"We choose to blow up the Moon": Revisiting Cold War ideology through "A Study of Lunar Research Flights" / by Adeene Denton

On June 19, 1959, the Air Force Special Weapons Center based out of Kirtland Air Force Base, New Mexico, published a new, comprehensive report. Its unclassified title: “A study of lunar research flights.” The somewhat unassuming name of this report belies its true purpose – to detail the scientific information that could be obtained from detonation of nuclear explosives on or in the vicinity of the Moon.

In ~190 pages, “A study of lunar research flights” summarizes a portion of the work carried out by a team of at least ten scientists and engineers on behalf of Project A119, a classified Air Force project. The goal: to successfully detonate a nuclear bomb on the Moon. Primary project work was conducted at the Armour Research Foundation (now the Illinois Institute of Technology’s Research Institute) from mid-1958 through spring 1959, when the project was cancelled by the Department of Defense for reasons that remain unknown, even to the project participants. According to scientists who worked on the project, all nine of the monthly progress reports that were prepared as part of their efforts were later destroyed the Illinois Institute of Technology. Thus, the report I’ll discuss here – “A study of lunar research flights” – may be all that remains of Project A119.

Previous writers have covered the basic gist of the project – a Cold War-driven military was open to setting off nuclear weapons on the Moon, and scientists were enlisted to help them think about whether they could (should) do that. However, many of these articles have focused on the few post-facto interviews. Here, I’ve chosen to return to the original report to look beyond the concept itself and determine what, if anything, the scientists actually planned to do as part of a project whose ultimate aim was to stoke national fervor through explosives. “A study of lunar research flights” may be much more difficult to parse than later interviews because of the unsparing use of scientific jargon, but as the only contemporary source it forms the primary basis for our understanding of Project A119, as well as the scientists themselves.

What can we learn from revisiting the initial report? In my experience both as a scientist and a historian, I have found that rarely is a report just a report, even if it’s clogged with field-specific verbiage at a surface level. In this case, the scientific procedures detailed in this document, and the reasoning left to justify them, reflect the desires of the authors to do legitimate scientific work on the back of a project grounded in absurdity. I’ll introduce some of the available information on the authors of the report, summarize a majority of the report’s scientific content, and then consider how much of the report might reflect the tenuous nature of the relationship between the members of Project A119 and the project’s military overseers. “A study of lunar research flights” offers one of a very few available windows into how scientists directly interface with the military on projects like these; further, it reminds us that the U.S. government’s recent overtures towards a more aggressive militarization of space are not new. They’re simply a continuation of an expansive desire that has persisted as long as space exploration itself.

...the most sensitive aspect of the project was, as with many other Department of Defense projects, its very existence.
— Leonard Reiffel, "Sagan breached security by revealing US work on a lunar bomb project", 2000

Doing Science in the Dark: Who were the Men of Project A119?

 Who were the scientists that participated in studies like these, and why did they do it? A quick perusal of the ten-member team affiliated with Project A119 includes numerous physicists and engineers focused primarily on energy transmission (examples of their study areas include sensor and telescope design) as well as astronomer Gerald Kuiper and a young Carl Sagan, then his PhD student. All ten men were sworn to secrecy about the work, as setting a nuclear bomb off on the Moon was considered a matter of national security. Despite being the most junior member of the team during its operation, Carl Sagan is now the most famous of the ten project members, going on to become one of the leading public scientists of the 20th century. However, his legacy concerning Project A119 is an unusual one: Sagan allegedly revealed classified details of the work in a 1959 fellowship application, a potentially serious national security breach that was rather fortuitously discovered by biographer Keay Davidson in 1999. Davidson, however, only cites “Sagan’s…Fellowship file,” which is not available for public perusal, so the actual contents of the security breach remain unknown. Still, this finding, and the subsequent attention given to it by scientists and journalists alike, pushed the leader of the project to publicly step forward in 2000.

