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The Starship in our Future

The relentless expansion implicit in the Kardashev scale ranks civilizations according to their use of power, with the notion that there is an upward movement from exploiting the energy resources of a planet to the entire home star and then on to the galaxy (Type III). Hence the interest in trying to observe civilizations that operate on such colossal scales. Surely a Kardashev Type III culture would, in its manipulation of such titanic energies, cast a signature that would be observable even by a relatively lowly Type .7 civilization like ours.

So far we see no signs of Type III civilizations, though early searches through our astronomical data continue (see G-HAT: Searching For Kardashev Type III, for example, which gets into the Glimpsing Heat from Alien Technologies work at Penn State). In Earth in Human Hands, David Grinspoon relates the question to our own survival challenges as we deal with the so-called Anthropocene, a time when our technologies are increasingly affecting our planet, creating a new set of challenges to survival.

Humans may have a history that implies expansion as long as resources hold out, but would alien societies necessarily parallel our own? If civilizations do not expand exponentially, perhaps because such models prove unsustainable, then the average technological culture may be on a much slower track, focusing on improving conditions a bit closer to home. That creates a set of SETI observables that we looked at yesterday, still engineering on scales beyond what we can manage ourselves, but well below Kardashev Type III.

The Inevitability of Space

Talk like this sometimes conjures images of planets where societies have turned sharply inward, moving away from exploration and adopting a low-tech way of life. But there are reasons to believe this would not be the case. In its own way, Grinspoon’s book is an example of this. The author is an astrobiologist who focuses on planetary atmospheres, their interactions with the surface, their evolution and contribution to habitability. His book includes planetary-scale projects that future humans may choose to deploy to keep the Earth healthy as we reduce atmospheric pollution and work for sustainable environments.

You can see that studies like this demand a space program as well as an advanced astronomy. If we want to understand the various paths of planetary evolution, we have to go to the planets themselves, gathering data on why Venus has turned out to be the hellish place it is, and why Mars has proven unable to sustain habitable conditions. We also have to study exoplanets with many of the same issues in mind, learning how stellar systems form around distant stars and witnessing the variety of outcomes in systems much different from our own.

Sheer curiosity drives at least our species to planetary exploration even as we learn how best to manage our own planet, and it seems reasonable that alien civilizations would do the same. Moreover, we have the imperative of protecting our world from catastrophes and mass extinctions, so vividly illustrated in our geological past. I’ve argued for a long time that the need to operate far from Earth is essential if we are to have the capability of changing dangerous asteroid or comet trajectories. These technologies are planetary insurance policies that emerge in tandem with our interest in how other worlds have followed their own evolutionary paths. Space is part and parcel of keeping a technological society healthy.


Image: Putting our technologies to work sustaining a planet cannot be done without a robust space program that delivers the lessons of planetary evolution and provides opportunities for deeper exploration.

And can we reach the stars? We can go back to Tsiolkovsky to find the origins of the so-called ‘generation ship,’ that staple of science fiction that presents an intriguing alternative to the all but instantaneous travel so many SF scenarios invoke. Traveling at a small percentage of lightspeed, the generation ship breaks no physical laws and sacrifices travel time for its own kind of sustainability, a functioning culture aboard a vessel in constant passage to the stars. Destinations are finally reached, but I’m persuaded that we may eventually see such ships become their own solution to habitability, an alternative to any kind of planetary surface.

Grinspoon finds the generation ship a useful analogy. For in many older SF tales (think Heinlein’s Orphans of the Sky for one), the knowledge of the ‘world’ as a ship on a voyage has been lost and must be recovered. Suddenly the passengers must be introduced to the idea that there is an entire universe outside the ship. The challenge now is to figure out where the ship is, how far along in its journey, and what to do with it upon arrival. Can we relate this to the early Anthropocene and the need to overcome its challenges? Grinspoon does it this way:

We are hurtling through space on the only place we know we could live, and we’ve discovered that it is indeed, in part, a kind of construct. We are piecing together its history, coming to understand our situation, and realizing that we have inherited a role for which we are not trained. Our current world, inhabited by seven billion, soon to be ten billion people, was created, in part, by the actions of our predecessors and will require smart engineering to return to a safe course. Our immediate task is to switch to auxiliary power and turn off the carbon generators that are overheating the ship. Our longer-term challenge is to shore up our world for the generations who inherit it.

But the generation ship is also a technological outcome in its own right. Here we can think about human migrations in the distant past, out of Africa, across the Bering Strait, into the deep Pacific by outrigger, and so on. Each such migration committed future generations to outcomes they could not choose, just as decisions we make today about our technologies will produce a civilization we hand off to descendants who have no voice in the matter. Like Grinspoon, I think that the nature of our species includes the will, the need, to explore, which is why we will eventually build such craft even as we develop faster technologies.

We are also pushing our space technologies to the limit as we start talking about true interstellar probes, sail-driven craft that will reach their targets within decades, the kind of project envisioned by Breakthrough Starshot. This drive to explore distant targets is not slowing down now that we have surveyed the planets in our own Solar System. Instead, we are trying to get data unavailable to our largest telescopes to expand our understanding of planets around the closest stars, each of which may offer lessons in planetary management.

No, space is woven into the very fabric of a culture coming to grips with the effects of its technologies on its own planet. Thus I think we can expect that even if a culture is not necessarily climbing the Kardashev scale as relentlessly as we might expect, it will still be exploring on its own timeframes the planets and stars closest to it. Who knows what protocols of contact might keep such a culture from making itself known to those it encounters? And who knows what kind of philosophies of time and space may be spawned by all this?

For when we start talking about leaving a home world, we confront the immensity not just of distance but of time. Grinspoon is eloquent on the matter:

Going interstellar means going long. We cannot imagine ourselves as interstellar actors without also conceiving of ourselves as intergenerational actors. We cannot reach the stars without a sense of identity and goals that span generations. This is true for interstellar communication as well as for travel. Neither makes sense unless we see ourselves as collaborating with our descendants. To travel, or even send messages, to the stars, we will have to start conversations, projects, and journeys for our descendants to finish. This cements the essential bonds between generations. We won’t be the first to attempt such projects. The builders of pyramids and cathedrals mostly never lived to see them completed. Sometimes they worked under duress or coercion, but sometimes they were moved by spiritual commitment to something beyond their individual lives. I think of science itself as such an effort, with individual researchers fashioning bricks in an edifice each of us can see only partly constructed, knowing that our students and theirs will continue to build.

The sense of commitment and sacrifice toward outcomes bigger than ourselves often feels missing in our day, but these are human traits that continually re-surface in our history. We keep hammering on these issues because their relevance persists, and the fog of short-term thinking occasionally lifts to offer a view of landscapes and stars so expansive as to take the breath away. Handing off ideas to our posterity is the best life-shaping goal I know. Our messages must reach across generations and we must see that they get there intact.


Comments on this entry are closed.

  • ole burde November 23, 2016, 13:36

    With ‘Breakthrough Starshot’ on its way , it is time to examine in what kind of circumstaces a very small starship could play a very big role : everybody seems to take for more or less granted that the universe i full of lifebearing planets , but if this should NOT be the case we should start thinking about how to bring life to a large number of relatively close planets , so that our descendants might have somewhere to go when they eventually get to build their giant generationships …. To do this we have to overcome a different set of problems than the ones normally associated with spaceflight , but if our ‘crew’ are extreemely tough one-celled creatures , it might be possible to sucseed with a large number of very small spaceships…..all it takes might be to overcome our fear of ‘ playing god’ …

    • Alex Tolley November 23, 2016, 15:21

      Agreed. Even if our descendants don’t travel to the stars, starting up life processes on dead worlds that might eventually create who new pockets of sentience is a worthwhile endeavor. Not particularly expensive either. Scale economies would be evident, both for the nano ships as well as the propulsion systems. Redundancy in numbers is the key here, to prevent single point of failure.

    • DCM November 23, 2016, 17:58

      Yes, that’s what we should aim for whether or not we discover some “drive” that avoids the time problem. Put life wherever it isn’t but can be. And we’re going to be able to preadapt it to some places.

      What some call generation ships I call biospheres. We can build really huge ones both for travel and life sowing.

      • ljk November 28, 2016, 11:21

        Actually the current term is WorldShip. Biosphere might be rather limiting if the “crew” is actually all artificial, or that the ship is a being/Artilect unto itself.

        Thinking outside the box, one step at a time. That is where the real progress and advancements get made.

    • David H December 4, 2016, 5:13

      I’d love to see a discussion of what would be the smallest buildable life-spreading starship. I don’t expect that it would carry biological material, but it would have a tiny printer that could build larger printers that could build a lab that could build life from blueprints, including human. Cultural continuity would actually be easier to achieve than in generation ships, because the first generation would be brought up by AI that transmits the values we think are worth defending. One comforting thing about such a seeding scenario is that millennia in the future, when Earth is ruled by ???, in other solar systems there would be fledgling colonies of very recognizable humans would be getting a kick from watching old Simpsons episodes that were a part of the very compact databank sent there by 21st century humans.

  • Alex Tolley November 23, 2016, 14:03

    This was a very eloquent piece, Paul.

    Going back to detecting planetary atmospheres, it strikes me that finding biosphere supporting atmospheres where theory says there shouldn’t be due to location in the HZ. or size, may be a sign of interplanetary civilization. Terraforming mars with a breathable, if relatively short term (cosmically) atmosphere would be a signal to ETI that there is a technological, still-biological civilization, perhaps based on the 3rd planet that can have such an atmosphere without technological help.

