“Don’t tell me the sky’s the limit when there are footprints on the Moon.”

We’ve all heard that clichéd phrase at least once in our lives. Leaving the high frequency at which this go-to motivational platitude is used to one side, it’s hard to deny that the traces of human activity on the bright white sphere in the starry ocean above is anything less than utterly inspirational.

It is, without question, a powerfully positive symbol – a timeless encapsulation of our collective ambition and scientific progress. This point in history wasn’t guaranteed to occur, though. Although there is no limit to the number of alternative timelines anyone could entertain regarding our relationship with the Moon, one in particular stands out.

Just as the Cold War was getting going, Project A119 was born. This covert operation, spearheaded by the US Air Force, never truly got off the ground, and it became little more than a detailed thought experiment. If it did, though, we would have lived in the world where the Apollo space program would be nothing more than a thought lingering in an alternative future.

This is the tale of how, once upon a time, humanity planned to trigger a nuclear explosion on the Moon.

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A Mushroom Cloud on the Dark Side of the Moon

The 1950s were a decidedly unnerving time. “The latest rumor going the rounds is that the Russians plan to explode a rocket-borne H-bomb on the moon on or about Nov. 7,” the Pittsburgh Press reported on November 1, 1957. “If that’s true – look out! The rocket and its cargo of violence are more likely than not to boomerang.”

The sensational article, which notes that the rumor is being checked out by US intelligence, explains that the aim of such a strike on our pale guardian would be to demonstrate how far Russian missile technology would have come. Indeed, this was a momentous year for the Soviet Union: A month earlier, Sputnik was launched, and just two days after this article was published, Sputnik 2 was also sent into space, complete with Laika the dog.

At the same time, President Eisenhower was handed a review that suggested US defensive capabilities had fallen far behind that of the Soviets, particularly in terms of missile technology. Later that month, Soviet premier Khrushchev dared the US to a shooting match to prove his point. The world was on edge, and rumors of a Soviet nuclear strike on the Moon perhaps didn’t seem so outlandish.

The event never took place, of course, but the US government was still nervous at the mere thought of it. Indubitably, they had fallen behind, and long before the Apollo program would see them stand victorious in front of all of humanity, they decided to take those rumors and see just how plausible such a scheme could be.

Dr Leonard Reiffel, a respected physicist, gained his doctorate from the Illinois Institute of Technology in 1953, and his star swiftly rose thereafter. He gained senior positions at NASA, and worked with other such famed scientists, including Enrico Fermi, the mind behind the very first nuclear reactor and someone widely considered to be the architect of the nuclear age. Reiffel also collaborated with several key scientists stolen from the collapsed Third Reich as part of America’s Operation Paperclip.

In 1958, officers from the Air Force approached him and, rather bluntly, asked him how possible it would be to detonate a nuclear device on the Moon. Intrigued by the possibility, he worked in complete secrecy as he attempted to answer this question. In the summer of 1959, Project A119 – as it became known – was summarized in one of the strangest scientific reports in human history.

Entitled A Study of Lunar Research Flights, it weighed the pros against the cons of the first atomic explosion on another world to our own. Describing the benefits of such a detonation as being scientific, military and political, it immediately dives in to the many ripples that such a colossal, surprising splash would cause.

Not only would the world find out just how possible it would be to engage in off-world nuclear warfare, but the political benefits the destruction would bestow were obvious: A lunar mushroom cloud, partly illuminated by sunlight if prominent enough, would send an unparalleled message of strength to the Soviet Union.

The report is a thesis on everything scientists knew about the Moon back in the 1950s, from its magnetic field and its lack of atmosphere, to its geological properties and the possibility of organic matter hiding in pockets up there. Every detail was provided in service to a sole question: would it be possible to show the world that the US Air Force could bring hell to a celestial sphere 384,400 kilometers away from home?

A blast on the dark side was preferred.

This document doesn’t envisage how the nuclear warhead would have made it to the Moon. Or, rather, it does, but those sections are redacted and still not publically viewable.

Interviews given by Reiffel in 2000 – when this document was finally declassified – reveal nothing concrete about the delivery system either aside from the fact that, per the Guardian, it was technically plausible. It’s most likely that it would have involved an intercontinental ballistic missile of some kind, the type that had just made their debut on the world stage in the late-1950s.

