Operation Crossroads at 70

This summer is the 70th anniversary of Operation Crossroads, the first postwar nuclear test series. Crossroads is so strange and unusual. 1946 in general ought to get more credit as an interesting year, as I’ve written about before. It was a year in flux, where a great number of possible futures seemed possible, before the apparently iron-clad dynamics of the Cold War fell into place. Crossroads happens right in the middle of the year, and arguably made a pretty big contribution to the direction that we ended up going. Such is the subject of my latest article for the New Yorker‘s Elements blog, “America at the Atomic Crossroads.” Today is the anniversary of the Baker shot, which Glenn Seaborg dubbed “the world’s first nuclear disaster.”

America at the Atomic Crossroads

There are a lot of things that make Crossroads interesting to me. The bomb was still in the hands of the Manhattan Project. The Atomic Energy Act of 1946 had not yet been signed into law (Truman would sign it in August, and it would go into effect in January 1947), so the Atomic Energy Commission did not yet exist.

There were these amazing interservice rivalry aspects: the whole backdrop is a Navy vs. Army tension. The Manhattan Project, and the Army Air Forces, had gotten all the glory for the bomb. The Navy didn’t want to be left out, or seen as irrelevant. Hence them hosting a big test, and glorying in the fact that a Nagasaki-sized atomic bomb doesn’t completely destroy a full naval squadron. (Which was no surprise to anybody on the scientific or military side of things.)

The US had only about 10 atomic bombs at the time. So they expended about 20% of their entire nuclear arsenal on these tests, for relatively little military knowledge gained. The Los Alamos scientists were pretty lukewarm on the whole operation — it just didn’t seem like it was getting them much. One wonders, if the bomb had not still be under military control, whether it would have happened.

Photograph of the early mushroom cloud by LIFE photographer Frank Scherschel, with a darkened filter to compensate for the brightness of the flash. Source.

Photograph of the early mushroom cloud of Crossroads Able by LIFE photographer Frank Scherschel, with a darkened filter to compensate for the brightness of the flash. Source.

The first shot, Able, was something of a flub. The fact that it missed its target meant that for public relations purposes it was seen as very ineffective, but it also means that their scientific observations were largely pretty useless. In fact, it missed its target and blew up over one of the main instrumentation ships.

If you read most sources about Crossroads they will say that the source of the Able miss was undetermined, but if you dig down a little deeper you find some pretty plausible solutions (and the reason why the official verdict was “undetermined”). Paul Tibbets, the captain of the Enola Gay and overall head of the atomic delivery group, was pretty clear that it was human error. He said that even before the shot they realized that the crew of the B-29 which dropped it, Dave’s Dream, had gotten bad information about the weather conditions, but that they ignored attempts at correction. Tibbets would re-run (with a dummy bomb) the drop with the correct information (and got very close to the target), and also re-ran it with the wrong information (which missed by nearly the same amount as the Able shot). But the USAAF really didn’t want to throw their bombardier and plane crew under the bus. So they hinted it might be a problem with the ballistics of the weapon (which were indeed a bit tricky), which infuriated the Manhattan Project officials. Anyway, everyone seems to have been satisfied by just saying they couldn’t figure out where the error was. But Tibbets’ account seems most plausible to me.1

Crossroads was not secret operation, though there was much classified about it. There were full-spread articles about its purpose in national news publications both before and after its tests. There was probably no test series so publicly conducted by any nuclear power — announced well in advance, covered by the press in real-time, and then heavily publicized afterwards. The fact that the Soviets were invited to a US nuclear test operation (something that would not happen again until the late-1980s) opens up whole other dimensions.

Mikhail Meshcheryakov ("Mike"?) in 1946. At right he is on the USS Panamint, at the Crossroads test. Source: Mikhail Grigorivich Meshcheryakov, on the 100th-anniversary of his birth (Dubna, 2010).

Mikhail Meshcheryakov  in 1946. At right he is on the USS Panamint, at the Crossroads test. Source: Mikhail Grigorivich Meshcheryakov, on the 100th-anniversary of his birth (Dubna, 2010).

The Soviets had three observers at the test: Professor Semyon P. Aleksandrov, a geologist who had worked on the prospecting of uranium; Mikhail G. Meshcheryakov, an experimental physicist; and Captain Abram M. Khokhlov, who attended as a member of the international press corps (he wrote for the Soviet periodical Red Fleet). I found a really amusing little anecdote about the Soviet observers from one of the men who worked the Manhattan Project security detail on Crossroads: Aleksandrov was someone they knew already (he was a “dear old geologist”), but Meshcheryakov was someone “whose name was known, but no one had met personally leading some of us to support he was really an NKVD agent watching Aleksandrov.”

I found nothing in the Russian source materials (mentioned below) that would indicate that Meshcheryakov was NKVD, though he was definitely the one who wrote up the big report on Crossroads that was given to Beria, who summarized it for Stalin. Meshcheryakov’s report is not among the declassified documents released by the Russians, so who knows if it has any political commentary on Aleksandrov in it. Meshcheryakov ended up having a rather long and distinguished physics career in the USSR, though there is almost no English-language discussion of him on the Internet. Aleksandrov, the “dear old geologist,” was actually a major Soviet big-wig in charge of mining operations, which at that time meant he was high in the Gulag system, which was run by the NKVD. For what it’s worth.2

Radiation from the Crossroads Baker shot — the radiation went up with the cloud, and then collapsed right back down again with it, resulting in a very limited extent of radiation (the entire chart represents only 4.5 miles on each axis), but very high intensities. Chart source: DNA 1251-2-EX. Collapsed cloud picture source: Library of Congress.

Radiation from the Crossroads Baker shot — the radiation went up with the cloud, and then collapsed right back down again with it, resulting in a very limited extent of radiation (the entire chart represents only 4.5 miles on each axis), but very high intensities. Chart source: DNA 1251-2-EX. Collapsed cloud picture source: Library of Congress.

It was also something of the real birth of “atomic kitsch.” There are some examples from before Crossroads, but there is just a real flourishing afterwards. It seems to have taken a year or so after Hiroshima and Nagasaki for enough time to have passed for Americans to start to regard nuclear weapons entirely frivolously. With Crossroads in particular, a deep connection between sex and death (Freud’s favorites) circled around the bomb. This is where we start to see the sorts of activities that would later result in the “Miss Atomic Bomb” contests, the release of the really kitchy songs, and, of course, the Bikini swimsuit, named after the “atomic bomb island,” as LIFE put it.