    We cannot imagine ourselves as interstellar actors without also conceiving of ourselves as intergenerational actors. We cannot reach the stars without a sense of identity and goals that span generations. This is true for interstellar communication as well as for travel. Neither makes sense unless we see ourselves as collaborating with our descendants. To travel, or even send messages, to the stars, we will have to start conversations, projects, and journeys for our descendants to finish. This cements the essential bonds between generations.

    I’m not sure that I agree with that. Non-sentient biology doesn’t much care for communication between generations. They just reproduce and spread to their ecological limits. I get a similar sense from Clarke’s aliens in the Odyssey series. They sow the seeds of intelligence, but do they live to reap or weed their crop which still biological species? Only when they become transcendant do they have this capability, and then it is no longer inter-generational.

    We could send biological seeds out into the cosmos today, with the aim of greening the galaxy, but with no hope of seeing any results before our civilization ends and our species goes extinct. If that effort is transient like a single seeding of an annual plant, then future generations will not even remember such an effort, nor care to know the results.

    • Larry Kennedy November 23, 2016, 17:22

      I’m sure spreading seeds of this biosphere into the Cosmos would be irrelevant to many people. All I can say is, it would not be irrelevant to me.
      People often say that Nature has little use for Humans. Perhaps this is that use. It’s very common in Nature to pay a high price for procreation and distribution.

    • Robert G November 26, 2016, 12:38


      If we seeded single celled life or simple multicellular life widely across space, given the sequence conservation across species and time of some parts of some proteins, even though we might never know the civilisations that one day evolved from it, they would be able to infer our existence and what we had done. As soon as they ventured to another star with a life bearing world and found the sequence homology with their own genes, they would know their planet had been the target of a seeding operation.

      And by the same token, if we were to discover a life bearing world around another star where the life had some genetic homology to earth life, we would know the same about ourselves.

      A further plausible inference would then be that given the timespan involved, such life might likely be broadly distributed throughout the galaxy. Even with quite slow spaceships, three and a half billion years is plenty of time to blanket a 100k light year galaxy. If such turned out to be the case, it would make it both easier and more interesting to go off exploring – a galaxy full of life promises much more to see than a galaxy of dead rocks.

      • Alex Tolley November 26, 2016, 13:03

        I agree that finding ET life with highly conserved sequences with be an indication that life was spread, possibly by agency. If we find such life in our solar system though, it might be by natural means. However it is spread, I would be delighted to see such a living galaxy to observe the diversity it produced. The downside would be that a future “Prime Directive” might make any human presence on such worlds unacceptable. We would need to colonize only dead worlds and also with space habitats and cities, leaving such living worlds pristine.

        Perhaps another reason why machines, rather than biological entities should do the exploring?

        • Robert G November 27, 2016, 8:09

          “We would need to colonize only dead worlds,” / “[F]inding biosphere supporting atmospheres where theory says there shouldn’t be due to location in the HZ. or size, may be a sign of interplanetary civilization.”

          So that is two reasons why searching for life on what would be expected to be non-habitable worlds might help us search out technological civilisations. One reason technical, the other reason ethical. Of course we could argue round in circles about whether or not aliens might share any of our ethical notions, but the simple answer has to be they might, and this improves the odds of the approach.

          It makes me think of Lovelock a bit. He said, if I understand him right, that evidence of a planet’s atmosphere being held away from chemical thermodynamic equilibrium with its surface is evidence if life. If I understand you right, you are saying that evidence of this happening on worlds where life would not be predicted to evolve naturally would be evidence of technological intervention, and hence the presence of a technological actor.

          What’s neat about this is that it is approachable through telescopes and spectroscopy.

        • Eniac November 29, 2016, 0:12

          The downside would be that a future “Prime Directive” might make any human presence on such worlds unacceptable. We would need to colonize only dead worlds and also with space habitats and cities, leaving such living worlds pristine.

          I am not sure that makes sense. There is no such thing as a “Prime Directive” on Earth, why should there be elsewhere? In fact, it would seem to be immoral to let indigenous people starve or die from curable diseases when help is available.
          When there are no people, it makes even less sense, except in the form of “Galactic Parks”, where nature is preserved in designated areas while allowing access for recreation and observation.

          • Alex Tolley November 29, 2016, 13:47

            We already have planetary protection which currently ensures as best we can that we do not contaminate other planets in our solar system, in case there is some extant life. As biological creatures, we would contaminate any living world we stepped on, so we may just avoid those.

            As for helping other cultures, that may or may not be actually helping. Given our problems, no other civ is helping us.

            • Eniac November 29, 2016, 23:30

              Yes, we have attempts at “planetary protection”, but it does not actually keep us from sending our probes there, nor should it.

              That no others are helping (or hurting) us is strong evidence that such others do not exist. Even if they were unimpressed by the moral imperative to help, I doubt they could overcome the impracticality of complete and permanent isolation, no matter how totalitarian their society and advanced their technology might be.

              • Wojciech J December 1, 2016, 10:42

                If intelligent technological life is unique, they might be wary of contacting us.The differences between civilizations will be millions of years, possibly hundreds of millions. Such gap would mean that our culture would dissolve in face of their unique development and advances. And if there are 3-4 civilizations in galaxy they might be more interested in how we will develop and possibly create something unique rather then become flawed copies.

                Alternatively space flight might be very difficult and differences in time and space make contact unlikely.Civilizations might be dispersed thinly across the universe.

          • Wojciech J November 29, 2016, 19:02

            “There is no such thing as a “Prime Directive” on Earth, why should there be elsewhere? ”
            Actually no-contact protocols are already in place towards certain tribes. The Indian government discourages contact with Sentinelese people for example


            Contact between two different cultures on vastly different levels of development results from our history in dissolution of the less developed culture.
            If intelligent life is rare in Universe, then any potential more advanced civilization(and they would be more advanced than we are to Sentinelese) would perhaps prefer us to grow on our own, as this would be more valuable to them. For instance they might have reached certain dead ends in theory, culture, history and would welcome fresh, unique thoughts.

            • Eniac November 29, 2016, 23:21

              If you read the article you link to, you will find several incidents of intentional contact (https://en.wikipedia.org/wiki/Sentinelese_people#Incidents_of_contact), plus the fact that the Sentinelese happily use metal artifacts such as knives they obtain from shipwrecks and other sources. If they don’t already, they will soon be using radios and cell phones, because it is impossible to keep such things away from them, nor is it desirable.

              Any “Prime Directive” is both impractical and morally wrong.

            • Eniac November 29, 2016, 23:51

              Interesting case, the Sentinelese. Apparently contact was attempted several times, but was always met with extreme hostility. The “no-contact protocols” you mention seem to be designed more for the safety of would-be contacters than the Sentinelese. Apparently most outsiders that made it to the island, accidentally or not, ended out dead. See here: http://www.odditycentral.com/travel/north-sentinel-island-the-worlds-hardest-place-to-visit-2.html

              • ljk November 30, 2016, 14:32

                Fascinating. I have to wonder if humanity and Earth are viewed in the same way we view the Sentinelese? I also wonder how they survived World War 2 as Japan was all over Indonesia along with many other Pacific islands. Spears, arrows, and hostility only get you so far against more sophisticated weapons and a determined threat.

              • ljk November 30, 2016, 14:45

                They are Number 1 on the 2013 Top Ten list of native tribes who do not want to join the United Federation of Planets, I mean Nations:


  • Douglas Dwyer November 23, 2016, 14:14

    like our ancestors who made the most of nature we must recognise succesful exploitaton by aliens across the universe will have involved the glacial speed of light.
    An interstellar intelligence could be expected to make use of available resources for communicaion transport & energy.This exploitation may be detectable in the future but unrecognized by our current technology, for example Fast Radio Bursts could be an ancient a resource for intergalactic communication.

    • DJ Kaplan November 23, 2016, 16:57

      FRB’s are very interesting. It should be noted that they would require huge amounts of power to generate, and I don’t think that their source has been nailed down yet. Perhaps they are carrying some sort of data that we haven’t yet teased out from the signal.

      • Douglas F Dwyer November 26, 2016, 5:44

        The coherence/narrow bandwidth of the original pre-dispersed signal level will have required a naturally occurring bulk resonator (MASER) and energy storage, for a big signal I favor a Plasma sphere generated by a supernova gravitational collapse or black hole.

  • Keith Henson November 23, 2016, 16:03

    I don’t think a lot about generation ships. But if human are going to build them, the do need to get into space in a substantial way.

    One of the few projects that might make economic sense for a large presence in space is power satellites. Two years ago I asked the people at NOAA to look into the potential ozone damage from up to a million Skylon flights per year. There is no point in solving the carbon and energy problem with power satellites if the cost is a billion cases of skin cancer.

    They put a lot of effort into modeling the problem, burned through hundreds of hours of super computer time,writing a paper and getting it through peer review. I really appreciate what they did.

    The paper is now available online at


    Click on the PDF symbol next to the journal title.

    Short answer: the damage to the ozone is not a showstopper.

    • Andrew Palfreyman November 24, 2016, 19:25

      Good to see someone else aware of the breakthrough efficacy of something like Skylon. If that’s appreciated, then so should be the cargo version of StarTram, which we could begin building right now. Talk about big structures in space is utterly moot unless the $/payload-Kg is sufficiently low. That is the key to opening up space to robust development.

