The Final Frontier is Closer Than You Think – An Interview with Dagomar Degroot

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How cosmic forces have shaped—and continue to shape—our world.

This interview was originally published on the Harvard University Press website.

That asteroid that obliterated the dinosaurs 66 million years ago? It cleared the stage for mammals—and eventually us. The solar shifts that melted the ice sheets 12,000 years ago? They made civilization possible.

But space keeps shaping our world in ways you’d never expect. Reports of strange lunar activity in the 1830s didn’t just fascinate astronomers—they became front-page sensations in New York’s penny dailies, and launched the birth of mass media. Those apocalyptic visions of nuclear winter that were everywhere in the 1980s? Scientists developed them by studying Martian dust storms.

Environmental historian Dagomar Degroot calls these cosmic forces “ripples on the cosmic ocean,” and his new book reveals how they have quietly driven centuries of human history. Degroot holds the Blumberg/NASA Chair in Astrobiology at the Library of Congress and serves as Associate Professor of Environmental History at Georgetown University. Here, he answers some of our questions about his groundbreaking research.

Cover of Ripples on the Cosmic Ocean

Most environmental historians focus on Earth. Why did you expand your scope to the entire solar system?

Environmental history is the study of how people and the environment have influenced one another through time. For environmental historians, “the environment” usually means the non-human Earth. In Ripples, I ask: why stop at the Earth? I show that the solar system is full of environments that change—that create “ripples on the cosmic ocean”—and I show that these ripples have influenced human history.

Earth as a pale blue dot in outer space
A pale blue dot. Look carefully: Earth is just right of center. Photograph of Earth taken by the Voyager 1 spacecraft from a distance of six billion kilometers. NASA/JPL-Caltech.

What’s the most surprising way space has shaped human civilization?

Our species may only exist because an asteroid wiped out the dinosaurs nearly 66 million years ago. Our societies may only exist because a change in the Sun’s influence on Earth ended what’s commonly called the Ice Age almost 12,000 years ago. More recently, did you know that reports of changes in lunar environments helped spark the emergence of mass media? Or that fears of nuclear winter stem from studies of Martian dust storms?

Instead of colonizing Mars, you argue we should focus on saving Earth. What’s your vision for how space technology could solve our environmental crisis?

In my view, the focus of human efforts in outer space should be to harness cosmic environments in order to preserve environments on Earth. We should explore how to use renewable rockets, artificial intelligence, and 3D printing to mine the environments of the Moon and asteroids. That will allow us to create large structures in Earth’s orbit, including solar power stations that could give us all the energy we need without pollution or global warming. That’s not to say human settlement beyond Earth is a worthless ambition. But in a time of environmental crisis, it shouldn’t be our immediate goal. After all, there’s no substitute for Earth—for a world teeming with life—and there may never be.

“There’s no substitute for Earth—for a world teeming with life—and there may never be.”

Dagomar Degroot
A martian dust storm
dark dunes surround the northern polar cap of mars in 2016

Left: A Martian dust storm. The European Space Agency’s Mars Express orbiter photographed dust clouds welling up around the Martian north polar cap in April 2018. ESA / DLR / FU Berlin, CC BY-SA 3.0 IGO. Right: Dark dunes surround the northern polar cap of Mars in a 2016 photograph by the Indian Space Research Organisation’s Mars Orbiter Mission, also known as Mangalyaan. ISRO / ISSDC / Emily Lakdawalla.

Existential threats like nuclear winter, killer asteroids, and deadly microbes from space sound terrifying. Which ones have we successfully tackled, and which should keep us awake at night?

Ripples shows how governments have worked with scientists to address some of these risks, many of which came to light through observations of environmental changes in outer space. The ozone hole could have compromised the biosphere and destroyed our civilization, for example, but effective regulation has meant that it’s no longer expanding and could be gone by the end of the century. We now know that the risk of an asteroid impact is vanishingly low, and we’ve recently developed the ability to redirect asteroids that could be headed for Earth. So there is good news! Our governments have a proven ability to reduce even “existential” dangers. Some of the worst-case scenarios for global warming also seem less likely than they once did, though urgent action is still needed to slow the climate crisis. Killer microbes, by contrast, appear more dangerous than ever. They may never be brought to Earth from outer space, but gene-editing technology is making it possible to engineer deadly pathogens with cheap and easily acquirable lab equipment. Nuclear winter is the biggest risk of all—and the likelihood of it happening is rising, not falling. In my view, that has to change for our species to survive the coming decades and centuries.

