Dark Skies: Space Expansionism, Planetary Geopolitics, and the Ends of Humanity
Daniel Deudney
Oxford University Press, $34.95 (cloth)

Tomorrow a manned orbital rocket will launch from U.S. soil for the first time since the Space Shuttle Program was cancelled in 2011. The astronauts are NASA boys, but the rocket belongs to SpaceX, Elon Musk’s most dazzling corporate brainchild. Though the objectives of this particular mission are modest, the company’s ultimate goal, Mars colonization, is anything but. Musk himself—along with those other ultra-rich space enthusiasts Jeff Bezos and Richard Branson—clearly believes this goal wears its merits on its sleeve. But does it? You might be disappointed if you visit SpaceX’s website seeking to understand the point of these otherworldly ventures. Apart from a will-o’-the-wisp video clip misleadingly titled “The Case for Mars,” there’s nothing there that might count as a sustained justification of this monumental project.

It is too easy to dismiss opponents of space exploration as astro-Luddites. Deudney is anything but.

In a way this absence mirrors the desolation of space, described by the political scientist and international relations theorist Daniel Deudney as an inhospitable wilderness extending for trillions of miles in all directions. His impressively synoptic new book throws down the gauntlet to “space expansionists” like Musk and his ilk. Dark Skies: Space Expansionism, Planetary Geopolitics, and the Ends of Humanity is a painstakingly researched, historically informed and theoretically sophisticated analysis centered on the disarmingly simple question: Is space colonization desirable? Deudney answers emphatically in the negative, in the process providing an invaluable history of Space Age dreams from the Enlightenment to the current interplanetary obsessions of libertarian plutocrats.


Over the course of this history two broad paradigms have emerged, each of which Deudney picks out by a pair of representative thinkers or promoters. The first is the von Braun-Tsiolkovsky paradigm (VTP), named after two early twentieth-century rocket engineers and space expansion enthusiasts, one German (Wernher von Braun) and the other Russian (Konstantin Tsiolkovsky). The second is the Clarke-Sagan paradigm (CSP), named after a Brit (Arthur C. Clarke) and an American (Carl Sagan), both of whom became famous for bringing the wonders of the Space Age to a wide popular audience. Taken together, the VTP and the CSP gather up a wide range of engineers, futurists, novelists, politicians, and outright hucksters. Sometimes the boundaries between the two paradigms are fuzzier than Deudney suggests, but on the whole it’s a richly informative analytic frame.

The main difference between the two paradigms is how they understand the problem of security and war in the context of the race both to weaponize and to inhabit space. The VTP endorses the migration to and militarization of the furthest reaches of interstellar space. The goal is to move from a situation in which near Earth orbit is controlled by a single hegemonic power to total interplanetary hegemony. As Deudney writes, von Braun, who was employed successively by Nazi and American governments to build rockets, was also “among the first to advocate establishing planet-wide military domination from space platforms equipped with nuclear weapons capable of striking anywhere on Earth on very short notice.”

Reagan’s Strategic Defense Initiative was an offspring of the VTP. So too is the United States Space Force, a new branch of the Armed Forces created by the Trump administration in December 2019. According to Vice President Mike Pence, with the Space Force America is writing “the next great chapter in the history of our Armed Forces.” The unabashed aim to militarize space—“to prepare for the next battlefield where America’s best and bravest will be called to deter and defeat a new generation of threats”—clearly echoes von Braun’s call in 1950 to establish “space superiority” over the Soviet Union.

The CSP, by contrast, strikes a far more cautious and defensive position, though of course Clarke and Sagan themselves were enthusiastic supporters of the general project of space exploration. Sagan, in particular, was always careful to couch his fascination with space in a way that emphasized simply observing, rather than seeking to possess, what we find there. He also believed that the wondrous urge to expand our knowledge of the heavens must never eclipse a resolute focus on enhancing the flourishing of life on this planet. As he put it, “there is nowhere else, at least in the near future, to which our species could migrate. Visit yes, settle not yet. Like it or not, for the moment the Earth is where we make our stand.”