The key fulcrum of my article is a meditation on the “crossroads” metaphor, and I should probably note that it was, to some degree, intentional. Vice Admiral William Blandy was reported by the New York Times to have told Congress, that the name was chosen for its “possible significance,” which the Times writer interpreted to mean “that seapower, airpower, and perhaps humanity itself — were at the crossroads.”3

An unusual color (but not colorized!) photograph of the Crossroads Baker detonation, from LIFE magazine. Source.

An unusual color (but not colorized!) photograph of the Crossroads Baker detonation, from LIFE magazine. Source.

What’s interesting to me is that Blandy clearly saw some aspects of the “crossroads,” but there was much he couldn’t have seen — the atomic culture, the arms race, the contamination, the nuclear fears. He knew that “crossroads” was a good name for what they were doing, but it was an even better name than he could have known, for both better and worst.

As before, I wanted to take a moment to give some credit/citation information that wasn’t workable into the New Yorker blog post (where space, and thus academic nicety, is constrained).

The best overall source on Crossroads, which I found invaluable, is Jonathan Weisgall’s Operation Crossroads: The Atomic Tests at Bikini Atoll (Naval Institute Press, 1994). Weisgall has been a legal counsel on behalf of the Marshallese, and his book is just a wealth of information. I was pleased to find a few things that he didn’t have in his book, because it’s a really tough challenge given how much work he put into it. If you find Crossroads interesting, you have to read Weisgall.

Rita Hayworth on the Crossroads Able bomb, "Gilda." Photo by Los Alamos National Laboratory, via Peter Kuran and Bill Geerhart.

Rita Hayworth on the Crossroads Able bomb, “Gilda.” Photo courtesy Los Alamos National Laboratory, via Peter Kuran and Bill Geerhart.

Bill Geerhart, who writes the excellent blog CONELRAD Adjacent (and is the one behind the Atomic Platters series of Cold War songs), has done some really wonderful work on the cultural aspects of Crossroads over the years. His posts on the mushroom cloud cake, and his sleuthing regarding the Rita Hayworth connection, are amazing and worth reading in their entirety. Peter Kuran, the visual effects wizard who made the documentary Trinity and Beyond, among other films and works, was very helpful in providing recently-declassified imagery of the Crossroads bombs, including photos (which I first saw on Geerhart’s blog) of the Rita Hayworth image on the side of the bomb themselves. (I will be writing more about Kuran and his work in the near future…)

Holly Barker’s Bravo for the Marshallese (Thomson/Wadsworth, 2004), is immensely useful as an anthropologist’s view of the Marshallese people and their experiences after the test. My invocation of the Marshallese language for birth defects comes directly from Barker’s book, pages 81 and 106-107. It is a powerful, disturbing section of the book.

Selection from Life magazine's coverage of Crossroads — two visions of the animal testing. Source.

Selection from Life magazine’s coverage of Crossroads — two visions of the animal testing. Source.

Most of the information I got about the Soviet view of Crossroads comes from the multi-volume Atomniy Proekt SSSR document series released by the Russian Federation. I had the full set of these before it was cool, but now Rosatom has put them all online. Scholars have been picking over these for awhile (I have written on them once before), I haven’t seen anybody use the particular documents relating to Crossroads before, but you in Tom (Volume) 2, Kniga (Book) 6, the documents I found most useful were 44 (pp. 130-132), 48 (135-136), 50 (137), 76 (184-188), and 106 (246-248). They show the picking of the delegation of observers, brief biographies of the observers, a summary of Meshcheryakov’s report (his full 110-page report on Crossroads is not included), and some later aspects of Meshcheryakov’s involvement with the planning of the first Soviet nuclear test in 1949 (in which his Bikini experience was offered up as his bonafides).

The other really unusual little source I used for my article is the letter from Percy Bridgman. The letter was sent from Bridgman to Hans Bethe, who relayed it to Norris Bradbury at Los Alamos, who sent it to General Groves. You can read it here. I have been sitting on it for a long time — I almost wrote a blog post about it in 2012, but decided not to for whatever reason. When I worked at the American Institute of Physics I had an opportunity to poke around Bridgman’s life and writings a bit, and he’s really an interesting character. He was the one at Harvard who served as J. Robert Oppenheimer’s physics advisor, and his own work on high-pressure physics not only won him the Nobel Prize of 1946 (which is a nice coincidence for the Crossroads article), but also was used (and is still classified, as far as I can tell) on the Manhattan Project (they seem to have sent him plutonium samples, so you can imagine the kind of work he was doing and why it might still be classified — almost everything on plutonium under high pressures is classified in the United States).

Percy W. Bridgman (L) talking with Harvard colleague (and future Trinity test director) Kenneth Bainbridge, 1934. Source: Emilio Segrè Visual Archives, American Institute of Physics

Percy W. Bridgman (L) talking with Harvard colleague (and future Trinity test director) Kenneth Bainbridge on a Massachusetts beach, 1934. Source: Emilio Segrè Visual Archives, American Institute of Physics.

Bridgman gave a number of talks associated with his Nobel Prize that really tried to get at the heart of what the effects of World War II would be for physics as a discipline. He was very much afraid that Big Science (which hadn’t yet been given that name) would really destroy work like his own, which he saw as small-scale, individual, and not focused on particular applications. He was also very interested in topics related to the philosophy of science, something that a lot of modern-day practicing physicists openly disdain. His Wikipedia page gives a nice, brief overview of his life, and even touches on the poignant circumstances of his death.4.

  1. This is discussed at length in Jonathan Weisgall’s Operation Crossroads, pp. 201-204.
  2. The account of the security officer is Charles I. Campbell, A Questing Life: The Search for Meaning (New York: iUniverse, 2006). This appears to be a self-published memoir, the sort of thing one would never run across without Google Books. On Aleksandrov’s Gulag connections (which seem plausible given his uranium connections), see this page on his Hero of Socialist Labor award. One of the few English-language articles on Meshcheryakov is available here.
  3. Sidney Shallet, “Test Atomic Bombs to Blast 100 Ships at Marshall Atoll,” New York Times (25 January 1946), 1. Blandy’s full quote on the name from the testimony: “The schedule of target dates for this operation, which will be known by the code word ‘CROSSROADS’—and I would like to explain that we have chosen that merely for brevity in dispatches and other communications, and we chose it with an eye to its possible significance—now calls for the first test to be accomplished early in May, over target ships at an altitude of several hundred feed.” A lot of the sources about Crossroads include Shallet’s bit about “perhaps humanity itself” as a quote of Blandy’s, but it’s not in the transcript that I can see. Hearing before the Special Committee on Atomic Energy, United States Senate, Pursuant to S. Res. 179, Part 4, 79th Congress, 2nd Session (24 January 1946), on 457.
  4. The citation for the Bridgman letter is: Percy W. Bridgman to Hans Bethe, forwarded by Norris Bradbury to Leslie Groves via TWX (13 March 1946), copy in the Nuclear Testing Archive, Las Vegas, NV, document NV0128609.