  • RobFlores November 23, 2016, 17:07

    In terms of Colonization attempts in practice, there is a general
    rule that I think will predominate for as long as it is expensive to speed
    up ships to high speeds. The rule is that the more complete and sophisticated (and supposedly higher chance of success)the
    vessel making the journey, the slower the time to the Destination.

    IMO it is worth going far afield to colonize Easily an (Oxygenable?) twin
    Earth. And No matter any wishful thinking a world like that not going to be 15 LY away. Taking into account that we want K6-G1 type stars that are on the younger side, means a 80-100LY distant target.

    But the paradox is that unless the colony ship uses cold sleep time share of some sort, what arrives at the end of a 800 Year journey in terms of society
    will not resemble it’s original drives and imperatives, if it arrives at all.

    • Wojciech J November 29, 2016, 19:14

      The real paradox is that once you have such ship, do you really need to colonize a much more hostile planet ? The ship already provides you with anything you need, in much more safer environment.
      Perhaps the travelers of such vessels would decide to pursue a nomadic existence, journeying from one world to another, staying for couple of centuries to study its uniqueness and move on ? Perhaps meeting with others in some hub worlds to exchange directly ideas and specimens from the places they encountered ?

      • Eniac November 30, 2016, 0:16

        What point would there be for the “nomads” to move on a second time? The reason they went the first time was to find a place to settle that is not already overcrowded by fellow humans. Even if they preferred staying in the ship, surely orbiting around a nice warm star with plenty of asteroids providing raw materials is preferable to packing up for another 800 years of interstellar journey. For what? A minor chance that the next target would be more suitable for living on or around? Hardly.

        More likely they’ll stay and thrive, and not send a new ship until a few hundred years later when some of their descendants decide they can’t stand the place or company anymore. Over time, many ships may take descendants to many different new targets.

        • Wojciech J December 1, 2016, 18:42

          Eniac, you missed the whole point of the journey in the first place.
          There is no reason to journey in order to settle if you have perfect artificial world. You journey to gain knowledge, experience new things and wonders of the galaxy. With biological or post-biological immortality the whole infinity would beacon and there is little reason to produce much offspring. Why stay at one system when they are billions more, billions more lifeforms, potential cultures, ruins-that is far more interesting, and if life doesn’t limit your choices then why not pursue this?

          Of course this is just imagination, as always we need more data to know what is out there.

          • Eniac December 2, 2016, 0:37

            No-one will embark on a generation ship to “see the wonders of the galaxy”. There are no wonders in interstellar space, only darkness and emptiness. No, the reason to go must be generation spanning, it must be to find a better place for your descendants. “Better” will not likely be measured in terms of nicer asteroids or more planets. Rather, the critical factor will be that these planets and asteroids are not already ruled by others, others that are, perhaps, not treating you well. So, when you get there, you stay and make a home. Later, when it gets crowded, a small band of your descendents might want to leave for the same reason. They, like you, will then be colonists, not nomads.

            • Wojciech J December 2, 2016, 16:29

              Eniac, I think you are trying to miss the point on purpose
              “No-one will embark on a generation ship to “see the wonders of the galaxy”. There are no wonders in interstellar space, only darkness and emptiness. ”
              If one is immortal there is no need for a generation ship. And if you are capable of hibernation/stasis/switching off(if post-biological) than a trip lasting 800 years will last for you a day or so.
              There are plenty of wonders in the galaxy, and perhaps in interstellar medium as well. Why confine yourself to just one planet ?

              ” No, the reason to go must be generation spanning, it must be to find a better place for your descendants. ”
              Why? If your lifespan isn’t constrained by natural biology, why should you think in terms of generations? Descendants wouldn’t seem that important as well. Even now most of our population in developed countries isn’t keen on having many children.

              “So, when you get there, you stay and make a home. Later, when it gets crowded”.
              Why stay at one planet or system when billions of others await ? If your lifespan is unlimited, there is potential for endless amazement at the universe. To colonize a planet by terraforming means waiting centuries for little results. And an alien biosphere is worth more than its destruction.
              As to the systems getting crowded-not likely, our own system can sustain trillions of humans for billions of years, and as our population growth slows down it doesn’t seem that space would get crowded anytime till the heat death of the universe. It is most likely that we will become post-biological eventually if we avoid extinction.


              Based on the limiting elements N and P, water-extractable materials in one kilogram of carbonaceous asteroid soils can support 0.6 grams of biomass. On this basis, bioavailabe extractable materials in the 1e22 kg carbonaceous asteroids can support 6e18 (six million trillion) kilograms of biomass, six thousand times more than the biomass presently on the Earth, that supports six billion humans. The extractable asteroid materials could then support on the order of 40e12 (40 trillion) humans. Using the total elemental contents of the carbonaceous asteroids could support a biomass and population a hundred times larger yet, 4,000 trillion humans, comparable to the population of a million Earths. Materials in the comets could support biomass and populations even ten thousand times larger, comparable to ten billion Earths, in our Solar System alone. Billions of similar solar systems throughout the galaxy can support amounts of life and human populations billions of times still larger.

              • Eniac December 3, 2016, 23:13

                I was under the impression we were talking about generation ships here. You seem to be referring to immortality, stasis, or uploaded AI. That would change things, indeed.

                Not immortality, though. Being immortal would not make it any more desirable for me to isolate myself on a ship for 800 years. Less. maybe.

              • Eniac December 3, 2016, 23:19

                By “crowded” I do not mean stepping on each other’s feet, or running out of resources. Very soon after a colony is established, in a few hundred years at most, each of the system’s rocks down to a certain size is likely catalogued and mapped, as well as owned or controlled by some government. That’s when certain people might decide that they can do better, elsewhere. You don’t need a very large population for that to happen.

  • Larry DePuy November 23, 2016, 18:50

    I am personally optimistic that a cure for aging will come soon, and with the knowledge that the Greenland shark doesn’t reach puberty until it is 150 years old, aliens may very well be nearly immortal and look at things on a very different time scale. I think our life span could exceed thousands of years, rendering multigenerational ships unnecessary. Multiple three hundred year trips to new star systems may be very doable for those who choose it. Go to a new planet, spend 500 years terraforming it and then on to the next and studying planets with life on the way. Procreation is very popular among the religious but we humans seem to be turning away from that as seen in Japan. Why have kids now when you can do it in three hundred years on a new world? And even if warp and EM drive don’t pan out, a new discovery and series of improvements on it will most likely get us to interstellar destinations ever faster. We need to get ourselves and as many species as possible established on other worlds as soon as possible, life on Earth is tenuous.

    • Mephane November 25, 2016, 5:49

      I agree that extreme longevity or immortality, either biological, non-biological or a combination thereof, has a good chance to happen within this century.

      But even if you put immportal people a worldship, after hundreds or thousands of years these people themselves will have changed. Consider just how much a person changes within a few decades. Instead of a nth generation deciding to not do planetfall but stay on the ship and keep flying, the very people that boarded the ship at the origin may by that time have become so used to living on the worldship and see no need to move to a planet, either.

      The effect may not be as stark, but it will still be there.

      • Eniac November 30, 2016, 0:20

        Right. Also, I disagree with the naive assumption that a longer life makes people more patient.

      • Larry DePuy November 30, 2016, 13:49

        Helen Blau (Blau Labs Stanford) has used mRNA to activate the hTERT gene, lengthening telomeres in cells. Successive treatments add additional length. Treated skin cells replicated 40 times and remained healthy, untreated cells senesced. Calico and other groups are working on longevity, so a cure for aging should come very soon. Whether people want to remain on a ship or not, “landfall” will be necessary for ship repair, fuel and supplies, especially on earlier small interstellar craft. Although we can’t predict what humans will be like when 10,000 years of age, boredom and curiosity are unlikely to die out, and even if it does in a segment of the population, as humanity spreads through the galaxy it is bound to diversify dramatically. There will no doubt be both explorers as well as xenophobes in our future. So even if some want to stay aboard an “infinity ship” others will have settled numerous plants and evolved both naturally and through deliberate genetic manipulation. The one thing all living things have in common is a drive to expand their territory. The universe is young so competition for space, hopefully will not pose a problem. And as impossible as it may seem, NASA has released a peer reviewed paper on EM drive.

  • Douglas Loss November 23, 2016, 18:52

    Hello Paul. This post gives me a perfect spot to promote the Tennessee Valley Interstellar Workshop (https://tviw.us). The next workshop will be held in Huntsville, Alabama, October 2-6, 2017. We will be opening the request for papers and working track proposals soon, with registration to begin early in the new year. Please take a visit to our website to see what we’ve done in the past and what we’re working on for the future. But a starship in our future is very much the point of our organization.

  • Dmitry Novoseltsev November 23, 2016, 22:39
  • hiro November 23, 2016, 23:54

    More than 200 years ago most if not all emperors wanted 10-100 tons of gold; now the US & other nations want several 100 qubits universal quantum computers or the blueprint is OK too, and what one could do with those “abnormal” machines is another different questions. It seems the advanced civilization classification in the last century might not be good enough to use it as a the only yardstick for space observations, there is a big gap between the current known sciences and the boundary of physical reality, Dr. Vinge labelled it as “technological singularity” I think. Honestly speaking, colonizing every stars in the galaxy and then building Dyson Sphere around them in order to obtain that “type III” title isn’t smart all at, it sounds like an annoying child who wants to be the US President + super soccer/football/basketball/baseball/tennis/golf player + famous singer/actor-actress + next Einstein + superhero + etc….

