Dagomar Degroot would like you to change your relationship with Venus … and Mars, Jupiter, Saturn, the Sun and Moon, comets, asteroids, and all the other forces at play in our solar system. With a new era of space exploration beckoning, he stresses, it’s high time we come to understand how planetary events across billions and billions of miles influence what happens here on Earth—and increasingly, how human activity is impacting other cosmic environments.

Author of the extraordinary Ripples on the Cosmic Ocean from Harvard University Press, Dagomar agreed to take some questions from Foreword’s Isaac Randel, reviewer of Ripples in our September/October issue. These three 2024 INDIES winners in the Science & Technology category are also well worth your attention.

Ripples on the Cosmic Ocean takes a unique approach to the connections between human history and the cosmic history of our solar system. In addition to giving an overview of our most recent models of the solar system and its influences, your book demonstrates how past human misunderstandings of space have shaped the progress of scientific research. Readers might be astonished to learn that some of these outmoded ideas—including the previous “consensus” view that Mars and the Moon, among other bodies, hosted civilized life—were only disproved within the last few generations. Which of the “misunderstandings” highlighted in your book did you find most interesting (or inspiring) to research?

Imagine: you’re an inventor, sitting in your lab on the foothills of the Rocky Mountains. The sun has set, and the stars are coming out. It’s a hundred years ago and you’re surrounded by a collection of steampunk instruments that harness unprecedented electrical powers.

Suddenly, one of them stirs. It registers a signal—very weak, but to your mind obviously artificial. You know that nothing nearby could have sent that signal. Yet after the signal stops, you realize that it lasted only as long as Mars had stayed in the night sky. Could it be? Have you heard the first signal from another world, another civilization?

That’s what Nikola Tesla thought in 1899. For two decades, he wrestled with the implications of the discovery. First, he kept it secret. After a year, he announced the news, and brainstormed how to respond. He built elaborate, fantastical contraptions to send a message. He worked out the principles of interplanetary communication. Over time, he lost his credibility, money, and sanity.

But it’s likely that he had received a message from space—except from Jupiter, not Mars. Its cause: interactions between the volcanoes of Io, a hellish moon, and Jupiter’s magnetic field. It was a fantastic discovery, albeit horribly misinterpreted, and a strange example of the influence of cosmic environments on human history. It may be my favorite story in the book.

The idea of “precarity” seems to be at the heart of Ripples on the Cosmic Ocean. Your book explores how Earth sits at the nexus point of unseen and frequently dangerous influences from all corners of our solar system—many of which went unknown or unappreciated for millennia. Some readers might find the enormous scale and range of these existential threats a bit disorienting (not to say alarming). How do you think everyday people can properly respond to the large-scale threats that your book investigates without feeling helpless or overwhelmed? (Or, on the other hand: do you think everyday people ought to be more actively concerned about these threats than they already are?)

Many people assume that space is somehow separate from everyday experience. The solar system and the rest of the cosmos are out there, but human lives take place down here. As an environmental scholar, I often hear that we should focus less on space exploration, and more on what seems to matter on Earth.

In Ripples, I argue that, in fact, space science originally revealed many of the worst threats to our lives on Earth. Some of those threats originate in outer space (solar storms and asteroid impacts, for example) while others disturb our relationship to cosmic flows of energy (such as global warming and nuclear winter).

The isolation of Earth from other cosmic environments is just an illusion. And because Earth is connected to fluctuating cosmic environments, its stability, too, is an illusion.

These are illusions we should now discard.

It may be a little overwhelming. In the book, I describe my own disquiet as I saw, with my own eyes, how much the Sun could change in real time. I view our little planet as a mote drifting for the moment in a tranquil eddy of the raging cosmic river. There’s not much we can do about that.

Still, we’re not powerless—not anymore. Ripples also offers hopeful stories, describing for example how governments successfully reduced existential risks such as the ozone hole.

The simplest advice I have is to consider the big risks—the existential risks—when you vote. Governments can slow down or even reverse global warming. They can work together to reduce the risk of nuclear war, or even the impacts of solar storms. The overwhelming majority of people don’t think about such matters when they vote. But if you do, and if you can convince your friends and family to as well, then you may make us all a little safer.

On the topic of precarity, your book also raises the idea that our very understanding of the solar system is less stable than we might realize. You offer many examples of how new discoveries in research, along with upheavals in cultural and political environments, can radically shift the ways that we understand our fundamental place in the universe. Given how drastically our models of the solar system tend to change over time, how do you think today’s scientists and researchers should approach the current state of space research to avoid making the kinds of false leaps made in previous eras?