A brief history of the nuclear triad

Summers for me are paradoxically the time I can get work done, and the time in which I feel I have the most work. I’m not teaching, which in theory means I have much more unstructured time. The consequence, though, is that I have about a million projects I am trying to get done in what is still a limited amount of time, and I’m also trying to see family, friends, and get a little rest. I sort of took June off from blogging (which I felt was my due after the amount of exposure I got in April and May), but I have several posts “in the hopper,” and several other things coming out soon. Yesterday I gave a talk at the US Department of State as part of their Timbie Forum (what used to be called their Generation Prague conference). I was tasked with providing the historical background on the US nuclear “triad,” as part of a panel discussion of the future of the triad. This is subject-matter I’ve taught before, so I felt pretty comfortable with it, but I thought I would return to a few of my favorite sources and refresh my understanding. This post is something of a write-up of my notes — more than I could say in a 20-minute talk.

There is a lot of buzzing about lately about the future of the United States’ “nuclear triad.” The triad is the strategic reliance on three specific delivery “platforms” for deterrence: manned-bombers (the B-2 and the B-52), long-range intercontinental ballistic missiles (ICBMs; specifically the Minuteman III), and submarine-launched ballistic missiles (SLBMs; specifically the Trident II missile carried by Ohio class submarines). Do we need all three “legs” of the triad? I don’t know — that’s a question for another day, and depends on how you balance the specific benefits and risks of each “leg” with the costs of maintaining or upgrading them. But as we think about the future of the US arsenal, looking at how the triad situation came about, and how people started talking about it as a “triad,” offers some interesting food for thought.

The modern nuclear triad. Source: Nuclear Posture Review, 2010.

The modern nuclear triad. Source: Nuclear Posture Review, 2010.

The stated logic of the triad has long as such: 1) bombers are flexible in terms of their armaments and deployments (and have non-nuclear roles); 2) ICBM forces are kept far from the enemy, are highly-accurate, and thus make a first-strike attack require a huge amount of “investment” to contemplate; 3) SLBM forces are, for the near term, capable of being kept completely hidden from attack, and thus are a guaranteed “second strike” capability. The combination of these three factors, the logic goes, keeps anyone from thinking they could get away with a nuclear attack.

That’s the rationale. It’s not the history of it, though. Like so many things, the history is rather wooly, full of stops-and-starts, and a spaghetti graph of different organizations, initiatives, committees, industrial contractors, and ideas. I have tried to summarize a lot of material below — with an idea to pointing out how each “leg” of the triad got (or did not get, depending on when) the support it needed to become a reality. I only take these histories up through about 1960, after which each of the three “legs” were deployed (and to try and go much further would result in an even-longer post).


The United States’ first approach to the “delivery” question was manned, long-range bombers. Starting with the B-29, which delivered the first atomic bombs, and some 80 million pounds of incendiaries, over Japanese cities during World War II, the US was deeply committed to the use of aircraft as the means of getting the weapons from “here” to “there.” Arguably, this commitment was a bit overextended. Bureaucratic and human factors led to what might be called a US obsession with the bomber. The officers who rose through the ranks of the US Army Air Forces, and the newly-created (in 1947) US Air Force, were primarily bomber men. They came out of a culture that saw pilots as the ultimate embodiment of military prowess. There were some exceptions, but they were rare.

The B-29's power was more than military — it became a symbol of a new form of warfare for the generals of the newly-constituted US Air Force. Source.

The B-29’s power was more than military — it became a symbol of a new form of warfare for the generals of the newly-constituted US Air Force. Source.

In their defense, the US had two major advantages over the Soviet Union with respect to bombers. The first is that the US had a lot more experience building them: the B-29 “Superfortress” was an impressive piece of machinery, capable of flying further, faster, and with a higher load of armaments than anything else in the world at the time, and it was just the beginning.

The second was geography. The B-29 had a lot of range, but it wasn’t intercontinental. With a range of some 3,250 miles, it could go pretty far: from the Marianas to anywhere in Japan and back, for example. But it couldn’t fly a bomb-load to Moscow from the United States (not even from Alaska, which was only in range of the eastern half of Russia). This might not look like an advantage, but consider that this same isolation made it very hard for the Soviet Union to use bombers to threaten the United States in the near-term, and that the US had something that the USSR did not: lots of friends near its enemy’s borders.

As early as late August 1945, the United States military planners were contemplating how they could use friendly airfields — some already under US control, some not — to put a ring around the Soviet Union, and to knock it out of commission if need be. In practice, it took several years for this to happen. Deployments of non-nuclear components of nuclear weapons abroad waited until 1948, during the Berlin Blockade, and the early stages of the Korean War.

US nuclear bomber deployments, 1945-1958. One of my favorite slides that I use when teaching — it shows what "containment" comes to mean, and amply demonstrates the geopolitics of Cold War bomber bases.

US nuclear bomber deployments, 1945-1958. One of my favorite slides that I use when teaching — it shows what “containment” comes to mean, and amply demonstrates the geopolitics of Cold War bomber bases. Shadings indicate allies/blocs circa 1958.

