Centauri Dreams
Imagining and Planning Interstellar Exploration
Arthur C. Clarke: On Cities and Stars
I’ve always wondered how Arthur C. Clarke coped with the news he received in 1986, when doctors in London told him he was suffering from amyotrophic lateral sclerosis, a terminal illness that in the States is often called Lou Gehrig’s disease. The diagnosis was mistaken — it turns out Clarke actually suffered from what is known as ‘post-polio syndrome,’ a debilitating but not fatal condition. For two long years, though, he must have thought through all the symptoms of ALS, knowing that the degenerative motor neuron breakdown could gradually sap him of strength and movement. How would such an energetic man cope with an agonizing, slow fade?
Neil McAleer’s revised biography (Visionary: The Odyssey of Sir Arthur C. Clarke) gives the answer, as recounted by Clarke’s brother Fred:
“…after the initial shock, Arthur more or less said, damn it, he’d got an enormous amount he wanted to do, and if he’s only got fifteen months to do it, he’d better whack into it. And he did whack into it, and the next year he produced four books.
“Eighteen months later he was still writing, and all the horrible things they told him might happen hadn’t happened to him. Of course they had told him all the things he should do to keep it under control—what diets to take and what exercises to do, which he very religiously did. He carried on working intensely and produced an enormous amount of work, which might have been the saving grace. If he had been the sort to say, ‘Oh my God, I’m going to die in fifteen months,’ he probably would have…”
That story speaks volumes about the man, identifying a resolve that kept him working despite his other ailments into his nineties. It also tells me that he was able to place himself mentally in a context that weighed a single human life against the broad movement of history. I think Clarke was happy to see himself as someone who instigated currents of thought, changed perspectives and launched careers. He did these things for people of all ages both by the example of his own life and by the lives he created in fiction that showed us what humanity might become.
Young Writer at Work
By the time Clarke moved from Somerset to London in 1936 he was already suffused with science fiction and in particular enraptured with Olaf Stapledon’s Last and First Men, not to mention the second-hand copies of American science fiction magazines that were then available in England. He spoke of the ‘ravenous addiction’ these magazines inspired and the effect that Stapledon’s novel, with a time scale spanning five billion years, had upon his imagination. He was twelve years old when he first read Last and First Men, awed by its cosmic reach and its placement of the evolution of humanity against the broader backdrop of the cosmos.
Think for a moment of 2001: A Space Odyssey. Has any film ever covered a wider swath of time, from the beginnings of tool making to the apotheosis of the species in an extraterrestrial encounter? This was Clarke’s stage, but the other great discovery of his youth, David Lasser’s The Conquest of Space (1931) gave him the technology he would spend a life examining. Lasser was the founder of the American Interplanetary Society (which became the American Rocket Society and, eventually, the American Institute of Aeronautics and Astronautics). He was also, for a time, the editor of Hugo Gernsback’s Science Wonder Stories and Air Wonder Stories. If Stapledon brought Clarke the cosmos, Lasser gave the boy a focus on the attainable, the idea of space as a reachable frontier.
In London, Clarke had a tiny flat in Norfolk Square and was soon co-editing (with science fiction writer William Temple) the fanzine Novae Terrae, whose editorial sessions were so cramped in Clarke’s quarters that Temple once said “…there was hardly room for the two of us, and A[rthur]’s Ego had to be left outside on the landing.” Clarke’s nickname of Ego derives from this period when Temple and Clarke both discovered the latter’s competitive nature. I think McAleer is right in stressing, though, that Clarke’s volubility was largely the result of his enthusiasms. This was a man who loved, above all else, the communication of an idea.
Into the Remote Future
For those keeping score, Novae Terrae would soon become, under the editorship of Ted Carnell, the influential magazine New Worlds. But in the days just before World War II, while working on issues of Novae Terrae and assorted publications for the British Interplanetary Society, Clarke found time to begin developing his first novel from ideas that had come to him back in Somerset. “Against the Fall of Night” would appear in an early version in Startling Stories in November of 1948, but that hardly ended the tale. Clarke kept rewriting the story, seeing it into print as a novel from Gnome Press in 1953 and then putting it through a major revision as The City and the Stars, published in 1956.
I seldom think of Clarke as a reader of poetry, but he clearly knew his Housman:
Here, on the level sand,
Between the sea and land,
What shall I build or write
Against the fall of night?
The words are from Housman’s poem “Smooth Between Sea and Land.” Maybe the idea of long stretches of sand and a metaphorical night that comes to us all fired his imagination. I came across The City and the Stars just a few years after it was published and was mesmerized by its setting in much the way Clarke was taken with Stapledon’s Last and First Men. Here was Diaspar, the city of the far future, the only city on planet Earth, whose inhabitants moved through a high-tech monument to stasis. Nothing changes in Diaspar even as the world around it loses its oceans and becomes desert. Clarke would have much to say about the kind of inward thinking that his characters have to overcome, but the unmistakable fact about Diaspar is that the city at the end of time is also achingly, eerily beautiful.
