Robin Wordsworth is a professor in Harvard’s School of Engineering and Applied Sciences. His research focuses on the evolution and habitability of terrestrial-type planets.
When the Hubble Space Telescope first launched in 1990, it quickly became clear that something was not right. Images that should have been razor-sharp looked scarcely better than those taken by an amateur telescope on Earth. Once the source of the problem — a microns-thick defect affecting the primary mirror — was identified, aerospace engineers came up with a clever solution: a system of small corrective mirrors akin to a pair of glasses to correct Hubble’s myopia.
Seven astronauts went up in the space shuttle on a repair mission, and after seven days of heroic efforts, the telescope was fixed. Hubble was once again pointed at deep space and began returning the now-iconic images of a cosmos that was, in the words of poet Tracy Smith, “so brutal and alive it seemed to comprehend us back.”
In the decades that followed, Hubble underwent four more astronaut repair and servicing missions. During this time, it unveiled images of incredibly distant stars, revealed supermassive black holes lurking in the centers of most major galaxies, and helped us probe the atmospheres of planets orbiting other stars (exoplanets). Arriving just as the internet was taking off, its stunning images of nebulae and galaxies were shared so widely that they’ve become universally recognizable parts of international culture. It’s now acknowledged as one of the most productive scientific instruments ever built.
The repair of Hubble is a beautiful example of human ingenuity and skill in space. But in retrospect, it was a high point compared to our progress since then. The International Space Station has cost over $150 billion, many times more than either Hubble or its successor, the James Webb Space Telescope — making it the most expensive human-made object in history.
Despite its undeniable contributions to our understanding of life in microgravity, its scientific contributions relative to its immense cost have been questioned. In the meantime, dozens of cheaper robotic spacecraft and rovers have raced across the solar system, bringing back a wealth of data on everything from Big Bang cosmology to the lakes of ancient Mars.
For some, this means we should prioritize robotic missions for the foreseeable future. For others, focusing on the cost of human spaceflight overlooks what they see as the ultimate goal of space travel: making us a multiplanetary species. The steady decrease in launch costs over the past two decades certainly suggests that more ambitious goals will soon become possible if we choose to prioritize them. However, the future of life beyond Earth is not a narrow choice between robotic and human exploration.
To better understand the nature of the current moment, we must shift from a purely humanist perspective to one that recognizes the deep connections between technological civilization and the rest of the biosphere, as well as the history of life up to this point.
Extending life beyond Earth will transform it, just as surely as it did in the distant past when plants first emerged on land. Along the way, we will need to overcome many technical challenges and balance growth and development with fair use of resources and environmental stewardship. But done properly, this process will reframe the search for life elsewhere and give us a deeper understanding of how to protect our own planet.
Conquering Space For All Mankind
Since before the dawn of the space age, an eclectic mix of futurists, visionaries and oddballs have pushed the idea that humanity’s future lies among the stars. Among the first to realize human spaceflight was possible and ponder its long-term implications were the Russian Cosmists, who were active in the late 19th and early 20th centuries.
Never a fully unified movement, Cosmism was founded by the philosopher Nikolai Fyodorov. Fyodorov believed the “Common Task” of humanity was to reach the stars, achieve immortality and bring back the souls of all deceased humans via advanced technology. In doing this, mankind would enact God’s will by achieving the biblical Resurrection.
Fyodorov’s esoteric views might have had limited impact were it not for his most famous disciple, Konstantin Tsiolkovsky. Virtually deaf from childhood, Tsiolkovsky spent most of his life in a log house in a provincial city 90 miles southwest of Moscow. Today, he is recognized as a genius for conceiving many of the fundamentals of modern spaceflight, including multi-stage rockets, liquid propellants and life support.
“The future of life beyond Earth is not a narrow choice between robotic and human exploration.”
Tsiolkovsky was passionate about human spaceflight but saw this work as secondary to his development of a pan-psychic philosophy of the universe. He was a utopian, but like many of his contemporaries, Tsiolkovsky saw the future as one of ever-increasing human dominion over nature. For example, in a memorable passage of his essay “The Future of Earth and Mankind,” Tsiolkovsky calls for “humanity to mount a united struggle against nature,” beginning with the systematic eradication of all wildlife in the “best lands of South America and Central America.”
Later space futurist visions were similarly human-centered. In the 1970s, Princeton University physicist Gerard O’Neill pushed for the construction of large-scale space habitats capable of housing millions of people. Drawing on concerns of the nascent environmental movement, he proposed this would provide a release valve for Earth’s growing population, shift heavy industry off-world and solve the energy crisis in the process.