Leonard Reiffel, an American physicist at the Illinois Institute for Technology before he was tapped to lead Project A119, is both the primary author of “A study of lunar research flights” and the reason why we today are aware of its existence. After the publication of Davidson’s biography, in which he made allusions to the existence of the project based on the contents of Sagan’s application, Reiffel became the only member of the team to publicly declare his affiliation with Project A119 through a letter to Nature and subsequent interviews with leading newspapers. As such, our understanding of “A study of lunar research flights” is unavoidably filtered through the opinions of the project’s leader. Because of the nature of scientific reports, it is unclear how much of the report was directly written by Reiffel as primary author and which sections were contributed by other members of the team. However, in his letter to Nature in 2000 and later interviews, he takes both credit for overall project direction and wording decisions made in all reports.  

Leonard Reiffel (left) and Carl Sagan (right), two key members of the Project A119 team. Images via Getty Images and NASA JPL, respectively.

Leonard Reiffel (left) and Carl Sagan (right), two key members of the Project A119 team. Images via Getty Images and NASA JPL, respectively.

It is crucial to note that the men who wrote this document, Reiffel included, were aware of their audience, i.e., military researchers and their higher-ups in command, and their role – to provide a premise, however, flimsy, for this exercise as one that might have scientific value. As such, the contents of the majority of the report are largely scientific speculation that avoids discussing any potential political ramifications of the project that might produce a dispute between the scientists and their benefactors. However, Reiffel and his colleagues did quietly express their viewpoints at many locations in the report – this much is apparent from the opening pages.

The introduction of the report is the most overtly realistic about the role of the scientists and their potential scientific products in the military’s decision-making process regarding the project. Here, the authors note that the information that scientists can derive from detonating nuclear weapons on or near the Moon was clearly “only part” of the motivation behind the project, and thus not the only factor in deciding whether it would continue. The military had specific goals for the project that went far beyond scientific data collection, which the report baldly lists – assessing the capacity for nuclear tests in space to be detected from Earth, continued demonstration of U.S. superiority in the realm of advanced destructive technology, and, of course, the “capability of nuclear weapons for space warfare.” The scientists and engineers of Project A119 were employed only to generate a more palatable justification for the public should the detonation proceed.

There was lots of talk on the part of the Air Force about the moon being ‘military high ground,’
— Leonard Reiffel, via LA Times, 2000

Okay, But What’s Actually in the Report? A Summary of Scientific Programming

 So, what science was supposed to be done during these explosive “lunar research flights”? The proposed scientific program detailed in the report defines four basic areas of interest: optical studies, seismic observations, radiation measurements, and direct measurements of lunar surface composition as well as magnetic field strength. The majority of the report’s content is self-admittedly qualitative, as befits a preliminary study done at a time when very, very little was known about the Moon. Despite this, the planned measurements and the reasoning behind them are described in detail over the course of a few hundred pages, and are supported by numerous back-of-the-envelope calculations; in total, the report roughly answers the Air Force’s biggest questions. Here, I’ll summarize the main scientific datasets defined by the report and discuss (some of) the logic behind their choices, as well as the importance of the language the authors used to frame the scientific value of their work.

The boldest proposal of the report is its suggested “best-case” experimental setup: to best utilize the opportunity offered by the nuclear detonation sensors were to be distributed across the lunar surface in advance, allocated in three separate but identical instrument packages. The team deemed identifying landing site selections for these instrument packages to be presumptive; the first close-up images of the Moon would not be delivered into scientists’ hands until 1964 with the success of Ranger 7. The Ranger project, also begun in 1959, was still in its earliest engineering stages. Thus, the following suggestions for scientific return are based on information derived from Earth-based remote sensing, which at the time was both relatively low-resolution and extensively hampered by atmospheric interference.

If a nuclear bomb goes off on the Moon and no one sees it, does the US win the space race?