In 1951, President Truman authorized small numbers of nuclear weapons (with fissile cores) to be deployed to Guam. But starting in 1954, American nuclear weapons began to be dispersed all-around the Soviet perimeter: French Morocco, Okinawa, and the United Kingdom in 1954; West Germany in 1955; Iwo Jima, Italy, and the Philippines in 1957; and France, Greenland, Spain, South Korea, Taiwan, and Tunisia in 1958. This was “containment” made real, all the more so as the USSR had no similar options in the Western Hemisphere until the Cuban Revolution. (And as my students always remark, this map puts the Cuban Missile Crisis into perspective.)1

And if the B-29 had been impressive, later bombers were even more so. The B-36 held even more promise. Its development had started during World War II, and its ability to extend the United States’ nuclear reach was anticipated as early as 1945. It didn’t end up being deployed until 1948, but added over 700 miles to the range of US strategic forces, and could carry some 50,000 lbs more fuel and armament. The B-52 bomber, still in service, was ready for service by 1955, and extended the range of bombers by another several hundred miles, increased the maximum flight speed by more than 200 miles per hour.2

Plane First flight Introduced in service Combat range (mi) Maximum speed (mph) Service ceiling (ft) Bomb weight (lbs)
B-17 1935 1938 2,000 287 35,600 4,500
B-29 1942 1944  3,250 357  31,850  20,000
B-36 1946 1948  3,985 435  43,000  72,000
B-52 1952 1955  4,480 650  50,000  70,000
B-2 1989 1997  6,000 630  50,000  40,000

So you can see, in a sense, why the US Air Force was so focused on bombers. They worked, they held uniquely American advantages, and you could see how incremental improvement would make them fly faster, farther, and with more weight than before. But there were more than just technical considerations in mind: fascination with the bomber was also cultural. It was also about the implied role of skill and value of control in a human-driven weapon, and it was also about the idea of “brave men” who fly into the face of danger. The bomber pilot was still a “warrior” in the traditional sense, even if his steed was a complicated metal tube flying several miles above the Earth.


But it wasn’t just that the USAF was pro-bomber. They were distinctly anti-missile for a long time. Why? The late Thomas Hughes, in his history of Project Atlas, attributes a distinct “conservative momentum, or inertia” to the USAF’s approach to missiles. Long-range missiles would be disruptive to the hierarchy: engineers and scientists would be on top, with no role for pilots in sight. Officers would, in a sense, become de-skilled. And perhaps there was just something not very sporting about lobbing nukes at another country from the other side of the Earth.3

But, to be fair, it wasn’t just the Air Force generals. The scientists of the mid-1940s were not enthusiastic, either. Vannevar Bush told Congress in 1945 that:

There has been a great deal said about a 3,000 mile high-angle rocket. In my opinion such a thing is impossible and will be impossible for many years. The people who have been writing these things that annoy me have been talking about a 3,000 mile high-angle rocket shot from one continent to another carrying an atomic bomb, and so directed as to be a precise weapon which would land on a certain target such as this city. I say technically I don’t think anybody in the world knows how to do such a thing, and I feel confident it will not be done for a very long time to come.

Small amounts of money had been doled out to long-range rocket research as early as 1946. The Germans, of course, had done a lot of pioneering work on medium-range missiles, and their experts were duly acquired and re-purposed as part of Operation Paperclip. The Air Force had some interest in missiles, though initially the ones they were more enthusiastic about were what we would call cruise missiles today: planes without pilots. Long-range ballistic missiles were very low on the priority list. As late as 1949 the National Security Council gave ballistic missiles no research priority going forward — bombers got all of it.

Soviet testing of an R-1 (V-2 derivative) rocket at Kapustin Yar. Soviet rocket tests were detected by American radars — and spurred US interest in rockets. Source.

Soviet testing of an R-1 (V-2 derivative) rocket at Kapustin Yar. Soviet rocket tests were detected by American radars — and spurred US interest in rockets. Source.

Real interest in ballistic missiles did not begin until 1950, when intelligence reports gave indication of Soviet interest in the area. Even then, the US Air Force was slow to move — they wanted big results with small investment. And the thing is, rocket science is (still) “rocket science”: it’s very hard, all the more so when it’s never been really done before.

As for the Soviets: while the Soviet Union did not entirely forego research into bombers, the same geographic factors as before encouraged them to look into long-range rockets much earlier than the United States. For the USSR to threaten the USA with bombers would require developing very long-range bombers (because they lacked the ability to put bases on the US perimeter), and contending with the possibility of US early-warning systems and interceptor aircraft. If they could “skip” that phase of things, and jump right to ICBMs, all the better for them. Consequently, Stalin had made missile development a top priority as early as 1946.

It wasn’t until the development of the hydrogen bomb that things started to really change in the United States. With yields in the megaton range, suddenly it didn’t seem to matter as much if you couldn’t get the accuracy that high. You can miss by a lot with a megaton and still destroy a given target. Two American scientists played a big role here in shifting the Air Force’s attitude: Edward Teller and John von Neumann. Both were hawks, both were H-bomb aficionados, and both commanded immense respect from the top Air Force brass. (Unlike, say, J. Robert Oppenheimer, who was pushing instead for tactical weapons that could be wielded by the — gasp — Army.)

Ivy Mike, November 1952. Accuracy becomes less of a problem.

Ivy Mike, November 1952. Accuracy becomes less of a problem.

Teller and von Neumann told the Air Force science board that the time had come to start thinking about long-range missiles — that in the near term, you could fit a 1-2 megatons of explosive power into a 1-ton warhead. This was still pretty ambitious. The US had only just tested its first warhead prototype, Ivy Mike, which was an 80-ton experiment. They had some other designs on the books, but even the smaller weapons tested as part of Operation Castle in 1954 were multi-ton. But it was now very imaginable that further warhead progress would make up that difference. (And, indeed, by 1958 the W49 warhead managed to squeeze 1.44 Mt of blast power into under 1-ton of weight — a yield-to-weight ratio of 1.9 kt/kg.)

The USAF set up an advisory board, headed by von Neumann, with Teller, Hans Bethe, Norris Bradbury, and Herbert York on it. The von Neumann committee concluded that long-range missile development needed to be given higher priority in 1953. Finally, the Department of Defense initiated a full-scale ICBM program — Project Atlas — in 1954.

Even this apparent breakthrough of bureaucratic inertia took some time to really get under way. You can’t just call up a new weapons system from nothing by sheer will alone. As Hughes explains, there were severe doubts about how one might organize such a work. The first instinct of the military was to just order it up the way they would order up a new plane model. But the amount of revolutionary work was too great, and the scientists and advisors running the effort really feared that if you went to a big airplane company like Convair and said, “make me a rocket,” the odds that they’d actually be able to make it work were low. They also didn’t want to assign it to some new laboratory run by the government, which they felt would be unlikely to be able to handle the large-scale production issues. Instead, they sought a different approach: contract out individual “systems” of the missile (guidance, fuel, etc.), and have an overall contractor manage all of the systems. This took some serious effort to get the DOD and Air Force to accept, but in the end they went with it.

Launch sequence of an Atlas-D ICBM, 1960. Source.

Launch sequence of an Atlas-D ICBM, 1960. Source.