Here’s science fiction writer Jo Walton on the book, nailing its essential allure:
The plot is quite simple. Diaspar is beautiful but entirely inward turned. Alvin looks out and discovers that there is more in the universe than his one city. He recovers the truth about human history, and rather than wrecking what is left of human civilization, revitalises it. By the end of the novel, Man, Diaspar, and Earth have begun to turn outward again. That’s all well and good. What’s always stayed with me is the in-turned Diaspar and the sense of deep time. That’s what’s memorable, and cool, and influential. Clarke recognized though that there isn’t, and can’t be, any story there, beyond that amazing image. It’s a short book even so, 159 pages and not a wasted word.
As to its author, I love the way he could never let this book go. It was, after all, his first novel, and as such it was perhaps the most deeply inspired by the reading of his youth. When he wrote a new preface to it in 1955, he noted that developments in information theory encouraged him to re-think the future course of humanity, a revision that would lead, says McAleer, to a whopping seventy-five percent new prose. The man was indefatigable; he couldn’t let go when ideas seized him, and when he had the wind behind him, no horizon was too far to strive for.
Restless Thoughts from Orbit
On the same visit to the United States in which he met Neil McAleer and learned that he did not have ALS after all, Clarke visited the National Air and Space Museum with Gregory Benford, long-term colleague Fred Durant and Hector Ekanayake, whose friendship with Clarke in Sri Lanka spanned decades. Benford noted the lack of long-term perspective in much contemporary science fiction and pointed out that The City and the Stars had been written before the discovery of DNA, so biology made no significant appearance in the story. Benford and Clarke’s Beyond the Fall of Night (1990) would be the result of that conversation.
McAleer’s biography gives the details on all of Clarke’s books, but my childhood fascination with The City and the Stars has kept me focused on the early stages of Clarke’s career in London and the ideas that began germinating both there and earlier in Somerset. The Signet paperback illustrated here is not the edition I first encountered, but I have to run it because of my love of Richard Powers, whose cover art appeared in so many paperbacks from this period. In this case, Powers’ surreal images go far toward capturing the timeless allure of the city in the desert.
The letters that McAleer has access to offer insights from Clarke’s old associates, and some new ones as well. In 2006 a British engineer named Nicholas Patrick was about to fly on a Space Shuttle mission, Discovery STS-116. He wrote Clarke to invite him to the launch, telling him he had been reading Clarke’s books since growing up in London. Due to his health problems, Clarke was unable to appear, though he wrote an enthusiastic response thanking Patrick, who replied:
“I am sad to hear that you will not be able to attend the launch, but understand completely given the circumstances. Perhaps instead, if you are willing, I might email you from orbit. “A month ago I reread The City and the Stars, perhaps my favourite book, and was again drawn by the ideas in it. Ever since I first read it, I have wanted to find an old spaceship and travel to distant suns. I shall be very happy in low earth orbit, but I don’t think it will completely satisfy me.”
And that’s the thing: Anyone who has grown up with The City and the Stars is going to find even the wonders of Earth orbit a bit tame. Clarke was always at his best as a science fiction writer when taking the long view. His characters would learn to burst free from Diaspar, but its very conception is as staggering and poetic as anything he ever wrote. From the book:
Here was the end of an evolution almost as long as Man’s. Its beginnings were lost in the mists of the Dawn Ages, when humanity had first learned the use of power and sent its noisy engines clanking about the world. Steam, water, wind-all had been harnessed for a little while and then abandoned. For centuries the energy of matter had run the world until it too had been superseded, and with each change the old machines were forgotten and new ones took their place. Very slowly, over thousands of years, the ideal of the perfect machine was approached – that ideal which had once been a dream, then a distant prospect, and at last reality: No machine may contain any moving parts. Here was the ultimate expression of that ideal. Its achievement had taken Man perhaps a hundred million years, and in the moment of his triumph he had turned his back upon the machine forever. It had reached finality, and thenceforth could sustain itself eternally while serving him.
Thus Clarke’s description of the computer that runs Diaspar free from all human intervention. What continues to confound me about Clarke is what McAleer brings out so well, the duality between an imagination capable of transcending time and the canny engineering horse-sense that spawned near-term space achievements. This is the man who dreamed up communications satellites when not dreaming of eternal cities of the far future. Tomorrow, then, let’s look at Clarke the space pioneer.
The Vision of Arthur C. Clarke
In a 1955 letter to the British rocket scientist Val Cleaver, Arthur Clarke wrote about his view from the island then called Ceylon:
“Beautiful night last night. Southern Cross (a very feeble constellation) just above the front gate, with Alpha Centauri beside it. It always gives me an odd feeling to look at Alpha and to realize that’s the next stop.”