  • Charlie November 24, 2016, 0:30

    This seems to be a quite timely article that there has supposedly just been recent confirmation that the EMdrive is now a real phenomenon, and not just an artifact or some error source that would account for its performance.
    However, I feel personally that it’s not convincing that this particular type of phenomenon violates Newton’s third law of physics. It has NEVER been shown at any time and any place that Newton’s law has failed to be satisfied, and when it has been challenged, there is always been at the last moment a saving confirmation, which had not been previously thought of or detected. I suspect that the same thing is going to happen in this particular instance.

    If I understand the operation of this particular device, it appears to work because of the fact that you have microwaves contained within a close cavity which in some fashion (as the most recent thinking has been) can alter the speed of light, with the result that you obtain some net thrust within the engine.

    However, in reading some of these reports that have appeared, I have not seen anyone make a presentation on whether or not an examination of any radiant energy being emitted by the engine while it is operating has been undertaken. For example, doesn’t it seem conceivable that if it was in operation with kilowatts of power that the walls of the apparatus would absorb some energy in the process and in turn, then radiate that energy out as some other wavelengths of photons? Wouldn’t this re-radiation of the internalized energy be EXPECTED to occur? It would seem reasonable that the walls of the engine would become in some fashion heated up and the fact that the two ends of the engine are of different size ‘MIGHT’ be sufficient to account for the Delta thrust that is seen ?

    But I haven’t seen anything concerning any types of measurements made in any wavelength whatsoever being recorded or what have you while the operation of the engine is in play. Wouldn’t an unbalanced emission of energy through the walls be a more reasonable explanation than having Newton’s law being overthrown ?

    • Paul Gilster November 24, 2016, 11:10

      Marc Millis is working with several colleagues within the Tau Zero Foundation to assess the peer reviewed paper recently published on this, so we’ll get a report down the road a bit.

    • Project Studio November 24, 2016, 19:10

      It’s official:
      NASA paper (free article):

      It is not a long or difficult read – they are not trying to optimise or explain the effect, only to demonstrate it clearly.* They have been able to characterise (and subtract) the displacement due to thermal effects, with a result on the milli-Newton scale, within a margin of error on the micro-Netwon scale. There are suggestions for how even more rigourous conditions can be applied to the experiment, but their results are convincing as they stand. I am sold.

      *There are some some musings at the end entertain the notion of virtual plasma carrying off the momentum. I personally favour the Machian explanation.

    • Robert November 25, 2016, 20:48

      What you’re proposing would just be an inefficient photon rocket. The NASA results are two orders of magnitude greater than photon propulsion.

      • Coacervate November 26, 2016, 22:32

        Robert, I’ve read that too…but microwaves are also photonic and the thrust is due to a transfer of momentum so how is this not an example of photon propulsion? I’m asking, not …stirring :)

        • Robert November 27, 2016, 13:01

          There appears to be, within the experimental margin of error, an effect that is amplified so it’s not merely the usual photon momentum coming off in some mysterious way. You could call it a form of photon propulsion but it’s enhanced. If it’s Machian, it’s likely borrowing momentum from the universe as a whole. The point is that it does not jive with the momentum one gets by tabulating the converted energy.

    • Eniac November 30, 2016, 0:35

      Even if this did work (it can’t), it would not help. Where do you get the energy to accelerate your ship to near light speed? Hint: AA batteries won’t do.

      As long as you have to take your energy source with you, energy density limitations give you something no better than the rocket equation, since you have to accelerate the power source together with the payload.

      The missions that have been proposed using a reactionless drive can be easily reduced to absurdity by calculating the energy put into the drive and comparing it with the kinetic energy of the ship at cruise velocity. Try it, look up a proposed mission, and do the calculations. What happened to energy conservation?

      • Robert November 30, 2016, 15:30

        You say it can’t work. NASA says it seems to. I would not assume the NASA scientists and all those working on EmDrive’s or equivalent thrusters are simply incompetent. This result is peer reviewed science.

        Understanding what I call the energy conundrum is certainly important but simply demanding equivalence between final kinetic energy and linearly expended energy is not a complete analysis in my view. I’ve done the analysis many times and know the apparent discrepancy. In the Machian view the momentum and thus energy, is borrowed from the universe as a whole. There are other views also. That will be sorted out eventually.

        I do not believe the EmDrive violates any laws if physics. We just need to understand its subtleties.

        • Eniac November 30, 2016, 18:06

          I fail to see the subtlety in “demanding equivalence between final kinetic energy and linearly expended energy”. It absolutely needs to be demanded, or else energy conservation goes out the window. It is not subtle, it is crystal clear.

          This will just have to be one of these (not so) rare cases where peer-reviewed science doesn’t quite cut it.

          • Robert December 1, 2016, 16:03

            A chemical rocket provides a fixed delta v for a fixed burn assuming the fuel used is small compared to the total mass. Say the delta v is 1000m/s for the argument. Now, do the burn wrt some frame the ship is at rest with and also wrt some frame moving at 10,000 m/s. Ten energy of the burn is the same. The kinetic energy gained by the ship is not. In the first case, the kinetic energy gained the ship is 1/2M 1E6 J. In the second case the gain in kinetic energy is 21 times that of the first for the same burn and thus the same energy released.
            Of course this can happen because the rocket actually borrows kinetic energy stored in its exhaust. There is no mystery.

            It can be speculated that the EmDrive does something similar, borrowing energy from some still debated source be it Mach’s Principle or some other. Thus the electrical input is like the fuel in that it has face value electrical energy plus some potential energy gained from its interaction with something and or it’s motion, just as the fuel has stored energy by virtue of its existing motion beyond its mere chemical energy.

            If an EmDrive can accelerate at all in space, there is no reason to assume it would just stop doing so if it reached some magical velocity wrt some arbitrary frame. Thus, with all due respect, I just think your analysis is incomplete and the data is showing the situation is more subtle.

            • Eniac December 1, 2016, 18:36

              If an EmDrive can accelerate at all in space, there is no reason to assume it would just stop doing so if it reached some magical velocity wrt some arbitrary frame.

              This is indeed the dilemma. If it did, that would violate relativity, and we do not want to go there.

              This is your dilemma, though, not mine. It arises from the assumption that propellantless propulsion is possible. Showing that this assumption inevitably leads to the creation of kinetic energy out of nowhere disproves the assumption by reductio ad absurdum.

              To keep holding on to your assumption in the face of this disproof, you are looking for an unspecified, “subtle” way out that allows you to conjure up energy and momentum from some mysterious omnipresent source for which there is no direct evidence whatsoever. The best candidate you come up with is Mach’s Principle. Not a bad principle, but one that has been looked at for a long time and which has been found to have no place in today’s understanding of physics. Nor has it ever been found to allow the “borrowing” of energy. It’s not really borrowing, anyway: How would they force you to give it back?

              It would be wonderful if the EM drive were possible. Not so much for star flight, but for its utility as an unlimited source of free energy. All you’d have to do is mount one on a wheel, and have it go faster than it’s break-even velocity.

              Possible? In a generous sense of the word and invoking “new physics”, perhaps. All I am saying is, I am not convinced. It would take much more than a shaky research paper teasing out a minuscule effect amongst dozens of known and unknown sources of error.

              • Robert December 2, 2016, 16:26

                I thought a lot about the free energy argument and I don’t buy it but I can’t tell you exactly why yet. Something about the frame being fixed for the observer in the starting frame or that it takes the same energy to stop it as accelerating it. My gut tells me it can’t work but the linear version can. I can’t prove that. Sorry!

                • Eniac December 3, 2016, 23:33

                  Mmmh, so you are saying that it will stop producing thrust when you put it on a curved path? How? With all due respect for your gut feeling, I need this a little more substantiated before I can consider it as an answer.

                  Does Sawyer have a better explanation? He must have been confronted with the free energy argument and it would behoove him to address it. If he can.

            • Eniac December 1, 2016, 18:49

              You correctly identify how the dilemma does not occur for real rockets, but let me just rephrase it lest someone overlooks it:

              For a rocket, energy and momentum are always conserved in all frames of reference if and only if the kinetic energy of the propellant is kept in consideration before and after it leaves the nozzle.

              Acceleration without propellant cannot be made to conserve either momentum or energy, no matter how subtle the approach. You would have to postulate something else that provides both, hence the need for the mysterious, omnipresent source.

              • Robert December 2, 2016, 13:40

                Of course we all realize the concept of propellentless only means propellent carried onboard and deployed by the ship, not that there isn’t some form of propellent available just as a ship on the ocean doesn’t need to carry propellent since it operates in a literal sea of water it reacts against.

                Consider two bodies interacting by gravitation. There is no propellent per se yet we can consider each body acts like the propellent for the other to conserve momentum.

                I do believe there is some form of propellent, I just don’t know what it is yet. Why should we be surprised?

                • Eniac December 2, 2016, 18:07

                  I suppose it is a valid theory. It just seems like a gigantic step backwards to reintroduce what amounts to the ether.

                  With an ether, it would absolutely make sense that the power/thrust ratio could be proportional to velocity. This is exactly the case for cars and trains, for example, or for the ocean ships you mention. Then, conservation of energy would be preserved.

                  However, for your interstellar mission you would be back to coping with the gigantic energy budget. What you really need is not just a passive ether, but one that also gives you free energy. To me, it seems a bit much to ask, but to others it may offer hope and comfort.