O’Neill’s vision was to open space migration to anyone who wanted to escape pollution and overpopulation on an increasingly overcrowded Earth. His ideas generated enthusiasm and interest but failed to gain serious traction in the 20th century. Nonetheless, they’ve had a heavy influence on contemporary industry figures — including Jeff Bezos, who founded the aerospace company Blue Origin with the goal of catalyzing mass space colonization.
In recent years, human space settlement as a societal goal has come under increasing fire from progressive thinkers. The scholar De Witt Douglas Kilgore wryly observed that O’Neill’s vision bears a remarkable resemblance to suburban “white flight” projected onto a cosmic canvas, which makes sense given the preoccupation with inner-city decay in 1970s America.
Others have argued that the whole premise of space habitation should be rethought, given the legacy of colonialism on Earth. Direct analogies between space settlement and 19th-century colonialism are not convincing, not least because of the absence of nearby alien civilizations for future settlers to exploit. Nonetheless, because such critiques question the underlying assumptions of a human-centered approach, they can help expand our thinking about what a desirable future for solar system exploration might look like.
Ecology & Human Life Support
Societal goals aside, the current state of the art of human life support reveals how far we remain technologically from O’Neill’s grand visions of giant cities in space. The small crew of astronauts on the International Space Station is kept alive via a chemical system that breaks water into oxygen and hydrogen, and a separate system that removes carbon dioxide. Waste gases are vented into space, solid waste is mostly burned up on cargo ships during re-entry, and over a metric ton per year of food, water and other essential materials must be resupplied from Earth for each astronaut, at great expense. While technologically sophisticated, the International Space Station’s life support system is not suitable for long-term missions or permanent space habitation.
Alternative ideas for life support on space stations and planetary outposts involve more biological closed-loop systems where algae or plants are grown in bioreactors to provide food and oxygen. The most ambitious attempt to create a functional closed-loop biosphere to date was the Biosphere 2 experiment. In full operation only between 1991 and 1994, Biosphere 2’s initial mission involved a group of eight people who completely sealed themselves off inside a specially designed, more than 3-acre building complex in Arizona.
With a total of seven biomes, including a rainforest, wetlands and a living coral reef, it was designed to operate as a microcosm of the entire Earth system. The project suffered from many problems, including in-group conflicts, unstable CO2 levels, and, at times, a lack of scientific rigor. Nonetheless, it provided a fascinating glimpse at how large-scale closed-loop biospheres in space might function in the future.
Biosphere 2 and experiments like it highlight the key challenge faced by all life-support systems: Our existence on Earth is still completely dependent on the natural world that surrounds us. Technology makes our lives more comfortable, but our civilization ultimately relies on a complex web of ecological interactions. A rough guide to these dependencies is captured by the ecological footprint concept, which measures humanity’s demand for natural resources by estimating the amount of land required to sustainably support a single human.
Per-person ecological footprints vary widely according to income level and culture, but typical values in industrialized countries range from 3 to 10 hectares, or about 4 to 14 soccer fields. This dwarfs the area available per astronaut on the International Space Station, which has roughly the same internal volume as a Boeing 747. Incidentally, the total global human ecological footprint, according to the nonprofit Global Footprint Network, was estimated in 2014 to be about 1.7 times the Earth’s entire surface area — a succinct reminder that our current relationship with the rest of the biosphere is not sustainable.
“Technology makes our lives more comfortable, but our civilization ultimately relies on a complex web of ecological interactions.”
In space, as on Earth, industrial structures degrade with time, and a truly sustainable life support system must have the capability to rebuild and recycle them. We’ve only partially solved this problem on Earth, which is why industrial civilization is currently causing serious environmental damage. There are no inherent physical limitations to life in the solar system beyond Earth — both elemental building blocks and energy from the sun are abundant — but technological society, which developed as an outgrowth of the biosphere, cannot yet exist independently of it. The challenge of building and maintaining robust life-support systems for humans beyond Earth is a key reason why a machine-dominated approach to space exploration is so appealing.
Rise Of The Robots
Robots have now orbited or flown by every planet from Mercury to the dwarf planet Pluto, survived crushing pressure and scalding heat at the surface of Venus, peered at stellar nurseries and ancient galaxies, and brought back samples from comets, asteroids and the far side of the moon. In the near future, NASA plans to fly a nuclear-powered robot helicopter called Dragonfly in the smoggy air of Saturn’s moon Titan. Robots — the first physical manifestations of complex life to escape Earth’s gravity well — currently rule the solar system.