The next stop indeed. Cleaver was a fellow member of the British Interplanetary Society who, like Clarke, was instrumental in energizing the society after World War II. Both men served the BIS as its chairman in those years, and after Cleaver’s wartime work at De Havilland, he would go on to start a rocket division for the company and become chief engineer for the rocket division of Rolls-Royce. He is perhaps best known as the man behind the Blue Streak missile, but for those with a passion for the works of Arthur C. Clarke, he will always be remembered for his deep friendship with the man, and his energetic contribution to British thinking on space travel.
Image: Arthur C. Clarke and Val Cleaver at Warwick Castle in August of 1973. Credit: British Interplanetary Society.
Neil McAleer’s new book on Clarke is called Visionary: The Odyssey of Sir Arthur C. Clarke (Clarke Project, 2012). It’s the place to go for the background on this period, and on any period, in Clarke’s life. I call the book ‘new,’ but it’s actually a major revision and update of McAleer’s 1993 biography that adds extensive coverage of Clarke’s last fifteen years, covering a lot of material that was new to me, including insights into Clarke’s synergistic relationship with Stanley Kubrick, his reaction to the tsunami of 2004, and the almost playful way he fielded questions about his private life until a newspaper scandal based on nothing more than innuendo delayed the ceremony conferring his knighthood for two years. Throughout, McAleer’s research is exhaustive, drawing on memoirs, interviews and letters from Clarke’s many friends.
I have no hesitation in pointing you to this book if, like me, you were influenced by Clarke in your thinking about the human future in space. McAleer, an accomplished author of both fiction and non-fiction about spaceflight, met Clarke for the first time in the summer of 1988, when the latter had just been released from Johns Hopkins after a period of medical tests. The 70-year old Clarke, by then renowned for his science fiction but equally for his contributions to spaceflight including the development of the communications satellite, had been diagnosed several years earlier with amyotropic lateral sclerois (ALS), a terminal illness also known as Lou Gehrig’s Disease.
Because the doctors found the diagnosis had been mistaken, we can assume that McAleer met Clarke at a propitious time, and he proved more than willing to let the younger writer begin a biography, armed with a contact list of 200 names that Clarke gave him. The final, revised biography is now available in several editions ranging from a beautifully crafted signed and numbered hardback, a limited edition paperback, and a soon to be available e-book edition from Rosetta Books. I think Clarke would appreciate the transition to electronic books and would find the idea of reading his work on a Kindle as natural as doing telecommunications from Sri Lanka.
Back in 2007 I published Gregory Benford’s two-part travelogue about his journey to Asia, part of which involved flying to Sri Lanka, Clarke’s adopted home, from which Clarke routinely addressed audiences throughout the world as he continued to battle post-polio syndrome. The visit would have occurred a scant year before Clarke’s death. Here is how Benford described him:
Arthur has post polio syndrome and thus very little memory or energy. He turns 90 this December and wants to keep in touch with the outer world, mostly through the Internet. He has few friends left in Colombo. He took us to the Colombo Swimming Club for lunch, a sunny ocean spot left over from the Raj. It felt somehow right to watch the Indian Ocean curl in, foaming on the rocks, to the tune of gin and tonics — and to speak of space, that last, greatest ocean. Science fiction is to technology as romance novels are to marriage: a sales pitch. But without vision and then persuasion, little would ever happen. Arthur has always known that.
Image: Elisabeth Malartre, Arthur C. Clarke and Gregory Benford.
Vision and then persuasion — how better to describe how Arthur Clarke operated throughout a lifetime that lasted longer, as McAleer points out, than it takes Halley’s Comet to orbit the Sun? His outlook was always positive and framed in knowledge of humanity’s possibilities when enriched with technology. But he was also believer in the deep context of time and that takes me back to McAleer’s hardcover edition for a moment. Like Clarke, McAleer is a believer in long-term thinking and the symbolic acts that link us with the generations that follow us. Thus he designed the hardcover edition to last, as noted in the comments at the beginning of the book:
The challenge was to create a physical book that might survive perhaps half a millennium. With that goal in mind, the biographer researched the use of preservation-quality materials in its production—paper, ink, binding, casing, Smyth-sewn signatures and silver die stamps evoking the stars… The author intends—although he may not be able to guarantee!—that this edition’s pages will last 500 years, even outside environmentally controlled rare-archive repositories. As such, it’s hoped that this artifact will carry the artistry of Gutenberg into a future when new physical books may be far fewer.
What better tribute to a man who, in Jo Walton’s memorable phrase, wrote so eloquently about ‘the poetry of deep time’? The book that exemplified that poetry was The City and the Stars, a work that elicits so many reactions in me that I want to discuss it with reference to McAleer’s book at greater length than I have time for today. The frustration of trying to write about a man whose contributions infused both the science and literature of his time is that he was almost too big for the page to hold him. I’m going to need several days with Clarke and McAleer, continuing tomorrow with the tale first known as Against the Fall of Night.