It is important to highlight the subtlety of this position, because it is too easy to dismiss all opponents of specific plans for space exploration, such as Mars colonization, as astro-Luddites. Like Clarke and Sagan, Deudney is anything but. He constructs a taxonomy of possible positions, with Promethean Technophilia at one extreme and Luddite Technophobia at the other. His own stance, Cautious Soterianism (named after Soteria, the Greek goddess of safety), gets between these extremes, favoring “decelerating” the race to space rather than abandoning it altogether. The goal Deudney urges is to “steer” the whole thing more prudently than is currently being done, an orientation that will result in numerous “regulatory restraints and even selective relinquishments” of some plans.

Deudney arrives at this insight by placing the drive to colonize the heavens in the larger context of the twentieth-century development of weapons of mass destruction as well as the efforts we have made—via bilateral and multilateral treaties and other legal regimes—to contain the threat they pose. The book’s thesis is that unfettered space expansion is likely to increase the threat of large-scale violence and generally exacerbate human insecurity. If we adopt this approach, Mars colonization should be shelved, for now at least, while we expand and enhance the terms of the Outer Space Treaty, an international agreement crafted in 1966 that places limits on various forms of space adventurism and militarization (for starters, nobody can own the moon).

Because it is unapologetically boring, hard-core expansionists will loathe the CSP. With its focus on rules and restraints, it can sound like the over-anxious parent wagging a scolding finger at the impetuous teenager who just wants to have some harmless fun. The problem is that there’s nothing harmless about space expansion. Deudney’s book exposes the persistent refusal of its advocates to think meaningfully about the consequences of their proposals. So just as we parents seek various ways of restraining the teenager who sees no problem with doing hard drugs, binge drinking, or driving at breakneck speed, we should find ways of curbing the urge to “leave the Earth.” Dull advice if your dream was to, say, terraform Mars. But perhaps boring is not so bad in this area. “Space choices,” Deudney remarks drily, “are too important to be left to space cadets.” The same has been said about several other meeting places of science and society in the twentieth century—the development of nuclear weapons, above all.

Deudney’s book exposes the persistent refusal of space expansionists to think meaningfully about the consequences of their proposals.

For Deudney, it is crucial to emphasize that the intercontinental ballistic missiles we already have are in fact “the quintessential space weapon.” They mark a major weapons innovation because they arc through space on their way across the globe. The frictionless medium allows them to travel at roughly 10,000 miles per hour and thus reach their intercontinental targets in under half an hour. (For a sense of scale, recall the Earth’s equator is just shy of 25,000 miles long.) In the beginning we went to space with the express mission of winning the Cold War and becoming more efficient at killing each other, a historical reality that tugs against the breathless visions of the technologists. In fact, this past looms over the whole subsequent project of space expansion. The quest to inhabit other worlds, Deudney suggests, has piggybacked on this darker purpose without ever fully coming to terms with it.

If this is right, we must look beyond the breezy pleadings of space expansion’s most ardent advocates and examine the actual arguments for this grand vision. There have been three broad patterns of attempted justification. The first appeals to evolution, the second to long-term human security, and the last to the expansion of human freedom.


To get a sense of the first attempted justification, by far the most ubiquitous of the three, return to that SpaceX promo-video. Narrated by Musk himself, the “case” for Mars it lays out has been invoked by space expansionists since humans began fantasizing about occupying other celestial bodies—asteroids, moons, and planets—and building rockets powerful enough to take us to them. The simple idea is that expansion is the next step in evolution and that we ought to push it forward. Life has evolved from single-celled organisms, has migrated from the oceans onto land, has exploded into myriad forms of multi-celled organisms, and has somehow produced consciousness. The next step, Musk says, is surely to make life “multiplanetary.”

With characteristic inarticulacy he summarizes the argument this way: “if something is important enough to fit on the scale of evolution, then it’s important.” It’s not obvious whether that’s a tautology or a non sequitur, but in either case it is breathtakingly facile. You get the impression that the appeal to evolution is semi-intellectual cover for Musk’s sense of wonder at his own chutzpah. This feeling that they are doing something so big that it defies all attempts at rational comprehension shows up frequently among technology’s high priests. To take just one example, neurosurgeon and entrepreneur Eric Leuthard launched a neuroprosthetic startup some years ago, with the aim of connecting the brain in various ways to a digitized environment. Why? “Maybe for no other reason than I think it’s amazingly cool.” Musk’s comment is no deeper than this, but there is something uniquely problematic about all the talk of evolution. For Deudney it represents the typical space expansionist “fusion of technological Prometheanism with large-scope narratives of the tendencies and trajectories of life,” and is thus “fundamentally troubled.”