Even then things were pretty slow until mid-1954, when Congressional prodding (after they were told that there were serious indications the Soviets were ahead in this area) finally resulted in Atlas given total overriding defense priority. Even then the people in charge of it had to find ways to shortcut around the massive bureaucracy that had grown up around the USAF and DOD contracting policies. In Hughes’ telling of Atlas, it is kind of amazing that it gone done at rapidly as it did — it seems that there were near-endless internal obstacles to get past.  The main problem, one Air Force historian opined, was not technical: “The hurdle which had to be annihilated in correcting this misunderstanding was not a sound barrier, or a thermal barrier, but rather a mental barrier, which is really the only type that man is ever confronted with anyway.” According to one estimate, the various long-term cultural foot-dragging about ballistic missiles in the United States delayed the country from acquiring the technology for six years. Which puts Sputnik into perspective.

The US would start several different ballistic missile programs in the 1950s:

Rocket family Design started Role Military patron Prime industrial contractor Warhead yield
Redstone 1950 IRBM US Army Chrysler 0.5-3.5 Mt
Atlas 1953 ICBM USAF Convair 1.44 Mt
Thor 1954 IRBM USAF Douglas 1.4 Mt
Titan 1955 ICBM USAF Glenn Martin 3.75 Mt
Polaris 1956 SLBM USN Lockheed 0.6 Mt
Minuteman 1957 ICBM USAF Boeing 1.2 Mt

As you can see, there’s some redundancy there. It was deliberate: Titan, for example, was a backup to Atlas in case it didn’t work out. There’s also some interesting stuff going on with regards to other services (Army, Navy) not wanting to be “left out.” More on that in a moment. Minuteman, notably, was based on solid fuel, not liquid, giving it different strategic characteristics, and a late addition. The Thor and Redstone projects were for intermediate-range ballistic missiles (IRBMs), not ICBMs — they were missiles you’d have to station closer to the enemy than the continental United States (e.g., the famous Jupiter missiles kept in Turkey).

The redundancy was a hedge: the goal was to pick the top two of the programs and cancel the rest. Instead, Sputnik happened. In the resulting political environment, Eisenhower felt he had to put into production and deployment all six of them — even though some were demonstrably not as technically sound as others (Thor and Polaris, in their first incarnations, were fraught with major technical problems). This feeling that he was pushed by the times (and by Congress, and the services, and so on) towards an increasingly foolish level of weapons production is part of what is reflected in Eisenhower’s famous 1961 warning about the powerful force of the “military-industrial complex.”4


Polaris is a special and interesting case, because it’s the only one in that list that is legitimately a different form of delivery. Shooting a ballistic missile is hard enough; shooting one from a submarine platform was understandably more so. Today the rationale of the SLBM seems rather obvious: submarines have great mobility, can remain hidden underwater even at time of launch, and in principle seem practically “invulnerable” — the ultimate “second strike” guarantee. At the time they were proposed, though, they were anything but an obvious approach: the technical capabilities just weren’t there. As already discussed at length, even ICBMs were seen with a jaundiced eye by the Air Force in the 1950s. Putting what was essentially an ICBM on a boat wasn’t going to be something the Air force was going to get behind. Graham Spinardi’s From Polaris to Trident is an excellent, balanced discussion the technical and social forces that led to the SLBM becoming a key leg of the “triad.”5

The USS Tunny launches a cruise missile (Regulus) circa 1956. Source.

The USS Tunny launches a cruise missile (Regulus) circa 1956. Source.

The Navy had in fact been interested in missile technology since the end of World War II, getting involved in the exploitation of German V-2 technology by launching one from an aircraft carrier in 1947. But they were also shy of spending huge funds on untested, unproven technology. Like the Air Force, they were initially more interested in cruise than ballistic missiles. Pilotless aircraft didn’t seem too different from piloted aircraft, and the idea of carrying highly-volatile liquid fueled missiles made Navy captains squirm. The Regulus missile (research started in 1948, and fielded in 1955) was the sort of thing they were willing to look at: a nuclear-armed cruise missile that could be launched from a boat, with a range of 575 miles. They were also very interested in specifically-naval weapons, like nuclear-tipped torpedoes and depth charges.

What changed? As with the USAF, 1954 proved a pivotal year, after the development of the H-bomb, the von Neumann committee’s recommendations, and fears of Soviet work combined with a few other technical changes (e.g., improvements in solid-fueled missiles, which reduced the fear of onboard explosions and fires). The same committees that ended up accelerating American ICBM work similarly ended up promoting Naval SLBM work as well, as the few SLBM advocates in the Navy were able to use them to make a run-around of the traditional authority. At one point, a top admiral cancelled the entire program, but only after another part of the Navy had sent around solicitations to aerospace companies and laboratories for comment, and the comments proved enthusiastic-enough that they cancelled the cancellation.

As with the ICBM, there was continued opposition from top brass about developing this new weapon. The technological risks were high: it would take a lot of money and effort to see if it worked, and if it didn’t, you couldn’t get that investment back. What drove them to finally push for it was a perception of being left out. The Eisenhower administration decided in 1955 that only four major ballistic missile programs would be funded: Atlas, Titan, Thor, and Redstone. The Navy would require partnering up with either the USAF or US Army if it wanted any part of that pie. The USAF had no need of it (and rejected an idea for a ship-based Thor missile), but the Army was willing to play ball. The initial plan was to develop a ship-based Jupiter missile (part of the Redstone missile family), with the original schedule was to have one that could be fielded by 1965.

But the Navy quickly was dissatisfied with Jupiter’s adaptability to sea. It would have to be shrunk dramatically to fit onto a submarine, and the liquid-fuel raised huge safety concerns. They quickly started modifying the requirements, producing a smaller, solid-fueled intermediate-range missile. They were able to convince the Army that this was a “back-up” to the original Jupiter program, so it would technically not look like a new ballistic missile program. Even so, it was an awkward fit: even the modified Jupiter’s were too large and bulky for the Navy’s plans.

What led to an entirely new direction was a fortuitous meeting between a top naval scientist and Edward Teller (who else?), at a conference on anti-submarine warfare in the summer of 1956. At the conference, Teller suggested that trends in warhead technology meant that by the early 1960s the United States would be able to field megaton-range weapons inside a physics package that could fit into small, ship-based missiles. Other weapons scientists regarded this as possibly dangerous over-hyping and over-selling of the technology, but the Navy was convinced that they could probably get within the right neighborhood of yield-to-weight ratios. By the fall of 1956, the Navy had approved a plan to create their own ballistic missile with an entirely different envelope and guidance system than Jupiter, and so Polaris was born.