A Starship Report from Brussels
Tau Zero’s founding architect brings news of a recent European Union meeting that included starships and their implications on the agenda. Here’s hoping that while he was there he also had the chance to sample some of those fabulous Belgian ales…
by Marc Millis
The European Union recently held a conference to collect information to plan for the coming decades of science and technology priorities. This included the theme of international collaboration and the implications for all humanity across the globe. As a part of this conference, the EU organizers invited Mae Jemison of the 100 Year Starship organization to chair a session about interstellar flight. Mae rounded up a suite of speakers including Buzz Aldrin (a genuine space celebrity), Jill Tarter (SETI), Lou Friedman (solar sail advocate and former Planetary Society director), Kathryn Denning (space anthropologist), Pam Contag (microbiologist), Marc Millis (propulsion physicist), and about half-dozen more.
Image: Outside the European Parliament building in Brussels. Credit: Marc Millis.
The presentations were recorded and can be accessed here either now or very shortly. Look for the link to 100 Year Starship Session at European Parliament 2013. There were 11 talks of roughly 4 minutes each, plus Q&A. The talks covered a healthy span of issues and approaches. This coverage included the motivations for star flight, the compelling reasons to begin now, the search for extraterrestrial intelligence, the degree of difficulty involved in achieving true star flight, and a variety of insights regarding the imperative to create sustainable closed loop life support.
The topic of sustainable life support was given a healthy dose of attention. For human star flight, this is an unavoidable imperative whose methods must achieve 100% recycling. This forces achievements beyond what is necessary for Moon and Mars bases. In addition to the obvious issues of sustainable biology and human physical health, issues such as clothing manufacturing and recycling, governance methods, and questions about what cultures and individual life experiences would be fitting for an interstellar world ship emerged in these discussions.
Image: Buzz Aldrin addresses the guests during a dinner session. Credit: Ronke Olabisi.
While some might think that issues like these can be postponed until we are closer to the goal, remember that all humanity is trapped on a spaceship with a malfunctioning life-support system (human-induced climate change) right now, along with a radiation shielding system whose permanence is not guaranteed and a ‘crew’ that is largely oblivious to their responsibility for maintaining the habitability of spaceship Earth.
But all is not dark despite such gloomy prospects. There were also plenty of discussions about using the goal of star flight to provide a positive view of the future, something to allow us all to thrive, not just survive. For example, one talk suggested that we use the context of the love for our children to frame this positive future view. It was interesting that the person who made this comment, Jennie Yeung, also made the observation that she was the only Asian in this interstellar session and that Asians represent roughly half of the population of starship Earth.
Image: The European Union session at work. Credit: Marc Millis.
Sustaining Spaceship Earth, and learning how to create more world ships, calls for a world-wide endeavor. The focus of subsequent discussions was, “What do we do next?” Recall that at our present rate of procrastination, two-centuries remain before starflight might become possible (not including precursor missions). What is not known is if human society will survive long enough to achieve that sustained survival ability. Amongst the speakers, deep thinkers in their own right, there was frank discussion about such unknowns and what we can each do to make a better future. While Mae Jemison assembles a proposal to the European Union for interstellar work, the individual speakers discussed amongst themselves how to collaborate and what we can each do as we pursue our own specialties to make relevant progress. Despite the encouraging invitation from the European Union that puts the focus on these possibilities, there is no guarantee that there will be funding for this type of work.
The effect of star flight on society was also discussed. First, when considering the levels of energy needed to achieve interstellar flight, our civilization will have had to have achieved sustainable peace amongst ourselves. Even a slight misuse of these levels of energy could destroy the entire surface of Earth. Humanity must mature to have the responsibility to use such prowess safely.
Image: Speakers’ stations at the meeting. Credit: Marc Millis.
John Carter McKnight, Kathryn Denning, and others articulated the dimensions of the ethics and regulatory issues involved in moving towards interstellar capabilities. And when it comes to how to tell the story of the values and risks of interstellar flight, Kathryn Denning suggested that we avoid using some common analogies that have been popularized to discuss spaceflight. Specifically she cautioned against analogies to Columbus and Magellan, since these events of discovery also included some of the uglier sides of humanity, such as greed, mutiny, and slavery. In short we need to create a new positive message that accurately conveys the opportunities risks and sensible steps to eventually achieve both the societal maturity and technological capability of star flight, and in so doing, vastly improve life on Earth.
In the meanwhile then, while we all wait for our ideal levels of funding to come in, we shall continue ad astra incrementis, to the stars in ever-increasing steps.