The six rovers sent to Mars by the U.S. and China from 1997 onward represent the pinnacle of interplanetary technology in the early 21st century. Ranging in size from a toaster oven to a small car and powered by solar cells or radioactive plutonium, they possess an array of sophisticated sensors to study the local rocks and air.
They have made major scientific breakthroughs, such as the discovery that lakes capable of hosting life existed on Mars for extended periods in its past. The next milestone for Mars science is the return of rover-collected samples to Earth, which at the time of writing appears most likely to be achieved first by China in the early 2030s, given the Trump administration’s proposed cancellation of NASA’s sample return plan.
In her book “Seeing like a Rover,” sociologist Janet Vertesi explored the melding of human and machine capabilities that drove scientific discovery during the Mars Exploration Rover missions of the mid-2000s. When I recently spoke with Vertesi to gain a deeper understanding of her findings, she stressed the power of rovers to achieve what humans cannot. For example, because rover cameras have imaging and spectroscopy capabilities that cover wavelengths that range far beyond human eyes, “robots get to see in ways we can’t,” she told me. “They can see the distinctions that we as geologists want to see.”
However, Vertesi also strongly emphasized that the way the rovers were designed and operated as scientific instruments emerged from the carefully planned social structure of the mission team. Collective decision-making, consensus-building and an openness to new ideas and perspectives are all integral to mission operations. At least for now, operating state-of-the-art machine technology in space remains an intensely human process.
Our mastery at projecting our intellects onto the objects we manufacture has allowed us to explore other planets, map the seabed and investigate the far reaches of the cosmos. Increasingly, though, it’s becoming possible to endow scientific machines with enough intelligence to allow them to operate autonomously or with minimal human oversight. For example, the newest NASA rover, Perseverance, has advanced terrain-mapping and navigation abilities that allow it to travel much faster than its predecessor, Curiosity.
Artificial intelligence on Earth observation satellites can now allow for automated on-board image acquisition and processing before data is beamed back to the ground, greatly improving efficiency. And in the increasingly crowded highways of low-Earth orbit, constellations of communications satellites are gaining AI capabilities to help them avoid collisions. If launch costs continue to decrease, future AI data centers may be placed in orbit and powered by solar energy, easing the ever-increasing burden they’re placing on terrestrial power stations.
Given our progress thus far, it might be reasonable to assume that the future of life in space will involve ever more capable and intelligent machines, with no need for humans at all. This is certainly plausible. However, it’s notable that machines in space have not yet accomplished a basic task that biology performs continuously on Earth: acquiring raw materials and utilizing them for self-repair and growth. To many, this critical distinction is what separates living from non-living systems. A microscopic bacterium cannot transmit radio waves or calculate orbital trajectories, but under the right conditions, it can replicate itself until it transforms its entire environment.
“Machines in space have not yet accomplished a basic task that biology performs continuously on Earth: acquiring raw materials and utilizing them for self-repair and growth.”
The question of whether machines can be constructed with truly lifelike properties was first seriously explored by the mathematician John von Neumann in the 1940s. Von Neumann developed the idea of a “universal constructor” — a machine capable of making copies of itself ad infinitum. His replicators were all theoretical, but later studies investigated whether physical self-replicating machines could be constructed. The resulting “von Neumann probe” concept, whereby a spacecraft uses locally available resources, such as asteroids, to reproduce itself, has become a staple of science fiction.
The state of the art of research in this area is extremely interesting, but it’s not yet close to achieving these kinds of abilities. The most advanced designs for self-assembling robots today begin with small subcomponents that must be manufactured separately beforehand.
Overall, industrial technology remains Earth-centric in many important ways. Supply chains for electronic components are long and complex, and many raw materials are hard to source off-world. The quartz sand that forms the feedstock for silicon wafers, for example, is common on Earth thanks to the effects of billions of years of plate tectonics and water, but it’s very rare elsewhere in the solar system. The characteristics of our present technology are far from universal; in many respects, they reflect the past evolution of the Earth system.
If we view the future expansion of life into space in a similar way as the emergence of complex life on land in the Paleozoic era, we can predict that new forms will emerge, shaped by their changed environment, while many historical characteristics will be preserved. For machine technology in the near term, evolution in a more life-like direction seems likely, with greater focus on regenerative parts and recycling, as well as increasingly sophisticated self-assembly capabilities. The inherent cost of transporting material out of Earth’s gravity well will provide a particularly strong incentive for this to happen.