Artist's conception of a Polaris missile launch. Source.

Artist’s conception of a Polaris missile launch. Source.

The first generation of Polaris (A-1) didn’t quite meet the goals articulated in 1956, but it got close. Instead of a megaton, it was 600 kilotons. Instead of 1,500 mile range, it was 1,200. These differences matter, strategically: there was really only one place it could be (off the coast of Norway) if it wanted to hit any of the big Soviet cities. And entirely separately, the first generation of Polaris warheads were, to put it mildly, a flop. They used an awful lot of fissile material, and there were fears of criticality accidents in the event of an accidental detonation. No problem, said the weapons designers: they’d put a neutron-absorbing strip of cadmium tape in the core of the warhead, so that if the high explosives were ever to detonate, no chain reaction would be possible. Right before any intended use, a motor would withdraw the tape. Sounds good, right? Except in 1963, it was discovered that the tape corroded while inside the cores. It was estimated that 75% of the warheads would not have detonated: the mechanism would have snapped the tape, which would then have been stuck inside the warhead. There was, as Eric Schlosser, in Command and Control, quotes a Navy officer concluding that they had “almost zero confidence that the warhead would work as intended.” They all had to be replaced.6

The first generation of Polaris missiles, fielded in 1960, were inaccurate and short-ranged (separate from the fact that the warheads wouldn’t have worked). This relegated them to a funny strategic position. They could only be used as a counter-value secondary-strike: they didn’t have the accuracy necessary to destroy hardened targets, and many of those were more centrally-located in the USSR.


The “triad” was fielded starting in the 1960s. But there was little discussion of it as a “triad” per se: it was a collection of different weapon systems. Indeed, deciding that the US strategic forces were really concentrated into just three forces is a bit of an arbitrary notion, especially during the Cold War but even today. Where do foreign-based IRBMs fit into the “triad” concept? What about strategic weapons that can be carried on planes smaller than heavy bombers? What about the deterrence roles of tactical weapons, the nuclear artillery shells, torpedoes, and the itty-bitty bombs? And, importantly, what about the cruise missiles, which have developed into weapons that can be deployed from multiple platforms?

Nuclear Triad Google Ngram

Relative word frequency for “nuclear triad” as measured across the Google Books corpus. Source.


It’s become a bit cliché in history circles to pull up Google Ngrams whenever we want to talk about a concept, the professorial equivalent of the undergraduate’s introductory paragraph quoting from the dictionary. But it’s a useful tool for thinking about when various concepts “took hold” and their relative “currency” over time. What is interesting in the above graph is that the “triad” language seems to surface primarily in the 1970s, gets huge boosts in the late Cold War, and then slowly dips after the end of the Cold War, into the 21st century.

Which is to say: the language of the “triad” comes well after the various weapon systems have been deployed. It is not the “logic” of why they made the weapons systems in the first place, but a retrospective understanding of their strategic roles. Which is no scandal: it can take time to see the value of various technologies, to understand how they affect things like strategic stability.

But what’s the context of this talk about the triad? If you go into the Google Books entries that power the graph, they are language along the lines of: “we rely on the triad,” “we need the triad,” “we are kept safe by the triad,” and so on. This sort of assertive language is a defense: you don’t need to sing the praises of your weapons unless someone is doubting their utility. The invocation of the “triad” as a unitary strategic concept seems to have come about when people started to wonder whether we actually needed three major delivery systems for strategic weapons.

A strange elaboration of the triad notion from the Defense Logistics Agency, in which the "new triad" includes the "old triad" squished into one "leg," with the other "legs" being even less tangible notions joined by a web of command and control. At this point, I'd argue it might be worth ditching the triad metaphor. Source.

A strange elaboration of the triad notion from the Defense Logistics Agency, in which the “new triad” includes the “old triad” squished into one “leg,” with the other “legs” being even less tangible notions joined by a web of command and control. At this point, I’d argue it might be worth ditching the triad metaphor. Source.

When you give something abstract a name, you aid in the process of reification, making it seem tangible, real, un-abstract. The notion of the “triad” is a concept, a unifying logic of three different technologies, one that asserts quite explicitly that you need all three of them. This isn’t to say that this is done in bad faith, but it’s a rhetorical move nonetheless. What I find interesting about the “triad” concept — and what it leaves out — is that it is ostensibly focused on technologies and strategies, but it seems non-coincidentally to be primarily concerning itself with infrastructure. The triad technologies each require heavy investments in bases, in personnel, in jobs. They aren’t weapons so much as they they are organizations that maintain weapons. Which is probably why you have to defend them: they are expensive.

I don’t personally take a strong stance on whether we need to have ICBMs and bombers and SLBMs — there are very intricate arguments about how these function with regards to the strategic logic of deterrence, whether they provide the value relative to their costs and risks, and so on, that I’m not that interested in getting into the weeds over. But the history interests me for a lot of reasons: it is about how we mobilize concepts (imposing a “self-evident” rationality well after the fact), and it is also about how something that in retrospect seems so obvious to many (the development of missiles, etc.) can seem so un-obvious at the time.

  1. The list of these deployments comes from the appendices in History of the Custody and Deployment of Nuclear Weapons, July 1945 through September 1977 (8MB PDF here), prepared by the Office of the Assistant to the Secretary of Defense (Atomic Energy), in February 1978, and Robert S. Norris, William Arkin, and William Burr, “Where They Were,” Bulletin of the Atomic Scientists (November/December 1999), 27-35, with a follow-up post on the National Security Archive’s website.
  2. All of the quantitative data on these bombers was taken from their Wikipedia pages. In places where there were ranges, I tried to pick the most representative/likely numbers. I am not an airplane buff, but I am aware this is the sort of thing that gets debated endlessly on the Internet!
  3. Thomas Hughes, Rescuing Prometheus: Four Monumental Projects That Changed the Modern World (New York : Pantheon Books, 1998), chapter 3, “Managing a Military Industrial Complex: Atlas,” 69-139.
  4. Eric Schlosser’s Command and Control has an excellent discussion of the politics of developing the early missile forces.
  5. Graham Spinardi, From Polaris to Trident: The Development of US Fleet Ballistic Missile Technology (Cambridge University Press, 1994).
  6. Spinardi, as an aside, gives a nice account of how they eventually achieved the desired yield-to-weight ratio in the W-47: the big “innovation” was to just use high-enriched uranium as the casing of the secondary, instead of unenriched uranium. As he notes, this was the kind of thing that was obvious in retrospect, but wasn’t obvious at the time — it required a different mindset (one much more willing to “expend” fissile material!) than the weapons designers of the early 1950s were used to.

