Category Archives: world ships

Centauri Dreams: Creative Constraints and Starflight

I discovered Karl Schroeder’s work when I was researching brown dwarfs some years ago. Who knew that somebody was writing novels about civilizations around these dim objects? Permanence (Tor, 2003) was a real eye-opener, as were the deep-space cultures it described. Schroeder hooked me again with his latest book — he’s dealing with a preoccupation of mine, a human presence in the deep space regions between ourselves and the nearest stars, where resources are abundant and dark worlds move far from any sun. How to maintain such a society and allow it to grow into something like an empire? Karl explains the mechanism below. Science fiction fans, of which there are many on Centauri Dreams, will know Karl as the author of many other novels, including Ventus (2000), Lady of Mazes (2005) and Sun of Suns (2006).

by Karl Schroeder


My newest science fiction novel, Lockstep, has just finished its serialization in Analogmagazine, and Tor Books will have it on the bookshelves March 24. Reactions have been pretty favourable—except that I’ve managed to offend a small but vocal group of my readers. It seems that some people are outraged that I’ve written an SF story in which faster than light travel is impossible.

I did write Lockstep because I understood that it’s not actual starflight that interests most people—it’s the romance of a Star Trek or Star Wars-type interstellar civilization they want. Not the reality, but the fantasy. Even so, I misjudged the, well, the fervor with which some people cling to the belief that the lightspeed limit will just somehow, magically and handwavingly, get engineered around.

This is ironic, because the whole point of Lockstep was to find a way to have that Star Wars-like interstellar civilization in reality and not just fantasy. As an artist, I’m familiar with the power of creative constraint to generate ideas, and for Lockstep I put two constraints on myself: 1) No FTL or unknown science would be allowed in the novel. 2) The novel would contain a full-blown interstellar civilization exactly like those you find in books with FTL.

Creativity under constraint is the best kind of creativity; it’s the kind that really may take us to the stars someday. In this case, by placing such mutually contradictory — even impossible — restrictions on myself, I was forced into a solution that, in hindsight, is obvious. It is simply this: everyone I know of who has thought about interstellar civilization has thought that the big problem to be solved is the problem of speed. The issue, though (as opposed to the problem), is how to travel to an interstellar destination, spend some time there, and return to the same home you left. Near-c travel solves this problem for you, but not for those you left at home. FTL solves the problem for both you and home, but with the caveat that it’s impossible. (Okay, okay, for the outraged among you: as far as we know. To put it more exactly, we can’t prove that FTL is impossible any more than we can prove that Santa Claus doesn’t exist. I’ll concede that.)


Read the rest here…

The Interstellar Mind of Robert Goddard

From Centauri Dreams:

Astronautics pioneer Robert H. Goddard is usually thought of in connection with liquid fuel rockets. It was his test flight of such a rocket in March of 1926 that demonstrated a principle he had been working on since patenting two concepts for future engines, one a liquid fuel design, the other a staged rocket using solid fuels. “A Method of Reaching Extreme Altitudes,” published in 1920, was a treatise published by the Smithsonian that developed the mathematics behind rocket flight, a report that discussed the possibility of a rocket reaching the Moon.

While Goddard’s work could be said to have anticipated many technologies subsequently developed by later engineers, the man was not without a visionary streak that went well beyond the near-term, expressing itself on at least one occasion on the subject of interstellar flight. Written in January of 1918, “The Ultimate Migration” was not a scientific paper but merely a set of notes, one that Goddard carefully tucked away from view, as seen in this excerpt from his later document “Material for an Autobiography” (1927):

“A manuscript I wrote on January 14, 1918 … and deposited in a friend’s safe … speculated as to the last migration of the human race, as consisting of a number of expeditions sent out into the regions of thickly distributed stars, taking in a condensed form all the knowledge of the race, using either atomic energy or hydrogen, oxygen and solar energy… [It] was contained in an inner envelope which suggested that the writing inside should be read only by an optimist.”

Optimism is, of course, standard currency in these pages, so it seems natural to reconsider Goddard’s ideas here. As to his caution, we might remember that the idea of a lunar mission discussed in “A Method of Reaching Extreme Altitudes” not long after would bring him ridicule from some elements in the press, who lectured him on the infeasibility of a rocket engine functioning in space without air to push against. It was Goddard, of course, who was right, but he was ever a cautious man, and his dislike of the press was, I suspect, not so much born out of this incident but simply confirmed by it.