Image: A group shot following discussions on the 100 Year Starship project in Brussels. The front four: Marsal Gifra, Buzz Aldrin, Jill Tarter, Jennie Yeung. In back curving from left to right, Kathleen Colgan, Gwen R. Artis, Lou Friedman, Kathryn Denning, Alires Alimon, Ronke Olabisi, Karl Aspelund, Mae Jemison, John Carter McKnight, Pam Contag, Marc Millis. Credit: Ronke Olabisi.
Into the Orion Arm
Although we have little observational data to go on, the existence of the Oort Cloud simply makes sense. We see new comets coming into the inner system that are breaking up as they approach the Sun, obviously not candidates for long survival. There has to be a source containing billions of comets to account for those we do see. The Kuiper Belt is stuffed with what we can call ‘iceteroids,’ all moving more or less along the plane of the ecliptic until, well beyond the Kuiper Belt itself at about 10,000 AU, the disk shaped belt of material spreads into the spherical Oort Cloud. A nudge from a rogue planet or passing star is enough to produce the velocity change to send a comet inward.
We’ve been looking this week at possible human uses for cometary objects, including the fact that they’re rich in water but also nitrogen and carbon wrapped up in interesting organic compounds. From the standpoint of resource extraction, we also find interesting elements like silicon, sulfur, nickel, chromium, magnesium and iron available in at least small amounts. Tiny worlds a few kilometers in diameter, rich in resources and loaded with water, existing by the trillions. Surely a space-oriented civilization of the future will find a way to exploit them.
Protecting the Inner System
But it’s likely that long before we start talking about a human presence in the Oort Cloud, we’ll be engaged in robotic studies driven by the sheer necessity of protection. Recent near-miss asteroid events have raised public consciousness about near-Earth objects that could pose a threat to our planet. Comets can wreak havoc as well, with the difference that near-Earth objects are gradually becoming tracked and catalogued. With an NEO, we can plot trajectories that give us time to consider how to move an object that might not be projected to hit for decades.
Comets are different. We can’t predict when a new one is going to appear. Robert Zubrin points out that when the huge comet Hale-Bopp was detected in 1995, it was well beyond the orbit of Saturn, but moving at a speed sufficient to cross the Earth’s orbit a mere two years later. An object like this, massive and moving at high velocity, would have been all but impossible to deflect if we had learned it was headed for us. Deflecting a fast-moving comet, as opposed to a nearby asteroid, means getting to it when it is still deep in the outer system. Planetary protection will all but ensure we’ll have a presence in the Kuiper Belt and Oort Cloud one day.
Image: Comet Shoemaker-Levy 9, torn into pieces as a result of a close approach to Jupiter in July 1992, before its later impact with that planet. The major cometary fragments range in size from one to a few kilometers. Credit: JPL.
Whether such a presence is largely robotic or not, it will spur the technologies we’ll eventually use for starflight. And not just the technologies — as we’ve seen, human settlements on O’Neill cylinders exploiting cometary resources would be case studies in isolation and social experimentation. Starships designed for fast crossings (multiple decades) or gradual voyaging (thousands of years) will have to incorporate what we’ve learned about people working together to keep communities in coherence when far from home. The Oort Cloud has a role to play.
The Fork in Interstellar Evolution
It’s possible that we may see two kinds of starflight in the next thousand years. I turn again to Richard Terra, whose article “Islands in the Sky” ran in the June, 1991 issue of Analog (it’s also reprinted in a 1996 hardcover from Wiley with the same name, a volume of essays edited by Stanley Schmidt and Robert Zubrin). Terra’s notion is that the wealthy inner system cultures will eventually develop what Ben Finney calls ‘fastships,’ spacecraft capable of moving at a substantial percentage of the speed of light. These will always be the first to cross the interstellar divide, but a slower wave of migration will follow.
The point is this: A small but growing human population in the Oort Cloud will master cometary motion, taking advantage of the fact that at 10,000 AU, the speed needed to orbit the Sun is just 300 meters per second. Compare this to the Earth’s 30,000 meters per second and it should be obvious that it takes only a small change in velocity to alter a comet’s orbit. We’ll have learned this in theory if not in practice because it factors into the engineering needed to divert a potentially dangerous comet from striking our planet decades in the future. Learn how to bump comets to change their orbits and you start thinking about what else you might do with such an object.
Interstellar space must be littered with comets that have been ejected from our system through the 4.6 billion years of its existence. Some estimates run as high as 1000 Earth masses in cometary material, so the resource base between us and the nearby stars should be plentiful. If Oort Cloud comets are separated by about 20 AU, these interstellar comets may be hundreds of thousands of AU from each other. The Oort Cloud should be in perpetual flux as some interstellar comets enter and move through it while other comets are pushed back out.