                  • Robert December 3, 2016, 16:51

                    Not an ether. I’m thinking along the lines that every frame is an equivalent center of momentum frame of the universe just as every frame sees the speed of light as c.

  • DC November 24, 2016, 2:27

    There may be no need to use more and more energy for the civilization to advance. Truly advanced civilization may go the direction of using up the available energy in a more efficient way. If this is the case, the Kardashev classification might not be correct and we will not find Dyson spheres..

  • Keith Henson November 24, 2016, 11:33

    It’s fairly easy to show in a thought experiment that a reactionless drive can make unlimited energy out of nothing. That doesn’t mean it does not work, just that it has really serious consequences for our understanding of physics.

    • Andrew Palfreyman November 24, 2016, 19:29

      Quite correct. The breakeven velocity equals the Watt/Newton figure.

      • Robert November 26, 2016, 1:55

        There is no “breakeven velocity”. The device would keep on accelerating given a constant power. Observer frames of reference are irrelevent.

        • Eniac November 30, 2016, 0:43

          Yes, but the kinetic energy of the ship would go up with the square of time, the energy put into the drive only linearly. “Break-even” is where the power put into the drive becomes less than the power provided to the ship by thrust. It implies perpetual motion, the creation of energy out of nothing.

          • Robert December 1, 2016, 16:59

            If you say it might work under breakeven, one can envision a frame in relative motion above breakeven also observing it at the same time. So it is observed to work in one but not in the other! It either works to all observers or none. Thus if it works starting from ‘rest’ according to someone, it would just work.

            • Eniac December 1, 2016, 19:00

              Right. If it can’t work for some observer, it can’t work for any. Relativity demands it. Now we have a third principle that the EM-drive breaks.

    • Mephane November 25, 2016, 6:33

      I am not so sure about that. A reactionless drive would be a device that receives for example eletrical energy as input, and produces a net thrust, plus waste heat. I am still very skeptical of the EMDrive, but maybe the waste heat is reduced by the amount of kinetic energy extracted from the device? Which would also put some limits on how fast you could accelerate – it could only ever add less kinetic energy per time than it receives as input.

    • Robert November 25, 2016, 18:47

      It’s not reactionless, it’s propellentless! I’ve had endless debates with folks that like to claim it couldn’t work, turning constant electrical power into a constant acceleration because, they say, it would violate energy conservation. I used to say that myself but now I don’t believe that (nor does prof. Woodward) and think it’s a flawed argument. As long as the input power can supply the instantaneous power to accelerate the device all is well.

      • Eniac November 30, 2016, 0:47

        Then how do you explain the mission profile where the kinetic energy of the ship ends out MUCH larger than the electrical energy fed into the drive? Or, given a mission where that not be the case, where do you suppose the ENORMOUS amounts of energy needed would come from?

  • Jer November 24, 2016, 22:15

    As glorious and inspirational as generational starships, extra-cislunar colonies, and re-seeding -or- co-seeding civilizations beyond our solar system may appear to be, I believe that this is very far from a post-Human future. As it becomes increasingly obvious that we prefer our screens to our neighbours, our online connections to our physical ones, and our immediate digital surrounds to anything natural, so will our ‘physical’ sense of community ‘change’ (i refuse to use the word deteriorate) as we ‘evolve’. So it will be how we inhabit the cosmos, plan our interactions, and choose to determine our necessary infrastructure. Kardashev scales will become increasingly meaningless even though we are spread far and wide, likely immortal, likely full of knowledge and experience, and capable of small-scale but immensely intricate technologies – from primitive sub-light speed mini pseudo-piloted craft to human data packets beaming and temporarily re-forming throughout the cosmos. Though there will be many trillions of ‘us’ across the galaxies within our Laniakea Supercluster, with our aggregate energy usage similar to a Kardashev type II, will we be a civilization as such? And if ‘others’ have gone this way, without starship fleets, without dyson spheres, and without even ‘outposts’, how could we detect or even quantify such alien systems? It may very well be that even when we have overcome space (extra-solar), time (human life span), and all that which could threaten us as a species, that we have become spread so thinly throughout the cosmos and are so immersed in our own inevitable narcissistic tendencies that our own kind becomes indistinguishable from the background technological noise of all other post-homeworld species. One may argue that this will be after the great exodus of spacefaring communities – but my point is that it will be the individuals in small, isolated, and self-contained vessels (be they sub-light ship, hollowed out asteroid chunk, or repurposed space junk) that will be the first (and only) ‘leavers’ from orbit – not convinced of the group/ community/ team as being the fundamental ‘unit’. And so the diaspora of the individuals will go – not as a ship christened and celebrated, but as escapees, lone wolf explorers, and others who seek a post-surface path. With eventual comforts, limitless knowledge, and other distractions, future singles craft will become mainstream and lead to a significant depopulation – extending the net of human experience but somehow dissolving human community. It will be a lonely yet ultimate future-proofing of human civilization.

    • Mark Zambelli November 26, 2016, 6:10

      Jer… have you read Charles Stross’ “Accelerando”? (he made it freely available to download)

    • Wojciech J November 29, 2016, 19:07

      I largely agree that this is one of more plausible scenarios.
      Still, mega-structures could happen, either as vanity projects or proof of theory.
      The elusive SETI detections that could never be probably explained are also fitting a more machine civilization/communication.

  • DCM November 25, 2016, 4:56

    Maybe a galactic civilization exists and since its effects are what we’ve always lived with we assume they’re natural.

    • Larry Kennedy November 25, 2016, 10:09

      I agree DCM. Time after time it’s proven we don”t know as much as we think. No real reason that we couldn’t be wrong about this.

  • Douglas Dwyer November 25, 2016, 11:12

    If we add up the mass of all discarded rubbish placed in orbit it may become regarded as a valuable resource. The first starship could be be built by a scrap dealer. The energy so reclaimed could be the most valuable asset. potental scrap could be designed to interlock like Lego.

  • Douglas Dwyer November 25, 2016, 11:15

    For reactionless drive we need to find a non-linearity in free space,

  • Jens Knudsen November 26, 2016, 15:40

    I have been thinking and thinking, having followed the space effort for more than three decades. Many of you have, too.

    Paul, I think you have a point where you say that future homes off the Earth might be built by humans. Looking at the only star system we know somewhat up close, our attention goes to Mars. But Mars isn’t going to become anything like another Earth very soon.

    And stars are far apart. Looking at the antimatter story, I can see that if we get the peace and the quiet to do the job, the voids will be crossed, and the stars will get visitors from the Earth. But sending lots of people on a ship that far away will be terribly risky, as they enter a star system where the most likely places to live could end up making Mars look friendly. Of course, we will send probes first, checking out the place, but… These are long shots indeed.

    We need a ‘grid’ of worlds that are more closely spaced than star systems. If there is going to be such a thing as a capable base supporting a colonization effort in a star system, it can’t be a star ship in the usual sense, no matter how it is built, because starships will have weight constraints to them.

    There is one more possibility, namely to build the worlds we need, so that we can have places to live, and sending some of them outwards, but not so fast that we would loose the emotional contact with them. They still need to be part of the human community. And there would be ships coming and going between them and us. ‘Drifting expansion’. Maybe some of them would anchor up in orbit around a moon orbiting a brown dwarf somewhere in instellar space, or deciding to settle with an object of some kind in the Oort cloud, taking up residence as an instellar gas station and repair shop. Maybe we would mount big lasers on them, and they could assist in beaming starships around, from their places far into the deep. Eventually, there would be star systems within range of ships connecting them with human built worlds, with people and resources in them.

    Which brings me to the point. Maybe we have an opportunity shaping up that hasn’t looked quite this way before. It looks to me like it is possible to use 3D printing technology to build (‘print’) big structures in space, using basically only robots, and using basically only locally available materials (asteroids, etc). The Europeans are studying a system that can build structures using the dust on the surface of the Moon – regolith. But a world must be built in space – in weightlessness, or in a very low gravity environment. I have this sensation that much of the primary structure of a large ‘place’ should be made of some kind of ‘concrete’, more like a civil engineering project than a typical aerospace project. There would be a need for materials with high strength, high melting points, glassy substances, liquids, gases and so on. But by far most of the ‘world’ would be made of ground asteroid material, somehow fused into ‘concrete’. And it must be built to last for centuries. It would not be the classic high tech project, because the weight constraints would be different. The primary structure must be immensely durable, conservatively designed, and made from resources already up there. We send the machinery.

    Is here any chance companies like 3Dspace and Planetary Resources can join forces and build some kind of a combined factory and a battery of 3D printers of sizes not quite seen before? I realize a project like this would be about one million times bigger than what they are doing at present. Being open for correction, I think something like this might be our best shot.


    • Alex Tolley November 26, 2016, 21:10

      Space resources include metals and carbon and water. These might be easy to work into metals and plastics for small printer bots to spin up a hull for such habitats. Perhaps glasses too.

      Once the hull is complete it can be pressurized for a shirtsleeves environment to complete the work by humans and robots.

      There are spider bot designs to create metal girder structures today. Adding ground based control to robots in near Earth space should allow more complex structures to be built.

      Other possibities include adapting Terrestrial building with inflatable forms, and joining the structures rather than having a monolithic hull. This might even be a safer design approach.

      I suspect the hard part is not building, but rather resource extraction and refining for use in the printer bots.