In the event, Goddard’s manuscript remained sealed and was not published until 1972. What I hadn’t realized was that Goddard, on the same day he wrote the original manuscript, also wrote a condensed version that David Baker recently published for the British Interplanetary Society. It’s an interesting distillation of the rocket scientist’s thoughts that speculates on how we might use an asteroid or a small moon as the vehicle for a journey to another star. The ideal propulsion method would, in Goddard’s view, be through the control of what he called ‘intra-atomic energy.’


Image: Rocket pioneer Robert H. Goddard, whose notes on an interstellar future discuss human migration to the stars.

Atomic propulsion would allow journeys to the stars lasting thousands of years with the passengers living inside a generation ship, one in which, he noted, “the characteristics and natures of the passengers might change, with the succeeding generations.” We’ve made the same speculation here, wondering whether a crew living and dying inside an artificial world wouldn’t so adapt to the environment that it would eventually choose not to live on a planetary surface, no matter what it found in the destination solar system.

And if atomic energy could not be harnessed? In that case, Goddard speculated that humans could be placed in what we today would think of as suspended animation, the crew awakened at intervals of 10,000 years for a passage to the nearest stars, and intervals of a million years for greater distances. Goddard speculates on how an accurate clock could be built to ensure awakening, which he thought would be necessary for human intervention to steer the spacecraft if it came to be off its course. Suspended animation would involve huge changes to the body:

…will it be possible to reduce the protoplasm in the human body to the granular state, so that it can withstand the intense cold of interstellar space? It would probably be necessary to dessicate the body, more or less, before this state could be produced. Awakening may have to be done very slowly. It might be necessary to have people evolve, through a number of generations, for this purpose.

As to destinations, Goddard saw the ideal as a star like the Sun or, interestingly, a binary system with two suns like ours — perhaps he was thinking of the Alpha Centauri stars here. But that was only the beginning, for Goddard thought in terms of migration, not just exploration. His notes tell us that expeditions should be sent to all parts of the Milky Way, wherever new stars are thickly clustered. Each expedition should include “…all the knowledge, literature, art (in a condensed form), and description of tools, appliances, and processes, in as condensed, light, and indestructible a form as possible, so that a new civilisation could begin where the old ended.”

The notes end with the thought that if neither of these scenarios develops, it might still be possible to spread our species to the stars by sending human protoplasm, “…this protoplasm being of such a nature as to produce human beings eventually, by evolution.” Given that Goddard locked his manuscript away, it could have had no influence on Konstantin Tsiolkovsky’s essay “The Future of Earth and Mankind,” which in 1928 speculated that humans might travel on millennial voyages to the stars aboard the future equivalent of a Noah’s Ark.

Interstellar voyages lasting thousands of years would become a familiar trope of science fiction in the ensuing decades, but it is interesting to see how, at the dawn of liquid fuel rocketry, rocket pioneers were already thinking ahead to far-future implications of the technology. Goddard was writing at a time when estimates of the Sun’s lifetime gave our species just millions of years before its demise — a cooling Sun was a reason for future migration. We would later learn the Sun’s lifetime was much longer, but the migration of humans to the stars would retain its fascination for those who contemplate not only worldships but much faster journeys.


Goddard was obviously influenced by his contemporary J.D. Bernal with his The World, the Flesh and the Devil  which predicted Man’s spread out into the Solar System and interstellar space with artificial worlds and hollowed out asteroids.


These worlds are needed because such journeys will take hundreds or perhaps thousands of years.


Of course that brings in natural evolution and what these people inside these places will become when they eventually reach their destinations and if they’ll actually have need of them.


Robert Goddard’s Interstellar Migration






Worldships and Planetary Chauvanism

From Centauri Dreams:

The assumptions we bring to interstellar flight shape the futures we can imagine. It’s useful, then, to question those assumptions at every turn, particularly the one that says the reason we will go to the stars is to find other planets like the Earth. The thought is natural enough, and it’s built into the exoplanet enterprise, for the one thing we get excited about more than any other is the prospect of finding small, rocky worlds at about Earth’s distance from a Sun-like star. This is what Kepler is all about. From an astrobiological perspective, this focus makes sense, as we want to know whether there is other life — particularly intelligent life — in the universe.

