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Starship Century: A Review of the Book

Could there be a more time-worn trope in science fiction than the arrival of colonists or explorers on a new world? The stage is set for adventure and the unwinding of whatever plot theme the author has in mind, but if the planet is Earth-like, we see the colonists quickly settling in, adapting to local conditions and, in relatively short order, creating a new society. Back in the 1950s the film When Worlds Collide showed the arrival of desperate survivors of a doomed Earth on a planet that would be their refuge, the assumption being that from this point on, everything would be no more difficult than setting up a camp on some new continent.

Would it be so? For that matter, would our human crew be able to survive the journey? Paul Davies has his doubts, and he expressed them forcefully at the recent Starship Century event in San Diego. While we tend to concentrate on time and distance problems — how do you get something moving fast enough to get your crew to another star within a human lifetime? — Davies is more concerned with long-term survival and the creation of a truly self-sustaining ecosystem, not to mention what happens to that ecosystem when it mixes with its counterpart on an alien world.


A huge part of the conundrum has to do with microbes. They account for almost all terrestrial species and thrive absolutely everywhere, down to kilometers below the surface. As Davies points out, microbes form a network of biological interactions that we know all too little about, into which are woven the equally complicated activities of viruses. We wind up with an ecological web of a complexity that defeats our best attempts at modeling. Thus the problem:

In the absence of sending the entire terrestrial biosphere, a fundamental unsolved problem arises: what is the minimum complexity of an ecosystem — dominated, as I have explained, by microbes — necessary for long-term sustainability? At what point, as more and more microbial species are dropped from the inventory of interstellar passengers, does the remaining ecosystem go unstable and collapse? Which microbes are crucial and which would be irrelevant passengers as far as humans (and their animal and plant food supply) are concerned?

Davies’ thoughts on this ‘Noah’s Ark conundrum,’ as he calls it, form the basis of his contribution to the Starship Century book, and you can see a video of his talk in San Diego online. The problem he outlines is one that won’t go away, for if we do solve the propulsion problem, what happens when we get light years from Earth only to discover that we left a bacterium behind that makes all the difference in keeping us alive? For that matter, can we predict how a sustainable ecosystem survives and changes in conditions of extreme long-term isolation?

The Fiction of Science

It’s one of the strengths of this collection of essays and short stories that it interweaves the science fictional impulse with the science. Thus Davies’ conjectures are anticipated by Richard Lovett’s story “Living Large,” which sketches a multi-century journey to the stars through the eyes of one of its future crew. Problems with closed-loop ecologies form the basis of the crew member’s interview with a journalist anxious to communicate starflight realities to the public, with all that means about radiation issues, efficiency in food production, recycling of nutrients and the rest. Through Lovett we see some of Davies’ key points illuminated in a tale that grew out of Lovett’s own thoughts on adapting to changing and ultimately alien ecosystems.

It was Freeman Dyson who said “Science is my territory, but science fiction is the landscape of my dreams.” Many of us, even those who do not claim science as native turf, can second that assertion about science fiction and dreaming. It is the sheer audacity of science fiction to take us out of the conventional world and into alternative possibilities that are vividly realized and challenge us to question our assumptions. Thus Nancy Kress’ “Knotweed and Gardenias,” a cautionary tale about a deep space mission whose crew begins to show behaviors that are inexplicable. Can they find the one thing mission planners left out of their own artificial ecosystem?

Readers with a taste for Heinlein will take huge pleasure in seeing a rough and vigorous future sketched out in Gregory Benford’s “The Man Who Sold the Stars,” a lively tale whose title makes a nod to Heinlein’s “The Man Who Sold the Moon.” Like Heinlein’s Delos Harriman, Benford’s Harold Mann is driven by his own inner compulsions to make things bigger, better and more innovative than ever before, creating a series of business breakthroughs that range from nanotech applications in orbit to asteroid mining, high-tech profit hunting all in the service of an innate drive to push boundaries or, as Mann says, “Man’s got to throw long in this life.”