Let me quote Terra on this:
Some of these interlopers are bound to be found within Sol’s own Oort Cloud, working their way free of the Sun’s grip, at perhaps one in every several thousand. Relative velocities between Solar and interstellar comets will be low, and it will be tempting for Oort Cloud residents to hitch a ride outward — perhaps farther out into the permanent Cloud, perhaps out into interstellar space. Drifting outward at about 10 km/s or about 2 AU per year, they will make slow progress indeed. In 50,000 years they will be halfway to the nearest stars. But by then they will be wholly adapted to life in interstellar space and will perhaps not be too concerned with visiting other star systems.
So maybe there’s no one way to depict interstellar expansion. Fastships propelled perhaps by fusion or beaming technologies or antimatter may eventually cut the journey to decades. Over the millennia, a species fully adapted to living in space — and surely evolving in ways we’ll be unable to predict — will populate the outer system and move in slow generation ships between stars that may no longer be so much a destination as a curiosity. Perhaps some Oort Cloud communities will, as Terra suspects, alter a comet’s orbit so as to make a gravity assist maneuver around the Sun, all the while shielding the nucleus with solar power collectors.
Gravity assist might pick the speed up to 150 kilometers per second, which works out to a bit over 8000 years to Alpha Centauri. Whether such a traveling colony world would actually put colonists on a planet around the destination star is conjectural. Perhaps more likely is the idea that they would study the new solar system and then set course for another. The human species will be in the process of evolutionary forking, and after a few such journeys between the stars, the meeting between the cometary travelers and their fastship brethren would be an interesting one to see. What would these two different branches of humanity still share?
I don’t know the answer to that question, but it gets at the meaning of what it is to be human. Our future Oort Cloud dwellers will have not only an isolated gene pool but the tools of genetic engineering at their disposal, which could make biochemical and even structural changes possible at a faster clip than straightforward natural selection. If our species survives its technological adolescence — by no means a sure thing, as the Drake Equation reminds us — then humans around other stars are going to take a wide variety of forms adapted to their environments, a flowering speciation that could spread humanity out into the Orion Arm.
Life Among the Comets
It’s hard to imagine a sane human being who would choose to live in the Oort Cloud, on a colony world where the outside temperature is in the single digits Kelvin and small bands of maybe 25 each would tend to the problems of energy production and resource extraction. Human contact beyond this would be sporadic, though Richard Terra makes the case (in “Islands in the Sky,” an Analog article I referenced yesterday) that a larger community dispersed through nearby settlements would meet regularly to ensure genetic diversity and relieve isolation.
History tells us that people do all kinds of inexplicable things, and perhaps a small number of adventurers, outcasts, zealots and other dissidents would find a home here. But given the abundant resources closer to the inner system, I’m more inclined to look at the Oort Cloud as a source of raw materials for colonies on the move between stars. These would be generation ships moving perhaps no faster than Voyager 1 moves now, about 17 kilometers per second. The main point is that the space between the stars is hardly empty, and future generations with the tools of advanced propulsion may take not one giant leap but many small steps in the direction of Alpha Centauri.
Image: The Oort Cloud in relation to the Solar System. Credit: UC-Berkeley/Comet’s Tale Development Team.
Whether we’re settlers or voyagers (and I suspect we’ll be both), we’ll learn all along the way from the experience of adapting to space. Ben Finney and Eric Jones put it this way in their paper “Fastships and Nomads” (reference at the end of yesterday’s post):
If interstellar settlement happens at all, it will come after our descendants have learned to maintain self-sufficient communities detached from Earth’s nurturing biosphere, learned to tap the knowledge and skill potential of advanced computers, learned to efficiently harness the energy that flows out of the Sun, and even learned to extract useful energy from the fusion of atoms. We are on the verge of achieving all these things. With sufficient skill and patience we will attain the stars.
Of course, we have been on the ‘verge’ for a long time when it comes to fusion. But taking the long view of human expansion and looking not just decades but centuries ahead, these words resonate.
Finding the Energy
Whichever scenario strikes your fancy, the energy conundrum is still huge. Yesterday I talked about Finney and Jones’ ideas of concentrating starlight through vast mirrors the size of the continental United States. Terra picks up on this to describe colonists living in O’Neill cylinders, each housing a band of outer system stalwarts who would tend a mirror farm stretching across 30,000 kilometers of space. Maybe ‘tending’ is the wrong word, though — robotic systems would surely do the heavy lifting with substantial human oversight. From Terra’s paper:
The primary sector of the economy — the exploitation of natural resources — is likely to be small and almost completely automated. Human involvement will be minimal. The primary sector will consist of two basic activities: energy production and the harvesting of cometary resources. Once the appropriate systems are established, both will be relatively simple activities.
The secondary sector — the transformation of the natural resources — will include refining and processing the raw cometary feedstock, manufacturing, construction and assembly operations, agriculture and food production, and recycling. Again, many of these activities will be highly automated, but closer human supervision will be necessary to tailor these activities to the current needs of the community.