Mapping the US nuclear war plan for 1956

A few months back, the National Security Archive made national headlines when they released a 1956 US target list they had obtained under the Freedom of Information Act. The target list outlined over a thousand Strategic Air Command nuclear targets in the Soviet Union, Eastern Bloc, the People’s Republic of China, and North Korea. The Archive had posted a small graphic of the ones in Eastern Europe, but hadn’t digitized the full list. Several weeks ago, the people at the Future of Life Institute did just this, digitizing the complete dataset — no small task, given that these were spread over several hundred, non-OCR-able pages of smudgy, 60-year-old government documents.1

A sampling of the 1956 target list obtained by the National Security Archive. The digits encode latitude and longitude points, among other bits of information.

A sampling of the 1956 target list obtained by the National Security Archive. The digits encode latitude and longitude points, among other bits of information.

I recently attended a conference that the FLI put on regarding nuclear war. FLI was co-founded by the MIT physicist Max Tegmark and his wife Meia (among a few others), both of whom I was glad I got to spend some time with, as they are interesting, intelligent people with interesting histories. They are interested in promoting work that decreases existential threats to the human race, which they see as possibly including things like nuclear war and nuclear winter, but also unhampered artificial intelligence, climate change, and the possible negative futures of biotechnology. These are all, of course, controversial topics (not always controversial among the same groups of people, to be sure). They’re an interesting group, and they are stirring up some interesting discussions, which I think is an unambiguously positive thing even if you don’t agree that all of these things are equally realistic threats, or threats on the same level.2

The FLI's digitized version of the target list. Click the image to view their interactive version.

The FLI’s digitized version of the target list. Click the image to view their interactive version.

The target list, mapped out as the FLI did above, is already pretty impressive. While I was at the conference, I got the idea that it wouldn’t be that hard to reconfigure a few parts of the NUKEMAP code to allow me to import huge numbers of target lists in the right format. NUKEMAP already supports the targeting of multiple nukes (the feature is a little cryptic — you create a detonation, then click “launch multiple,” then move the cursor and can then create another one, and repeat as necessary), but it didn’t have any automatic way of importing a large number of settings. Once I had done that, I then thought, what would it look like if I used realistic weather data to determine the fallout patterns from surface bursts? It only took a little bit of further work to write a script that can poll OpenWeatherMap‘s public API and grab information about real-time wind speed and direction information about any given set of coordinates.3 This renders quite an impressive image, though to do this for some 1,154 targets requires a lot of RAM (about 1.5 GB) and a fast computer. So it’s not something one wants to necessarily do all the time.

I have captured the results as a series of interactive screenshots, to better save you (and your web browser) the trouble of trying to render these yourself. You can see how changing the yield dramatically changes the fallout (assuming surface bursts, of course). The interactive viewer is available by clicking the image below, or this link.4

Screenshot of my interactive viewer for the nuclear war plan. Click to view.

Screenshot of my interactive viewer for the nuclear war plan. Click to view.

I also sampled weather data from a few days in a row, to see what differences it made from a practical standpoint. It is remarkable how different wind speed and direction can vary from day to day. In some of these “simulations,” Copenhagen, Denmark, avoids fallout. In others, it does not. Under some weather conditions (and yield selections), northern Japan gets some fallout from an attack on the Soviet-controlled Kuril Islands; in others, it does not. The NUKEMAP’s fallout estimator is, of course, a very simplified model, but even with that you can get a sense of how much difference a shift in the winds can make.

Having done that, I started to wonder: what would the casualties of such an attack look like? I don’t have population density data of the relevant areas from 1956 that has sufficient granularity to be used with my normal NUKEMAP casualty estimating script, but I figured that even the present-day population figures would be interesting. If you try to query the casualty database with over a thousand targets it just says “no,” so I wrote another script that would query it target-by-target and tally the results.

The results were a bit staggering. I mean, I assumed it would be a large number. But they are really large numbers. Some of this is because the casualty script is double-counting “victims” when they are inside the relevant blast areas of multiple detonations. At the moment, there’s no easy way around that (even for a small number of detonations, keeping track of who is already “dead” would require a lot of time and processing power, and to do it on the scale of a thousand is just not possible with the way it is set up currently).

An example of an area where a lot of "double-counting" is taking place — St. Petersburg. The circles show various pressure rings for 1 Mt weapons, which are used by NUKEMAP to calculate casualties. Maybe just a little overkill...

An example of an area where a lot of “double-counting” is taking place — St. Petersburg. The circles show various pressure rings for 1 Mt weapons, which are used by NUKEMAP to calculate casualties. Maybe just a little overkill…

On the other hand, the casualty estimate does not take into account fallout-related casualties, or the long-term casualties caused by the destruction of so much infrastructure. The target list also doesn’t tell us how many targets were, in fact, targeted redundantly with multiple weapons — the idea that it might have been “one nuke, one target” is definitely an incorrect one. Even before World War II had completely ended, US planners for nuclear war against the Soviet Union understood that not every bomb would make it to a target, and so planned for multiple weapons to be targeted on each. So “double-killing” those people in some of these locations is probably not so wrong. It likely isn’t all that crazy to think of these numbers as back-of-the-envelope estimates for what would result if you waged this kind of attack today (which is not to imply that the US would necessarily do such a thing). But I don’t want anyone to think I am implying any kind of real certainty here. I would, in fact, be dubious of anyone, at any time, implying a lot of certainty about these kinds of things, because we (fortunately) lack very much first-hand experience with this kind of “data,” outside of the results at Hiroshima and Nagasaki, which were in many ways particular to their time and place.