“If you’re young and lean,” Harold’s future wife tells him, “things can fail and you still keep going. For the big space companies, the whole competition is just getting the government contract, then it’s all risk aversion. It’s not at all about doing something cool, first to market, then making money so you can do more. That is what I like: not playing it safe. To shift gears, to follow your nose.”

As indeed she does in a lifetime with steadily expanding technologies that eventually take her and her husband on an improbable journey to the nearest star. Along the way the roadblocks thrown by bureaucrats, hostile competitors and public indifference are progressively overcome, and we watch the development of a Solar System infrastructure enabled by the production of nuclear thermal rockets that become the Conestoga wagons of an expanding spaceward push. But as the tale shows, it takes more extreme measures when the distances become interstellar.

An Industrialized Solar System

Geoffrey Landis, a crack science fiction writer who also favors this book with a poem, puts the focus on nuclear thermal technologies in an essay that explains the limitations of the chemical rocket and the technologies that can surmount it [video]. Both Landis and Adam Crowl touch on these matters, with Crowl offering a comprehensive overview of starship ideas in the literature — more about the Crowl essay later this week — while Landis homes in tightly on a technology that’s exceedingly simple. Gas is moved over a hot reactor core, to be expanded and pushed out a nozzle to produce thrust. Landis calls it the “spaceship equivalent of a pickup truck.”

Interesting outer system scenarios emerge in the consideration of rocket fuel:

Water is abundant in the outer system… After all, once you get far from the Sun — roughly past the middle of the asteroid belt — water ice is just another kind of rock. Closer in to the Sun, many asteroids have water as part of their composition in the form of water of hydration. So you can refuel your nuclear rocket using hydrogen generated from harvesting rocks in the Trojan asteroids, or short period comets — and, since you have a transportation system, you can haul fuel wherever you need it in the inner Solar System as well. You can either use electrolysis to split out the hydrogen for reaction mass — or, if you want higher thrust but can afford lower performance, you can use water (or ammonia — another ice common in the outer reaches of the Solar System) as the reaction mass.

Thus we get the space-age ‘Silk Road’ trading routes of space, with our craft going out to the outer system, gathering up the water to split into hydrogen and oxygen, and bringing it into the inner system. Our ships return from the outer dark laden with fuel, water for life support and the myriad uses of industrial processing. Landis runs through the history of nuclear thermal designs at NASA, considering the NERVA (Nuclear Energy for Rocket Vehicle Applications) work of the 1960s that produced designs (and tests on) a number of nuclear rockets. Including the Rover program, NASA did 28 full-power test firings of nuclear engines at the Jackass Flats test site in Nevada. We’ve never flown them, but these rocket engines have been thoroughly tested.

Landis’ thoughts on a bi-modal rocket, one that uses the heat of the nuclear core when high thrust is needed and otherwise taps nuclear power to run an ion engine, show us the kind of rocket that might one day colonize the Solar System. Just how nuclear thermal fits into the wider panorama of deep space propulsion concepts is something we’ll be talking about in coming days not only with Jim Benford’s thoughts on solar and beamed-sail missions but also with a long look at Adam Crowl’s survey of interstellar concepts, ideas that range from fusion through sails and into exotic possibilities like particle beam propulsion and interstellar ramjets. I also want to discuss Martin Rees’ thoughts on where we are going and revisit Freeman Dyson’s provocative speculations about what might happen at the edge of the Solar System.

The Case for Deep Space

Two other titles that meld science and science fiction come quickly to mind, the first being Project Solar Sail, a 1990 book edited by Arthur C. Clarke, and the more recent Going Interstellar, edited by Les Johnson and Jack McDevitt. Starship Century puts an exclamation point on the idea with a series of thought provoking essays and compelling science fiction tales that link thematically to the idea of building a pathway that will eventually take us to interstellar flight through wise use of Solar System resources.