There are many ways in which our fundamental understanding of the solar system will not change as much as it has in the past. It was possible to develop wild theories about the appearance of Mars, for example, before the first spacecraft visited the planet. Now, we know what it looks like. We won’t find out tomorrow, for example, that it’s really covered with canals.

But there are ways in which our basic ideas about cosmic environments may yet evolve.

Just consider how many scientists have reimagined the Earth in recent decades. In the middle of the twentieth century, it seemed like a stable place where change happened slowly, due to geological processes independent of life. Scientists have since discovered not only that planetary changes can happen abruptly but also that life responds to and even moderates those changes, to such an extent that we can think of the Earth as a living entity: Gaia.

Well, what if the entire universe is more alive than we think?

It’s an idea with ancient origins. The science fiction author Liu Cixin memorably explored its implications in his Remembrance of Earth’s Past series, where the very dimensional structure of the cosmos is a product of intergalactic war.

It’s also a notion espoused by the maverick astronomer Avi Loeb, who sees evidence for extraterrestrial intelligence where his colleagues perceive natural phenomena. The recent discovery of comets entering our solar system from other stars, for example.

Now, scientists often espouse the principle of Occam’s razor: the idea that the simplest explanation, the one that requires the fewest assumptions, is usually the right one. Occam’s razor is often used to discount seemingly exotic explanations—like extraterrestrial activity—for phenomena that appear more likely to be natural in origin.

In truth, we don’t know which explanations are simplest. If life is common across the universe, then the likeliest explanation for an interstellar comet may well be an alien civilization, as Loeb alleges.

Loeb’s speculations are, to my mind, misplaced. They may even be corrosive to public trust in science. But Ripples is full of maverick astronomers who, in erring, hit on grand truths that were hidden from their more cautious colleagues. Time will tell if Loeb is one of them.

Until then, Ripples should caution scientists to be humble about what they know and do not know.

Throughout Ripples on the Cosmic Ocean, you offer some forecasts for the direction of future human space settlement: from building floating cities atop the clouds of Venus, to constructing outer space solar power plants that beam energy straight to earth, to settling future humans in off-world “O’Neill cylinders.” Many of these possibilities sound almost like science fiction, but your book makes the point that we’ve managed seemingly impossible feats in outer space before. Which of the space colonization schemes mentioned in your book did you find the most exciting over the course of your research—and which do you think have the best chance of success within the next few generations?

From Konstantin Tsiolkovsky to Elon Musk, the dream of space visionaries has been to settle humans beyond Earth. There are many obstacles to building a colony on, say, Mars. Some of the most important are now beginning to crumble. The cost of launching payload into Earth orbit, for example, is dropping as space companies pioneer increasingly capable, reuseable rockets.

But why create a settlement beyond Earth? The most benign environments of other planets—the cloud tops of Venus, for example, or the riverbeds of Mars—are hellish compared to the worst corners of our world. Even in the wake of runaway climate change or a total nuclear war, Earth would remain far and away the most habitable planet in the solar system for human beings.

Advocates for space settlement justify their plans by arguing that a colony on another world would provide insurance for humanity in the case of a world-ending catastrophe on Earth—a comet impact or a lab-grown pandemic, for example. Some claim that a space settlement would spark the development of new ideas and even new forms of social organization, owing to the unique environmental and psychological stresses that would exist on another world. Others believe that humanity has an innate need to expand and explore.

I find such arguments both compelling and unsatisfying. They read like rationalizations for a preexisting goal. To me, they are not clear and concrete benefits that justify a return on investment. For example, could a colony on Mars really provide a more effective backstop for human civilization than a vastly less expensive settlement in Antarctica, or underwater?

So in Ripples, I ask: what if space settlement could actually enhance the habitability of the only world known to sustain life—of our Earth?

That, to me, is the attraction of building stations and eventually settlements not on planetary surfaces, but in outer space. Harvesting the nearly infinite resources of the asteroid belt, beaming solar power back to the Earth, shading the Sun—just a little—in the event of runaway global warming, and eventually moving some people into rotating cities: that is a dream that could, in time, begin to ease the unsustainable pressure that humans have imposed on Earth’s biosphere.

At many points in the book, you allude to the fact that—at least in some pockets of the post-industrial world—we seem to be entering a “Second Space Age.” We have public figures like Elon Musk and Jeff Bezos using enormous wealth and political capital to make space travel a priority at the international scale, even if the traction mostly seems to come from the private sector. At the same time, in the United States and elsewhere, there seems to be a retrenchment toward climate change skepticism and disinvestment from the kinds of valuable data collection that your book spotlights. How do you see these political and cultural trends playing out in the coming decades, and what might this mean for the future of space research?