A large section of the report focuses on “optical studies” – a generically bland term whose proposed procedures cover both identifiably scientific measurements, such as obtaining the thermal conductivity of the lunar surface and the visibility of lunar geologic features during spacecraft transit and approach, as well as completely untested territory: whether high speed spectroscopy could detect the lunar nuclear blast, as well as whether the explosion could be seen with the naked eye. The “optical studies” section meanders between discussions of what we might consider “normal” scientific measurement collection and much more aggressive methodologies; for example, the authors briefly discuss using 100 to 100,000 kilograms of sodium as part of the explosion to enable it to be better seen by naked eye (sodium fluoresces yellow as it vaporizes and thus could be an excellent tracer, as both the US and USSR discovered during atmospheric vaporization tests in 1955 and 1959).

Given its heavy emphasis in the section’s accompanying tables, it is highly likely that the members of Project A119 were required to determine what was necessary to ensure that the blast would be visible from Earth, both for U.S. citizens and the Soviet Union. The authors provide a range of required intensities produced from kiloton and megaton detonations –because of the geologic variability and unknown composition of the lunar surface, the authors argued that explosive capacity of any blast needed to far exceed minimum visibility estimates. The destructive power of a megaton blast increased the danger of severe disruption of the lunar surface, but would easily accomplish the primary mission goal: to be seen.  For scientists, the blast’s power also had some potential benefits: the resulting data products would be delivered nearly instantaneously. High-speed spectroscopy collected during the explosion would yield direct compositional information about the Moon from depths far below the immediate surface, as well as whatever signatures the lunar surface might yield with its materials in an excited energy state, all within a matter of seconds to minutes after detonation.  

One purely scientific return that appears to have excited the team was the potential for high-resolution thermal conductivity measurements in the aftermath of the explosion. At the time, the only available measurements of the Moon’s thermal conductivity – a valuable indicator of surface roughness and, potentially, surface composition – were collected during lunar eclipses at depressingly low spatial resolution. From those measurements, all scientists could say for sure was that the Moon as a whole cooled very quickly; however, this line of thinking did lead to the first (ultimately correct) hypotheses proposing an extensive lunar regolith. Given the struggle to get more accurate thermal conductivity information, the report authors noted that measurements from a nuclear blast would almost certainly speed up the knowledge collection process. If they managed to collect measurements of the radiant flux around ground zero over time, the cooling rate in the area would permit measurements of the thermal conductivity at an incredibly high resolution – and much higher temperatures. However, the authors also note that the potential interference of radioactive decay with the returned thermal signal could derail their scientific ambitions entirely.

Big bomb, big data?

Following their discussion of optical studies, Reiffel and his coauthors then briefly propose one of the first conceptual implementations of lunar seismology. Here, they outline how a team of seismologists could theoretically use the nuclear blast as a supercharged point source to constrain the structure of the lunar interior. Their approach largely follows traditional seismological techniques used at the time, and thus requires placement of seismic detectors on the lunar surface prior to detonation. In a precursor to more modern spacecraft instrument proposals, the authors emphasize some low-cost, minimum-return options in their opening argument for the benefits of lunar seismology. If the microseismic detectors being developed at Lamont Earth Observatory could be feasibly emplaced on the lunar surface, the report arguments, then scientists could theoretically obtain “pristine” observations of the “creaking noise” of the Moon during its elastic adjustment to the gravitation pull of the Earth – yielding potential information about the Earth-Moon system as a whole.

Interestingly, the report goes a bit off-topic in this section. In particular, extensive space is devoted to emphasizing that “a considerable amount of interpretable data” could be obtained from just a single lunar seismometer and no nuclear explosion (though of course they ultimately ask for three seismometers over one). Adding small, low-cost tools to the lunar surface would yield much more scientific return on the project, the writers note, particularly since the Air Force already has to house the missile in some sort of spacecraft. The authors argue that scientists would gain immediate, immensely valuable knowledge of the Moon’s interior structure, surface layering, and compositional variation, even if the detonation were to ultimately fail or if the bomb was not sent at all.

Here, it seems as though the authors have attempted to invoke an argument against a nuclear detonation based on scientific and cost principles; however, the subject is subsequently dropped. At the end of the seismic section Reiffel and his co-authors return to the task at hand – discussing how much of the lunar interior could be resolved from kiloton vs. megaton explosions: they estimate that these would yield earthquake magnitudes of ~4.5 and 6.2 on the Richter scale, respectively, which in turn would propagate initial seismic waves across the moon with an effective radius of hundreds of kilometers from ground zero (kiloton) to potentially disrupting the entire lunar surface (megaton). The resulting destructive capacity these waves might have on the upper layers of the Moon, the authors note, remains unknown.