With authors like Martin Rees, Freeman Dyson, Neal Stephenson, Stephen Baxter, David Brin, Ian Crawford and John Cramer, the ideas fly, and it was delightful to see an old favorite, Joe Haldeman’s “Tricentennial,” reprinted long after its 1976 appearance in Analog (and also delightful to see that it has lost none of its punch). The profits for Starship Century go toward “experiments, theory and concept studies” involving interstellar flight at a time when interest in space-related technologies seems to be surging, as witness the success of Planetary Resources’ recent fundraising, and the suddenly burgeoning series of upcoming conferences which includes Starship Congress in Dallas this August as well as the 100 Year Starship Symposium in Houston this September. Starship Century should further ramp up public interest. It is a provocative cri de coeur that belongs on the shelf of anyone with an interest in starflight.


Comments on this entry are closed.

  • Eric SECT July 1, 2013, 14:10

    Nuclear fission/thermal rockets with water as propellant mined from asteroids and comets makes for good common sense… in the depths of space far from the Earth I dare say we have mastered the technology (of fission) so now let’s get to it and fly some proto-types.

  • Christopher Doll July 1, 2013, 14:30

    I’d like to see some of the speculative mission planning for efforts like the 100 Year Starship take these destination-specific concerns into consideration. The spacecraft must be capable of being a robust platform for extended periods of time in the destination system – perhaps as an orbital platform for extended sorties to and from the surface. Obviously this complicates the payload requirements of such a vessel, but there’s also the option of bringing along the mechanisms needed to construct vehicles at the destination system using materials mined there. The entire vehicle could be re-configured in-system, or split apart as needed. Lots to consider here.

  • Alex Tolley July 1, 2013, 15:48

    The ecology and microbe problem will either be reasonably solved, or not, by development of colonies in the solar system. If they turn out to be stable, including our human microbiome, then so well and good. If not, that is only a problem if you are wedded to the idea that biological humans must go to the stars. If we can get past that, then our non-biological descendants should be able to make the journey. That alone solves a lot of problems, both with human survival and interacting with the target world biota. Which leaves us back with solving the time and distance problems.

    If there is one big difference between our current knowledge and Asimov’s when he wrote his robot stories, is that the “germ free” Spacers probably couldn’t exist without a microbiome, or at the least, be weak and sickly, with developmental problems.

  • Alex Tolley July 1, 2013, 15:56

    A small plea. If it hasn’t already been addressed, could the Benfords or others please tidy up the many typos and grammatical errors in the text before it is finally released for general circulation? They mar a really well constructed book.

    BTW, I would really like a hard cover version for my library.

  • coolstar July 1, 2013, 20:23

    I agree with Alex Trolley on the closed ecosystem problem: it will be solved, or found unsolvable (which I doubt), long before anyone leaves for the stars. And when they do, they will be able to take the complete genomes of a zillion or so living things, and create the ones they forgot to take in living form either on the way or after they reach their destination. Modern biology seems to me to be advancing considerably faster than modern physics and probably as fast as astronomy and astrophysics.

  • Alex Tolley July 1, 2013, 22:34

    coolstar is probably correct about having the genomes of all living organisms on tap. I would be very surprised if we don’t have libraries of all organisms including viruses with enough examples for genetic diversity withing 50 years.
    I also expect that being able to create most species de novo will be possible, although it may be somewhat harder to ensure growth and reproduction. I’m sure we will have plenty of examples of artificial ecologies to determine what works, or at least for how long. The complexity doesn’t concern me so much, as we can live with recipes rather than complete modeling. But opinions on that will differ.

    Which opens up a point about what Starship organizations could do. Why not simulate the spectra of other stars and test out the effect on some simple tank sized ecosystems? That could help us understand what will need to be engineered to survive on another world. My guess is that plants will do fine, even with red dwarf light spectra, but that insects will do badly there, without enough UV.

  • Mephane July 2, 2013, 2:35

    My take on the problem with ecosystems: synthetic DNA. Take the decoded DNA of literally all known species, in digital form, to the other star, so in case it turns out that a specific species is missing, its DNA can be synthesized and used to turn another bacterium into this species. I am not sure if we are able to do this already, but from what I’ve read so far this sounds like a very plausible possibility in the near future.