Canals on the Moon
Canals on the moon? Rilles surround the central peaks of Gassendi, in a photo taken during Apollo 16. NASA, AS16-120-19295, View of the Gassendi Crater. National Archives.

Scientists once claimed to see forests on the Moon and canals on Mars—ideas we now know were completely wrong. How did these “spectacular mistakes” actually advance science?

Because they sparked widespread excitement, intense scholarly debates, and rigorous observations of cosmic environments. In many cases, they were also based on more accurate, not less accurate, understandings of those environments. It was the idea that the Moon was a world like the Earth that informed sightings of forests and even cities on its surface. And it was the correct belief that Mars had dried out over huge timespans that encouraged sightings of canals on its surface. Popular histories of science have mocked scholars who proposed fantastic ideas that we now know were wrong. But Ripples shows that it was often these ideas that ultimately led to some of the most important scientific discoveries.

As asteroid mining and space tourism take off, what’s stopping us from turning Mars into another polluted wasteland? Is space law just wishful thinking?

We can’t harm other worlds the way we’ve harmed our own because the worlds we’re likely to mine, explore, and settle are worlds that don’t harbor complex life. At the same time, they are worlds with environments, with landscapes of inherent beauty and cultural significance, and—in the case of Mars or Venus—perhaps even microbial ecosystems. The Outer Space Treaty of 1967 contains non-binding guidelines that require governments to prevent the microbial contamination of planetary ecosystems. Yet it’s far from certain that these guidelines have been effective or would be sufficient if humans, with all their microorganisms, land on Mars, for example. The Moon Agreement of 1979 would have gone further to protect planetary environments, but no major space power has ratified it. It’s not even certain that space law could be enforced far from Earth. The reality, then, is that the environments beyond Earth are a wild west where anything might go in the years and decades to come.

The imagined interior of a Bernal sphere, one of the space settlements proposed by Gerard O’Neill. In the 1970s the artist, Rick Guidice, was commissioned by NASA to create a series of paintings that would help policymakers and the public imagine the possibilities for space settlement. NASA / ARC / Rick Guidice
The imagined interior of a Bernal sphere, one of the space settlements proposed by Gerard O’Neill. In the 1970s the artist, Rick Guidice, was commissioned by NASA to create a series of paintings that would help policymakers and the public imagine the possibilities for space settlement. NASA / ARC / Rick Guidice.

Elon Musk wants to colonize Mars, while Jeff Bezos envisions millions of people living and working in space. Which billionaire has the right vision—and should billionaires be making these decisions for humanity?

The ultimate ambition of Elon Musk, the founder and CEO of SpaceX, is to make human life multiplanetary by colonizing and, eventually, terraforming Mars. The ambition of Jeff Bezos, the founder and owner of Blue Origin, is, by contrast, to move manufacturing, heavy industry, and ultimately human settlement into outer space, and thereby to preserve Earth’s web of life. That ambition, rather than Musk’s, aligns with the environmental opportunities and responsibilities that I outline in Ripples. The question, as you point out, is whether a billionaire should be the one to realize this ambition for humanity.

If someone reads your book and walks away with just one idea that changes how they think about our planet’s future, what should it be?

That space matters profoundly for life on Earth. That there’s no clear division between what happens “out there” and “down here.” And that environments in space change, just like they change on Earth, owing both to their own internal dynamics and—very recently—to our own actions. These changes can threaten us, but they also provide opportunities for a better future.

Read more about Ripples on the Cosmic Ocean
Feature Image: “Earthrise / Apollo 8” by woodleywonderworks is licensed under CC BY 2.0.
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Dagomar Degroot

Dagomar Degroot is the 2024/25 Baruch S. Blumberg Chair in Astrobiology, Exploration, and Scientific Innovation at the Library of Congress, and Associate Professor of Environmental History at Georgetown University. He hosts The Climate Chronicles, a podcast on the history of climate change.

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