We have entered a period of tremendous uncertainty, with great opportunity and danger. Trends are coalescing and accelerating in ways that make the future very difficult to predict.

For example, the Second Space Age—or to use a term more in vogue, the NewSpace Age—is transforming how large parts of humanity engage with outer space. It is an era of commercialized resource exploitation and, possibly, settlement in outer space. It involves not only Musk’s SpaceX and Bezos’s Blue Origin, but hundreds of different companies and many new or newly capable space agencies. Its causes include technological breakthroughs that have radically democratized access to space by enabling reuseable rockets and miniaturized satellites. They also include the accumulation of wealth and power in tycoons and authoritarian governments with towering ambitions and few restraints.

Now consider climate change. The rise in global temperatures seems to be accelerating exactly as progress in lowering emissions is being reversed in the United States. Continued warming may soon begin to trigger interconnected tipping elements in the climate system that could cause abrupt, irreversible, and profound changes in the habitability of our world. The collapse of North Atlantic currents, for example, or the transition of large parts of the Amazon rainforest into savannah landscapes. At the same time, the green economy is far from dead. Worst-case scenarios for the future of global warming have actually become less likely owing to the explosive growth of renewable energy in China, and the corresponding decline in the cost of green energy worldwide.

Then there’s the development of artificial intelligence. The recent, disappointing rollout of ChatGPT 5 has convinced many that artificial general intelligence (AGI)—an AI capable of thinking at a human level—is not on the horizon. AI safety advocates, however, warn that large language models (LLMs) may soon be able to improve themselves, clearing the way for an exponential increase in their capabilities. Many AI researchers believe that even if LLMs cannot develop general intelligence, let alone superintelligence, other AI systems will achieve these benchmarks by the middle of the century. The consequences are impossible to predict.

We can go down the list, considering everything from genetic engineering (ever easier and cheaper) to slumping birthrates (in developed countries) and geopolitical competition (between China and the United States). One thing seems for sure: the future, not the distant future but the near future, will be very different from the present.

I predict that, sometime in the next three decades, a national government or a group of governments will initiate a large-scale geoengineering project. Geoengineering is a deliberate intervention in Earth’s climate system—to counteract global warming, for example. There are many geoengineering schemes, and they all come with drawbacks. Most would not stop the accumulation of carbon dioxide in the atmosphere, or the consequent acidification of the oceans. Still, there’s a good chance that geoengineering would cool the Earth, and provide time for a durable shift away from fossil fuels.

I also predict that, in the same period, artificial intelligences will emerge that can genuinely think and reason at a more-than-human level. These systems will acquire more control over our world, but they may be imperfectly aligned with human values and needs.

Meanwhile, I believe that the explosive growth of the NewSpace industry will continue. The cost of accessing space will further decline, permitting largescale construction projects in orbit. Solar power stations will come online. Bases will be constructed at the Moon’s south pole, where water seems to be accessible. A settlement effort will be underway on Mars.

It’s easy to imagine how these trends could intersect. AI systems and three-dimensional printing could automate resource extraction and construction in outer space. The largest construction project could be the creation of a swarm of tiny spacecraft that block a small percentage of incoming solar radiation. It could be the most benign geoengineering possibility, since it would not involve manipulation of Earth’s atmosphere. It might just save our planet.

On the final pages of Ripples, I dream of the possibilities for human expansion into outer space. I’d love for that dream to come true. But realistically? I suspect that the cosmos will belong to the machines.

What kinds of hopes—or fears—do you have for future generations of researchers who will continue to explore the kinds of system-wide connections that your book offers?

In Ripples, I only scratch the surface of how environmental history—the study of the mutual interactions between people and environments—could incorporate the cosmos into the story of humanity’s past. Other environmental historians have explored how different corners of the solar system have been imagined, polluted, and managed. This is a subfield that is young, small, but growing.

I would love to read environmental histories of the outer solar system—the ocean worlds of Jupiter and Saturn, for example—or even of the broader galaxy. I can imagine deep histories of interstellar dust clouds and supernovae. The possibilities seem endless.

Of course, there will be more cosmic environmental histories to write with every year, as the NewSpace Age continues to gain momentum. Maybe, at the end of my career, I’ll be able to write an environmental history of a settlement on Mars. Or maybe one of my students will write a book about the first solar power station in Earth orbit.

Artificial intelligence is changing the practice of history. I don’t know what it will mean to be a historian in ten years, let alone by the end of the century. It does make me a little fearful for the future.

But if environmental history remains a vibrant field of study, then I believe there will be many publications, written in the years and decades to come, that consider the history of human interactions with outer space environments.

I can’t wait to read them.

Isaac Randel
October 23, 2025

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