Aside from the mysterious delivery system, it’s also uncertain how the package itself would be tracked from terra firma. Nevertheless, various methods were assessed in the report, which focused heavily on visual monitoring through the use of telescopes – both ground-based, and some floating from balloons.

One option was to use flares made using the vaporization of sodium, something tested out by both superpowers that decade and proven to be intensely incandescent. Reiffel and his team even calculated the requisite amount of sodium required for the delivery vehicle on the Moon to be seen with the naked eye, on both the dark and bright sides.

The way in which the blast would be carried out was also undecided at the time, but again, multiple pathways were explored. The document does suggest that, based on plenty of simulations, three instrument packages assessing the nature of the blast would be placed in arbitrary places on the visible hemisphere of the Moon. The bomb itself would likely explode on the very edge of the dark side of the Moon, the part that just about wobbles into our terrestrial line of sight, so that the fire and fury could be seen back on Earth more clearly.

The warhead could be unleashed above, on, or under the lunar soil. Some back-of-the-envelope calculations suggested that, no matter which option is used, the pressure waves a powerful nuclear explosion would generated would create artificial “earthquakes” on the Moon, rocking an otherwise seismically silent body. If a one-megaton bomb was used, tremors would be detectable anywhere on our planet’s solitary satellite mere moments after the red switch was flicked.

As on Earth, the geology in the explosion’s midst would be immediately vaporized. “we have the picture of the lunar material moving upward as a gaseous piston from the moon… with a considerable fraction of the radioactive material [being] expelled into space.”

The report adds that although the distribution of the irradiated, ejected dust would be somewhat unpredictable, calculations suggested that the volume of radioactive material reaching Earth would be expected to be very low. For that assessment, we can thank a young graduate student named Carl Sagan, recruited by Reiffel as part of the project.

From Earth, scientists could track the development of the blast’s light much in the same way that they track the flickering of the Sun’s corona, its outermost atmospheric extremities. Apt, considering that the Air Force would have been effectively creating an ephemeral new star on the Moon.

It would have been an undoubtedly epochal moment. Much like the hundreds of millions of people that would have sat around television sets watching Neil Armstrong make our species’ first mark on the ancient volcanic soil, recordings of America’s might would have indelibly burned themselves into the public consciousness.

Extinguishing Lunar Life

The legacy of nuclear fires on our pale blue dot are explicitly clear.

When nuclear tests were carried out in the Cold War, they were done so with a near-nonchalant disregard to the environment and the health of others. Surrounded by scientific instruments and recording equipment, the increasingly powerful blasts set the skies ablaze.

Sometimes old battleships were annihilated in atolls, with the wind sweeping radioactive fallout onto fishermen or settlements. On other occasions, soldiers were asked to march toward the mushroom cloud that was rushing up into the azure air – practice for a future where a ground invasion would follow on from a nuclear strike on the enemy’s position.

As time ticked away, the effects of the blast and the resulting radiation became ever clearer. Aside from the clearly dangerous contaminated veils they would leave in their wake, such blasts also led to scientific revelations in fields outside the realm of nuclear physics.

The craters generated by subterranean blasts were curiously similar to a type of volcano – maar-diatremes – whose formation and destruction still eludes volcanologists today. Along similar lines, the document explains that – whether it’s a nuclear or chemical bomb, the subsurface layers of the Moon would be revealed, ending years of scientific debate on the subject.

At the same time, the isotopes forged in such blasts proved to be oddly useful to oceanographers, who used them to provide detailed cartography of the major aquatic currents transporting heat and nutrients all over the planet.

There’s a good chance that, one day, we’ll be officially living in the Anthropocene Epoch, a brand-new unit of geological time created thanks to our irrevocable decisions. Take your pick: plastics littering our oceans, carbon dioxide smothering our atmosphere, species extinction rates – all make good markers denoting when we first left a clearly detectable signature in the sedimentological record.

Committees looking into the matter, however, have decided that the so-called Golden Spike should instead be represented by the spike in plutonium debris those nuclear weapons tests have left laying around. As a result, the Anthropocene would have begun in 1950, or perhaps in the 1960s, depending on which version of “global distribution” wins out in the end.