      • Jens Knudsen November 27, 2016, 17:21

        I concur.

    • Paul Gilster November 27, 2016, 12:27

      These are very interesting thoughts, Jens. I do wonder whether, rather than using 3D printing technologies (as evolved and expanded over time), we wouldn’t be better to think in terms of converting existing spaces to such uses. Hollowing out asteroids has been considered by various scientists over the years, and would seem to offer a simpler path than breaking the asteroid down first and then reconstituting it as a new habitat. Whatever the case, what you are talking about certainly does fit in with the various posts on ‘slow expansion’ that we’ve discussed here in the past.

      • Jens Knudsen November 27, 2016, 17:19

        Thank you for a constructive response. I may be wrong, but I find myself thinking that it is easier to control the physical properties of a cocoon made of ‘concrete’, than one made of carved stone?

    • Stephen November 28, 2016, 14:29

      I like your ideas Jens. My question would be just how big could such man made worlds get? My understanding is that the biggest artificial habitats would be the hypothetical bishop rings that would contain a habital area about the size of India inside (and such land would be smaller if the bishop ring had an artifical ocean). Is it possible to build a habitat bigger then a bishop ring or would that not be possible based on the physical restrictions and restrictions in the strenght of building materials?

      • Larry Kennedy November 28, 2016, 16:18

        Given a way to light the inside I don’t see any restriction on how long a cylinder could be. Cylinders could also be connected (O’Neill). The micro gravity connection would be analogous to a mountain range that organisms would need to pass.

        • Alex Tolley November 28, 2016, 17:31

          Like “The Way” in Greg Bear’s “Eon”?

          • Larry Kennedy November 28, 2016, 19:38

            lol I wasn’t thinking of quite that unrestricted .

      • Alex Tolley November 28, 2016, 16:26

        If one avoids thinking of massive, monolithic structures, like Rama or O’Neill Island 3’s, then the space can be enormous if built as connected separate rotating habitats, rather like Karl Schroeder’s “Virga” series habitats. Alternatively, build lots of different levels within a single rotating vehicle, rather like the structure in Clarke’s “3001….”. The land area could be truly immense with such designs.

        Then replicate the structures so that easy travel between them is possible, and you could potentially have areas approaching Dyson sphere values. How much Lebensraum do we need?

        Control the population and you could live as isolated as Solarians in Asimov’s “The Naked Sun”.

      • Jens Knudsen November 28, 2016, 16:43

        Hi Stephen. I just had a look at the bishop ring. Important question, and it can be studied – the right people could put some numbers on this one. They would have to be rather big. My question is if it is possible to use robotic/remote controlled machinery to build a ‘world’ using additive manufacturing – like a good sized ‘3D printer’ that can print out very big structures. It is too costly to build things in space. But can we build machines that can build things?

        I think in terms of something smaller than the bishop ring for a start, as it requires the use of almost exotic construction materials. But is it possible to use steel? What are asteroids made of? Can we use it?

        • Eniac November 30, 2016, 10:10

          I believe there are asteroids made of iron/nickel, perfect for steel, and others mostly of silicates, perfect for glass and ceramics. Carbonaceous asteroids could provide plastics, but I think carbon is in relatively short supply compared to silicate and iron. Glass and steel are favorite building materials in these modern times, so I think there is, in principle, a wonderful match between asteroidal resources and need for building materials.

      • Eniac November 30, 2016, 1:15

        There is another way space settlements can be built, and grow organically: Start out with two cylinders tethered to and rotating around a central hub. Each cylinder would be built as a multistory building, like high-rises on Earth. Then, add more buildings hanging in different directions from the same hub. Then extend the hub sideways along its axis to add even more buildings. Keep doing so indefinitely.

        These would NOT look like monolithic cylinders with an enormous air-filled space inside and farms and fields at the rim, rather they would look like cylindrical cities with skyscrapers reaching outwards (or “down”). They would be far more economical in air-mass, area and energy than the O’Neill dream structures. Way more practical, all around, and very easy to build and grow. And, most importantly, much, much safer.

        No countryside, sorry, no lakes and streams, but that really was an enormous waste of resources, anyway. Time to embrace city life, as many already do here on Earth.

    • Jens Knudsen December 1, 2016, 20:29

      Hmm… Look at this one. Frame #12, and several others: https://deepspaceindustries.com/media/gallery/ These people are designing the systems we need.

      There are a few ideas out there. If I am getting this right, ‘going to the stars’ entails at least two very different scenarios. It is one thing sending probes there, or, for that matter, sending human visitors there. But if we talk about settling a moon or a planet, ‘visiting’ is not the idea. So we talk in terms of starships that are accelerated up to, say, 10% of the speed of light, which is a horrendously high speed. And then they need to slow down when getting there, and their supplies have to last until the on board community can harness local resources. And still, a one way trip will easily take generations.

      Some think in terms of building bigger ships going at slower speeds, in which case the transits will take centuries. So, in one sense, we do not talk about a ‘ship’ anymore. Of course, something that might work, is to send the occupants in hibernation, but presently, we don’t know how to do it. So if we send ‘live’ people to a star system, in a well equipped vessel, we talk about a ship which will be the only place their children and grandchildren ever knew. It will be their home. They go to work. They raise families. There are cemeteries there. It’s their world. If such a vehicle is built with speed as a design driver, it will drive down the size of the section of the ship where people live. But they need space! It will also constitute an incentive to save weight wherever possible, and design margins will be a major consideration, and we are talking about a structure that must last almost indefinitely, and about a vehicle that must bring with it an abundance of supplies no matter what happens when it gets there. It will weigh several million tons, and be maneuverable, and even reasonably fast. It could end up needing millions of tons of just fusion fuel.

      I don’t see how we can fit both functions – 1), requirement for a high speed transit, and, 2), space and capacity for a robustly self contained, sound, reasonably high tech community – into one vehicle.

      There is no question we will need fast ships. But with any ship that can be considered ‘fast’ in this context, the propulsion systems are bound to be a major part. We might be able to build ‘racing cars’. We can’t build ‘trucks’. We need trucks. What do we do?

      So I ask if it is feasible to build worlds, and settle into places that are not so extremely far away, only, say, a little bit extremely far away? A world orbiting planet 9? Or one that is on an escape trajectory, but not beyond visiting? There have been design studies made regarding ‘world ships’ that would in one sense fall into this class. They are self contained worlds moving from one star system to the next. But they are enormous, say, 200 billion tons + fuel. We can’t do it right now.

      What can we do with what we have? A ‘small’ space colony with some means of propulsion, and volume for a good sized, healthy community, sufficient shielding to make it safe to live in, and a storage/industrial area so stuffed with resources and equipment that physical lack would not be an issue, and an almost completely ‘passive’ design that would permit life to go on almost no matter what might go wrong. Inherently safe. A place to visit if we get in trouble too far from home. A world so permanent we could put it on a star map. Yes, something like that.

  • randomengineer November 27, 2016, 12:00

    Doesn’t the notion of generational starships assume that humans are self-contained entities? Given that we eat probiotic yogurt for the flora this suggests that humans require a few million symbiotes; we are not so much as self-contained in that case as collaborative. One wonders if we understand biology and such well enough to survive: say 1.5 generations into the project the gut flora we started with evolve to something harmful. How do we know, how do we fix that? How do we catalogue all possible flora well enough to ensure survival? I don’t know, but it seems to me that we could well be trapped on the planet if for no other reason than evolutionary scale and control of our symbiotes. i.e. assume nature on earth has a way of keeping flora from going off the rails due to constant change via evolutionary pressures; remove these trillions of flora from the ecosystem and said flora may ‘mis’-evolve in a closed environment in a way detrimental to us.

    I know nothing about this subject. Nor do I pretend such. So my comment is more of a question: is anyone seriously studying this sort of thing? Do we actually *know* anything? If so, how do we know it?

    • JohnHunt November 27, 2016, 17:45

      That’s a pretty good question that I haven’t heard anyone else discuss. Space radiation is controllable with enough mass. It is the reduced gravity that could negatively affect the selection of gut bacteria. We might be able to get a somewhat quicker insight into that with centrifuge studies with animals with a shorter lifespan. If it turns out that this a real problem then we would need to become O’neillians. So it wouldn’t be a complete show-stopper.

    • DCM November 27, 2016, 17:56

      Such a ship would need to spend a long time nearby its home planet, exchanging life and taking on different plants and animals, offloading them, and so forth, to build up the biosphere.

    • Eniac November 30, 2016, 18:29

      There is really no reason to think that gut flora depends on some “mysterious factor” that would be absent on a ship but universally present on Earth. Due to their size, bacteria generally do not feel gravity at all, so that would not be it.

      Also, germ-free mice survive with minor problems, without any gut flora (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1500832/#__sec2title).

  • JohnHunt November 27, 2016, 17:41

    I don’t find the Kardeshev Scale to be particularly useful. I would anticipate that we will be able to beam a probe to Alpha Centauri well before we are using all of the power on a planetary scale. By the time it reaches there, we might have the technology to beam probes faster and farther and be able to have the probe replicate the technology at destination and send probes from there further on. Or, the probes would be able to self-maintain / regenerate thereby allowing for us to bypass the need to replicate at destination and beam directly from Earth/Moon further. The power necessary to send nano-designed craft is well within our current power production. It’s the spacecraft and beaming technology that lags. Also, a civilization could become more efficient with its power use and so begin to decrease the amount of it that it harvests.