Table 3 from the lunar seismology section of the report, which details the relative effect of the potential detonation options using the Gutenberg-Richer scale, as well as the potential distance of detection with remotely placed seismometers.

Table 3 from the lunar seismology section of the report, which details the relative effect of the potential detonation options using the Gutenberg-Richer scale, as well as the potential distance of detection with remotely placed seismometers.

Will we irreparably irradiate the Moon?

The last main scientific sections of the report cover the potential mechanisms for detecting the Moon’s radiation environment and its putative magnetic field through the placement of sensors on the surface in conjunction with the seismometers – thus creating the complete instrument package proposed in the introduction. However, the authors also use the section to try to estimate how much radioactivity would be produced from nuclear detonation, largely to assess the very real concern that a nuclear detonation might irradiate the Moon. Based on a back-of-the-envelope calculation derived from the assumption of a 500 kiloton yield from a one megaton weapon, Reiffel and his coauthors posit that the radiation would potentially decay to the general cosmic ray background level within one to two months; however, it might not. The decision of whether this is an acceptable uncertainty is left as an exercise to the report’s readers.

The authors use careful language in their last scientific section, concluding that while detonation of a nuclear weapon would likely produce only modest radioactive decay that could theoretically be easily tracked, the same instrumentation they propose for their surface packages to measure the radiation post-explosion would be “capable of making meaningful measurements” without the presence of a detonation. Thus, similar to their discussion in the seismology section, the authors once again take care to note that the value of these instrument packages is not limited to what they could measure during a nuclear detonation, but also during their transit and deployment on the lunar surface.

 In the end, it seems as though the authors of “A study of lunar research flights” devoted notable time to quietly voicing opinions against nuclear detonation within their scientific assessments, without firmly committing to an aggressive stance. However, their argument does become somewhat more forceful in the closing sections and appendices of the report, when Reiffel and his co-authors combine their lightly voiced concerns with a growing movement in the scientific community: planetary protection.

It might be argued that since the first moonfall is very likely to be by a Soviet vehicle, the concern [of terrestrial contamination] ... is somewhat academic.
— Reiffel et al., "A study of lunar research flights." (1959).

“Pride Goeth Before Destruction”: Raising Early Concerns of Planetary Protection

If, hypothetically, you were enlisted by the Department of Defense to do some Cold War-era science, how would you tell the military that their latest nuclear idea is poor? Reiffel and his coauthors appear to have at least attempted this in their report through a specifically identified examination and explanation of the negative effects that could be produced from a lunar nuclear detonation “from a scientific viewpoint” (underline in original document). Their objections include: (1) the massive physical disturbance to the local and regional lunar environment, (2) radiological contamination, and (3) the potential for additional biologic contamination through deposition of terrestrial microbes, a fear which continues today. To back up their arguments, the authors include a brief survey of the burgeoning planetary protection/astrobiology community. Ultimately, the question the report authors chose to emphasize was not “will we contaminate the Moon?” – that answer was a solid “maybe” – but rather, “if we do, do we care?”

For Reiffel and his co-authors, it’s a critical question: if terrestrial organisms are deposited on the Moon during the initial detonation it would “represent an unparalleled scientific disaster,” which “may not be recouped” by further studies elsewhere in the Solar System. The Earth-Moon system may be unique, the authors remind their audience, and the lack of concrete information about the lunar environment means that the authors cannot adequately even estimate the potential cost to future science. By enlisting the concerns of the broader scientific community referenced in the report, the authors note that the majority of early astrobiological organizations felt that the threat of lunar contamination was too strong to continue; a nuclear detonation could ballistically emplace contaminants, biological and otherwise, over a massive swath of the surface. However, the authors stop short of outright recommending the project be cancelled; instead, the project should be delayed “until more information is available.”