Engaging In The Future
If building space habitats is hard and machine technology is gradually developing more life-like capabilities, does this mean we humans might as well remain Earth-bound forever? This feels hard to accept because exploration is an intrinsic part of the human spirit. Some of the defining moments of the 20th century, such as Tenzing Norgay and Edmund Hillary’s ascent of Everest, or Neil Armstrong’s first steps on the moon, happened when people walked where no human had before. But there’s no escaping the fact that technology now permits us to explore most faraway locations in intricate detail without ever being physically present.
To me, the eventual extension of the entire biosphere beyond Earth, rather than either just robots or humans surrounded by mechanical life-support systems, seems like the most interesting and inspiring future possibility. Initially, this could take the form of enclosed habitats capable of supporting closed-loop ecosystems, on the moon, Mars or water-rich asteroids, in the mold of Biosphere 2. Habitats would be manufactured industrially or grown organically from locally available materials. Over time, technological advances and adaptation, whether natural or guided, would allow the spread of life to an increasingly wide range of locations in the solar system.
The past is no infallible guide to the future, but at most stages of Earth’s evolution so far, extension of the biosphere to new environments has greatly increased diversity and complexity. The ongoing co-evolution of organic life and machines that has characterized the last few hundred years will be accelerated by the leap beyond Earth, likely leading to a dramatic increase in the variety of forms and ways of living and thinking.
Besides being inspirational, creating new ecosystems beyond Earth would have significant scientific value, broadening our understanding of how life behaves across a wide range of environments and conditions. The search for life on other worlds has always been limited by the fact that Earth is our only known example of a habitable planet. Once we have direct experience of life beyond our home planet, our perspective on this problem will inevitably be transformed.
The multiple overlapping ecological and political crises that are currently engulfing our planet can make space exploration — not to mention permanent space habitation — seem like a distraction from more pressing issues, at best. But robust public engagement in positive ideas for the future of this area has never been more critical. The space economy is currently expanding rapidly, which means that decisions made now will have outsized consequences in the future — on Earth as well as beyond it.
“The ongoing co-evolution of organic life and machines … will be accelerated by the leap beyond Earth, likely leading to a dramatic increase in the variety of forms and ways of living and thinking.”
As the influence of the private sector in space has grown over the past two decades, I have observed a strong trend emerging among many people to dismiss the expansion of life beyond Earth as something to be left to billionaires or halted altogether. This inward turn is an understandable reaction to the chaos and destruction of the Anthropocene, but it is a grave mistake.
Historically, the rich tradition of creative thinking in science fiction and futurism has expanded our conceptions of what human societies, and life itself, can be like. We need to reinvigorate this tradition. Key issues of governance, economics and environmental protection beyond Earth will require engagement from a wide range of voices, not just the ultra-wealthy.
A Lonely Species
In the novel “Orbital,” author Samantha Harvey imagines the thoughts and dreams of six astronauts during a single day on the International Space Station. She writes poignantly about the intense loneliness of the human species as we peer out at the cosmos and search endlessly for beings like ourselves. In one passage, she notes the search for life elsewhere has so far revealed nothing but frozen deserts and craters and suggests that modern human destructiveness and nihilism may be a kind of teenage rebellion caused by finding ourselves so “unjustly darkly alone.”
But we humans are not alone: We are part of a stunningly complex and dynamic biosphere. In fact, a growing body of research ascribes sentience to many of our fellow animals, including cephalopods, whales and great apes. And it seems likely that sooner or later, we’ll be joined by new silicon-based consciousnesses. I suspect the resolution to our modern existential crisis, if it comes, will involve finally accepting we’re just one rather unusual part of a diverse and vibrant living community.
Recognizing the interconnected nature of the biosphere is key both to preserving Earth’s diversity and to expanding life outward into the solar system. The future of AI is difficult to predict, but a civilizational worldview that values ecology and species diversity bodes better for humans than one that does not, as we approach the point where we’re no longer the most capable agents either on Earth or beyond it.
Caring about diversity in the current era lays the groundwork for the continued survival of our own species in the long term, no matter what the future holds. And finally, if genuine alien life is out there somewhere, we’ll have a much better chance of comprehending it once we have direct experience of sustaining life beyond our home planet.