Symbolically, the 1950 version works even better when you look at the concerns Reiffel et al. had when considering what environmental impact a nuclear detonation on the Moon would engender. Forget the impact of spreading radioactive ash all over the place: Years before the mission to send manned astronauts to the Sea of Tranquility took place, scientists were wondering that delivering a nuke to the Moon would bring with it hazardous organic or biological material from Earth.

By the 1950s, it was thought that Mars and Venus should definitely not be contaminated in any such way. The Moon was considered to be far less hospitable to biology, but nevertheless it remained unclear how correct this notion actually was, particularly with regards to the subsurface.

The report stresses, therefore, that “if such biological contamination of the moon occurred, it would represent an unparalleled scientific disaster, eliminating several possibly very fruitful approached to such problems as the early history of the solar system, the chemical composition of matter in the remote past, the origin of life on earth, and the possibility of extraterrestrial life.”

The document does argue, however, that such a concern may be merely academic. “The first moonfall is very likely to be by a Soviet vehicle,” the report notes, implying that the biological contamination issue was out of their hands anyway. “The US propaganda possibilities following a USSR lunar contamination – or vice versa – should not be overlooked,” Reiffel suggests.

The danger of biological – and of course radiological – contamination wasn’t the only obstacle that the document outlined. Reiffel explained that there were so many potential problems with carrying out this plan that it was impossible to actually foresee them all.

One passage, in particular, emphasizes just how much time it would take to even go through the issues that the document touched on: “The enormous effort that would be involved in any controlled experiment on or near the moon demands nothing less than an exhaustive evaluation of suggestions by the many qualified persons who have begun to think about this general problem.”

The document deals heavily in abstractions, but one concern that seemed absolutely concrete to Reiffel was the affect such a blast would have on public opinion. Detonating a nuclear bomb on the Moon was expected to garner a hugely negative public reaction: America may demonstrate that it’s more technologically advanced than the Soviet Union, but by assuming the mantle of extraterrestrial vandals.

That of course assumed that the warhead would even make it to the Moon. One thing that’s clear from several high-profile disasters is that spaceflight is incredibly difficult to get right. We do succeed more often than not, but enormous risks are always involved, particularly if such spacecraft have had human payloads. The delivery vehicle in this case wouldn’t involve any such passengers, of course, but a failed launch – perhaps one ending in a high-altitude fireball – would spread radioactive debris over an enormous area.

The risk to public health, for once, took precedent – but perhaps not as much as the risk to public opinion did if the plan was to go awry. “Unless the climate of world opinion were well-prepared in advance, a considerable negative reaction could be stimulated,” the report muses.

“The foremost intent was to impress the world with the prowess of the United States,'” Reiffel said in an interview, per The New York Times. '”It was a P.R. device, without question, in the minds of the people from the Air Force.'”

It just wasn’t worth it in the end. In the coming months, the project was abandoned. The Moon’s pristine, alien environment would remain untouched, aside from a few probes sent by both superpowers crashing down onto its surface.

Thanks to the Outer Space Treaty, which came into force on October 10, 1967, we are unlikely to hear about such a plan ever again. Under terms agreed by both the Soviet Union and the US, among others, it became prohibited to place nuclear weapons – and any weapons of mass destruction – in orbit, on the Moon, or on any other physical body in space.

Fear and Loathing on Planet Earth

A Study of Lunar Research Flights is the only declassified document relating to Project A119. Several others likely exist, based on Reiffel’s comments prior to his recent death, and others have been destroyed. Much about it remains tantalizingly under wraps, and little will change in this respect for many years to come.

The plan’s legacy is one of juxtaposition in the starkest of terms. Driven by fear, there was a chance that humanity could have decided to prove that, for all intents and purposes, it could have killed the Moon. Not long after the plan was shuttered, we chose to land on the lunar surface.

Buzz Aldrin, photographed by Neil Armstrong, who you can spot reflected in Aldrin's visor.

Project A119 is a microcosm of our species’ ability to be dangerously absurd; an example of what could happen if the darker sides to our imaginations are allowed to run riot, catalyzed by doubts and terrors. Although the antagonizing factors have evolved, plenty of us still remain ruled by such hard to control notions today, just as previous generations were in 1959. That doesn’t mean we have to give into them, though.

So by all means, ponder on those footprints if it gives you a sense of optimism. I’d argue, though, that they become even more powerful when you consider that there was a chance that we almost decided to leave a radioactive crater up there instead.