  • spaceman July 2, 2013, 4:23

    When it comes to the nuclear thermal rocket development in the 1960s vs. the redevelopment of this same technology in the present, correct me if I am wrong, but wouldn’t advances in computer technology and materials science allow us now vs. then to (i) cut down on the time it takes to redevelop nuclear thermal rockets (NTRs), and (ii) build NTRs that are fundamentally better from an engineering standpoint? This also leads me to a more general question: to what extent does the general advancement in materials science and information technology allow us to make better strides into space than what was possible with the state of technology in the `60s and `70s? After all, it sure seems paradoxical that despite the enormous advances made technologically overall we had the means of traveling to the Moon then whereas now we lack that means. Perhaps the resolution of this paradox lies in the political/fiscal arena more than it does in the scientific/technological arena…

  • Doug M. July 2, 2013, 5:31

    Modern biology is indeed advancing quickly, but nobody is putting much money into the problem yet. The science of keeping humans alive in a closed system has pretty much stopped dead since the closing of Biosphere 2. (Not a plug for Biosphere 2; it was badly designed, badly run, and produced depressingly little actual science.)

    There are a number of plausible on-ramps to this: partial recycling and shorter periods of time, moving gradually to full recycling and longer periods. But at the moment, nobody seems interested.

    Doug M.

  • David Cummings July 2, 2013, 7:27

    Alex and coolstar have it exactly right. Long-term colonization of distant parts of the solar system will be happening all through the development of starship technology. Part of that technological development will be coming up with solutions to the problems of long-term colonization of distant parts of the solar system.

    I think in the scheme of things, microbe ecosystem viability is going to be a much smaller problem than a) acceleration from the solar system to a decent travel speed, b) radiation protection en-route, c) starship/debris collision protection en-route, d) energy production (or conservation) en-route, e) deceleration at the far end.

    These are the 5 biggest problems in star travel, in my opinion. Long before we solve these 5 probles we will solve the microbe ecology problem.

  • A. A. Jackson July 2, 2013, 8:17

    There was one slide that Paul Davies showed that bothered me.
    It looked like this:
    Fundamental conceptual obstacle
    physics/chemistry -> biology

    physics/chemistry: matter, force , energy
    biology: coding/signals/instructions

    Left off the slide was:
    (My nephew , who has an MD/Ph.D from The Sloan-Kettering Institute institute , when I showed him the slide wrote of a piece of paper):

    molecular biophysics -> matter, force, energy, coding signals, instructions

    He said in gaining his Ph.D he had done a lot of physics and chemistry.
    This does not answer the question , yet, as to how organisms arouse from inorganic chemistry but it does challenge the idea that ‘biology’ is only formed of information theory.
    He used physics and chemistry and even mathematics in his Ph.D work , not at the level quantum field theory, and as a biology friend of mine said “Biology is a Mess”. Finding the mechanism of transition from inorganic matter to organic is going to be harder than finding a quantum theory of gravity.
    So I dispute Davies characterization , the tools are there as long as one has a long long long supply of patience.

  • coacervate July 2, 2013, 8:37

    what happens when we get light years from Earth only to discover that we left a bacterium behind that makes all the difference in keeping us alive?

    Many years ago I needed an enzyme to cleave a specific sequence in a protein…a proline-proline endopeptidase. A close friend in the micro department suggested that I grow a common strain of E. coli on media containing pro-pro as the obligate carbon source. I picked a dozen colonies from the dish and sure enough they were loaded with the enzyme activity I sought.

    My take is, although we give bacteria species names, their generation times are so short they will rise to whatever challenge the isolation of space travel may present. E. centauri will exist a long time before H. centauri catches up!

  • johnq July 2, 2013, 10:46

    >the problem he outlines is one that won’t go away, for if we do solve the propulsion problem, what happens when we get light years from Earth only to discover that we left a bacterium behind that makes all the difference in keeping us alive?