The question then remains: would this argument have been effective for the report’s audience? Are the authors’ arguments kept so light to ensure that their concerns, however diluted, would be read by those that needed to hear them, or did they censure out of caution to protect themselves and their careers? Of the authors’ written objections to Project A119’s stated goal, all are couched in guarded language and many are buried in the report’s appendices. Such caution also influenced outside scientists consulted on the project: some of the experts interviewed by the authors also confided that they feared “stating the contamination case too strongly for fear [their] advice would not be heeded.” There is a depressing fatalism inherent in the authors’ assumption that a strong objection would be dismissed by the military outright – and yet, that fear is buried in real truth.

 To conclude the discussion, the authors encourage the U.S. to be on the side of planetary protection and against contamination, not least because “[t]he U.S. propaganda possibilities following a USSR lunar contamination – or vice versa” could have considerable sway in the national and international spheres. Permanently contaminating a heavenly body in the name of national prestige, the authors suggest, is something that the public likely would not abide. With the Cold War as a game of prestige, the threat of public opinion might be the only bargaining chip that could be used to persuade an impulsive military to hesitate before barreling headlong into the militarization of space.

The cover from volume I of the report - volume II was allegedly destroyed.

The cover from volume I of the report - volume II was allegedly destroyed.

In Conclusion: What (Who) is Space for? 

Just a few short years before JFK declared that we would send humans to the Moon, a small cadre of scientists, engineers, and military personnel were considering whether it might be better to blow part of it up. Today, we can only wonder what the other, more technical reports of Project A119, with titles such as “Possible Contribution of Lunar Nuclear Weapons Detonations to the Solution of Some Problems in Planetary Astronomy,” and “Radiological Contamination of the Moon by Nuclear Weapons Detonation,” could have contained. Did they elaborate on scientific methodologies? Did the scientists change tactics in their attempts to communicate opinions to their military employers?

As Reiffel stated in his letter to Nature in 2000, his team was well aware of their sponsors’ lack of concern surrounding the scientific cost of “destroying the pristine lunar environment.” Sagan’s inadvertent breach of national security, and the subsequent discovery of said breach, raises important questions about the conduct of scientists that we should continue to consider – when, as scientists, do we become complicit in projects that we fundamentally disagree with, as Reiffel alleges that he felt? We may never fully grasp how the A119 scientific team felt about the work they did, and whether those feelings evolved over time. The scientists themselves are dead, and nearly all of the evidence of their work destroyed. What scientific legacy Project A119 could have left was suppressed by the military’s intense, unceasing need for secrecy. To try to observe evidence of personal opinion in the remaining scientific report may seem like squeezing water from a stone. 

Bombing the Moon would have resulting in an unquantifiable scientific loss; the radiation would have transformed large swathes of the Moon’s surface, potentially permanently, or at least on the scale of a human lifetime. Planetary scientists working now would never have known a pristine Moon. Today, we can be thankful that the Air Force and the Department of Defense did not, in fact, end up bombing the Moon. But it’s just as important that we consider how close they may have come, and what opportunities scientists had to stop them. How persuasive was this report, which ultimately equivocates far more than it takes a stance? Given the potential loss the community faced, is this the best we could do?

There is always a choice: a choice to work on a project that terrifies, in the hopes of changing it for the better; a choice to say no altogether, and make a statement of personal, professional, and scientific integrity in the face of a well-funded military-industrial machine. As the future of space as a realm of international cooperation is threatened by a return to overt militarization, scientists today will have to make those same choices. I’d argue we should think long and hard, and choose wisely.


“A study of lunar research flights.” (1959). Via Defense Technical Information Center.

Associated Press (2000), “U.S. Weighed A-Blast on Moon in 1950s.” Los Angeles Times.

Chyba, C. (1999). “An exobiologist’s life search.” Nature 401, 857-858.

Davidson, K. (1999). Carl Sagan: A Life. John Wiley and Sons, New York, NY. Page 95.

Reiffel, L. (2000). “Sagan breached security by revealing US work on a lunar bomb project.” Nature 405, 13.