Terra goes on to cite a third sector where most of the human skill set will go to work. Here he’s talking about support services that maintain the life support systems and needed repairs to the colony world. Information processing, education, administration, and eventually business and commerce between settlements will command the attention. The latter, keeping colonists in contact with other colonies, has also been proposed in various starship scenarios over the course of long voyages, with multiple ships accompanying each other on the journey.
Both Terra and Finney and Jones, of course, are talking about full time colonies rather than crews in transit. Their mirror farms are themselves components of even larger arrays, spread out perhaps 200,000 kilometers from the cometary nucleus. Growing the community would mean creating comet clusters by moving new comets into range, which would allow populations up to 100,000 or so to exist, though spread out widely through the cluster. With perhaps a light-day of separation between communities living in such clusters, the colonists would be in constant electromagnetic communication with other settlements scattered throughout the inner and outer Oort.
The Fusion Alternative
As wondrous a science fictional setting as this provides (and vast mirrors inevitably call to mind the continent-sized sails of Cordwainer Smith’s “The Lady Who Sailed the Soul”), I’d like to think there are more practical ways to produce the needed energy. But what? Fission doesn’t fly out here because the heavy elements are found in only minute amounts. Remember, we’re not talking about a colony world that is sustained by regular supplies from the inner system. We have to exploit local resources, and that takes us to the deuterium available in comets.
If fusion can be mastered, we have changed the game. In his book Entering Space: Creating a Spacefaring Civilization (Tarcher, 1999), Robert Zubrin points to the progress in both robotics and artificial intelligence that will be needed to sustain widely scattered colonies, adding that previous experience settling the asteroid belt may teach us many lessons. But he doesn’t like the starlight mirror idea one bit:
While some have suggested concentrating starlight, it doesn’t really make sense. To get a single megawatt of power, the mirror would have to be the size of the continental United States. The only viable alternative based on currently known physics is fusion. In the Kuiper Belt, it might be possible to get helium-3 shipped out from mining operations around Neptune. Oort Cloud settlements would be too far out to obtain much from the solar system, though deuterium should be available in all iceteroids, so perhaps the colonists might choose to build reactors based on that fuel alone. However, helium can exist in the liquid phase below 5 K (-268 degrees C), which is the environmental temperature at about 3000 AU. It is therefore not impossible that liquid helium could exist within Oort Cloud objects beyond that distance.
But even if we can make fusion work — and I’m assuming that a civilization that can move large payloads to the Oort Cloud is one that probably has — our isolated communities still have an energy conundrum. They’ve got a couple of centuries worth of fusion fuel in the comet cluster they’ve cultivated, but it’s still a non-renewable resource. That’s going to mean tight rationing of fusion fuels even if the technology is available, unless somehow proton fusion can be mastered. Maybe an Oort Cloud settlement of any size would have to have Finney and Jones’ mirrors after all, constructing them as the only renewable solution for succeeding generations.
Zubrin thinks wanderlust and the pioneer spirit will drive some humans outward to test out such scenarios. After all, the great bulk of human society will remain in the inner system where the warmth is, and its possible that the growing centralization and homogeneity of culture here over the course of centuries would incline the more independent-minded to emigrate. O’Neill cylinders, asteroids and comets may be the ideal home for dissident groups trying social experiments and pushing the envelope on what a human society can become. “Why live on a planet whose social laws and possibilities were defined by generations long dead, when you can be a pioneer and help to shape a new world according to reason as you see it?” Zubrin asks.
But there may be other scenarios that would force us into the Oort Cloud. Tomorrow I’ll look at a couple of possibilities that could make the outer system our stepping stone to the nearest stars.
Into the Oort Cloud: A Cometary Civilization?
Jules Verne once had the notion of a comet grazing the Earth and carrying off a number of astounded people, whose adventures comprise the plot of the 1877 novel Off on a Comet. It’s a great yarn that was chosen by Hugo Gernsback to be reprinted as a serial in the first issues of his new magazine Amazing Stories back in 1926, but with a diameter of 2300 kilometers, Verne’s comet was much larger than anything we’ve actually observed. Comets tend to be small but they make up for it in volume, with an estimated 100 billion to several trillion thought to exist in the Oort Cloud. All that adds up to a total mass of several times the Earth’s.
Of course, coming up with mass estimates is, as with so much else about the Oort Cloud, a tricky business. Paul R. Weissman noted a probable error of about one order of magnitude when he produced the above estimate in 1983. What we are safe in saying is something that has caught Freeman Dyson’s attention: While most of the mass and volume in the galaxy is comprised of stars and planets, most of the area actually belongs to asteroids and comets. There’s a lot of real estate out there, and we’ll want to take advantage of it as we move into the outer Solar System and beyond.