    For heaven’s sake, but this is bordering on silliness. Look, if we left that incredibly vital bacterium behind, we die. Like this would be the first time a colony, or prospective colony was wiped out. I was just reading about cannibalism in the Jamestown colony (the forensic evidence is overwhelming). Frankly, I would much rather deal with some missing bacterium than devouring a fellow colonist, child or adult. I can well imagine someone centuries ago agonizing over what might be the fate of those heading for the New World: “Why they might run out of food. What do we really know about the flora and fauna of this unknown continent? What if the animals are scarce or inedible, the plants poisonous? How can we ever hope to know for sure? And if the colonists die horribly from starvation, reduced to the level of beasts in the wilderness . . . God would curse us. I think we had better give up now. Leave it too the Spaniards. Sorry, way too scary.” And can you imagine when the videos beamed back to Merry Olde England show up on YouTube? How very gross.

    John Campbell once said (words to the effect) that exploring new frontiers inevitably involved discovering exciting new ways to die. So what? It’s the process of interstellar exploration that is crucial to the endeavor, not the destination, which if you have done it often enough might even become something of a bore. If we can’t handle the risk, if we are going to be ninnies (yes, I was thinking of other words but that will do) about this, we will remain stuck in earth orbit forever, which I think would be appropriate for a species of losers.

    >For that matter, can we predict how a sustainable ecosystem survives and changes in conditions of extreme long-term isolation?

    Gee whiz, I don’t know. I suspect we will learn, quite a lot actually and that should be fun. I also expect we will find perfection in the predictions to be unattainable, chaotic and all that. We will do the best we can at all times, suffer ghoulish disasters at some point — just like on planet earth — and one expects, move on. It’s dangerous and deadly no matter what we do!

    At one point in the Apollo program, I forget the full context, the question arose as to what if astronauts were stranded on the moon or in lunar orbit? Well, the answer was they would do what astronauts do: observe, report, all that. Until they died.

    In short, let’s note the possible problems (thanks for sharing, Mr. Davies) — the list will be rather long — and carry on regardless.

  • Alex Tolley July 2, 2013, 10:59

    @coacervate – that approach will work if the bacteria already has a gene that can be modified to do the task. If you need a completely novel function, that approach will probably fail. Having said that, we will probably have vast libraries of genes that have been functionally characterized that can be selected from and inserted into a target organism. I would hope that we would also have good tools to design genes for certain functionality. But if we can do that, maybe we can engineer our starfarers too?

  • James Benford July 2, 2013, 12:53

    Alex: Paul tells me you likely got the limited edition (only 200) sold at the La Jolla Symposium. I’m aware that had flaws, as you note. Two weeks later we had a corrected version, so the version on sale at starshipcentury.com is corrected..

    Hardcover? We looked into that. With 57 color figures the cost was very high. We thought not. However, the e-book version, out mid-August, will be in color!

    Jim Benford

  • Gregory Benford July 2, 2013, 12:54

    Progress on stable biospheres offplanet is essentially zero for deep reasons. The major point is that NASA doesn’t want to be seen by Congress as seriously planning for a Mars expedition level mission. (I learned this while on the NASA Administrator’s kitchen cabinet in the 1990s.) That’s reality. To quote from STARSHIP CENTURY:
    Congress came to see NASA primarily as a jobs program, not an exploratory agency. Slowly, NASA complied with the post-1972 vision—safety-obsessed, with few big goals for manned flight beyond low Earth orbit. Very little science got done in the Station. NASA never did the experiments needed for a genuine interplanetary expedition – centrifugal gravity to avoid bodily harm, and a true closed biosphere. We’re not doing that. The Station was not about living in space, but camping in space. This echoed the earlier Russian Mir station, where crews got a weekly vodka, cognac and cigarette ration to pass the time.
    “We had the Shuttle to reach the Station, and the Station to give the Shuttle a destination,” an old NASA hand remarked: “A school bus route writ large.”
    What’s needed is a closed recycled ecosystem, which is far from risk free and is far beyond our present capability. After survival challenges, there are the psychological and social issues-confinement, limited companionship, social dynamics. The principles of dealing with prolonged isolation and confinement were to stay busy, keep a steady day-night schedule and watch your health. And in a crewed starship, there are gong to be both sexes, especially if they are going to colonize, which brings interesting issues. Slowing down or ceasing of the metabolism at low temperatures with reanimation at the end of the voyage would greatly lessen the need for supplies and eliminate the long-term psychological and social issues. Bears do it naturally, but we don’t know how. But some progress is being made in cyrogenics, the preservation of the dead, trying for survival to a time they might be revived. We know far too little now of this short cut to either embrace or dismiss the prospect of suspended animation. These issues are dealt with by Richard Lovett, in “Living Large”.