But interstellar expansion may not involve terrestrial-class worlds at all, though they would still remain the subject of intense study. Let’s assume for a moment that a future human civilization expands to the stars in worldships that take hundreds or even thousands of years to reach their destination. The occupants of these enormous vessels might travel in a tightly packed urban environment or perhaps in a much more ‘rural’ setting with Earth-like amenities. Many of them would live out their lives in transit, without the ability to be there at journey’s end. We can only speculate what kind of social structures might emerge around the ultimate mission imperative.

Moving Beyond a Planetary Surface

Humans who have grown up in a place that has effectively become their world are going to find its norms prevail, and the idea of living on a planetary surface may hold little interest. Isaac Asimov once wrote about what he called ‘planetary chauvinism,’ which falls back on something Eric M. Jones wrote back in the 1980s. Jones believed that people traveling to another star will be far more intent on mining asteroids and the moons of planets to help them build new habitats for their own expanding population. Stephen Ashworth, a familiar figure on Centauri Dreams, writes about what he calls ‘astro-civilizations,’ space-based cultures that focus on the material and energy resources of whatever system they are in rather than planets.


Ashworth’s twin essays appear in a 2012 issue of the Journal of the British Interplanetary Society (citation below) that grew out of a worldship symposium held in 2011 at BIS headquarters in London. The entire issue is a wonderful contribution to the growing body of research on worldships and their uses. Ashworth points out that a planetary civilization like our own thinks in terms of planetary resources and, when looking toward interstellar options, naturally assumes the primary goal will be to locate new ‘Earths.’ A corollary is the assumption of rapid transport that mirrors the kind of missions used to explore our own Solar System.

Image: A worldship kilometers in length as envisioned by space artist Adrian Mann.

An astro-civilization is built on different premises, and evolves naturally enough from the space efforts of its forebears. Let me quote Ashworth on this:

“A space-based or astro-civilisation…is based on technologies which are an extension of those required on planetary surfaces, most importantly the design of structures which provide artificial gravity by rotation, and the ability to mine and process raw materials in microgravity conditions. In fact a hierarchical progression of technology development can be traced, in which each new departure depends upon all the previous ones, which leads ultimately to an astro-civilisation.

The technology development Ashworth is talking about is a natural extension of planetary methods, moving through agriculture and industrialization into a focus on the recovery of materials that have not been concentrated on a planetary surface, and on human adaptation not only to lower levels of gravity but to life in pressurized structures beginning with outposts on the Moon, Mars and out into the system. Assume sufficient expertise with microgravity environments — and this will come in due course — and the human reliance upon 1 g, and for that matter upon planetary surfaces, begins to diminish. Power sources move away from fossil fuels and gravitate toward nuclear and solar power sources usable anywhere in the galaxy.

Agriculture likewise moves from industrialized methods on planetary surfaces to hydroponic agriculture in artificial environments. Ashworth sees this as a progression taking our adaptable species from the African Savannah to the land surface of the entire Earth and on to the planets, from which we begin, as we master the wide range of new habitats becoming available, to adapt to living in space itself. He sees a continuation in the increase of population densities that took us from nomadic life to villages to cities, finally being extended into a fully urbanized existence that will flourish inside large space colonies and, eventually, worldships.

An interstellar worldship is, after all, a simple extension from a colony world that remains in orbit around our own star. That colony world, within which people can sustain their lives over generations, is itself an outgrowth of earlier technologies like the Space Station, where residence is temporary but within which new skills for adapting to space are gradually learned. Where I might disagree with Ashworth is on a point he himself raises, that the kind of habitats Gerard O’Neill envisioned didn’t assume high population densities at all, but rather an abundance of energy and resources that would make life far more comfortable than on a planet.


This reminds me of an old Analog article I read back in the 1970s by Larry Niven titled “Bigger Than Worlds” in which Niven gave several examples of structures that evolved into massive structures from interstellar vessels to Ringworlds and Dyson Sphere, all of which were safer than natural planets.

Of course this goes by the assumption if human goes by the “expansion” route, or the “evo devo” route proposed by Jon Smart.

Toward a Space-Based Civilization