Comets and Resources
Embedded with rock, dust and organic molecules, comets are composed of water ice as well as frozen gases like methane, carbon dioxide, carbon monoxide, ammonia and an assortment of compounds containing nitrogen, oxygen and sulfur. Porous and undifferentiated, these bodies are malleable enough to make them interesting from the standpoint of resource extraction. Richard P. Terra wrote about the possibilities in a 1991 article published in Analog:
This light fragile structure means that the resources present in the comet nuclei will be readily accessible to any human settlers. The porous mixture of dust and ice would offer little mechanical resistance, and the two components could easily be separated by the application of heat. Volatiles could be further refined through fractional distillation while the dust, which has a high content of iron and other ferrous metals, could easily be manipulated with magnetic fields.
Put a human infrastructure out in the realm of the comets, in other words, and resource extraction should be a workable proposition. Terra talks about colonies operating in the Oort Cloud but we can also consider it, as he does, a proving ground for even deeper space technologies aimed at crossing the gulf between the stars. Either way, as permanent settlements or as way stations offering resources on millennial journeys, comets should be plentiful given that the Oort Cloud may extend half the distance to Alpha Centauri. Terra goes on:
Little additional crushing or other mechanical processing of the dust would be necessary, and its fine, loose-grained structure would make it ideal for subsequent chemical processing and refining. Comet nuclei thus represent a vast reservoir of easily accessible materials: water, carbon dioxide, ammonia, methane, and a variety of metals and complex organics.
Energy by Starlight
Given that comets probably formed on the outer edges of the solar nebula, their early orbits would have been more or less in the same plane as the rest of the young system, but gravitational interactions with passing stars would have randomized their orbital inclinations, eventually producing a sphere of the kind Jan Oort first postulated back in 1950. Much of this is speculative, because we have little observational evidence to go on, but the major part of the cometary shell probably extends from 40,000 to 60,000 AU, while a projected inner Oort population extending from just beyond the Kuiper Belt out to 10,000 AU may have cometary orbits more or less in the plane of the ecliptic. Out past 10,000 AU the separation between comets is wide, perhaps about 20 AU, meaning that any communities that form out here will be incredibly isolated.
Image: An artist’s rendering of the Kuiper Belt and Oort Cloud. Credit: NASA/Donald K. Yeomans.
Whether humans can exploit cometary resources this far from home will depend on whether or not they can find sources of energy. In a paper called “Fastships and Nomads,” presented at the Conference on Interstellar Migration held at Los Alamos in 1983, Eric Jones and Ben Finney give a nod to non-renewable energy sources like deuterium, given that heavy elements like uranium will be hard to come by. Indeed, a typical comet, in Richard Terra’s figures, holds between 50,000 and 100,000 metric tons of deuterium, enough to power early settlement and mining.
But over the long haul, Jones and Finney are interested in keeping colonies alive through renewable resources, and that means starlight. The researchers talk about building vast mirrors using aluminum from comets, with each 1 MW mirror about the size of the continental United States. Now here’s a science fiction setting with punch, as the two describe it:
Although the mirrors would be tended by autonomous maintenance robots, the nomads would have to live nearby in case something went wrong… Although we could imagine that the several hundred people who could be supported by the resources of a single comet might live in a single habitat, the mirrors supporting that community would be spread across about 150,000 km. Trouble with a mirror or robot on the periphery of the mirror array would mean a long trip, several hours at least. It would make more sense if the community were dispersed in smaller groups so that trouble could be reached in a shorter time. There are also social reasons for expecting the nomad communities to be divided into smaller co-living groups.
Jones and Finney go on to point out that humans tend to work best in groups of about a dozen adults, whether in the form of hunter/gatherer bands, army platoons, bridge clubs or political cells. This observation of behavior leads them to speculate that bands of about 25 men, women and children would live together in a large habitat — think again of an O’Neill cylinder — built out of cometary materials, from which they would tend a mirror farm with the help of robots and computers. Each small group would tend a mirror farm perhaps 30,000 kilometers across.
The picture widens beyond this to include the need for larger communities that would occasionally come together, helping to avoid the genetic dangers of inbreeding and providing a larger social environment. Thus we might have about 500 individuals in clusters of 20 cometary bands which would stay in contact and periodically meet. Jones and Finney consider the band-tribe structure to be the smallest grouping that seems practical for any human community. Who would such a community attract — outcasts, dissidents, adventurers? And how would Oort Cloud settlers react to the possibility of going further still, to another star?
More on this tomorrow. For now, the Terra article is “Islands in the Sky: Human Exploration and Settlement of the Oort Cloud,” Analog June, 1991, pp. 68-85. The Jones and Finney paper is “Fastships and Nomads,” in Finney and Jones (eds)., Interstellar Migration and the Human Experience, University of California Press (1985), pp. 88-103.
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