Casualty figures, of course, require making assumptions about the size of the nuclear weapons used, as well as the fuzing settings (airbursts generate far less downwind fallout in comparison to surface bursts, but they can greatly increase the casualties for people in civilian structures). For 1956, there would have been a “mix” of yields and types of weapons. We don’t have data on that to my knowledge. As a simplifying assumption, I just ran the casualty calculation with a number of yields, and with both surface burst and airbursts (optimized to increase the range of the 5 psi blast area) options. For the sake of space and avoiding the appearance of false precision, I have rounded them to their nearest million below:

surface burst airburst
injuries fatalities injuries fatalities
10 Mt 259 239 517 304
5 Mt 210 171 412 230
1 Mt 120 70 239 111
500 kt 89 46 185 77
100 kt 39 16 94 30
50 kt 25 10 66 19

At first I thought some of these numbers just seemed fantastical. Russia today only has a population of 140 million or so. How could we get up to numbers so high? Some of this is, again, because of double-counting, especially with the very big bomb — if you run a 10 Mt bomb on Moscow kills 5.5 million people, and injures 4 million, by NUKEMAP’s estimate, which combined is 70% of the 13 million people in the area of the 1 psi blast radius of such a weapon. (If that seems high, remember that a 10 Mt bomb goes well outside the city of Moscow itself — the Great Moscow Metro Region is about 16 million people total.) Since a large number of nukes were targeted around Moscow, that’s a lot of double counting, especially when you use them with such high-yield weapons.

So the very-big numbers I would take with a very hefty grain of salt. NUKEMAP’s casualty estimator really isn’t meant for guessing multiple, overlapping damage areas. At best, it attempts to give back-of-the-envelope estimates for single detonations. Separately, the US arsenal at the time was around 10,000 megatons worth of destructive power. So they obviously couldn’t have been (and wouldn’t have been) all multi-megaton monsters. But, all the same, I don’t think it’s at all improbable that the multi-megaton monsters that were in the arsenal would have been targeted at heavily populated regions, like Moscow. Especially given the fact that, again, there would have been multiple nukes aimed at each target.

I also thought it would be interesting to take the casualties and break them apart by region. Here’s where I found some really startling results, using a 1 Megaton (1,000 kiloton) airburst as my “model” detonation, again in millions:

injuries fatalities
Soviet Union 111 55
Warsaw Pact 23 10
China + North Korea 104 46
239 111

To make this point more clearly: 820 of the 1,154 targets were inside the Soviet Union proper. They are responsible for 48% of the casualties in the above scenario. Non-Soviet countries in the Warsaw Pact (Eastern Europe, more or less), were responsible for “only” 188 of the targets, and 9% of the casualties. China and North Korea had only 146 of the targets, but were accountable for 43% of the casualties. Which is to say, each “detonation” in the USSR on average produced around 203,000 casualties on average, each one in Eastern Europe around 176,000, and each one in Asia is over 1 million. That’s kind of bananas.

Now, these use modern (2011) population density figures, not those of 1956. But it’s still a pretty striking result. Why would this be? Partially because the Asian targets seem to be primarily in large cities. Many of the Soviet targets, by contrast, are of pretty isolated areas — remote military airfields in some cases — that only kill a few hundred people. It would make for a very interesting study to really get into the “weeds” of this target plan, and to sort out — systematically — what exactly was being targeted in each location, as best as we can. If we did that, we’d possibly be able to guess at whether an airburst or a surface burst was called for, and potentially even be able to judge target priorities, though the “bomb-as-you-go” method of attack used in the 1950s probably means that even low-priority targets would get nuked early on if they were on a path to a higher-priority one.

Total megatonnage of the US nuclear stockpile — nearly 10 gigatons by 1956, climbing to a peak of over 20 gigatons in 1959. Source: US Department of Energy

Total megatonnage of the US nuclear stockpile — nearly 10 gigatons by 1956, climbing to a peak of over 20 gigatons in 1959. Source: US Department of Energy

What does this exercise tell us? Two things, in my mind. One, this 1956 target list is pretty nuts, especially given the high-yield characteristics of the US nuclear stockpile in 1956. This strikes me as going a bit beyond mere deterrence, the consequence of letting military planners have just a little bit too much freedom in determining what absolutely had to have a nuclear weapon placed on it.

The second is to reiterate how amazing it is that this got declassified in the first place. When I had heard about it originally, I was pretty surprised. The US government usually considered target information to be pretty classified, even when it is kind of obvious (we target Russian nuclear missile silos? You don’t say…). The reason, of course, is that if you can go very closely over a target list, you can “debug” the mind of the nuclear strategist who made it — what they thought was important, what they knew, and what they would do about their knowledge. Though times have changed a lot since 1956, a lot of those assumptions are probably still at least partially valid today, so they tend to keep that sort of thing under wraps. These NUKEMAP “experiments” are quick and cheap approaches to making sense of this new information, and as the creator of the NUKEMAP, let me say that I think “quick and cheap” is meant as a compliment. To analyze something quickly and cheaply is to spark new ideas quickly and cheaply, and you can always subject your new ideas to more careful analytical scrutiny once you’ve had them. I hope that someone in the future will give this target data some real careful attention, because I have no doubt that it still contains many insights and surprises.

  1. Because there has been some confusion about what this list is, I want to clarify a bit here. It is a “Weapons Requirements Study,” which is to say, it’s the way in which the US Air Force Strategic Air Command said, “here are all the things we might want to nuke, if we could.” The might and if we could parts are important, because they are what makes this difference from an actual war plan, which is to say, “what we would actually do in the event of a nuclear war.” The might means that not necessarily all of these targets would have been nuked in any given war situation, but indicates the sorts of things that they considered to be valid targets. The if we could means that this would require more weapons than they could afford to use at the time. In 1956, the US stockpile contained “only” 3,692 warheads. This target list is meant to imply that it needed to be bigger, that is, that by 1959 they would want more weapons to be produced. So by 1959 they had 12,298 weapons — more than three times as many. Why so many weapons for the same number of targets? Because, as noted in the post below, the idea of one-nuke, one-target isn’t how they planned it. Anyway, the long and short of it is, this isn’t exactly the same thing as a war plan, much less for 1956. It may over-count, but it also probably under-counts (because it ignores tactical use, targets of opportunity, the overkill that would occur when targets were multiple-targeted, etc.). But it does give you a flavor of the war planning that was going on, and is probably closer to that than any other document that has been released for this time. As for how that would affect what would have happened in 1956, it’s hard to say, but this is in line with many of the other things we know about nuclear war planning at that time, so I think it is a fair illustration.
  2. I think my students were probably the most happy that FLI digitized all of this target data because if they hadn’t, I was going to force my undergrads who take my data visualization course to do it in the name of a practical example of what “crowdsourcing” can mean.
  3. In some cases, OpenWeatherMap did not have information about some of the coordinates. In such cases, the script averaged the missing point from several surrounding points, weighting them by distance. The results it gives in doing this seem plausible enough. For each time I ran it, there were only about two or three missing pieces of data.
  4. For those who want to look at the dataset themselves, the CSV file that the visualization uses is available here.