  • Mark Wakely July 2, 2013, 14:22

    I’ve mentioned this before, but Pratt & Whitney’s TRITON trimodal nuclear engine (as opposed to a bimodal design) is still a viable option despite having been proposed nine years ago this month:


    A year ago, a study done at Virginia Polytechnic Institute selected the TRITON for its proposal for a manned Mars mission. Scroll down to the middle of page 11 to read a brief summary of TRITON and why it was selected:


  • David Cummings July 3, 2013, 8:32

    Gregory Benford, interesting what you wrote. Interesting and depressing. Camping in space, not living in space. That really is a shame.

    I’ve heard this quote before:

    “We had the Shuttle to reach the Station, and the Station to give the Shuttle a destination,”

  • Marc Millis July 3, 2013, 10:45

    to Greg Benford,

    Thanks for sharing that info about NASA. It is news that needs to be spread so that those who are looking for progress know the realities of the situation.

    It was a hard and financially difficult decision to leave NASA when they offered a buyout, after elliminating my position. I could have continued there, but my next assignment would have been reading papers from the 1960’s about large propellant tanks in orbit. Serioulsy… we’re into the next century and NASA is still stuck in the 1960’s.

    Sorry folks, it is how it is.

    Marc Millis

  • Rob Henry July 3, 2013, 18:00

    A.A. Jackson, I also agree that Davies angle on Biology was provocative, but I take the opposite view. His non-traditional approach had a searing brilliance to it, that if adopted by others, could be of great further benefit to that science.

    Think of how often you hear a biologist confuse ‘chemical evolution’ with the well know processes of the Modern Synthesis (actually, though I’m sure I must be wrong, I seem to recall that you were also slightly confused as to what Modern Synthesis was last year, so I will put a reference here just in case. In particular there seemed confusion as to why it was merely inspired by Darwin, but a direct descendant of the work of others, particularly his contemporary Mendel)

    If only they could come to see it as stamp collecting, then they would realise that there it really is a major difficulty as to how abiogenesis created a von Neumann machine. To me this process almost certainly invoked some “special cases” of complexification to give highly specific function of biological use, that are somehow written into our laws of chemistry. We should be able to find these only by direct experimentation, simply because biology outside evolution is stamp collecting, not the result of supernatural forces such as Haldane using ‘dialectic materialism’.

  • John Hartley July 4, 2013, 19:48

    If you look at the progress of Moore’s law just as a metric of design complexity, by the middle of the century designs will rival the complexity of the human egg cell. On the timeframe for interstellar flight we will have the ability to synthesize by design, any microbe left behind. Understanding what needs to be synthesized for a stable ecosystem is a different question especially important if we can’t develop relativistic propulsion. The ability to synthesize enroute does ease the launch constraints on the ecosystem.

  • D. Wayne Dworsky September 8, 2013, 12:56

    I think Starship Century hit the nail right on the head. Not only does it incorporate science and science ficftion in a unique way, but it fosters some of the greatest visionaries of the Twentieth Century. I applaid all those who helped put together this unique volume–a momument to the science and science fiction arena.