  • Jim Franklin November 27, 2016, 18:03

    Whilst I applaud the idea of seeking to discover and investigate possible atmospheres on extra-solar worlds the problem with making assumptions about what any such atmosphere may mean for the implications of life is fraught with problems.

    It is highly likely that nature has found a way to create life in a wide variety of environments and out basic assumptions are incorrect. Further, life may exist in places where there is no atmosphere or where the atmosphere could be toxic, underneath a frozen surface in a sub-surface ocean and tectonic activity to provide a source a energy, as is suspected with several moons in the solar system.

    Clearly we need to start somewhere, and clearly we need to set some criteria as a baseline, but the baseline must be a moving target, one that changes as our knowledge and understanding increases.

    I think it highly probable that we are on the cusp of finding life in places that only 5 years ago would have been dismissed, and even now I fear many would simply be dismissed by the closes minded and myopic.

  • J. Jason Wentworth November 30, 2016, 10:05

    Jim Franklin, I agree with you. We are not even 100% certain that the Moon is lifeless. In addition to the luminous and local feature-obscuring TLP (Transient Lunar Phenomena) that have been observed, other phenomena which suggest the growth of vegetation–such as dark patches that appear, change size, and change location throughout the long lunar day–have been observed for centuries, particularly in and around the craters Eratosthenes and Aristarchus, on the rays from the crater Tycho, and around the Herodotus Valley. Also:

    Both Arthur C. Clarke and Patrick Moore–decades before the polar ice deposits were found on the Moon (or indeed, even hypothesized)–suggested that lunar plants might be responsible for these variable markings (Clarke even described a possible living analog on Earth, the African “Window Plant,” a cactus with a wholly-sealed body that lives in ultra-arid areas). In addition:

    Clarke also pointed out odd optical properties of some lunar mountain peaks, which shine dazzlingly bright only when first illuminated by the rays of the rising Sun, as if they were made of mirror-type material instead of rock, the temporary nature of their high reflectivity suggesting that they might be capped with temporary deposits of ice. If water was driven into the soil of these peaks from impacts of comets and/or water-bearing asteroids, it may be possible that water–in the form of ice and/or hydrated minerals–is more common at/near the lunar surface (and perhaps in spots away from the polar regions) than has been suspected. If so, this would improve the prospects for native or aboriginal (perhaps originally arriving as terrestrial microbes “riding” meteoroids splashed out of Earth impact craters) lunar plant life (the same could also apply to Mars).

    • Alex Tolley November 30, 2016, 13:31

      Despite depictions of life forms in SciFi movies and books, life must be part of complex biospheres, even bacterial-only ones. Clarke’s cacti could not be a life form on its own on te moon. While we cannot rule out life deep underground, core samples taken by the Apollo missions ruled out bacterial life in these samples.

      Maybe if we drilled down a kilometer we might find life in the lithosphere. That potential discovery will have to wait for a lunar mining operation or colony.

      • ljk November 30, 2016, 17:56

        I wonder if something could survive in all those lunar ice deposits?



        In the late 1950s there was a US plan to detonate a nuclear bomb on the Moon as a show of Cold War strength towards the USSR. The Soviets also had a similar plan. Both cancelled their respective lunar nuke projects. However, one of the hopes from such an explosion was that material from deep within the Moon would be excavated and sent flying out into space, where it could be examined at least remotely for the presence of any microorganisms present. Carl Sagan was on the science team for this project.


        • Alex Tolley November 30, 2016, 21:56

          The moon’s core is fairly hot, so there must be regions between the core and the surface where there are fairly constant, warm temperatures for bacteria to survive. The recent discovery of water at extreme depths in the Earth give some encouragement to me that interstitial water may also exist in the lunar crust, which would allow lithophilic bacteria to live. That latter speculation depends on whether water can be retained or whether the moon has completely dried out as it has over most of its surface. Just possibly, the presence of ice in the shadowed poles might allow water to be found at depth too. I would certainly like to see some attempt to look for such life as part of the search for life in the universe. If it is there, I would expect a common genesis with Earth [Mars?] life but with considerable evolutionary divergence.

        • J. Jason Wentworth December 1, 2016, 9:28

          That’s fascinating–thank you for posting those links! Even if those slowly-formed (by cosmic and solar radiation) organic molecules in the lunar and hermian (on Mercury) polar ice deposits don’t eventually become living cells, those organic molecules might serve as food for aboriginal microbes that arrived from Earth, in meteoroids. Also:

          The orbital dynamics for such terrestrial impact ejecta reaching the Moon, Venus (where microbes in the atmosphere are possible–there are sulfuric acid-loving Earth bacteria), and Mars are pretty straightforward. Such “crater-splashed” rock getting inward to Mercury from Earth seems a bit of a stretch, but the proper gravity-assist encounters with Venus–and/or the Yarkovsky Effect of anisotropic thermal photon emission thrust from rotating meteoroids (which might be stronger closer to the Sun) could deliver microbe-bearing meteoroids to Mercury.

      • J. Jason Wentworth December 1, 2016, 8:26

        Complex biospheres are not required for life to exist (although they make it much easier, of course). At one time on Earth, there was almost certainly only one living micro-organism, and for a long time thereafter probably the only life on Earth consisted of its species. Also:

        Arthur C. Clarke–who did not write about such lunar plants only in his fiction, but mostly in his non-fiction works such as “The Exploration of Space” (1951) and “The Promise of Space” (1968), although he did mention them in a mid-1950s lunar tourism speculative article (“Journey by Earthlight”) for “Holiday” magazine–also pointed out that there are bacteria which have partly replaced the carbon in their bodies with sulfur, and they can live happily in boiling sulfuric acid. Other bacteria oxidize metals and minerals as food, and need no other “biosphere” than those very basic constituents of terrestrial-type planet and satellite crusts (plus adequate warmth–their required temperature ranges are quite wide) in order to live and reproduce. In addition:

        The African Window Plant-like cacti that Clarke posited would not be, if they exist on the Moon, “low” or primitive; in fact, they would almost have to be the exact opposite–highly-advanced and specialized descendants of long-dead unspecialized forms–in order to live in such unfavorable conditions.

        The lunar plants, as he described them (biologists have “designed” various plausible forms of lunar flora), would be tall and slender and have tough, gas-tight, impermeable skins, with “windows” of horny material in their upper parts to admit sunlight for photosynthesis. Systems of pores and internal tubes, acting as virtual air compressors, would absorb traces of carbon dioxide, sulfur dioxide, and possibly water vapor that issue from clefts and craters where short-lived mists and other types of TLP (Transient Lunar Phenomena) are observed. (Patrick Moore suggested that any lunar plants–particularly in the Tycho ray regions that strangely change appearance as if plants are pushing up through the surface during the lunar day–might be more squat in form, perhaps somewhat resembling lichens or arctic flowers.) As well:

        I am *not* saying that there is *any* life on the Moon, either native or aboriginal. I’m just saying that even the severe lunar conditions do not rule out the possibility of life there, of which the odd variable lunar markings could possibly be signs. Since–to my knowledge–none of those craters, clefts, or crater ray regions (where the variable markings occur) have yet been explored by astronauts or by robotic landers or rovers, the question of life in those areas remains open, although I personally would not bet a large sum on life being present there (or anywhere on the Moon). But even if lunar vegetation is not the cause of those variable, slowly-shifting surface markings, what *is* the cause behind them would be nearly as interesting to find out.

        • Alex Tolley December 1, 2016, 14:14

          Complex biospheres are not required for life to exist

          Biospheres are the result of evolution. Look outside and see if you can find any natural area where there are just 1 species. Never occurs. That is because life doesn’t appear fully evolved, but keeps spawning new species to fill niches, often niches produced by other life. Clarke’s cacti, as he wrote about them in fiction, were single species living on their own without other accompanying life forms. Even those rare, extreme environments are not populated by just one [bacterial/archaean] species, but many. Those cacti would have evolved from an ancestral forms, many of which also evolved different approaches to surviving on the moon.

          If I were to look for life on the moon, my first option would be to look in ancient, sealed lava tubes or caves, where life might have clung on in small ecosystems that are discoverable with relatively simple instruments and tools. My 2nd option would be to drill deep into the lithosphere to recover cores that have signs of water and which might contain unicellular life between the rock grains. Even in this case, I would expect to recover organisms with different genomes living in proximity to each other.

          • J. Jason Wentworth December 2, 2016, 4:39

            What you mention about biospheres may be–as Carl Sagan sometimes liked to say–an “Earth chauvanism,” fostered by our world’s unusually-friendly-to-life environs on and even below most of its surface. In a harsher place, there is no reason why one life form that manages to hang on through a lucky adaptation has to have relatives (or competitors) living with it, particularly if the adaptation allows it to utilize ordinary minerals or metals for food; as a harsh place grows harsher, it can squeeze out all but the very hardiest type of organism. Also:

            Clarke also suggested that favorable micro-climates might exist just below the lunar surface in sealed caverns and/or near some craters.

            • Alex Tolley December 2, 2016, 12:31

              In a harsher place, there is no reason why one life form that manages to hang on through a lucky adaptation has to have relatives (or competitors) living with it

              It is hard enough to try to do that in a lab. It is extremely improbable in a natural setting. What you don’t appear to realize is that the interconnectedness of organisms essentially prevents this. For such an ecosystem, food and wastes would only be disposed and recreated on geological times scales, rather than biological. Or the organism would have to be both autotroph and heterotroph. That would conflict with the Darwinian replication model. A single species would have to be a total breeding population with no scope for further evolution, so evolution would effectively stop. But if that were true, how could the organism even have reached this fitness landscape pinnacle, and how unlikely that we just happen to find it at that “end of evolution” state.