Space expansionists have lofty and inspiring rhetoric. But uglier realities have a way of hijacking good intentions.

On Earth, speciation can occur when spatially expanding populations become geographically isolated from one another (the unique diversity of species on the Galapagos Islands is the paradigm example of this phenomenon). Because of the vast distances between planets it is likely that similar fragmentation would eventually occur in outer space. Along with the interplanetary spread of cyborgs and artificial intelligences, the result, centuries after a viable Mars colony is established, will probably be a plethora of intelligent species, all of which will have evolved to fit their distinctive ecological constraints—an archipelago of politically distinct worlds. The idea is common in sci-fi, from Verner Vinge’s 1993 A Fire Upon the Deep to Mark Fergus and Hawk Otsby’s The Expanse, both Hugo Award winners.

Multi-world pluralism can look attractive if we assume that everyone will get along, regardless of the profound morphological, technological, and ideological differences that are bound to grow up around and between these groups. Here, however, the space expansionist invocation of natural selection bites back. Radiating and diversifying species notoriously compete with one another for available space and its resources or, in the case of intelligent species, just for glory and prestige. This is all familiar enough from the history of life on Earth, as is the mostly sorry result of the human interaction with other species as well as earlier human groups. We exterminated the Neanderthals (after breeding with them for a while) and are, according to the United Nations, currently in the process of eviscerating the non-human biosphere.

Doesn’t it seem likely that our deep-space descendants will inherit these destructive tendencies and turn them on each other? A space archipelago will be composed of mutually suspicious and competitive groups, millions of them eventually. But the bonds of sameness that can foster respectful recognition or mutual forbearance will surely diminish with increased interplanetary spatial dispersion and the ordinary workings of evolution. Not that we should expect a space-based Hobbesian war of all against all. There will doubtless be a good deal of room for interspecies and interworld diplomacy in this scenario. However, in the absence of a pacific trans-planetary government—and given our inability to create a single world government here, the chances of that seem slim—opportunities for plunder and general mayhem will likely abound. The temptation to cast the interplanetary Other as subhuman will be pronounced. Remember that the intelligent aliens in Starship Troopers are “bugs,” and in Battlestar Galactica they are “toasters.” Even in our fiction, it seems, we have a difficult time imagining what peaceful co-existence among wildly disparate beings might look like.

Because of this, all minimally viable colonies will have compelling reasons of state to stockpile awesome weapons of mass destruction: not only hydrogen bombs, but more importantly the ability to convert asteroids into planetoid bombs. Somehow this possibility—potentially genocidal or xenocidal wars of worlds—seems not to matter much to space expansionists, even though it’s standard fare in the well of sci-fi from which many of them have drunk so deeply.


We might shrug off this worry. After all, we are talking here about wars among humans and semi-humans unfolding at the farthest reaches of traversable space. But the risks to Earth security posed by even minimal expansion—say, establishing a fully independent Martian colony—is just as dire. Earth will be extremely difficult to defend from hostile galactic groups since we Terrans are stuck at the bottom of a relatively deep gravity well. Rockets must achieve an escape velocity of 25,000 miles per hour to break free of Earth’s gravitational pull, which is why almost all the rocket’s fuel is burned in this stage of the flight; getting back is comparatively easy. So, unfortunately, is lobbing weapons down at us from the elevated height of the Moon, a nearby asteroid, a space platform or Mars itself (whose gravity well is shallower than ours). We might suddenly find ourselves occupying catastrophically low strategic ground vis-à-vis our Martian (or other interstellar) enemies.

Despite being influenced by sci-fi, space expansionists pay little attention to the possibility of wars of worlds.

The failure to grapple with this kind of scenario underlines what Deudney takes to be an entirely unexamined assumption of space expansionists: that “humanity will be succeeded by creatures who are significantly better than humans.” He calls this the ascensionist assumption, the notion that by going up we will inevitably become morally and politically better. So of course space colonists and their descendants pose no threat to us. Again, the point is not limited to space cowboys. Most techno-utopians—the giddier boosters of geoengineering, Artificial Superintelligence, nanotech, de-extinction, genetic enhancement, you name it—operate with some version of this background assumption. And that is putting the case charitably, because the other alternative is that they simply don’t care about the potentially catastrophic consequences of their dreams and schemes.

