they started really cutting stockpiles, dramatically reducing what the actual impact would be.

Enlarge / President John F. Kennedy signs the Partial Nuclear Test Ban Treaty on October 7, 1963, before W. Averell Harriman, Lyndon B. Johnson, Dean Rusk, and others.
Public domain

In terms of where we are today, we have a lot of choices. The difficulty is that, for some of those choices, we’ve already chosen the path and most people don’t realize it. There are baked-in consequences of a decade of policy decisions. So even if we decided today, let’s not go in this direction, it would still take active work to undo our policy decisions, much less convince the Chinese to undo theirs.

So the knife-edge has passed in one sense, and we already are on one path. That doesn’t mean it’s irreversible. There have been a lot of instances historically, in which things seemed like they were going in one direction, and then they very quickly pivoted to another. The most famous of these was right at the end of the Cold War. President George H.W. Bush radically changed US policy without going to Congress almost overnight. He decided that we were not going to put active nuclear weapons on American ships anymore, except for our nuclear submarines. Boom! That eliminated a whole category of weapons.

But closing ICBM bases, for example, involves Congress, and congressmen like having these bases in their jurisdictions. And right now, our Congress is not extraordinarily functional. Making a new treaty is difficult on its own. It’s essentially impossible if you can’t imagine getting bipartisan support in the Senate. So the way the system is set up, it’s a lot harder to go in a different direction at this point. Even if there was a huge amount of popular interest in this—which there isn’t—or even popular knowledge of it, it’s hard to see viable pathways politically to achieving that shift, which is an indictment of our current political situation.