But evolutionary theory gives us no reason to endorse any version of the ascensionist assumption. It is obviously not the case that over 3.5 billion years of development, species—including Homo sapiens—have become appreciably more tolerant of each other. Life has always been, and remains, red in tooth and claw. In fact, while appealing to evolutionary arguments, space expansionists are covertly counting on the magical disappearance of this aspect of the evolutionary process. It appears that even as we bring life generously to space, we run the very significant risk of erasing our own future:

Habitat space expansionists are in effect saying that humanity will—and should—pursue a series of steps that will lead inevitably to its own demise. Space expansion may be an agenda of survival for life, but for humanity it is an expensive suicide cult.

Unlike every other species that has ever existed, we humans are assumed to be “uniquely stupidly suicidal.” But our destiny, if we’ve got such a grandiose thing, is surely not to be mere vehicles for the dispersal of other life forms to the farthest reaches of space. To the extent that the whole program of space expansion rests on this faulty evolutionary logic, Deudney shows that it is a moral and intellectual sham.


That brings us, finally, to the other two attempted justifications for space expansion: that the program will safeguard the long-term future of our species and that it will enhance human freedom. The first idea arises from the observation that given the inevitable heat death of the sun a billion or so years from now, our career on this planet is ultimately doomed, so we’d better figure out a way of transporting ourselves out of the solar system as soon as possible. The idea seems to be that discovering the planet’s finitude has somehow massively accelerated the imperative to leave it. In a remark quoted by many space expansionists pushing this line of thought, Tsiolkovsky once said that “Earth is the cradle of humanity, but one cannot live in a cradle for ever.”

To the extent that space expansion rests on faulty evolutionary logic, Deudney shows that it is a moral and intellectual sham.

This is a stunningly silly argument. It’s a bit like learning you will have to leave the family nest several years down the road, then deciding you had better start packing right away. As Deudney notes, we have a few hundred million years to prepare for the Sun’s death, making that event completely irrelevant to our policy choices in the coming decades and centuries. Perhaps instead of worrying about being swallowed up by an expiring star in an impossibly distant future we might devote an equivalent amount of intellectual and political energy to avoiding climate catastrophe on this planet within the next decade or two. Just a suggestion.

What about freedom? There’s a strong strain of libertarianism among recent space expansionists (as well as among many Silicon Valley types, especially when it comes to the regulation of technology), but it is not obvious that the project will enhance human freedom overall, whether for remaining Terrans or in space. This is in large measure a product of the perpetual war footing on which such adventurism will place us all. Each world in the space archipelago can legitimize steep political hierarchies as a necessary means for dealing with perceived external threats. And such security-based political hierarchies inevitably bring more or less severe restrictions of individual liberties, at least for those on the bottom of the heap.

Deudney concludes:

The association of space expansion with the preservation and expansion of individual freedom is probably extremely dubious. Space expansion, far from being a form of freedom insurance, is more likely to produce the perfection of despotism and the complete subordination of the individual to the collective. Those who value individual liberty should be strong skeptics and opponents of space expansion, not enthusiastic supporters.

Contemporary space expansionists will bristle at this, not least at being associated with a Nazi rocket engineer. But the shoe fits. Von Braun, recall, said infamously that where the rockets come down was “not my department” (an attitude lampooned memorably by Tom Lehrer). By highlighting the lack of serious ethical thinking about consequences running through this entire tradition, Deudney forges plausible connections among otherwise disparate figures and ideas. Many space expansionists have expressed moving visions of scientific progress in lofty and inspiring rhetoric, but the uglier realities of nature and geopolitics have a way of hijacking good intentions.

The political naiveté of our fantasy-engorged billionaires might just get the rest of us killed or enslaved. As Deudney says, “though they aim for the stars, they might obliterate the Earth.” It’s time to take the space toys away from them. At the very least this searching study should compel them to drop their uncritical appeals to inevitable technological progress, propped up by a bit of bowdlerized Darwin, and instead provide some real arguments for their grand visions of galactic dispersal. Much more than the latest rocket design, that would mark a genuine advance in our understanding of this cosmically important issue.