              I find the idea extremely unlikely. Food for a hypothetical thought experiment perhaps, but not a state we would find.

              • Eniac December 2, 2016, 20:19

                It is quite possible that only a very specialized lifeform occurs in a harsh ecosystem. Still, speciation will happen and there will eventually be many similar lifeforms sharing those properties that are essential.
                On Earth, having proteins and DNA has become the norm, there aren’t any other forms of life left over from the RNA world. Not even any rival genetic codes (besides small differences). So we have a “single-species” specialisation here, despite the great variety in other respects.
                On the moon’s surface, single celled life is impossible, because of the vacuum. Some form of cactus, on the other hand, may well be viable. So it is entirely plausible to find an ecosystem that is all cactus, but there will still be different species of cactus, I would expect. Plus, parasites and pathogens that like cactus.

              • Eniac December 2, 2016, 20:24

                Critically, I think Jason is right. An ecosystem does not need to be diverse. A cactus autotroph (plus relatives) could thrive all by itself, with no single-celled organism present at all.
                It would, of course, have had single-celled ancestors, but those could all be long gone, on account of the lack of liquid water.

                • Alex Tolley December 3, 2016, 0:22

                  Think about it for a moment. Ab autotrophic cactus needs to harness sunlight and using various elements grow and reproduce. Without biological recycling, where are these elements going to come from? Physical processes are all that is left, but they tend to be slow in comparison, because biology uses enzymes to speed chemical reactions. The cactus grows reproduces and dies. But without metabolism, it will not decay on biological timetables, so its carbon will accumulate (as happened with carboniferous lignin until fungi evolved to digest it). This simple case shows why ecosystems cannot be single species. There must be complementary species to recycle the materials. Single species might last for a while until the resources are used up, but then they will go extinct. Biospheres cannot function like that. Apply evolutionary pressures that drive speciation, and a biosphere should be rich in species. Parts of the biosphere may be poorly inhabited, e.g. a desert, but those desert species require the ecosystem services of species outside the immediate ecosystem. Which is why I stated that these isolated cacti of Clarke’s idea couldn’t exist in isolation. There must be supporting organisms, even if just bacteria in te immediate vicinity. Elsewhere on te moon would have to be richer ecosystems, which of course would be more easily discovered.

                  Pocket ecosystems, like pocket utopias, may exist for quite some time, although I wonder how long a completely isolated system can last. Without some external energy input they will eventually run down. Slow infusion of chemical energy in reduced carbons might sustain such isolated ecosystems for geological time periods, as long as wastes can also be dispersed. Are there any examples that exist on Earth? (Even those weed and shrimp toy ecosystems in sealed glass bulbs run down eventually.)

                  • Eniac December 3, 2016, 14:26

                    I am not talking isolated, here. Obviously, the cacti would be needing water and carbon and sunlight, plus some minerals, which would need to be supplied by the regolith. Now, the moon has very little carbon, so the lunar cacti would probably have to be silicon-based lifeforms to actually exist, and we do not know how plausible that is.

                    Nevertheless, an autotroph by definition can survive on its environment alone, without the need for other organisms. Recycling can still happen, as dead cactus become part of that environment.

                    • Alex Tolley December 3, 2016, 19:46

                      It can survive for a while, but not for a long period. The plant cannot break down back to the constituents and recycle them. Even trivially, if the cellulose degrades under the sun, it will become water and carbon dioxide, both of which will escape. Or the cellulose will just dry out and become unusable for the offspring. These cacti are presumed to evolve from simpler forms, so they must have been present on the moon for at least millions, if not tens of millions of years. Without a supporting biosphere, this cannot happen.

                      Clarke’s cacti were engineered by the Russian, Surov, (“Green Fingers” short story, from the set of stories in “Venture to the Moon”). As such, his plants were a short term experiment, and therefore they are improbably but not impossible constructs. But as natural, evolved organisms that would need other ecosystem services, that is not possible IMO, for the reasons I have already given. I trust we are not arguing as cross purposes here. Engineered life that is supported by artificial means, like farming, is very different from life that evolves.

                    • Eniac December 6, 2016, 1:34

                      The cacti could easily evolve to thrive on both minerals and dead cacti. With the proper enzymes to break down whatever is the “cellulose” equivalent for the Lunar cacti. The presence of bacteria makes Earth based life forms lazy, they leave a lot of the hard work to others. But there is no reason a single autotroph life form could not do it all by itself. Think cyanobacteria, I think they do just fine without other organisms around.

                      The problem of escaping nutrients exists for any ecosystem, single or multiple species alike. There has to be an inexhaustible source of nutrients. On Earth, Water, CO2, and sunlight as the primary nutrients are all for practical purposes inexhaustible, although CO2 is rare and indeed limits the amount of biomass that can grow. Interestingly, microorganisms are not required to recycle the carbon. Fire can do it, too.

                      For silicon-based lunar cacti, silicates and light would be inexhaustible, and water would be the limiting factor. The cacti would only thrive in the shadowed craters at the pole where water accumulates from space. Oh, wait, but then there would be no light. Mmmh, I guess not much chance for these particular cacti, unless they can do without water. Or they grow tall, with one part in the light and one part in the ice. A shining example of multicellular organisms that can thrive where single cells can’t.

                    • Alex Tolley December 6, 2016, 12:29

                      With the proper enzymes to break down whatever is the “cellulose” equivalent for the Lunar cacti.

                      This is energetically inefficient. Free-riders would live off the those that evolved the enzymes and out compete them.

                      Think cyanobacteria, I think they do just fine without other organisms around.

                      AFAIK cyanobacteria do not feed off others. Therefore there must be some separate breakdown mechanism, e.g. heterotrophic bacteria. Otherwise they will just become fossil carbon deposits.

                      Interestingly, microorganisms are not required to recycle the carbon. Fire can do it, too.

                      In water? Fossil coal beds are proof that fire is insufficient. The O2 level has to remain high enough, or fires can be maintained. Fires can only be effective on terrestrial carbon, not aquatic. Therefore aquatic environments will become carbon sinks either by direct laying down of dead organisms, or by absorbing and precipitating carbon dioxide from the carbon liberated by the fires. In addition to carbon, you need N & P recycling. On Earth, nitrogen is primarily fixed from the atmosphere by bacteria. P recycling is more complex.

                      For silicon-based lunar cacti

                      Now you are invoking an even more speculative biology. There is plenty of evidence why silicon is not a suitable substrate for biology, even as silicones, rather than as silicon compounds.

                      Nevertheless, an autotroph by definition can survive on its environment alone, without the need for other organisms.

                      That is not the definition of an autotroph.

                      Definition: “A organism capable of making nutritive organic molecules from inorganic sources via photosynthesis”

                      This says nothing about not needing assistance from other organisms to support this process.

                    • Alex Tolley December 6, 2016, 21:51

                      Hmmm. It appears engineered bacteria can be coaxed into making organo-silicon compounds. Maybe not biologically useful, but interesting all the same.


                    • Eniac December 7, 2016, 0:20

                      The enzymes evolve under the pressure of depletion of primary resources, so the cacti who did not have them would starve, far from getting a free ride.

                      Fire works only on land. What do you mean sufficient? Fossil coal beds are recycled in a different way, through subduction and eventual volcanism. Also no organisms needed for that, and it works for the ocean, too. There may be other inorganic ways to recycle carbon from biomass to CO2. The point is that the carbon is not going away, and organisms are not required for recycling it. The same goes for nitrogen, phosphor and any other primary resource.

                      Some cyanobacteria can fix atmospheric nitrogen, interesting news to me.

        • Eniac December 2, 2016, 20:36

          At one time on Earth, there was almost certainly only one living micro-organism, and for a long time thereafter probably the only life on Earth consisted of its species.

          I believe this is incorrect. There was never just one species.

          • Larry DePuy December 4, 2016, 21:21

            So what are you saying? That multiple separate species of life evolved simultaneously?

            • Alex Tolley December 5, 2016, 12:18

              Our phylogenetic tree constructs assume a single common ancestor. This assumes a unique genesis. This is not certain at all. There may have been a number of early life/pre-life forms that competed. Even the “winning” form would have quickly evolved variations and effectively speciated.

              Consider human evolution. We usually think of it as a tree, with Neanderthals and modern humans having a common ancestor. However, we know that we posses abot 2-4% of Neanderthal genes, most likely by interbreeding. So the model is not as tree-like as we represent it.

              The idea of a last universal common ancestor (LUCA) is a construct, based on our model, possibly even with a touch of religious overtone, but the reality is probably a lot fuzzier.

            • Eniac December 6, 2016, 19:32

              No, I am saying that at any time during evolution, there were always a variety of species around. Even during abiogenesis there were probably several related “hyper cycles” (or whatever there was then) evolving in parallel. Later, all but one of these lines died out.

              Much, much later, there lived a last universal common ancestor (LUCA), a single species that all currently existing species descends from. However, it was not the only species living at the time. There were many others around it, all of which died out some time between then and now. LUCA was very evolved already, it had DNA and proteins, and a long line of ancestors that went before it. Most of it’s sister species would have been similar, but some might have been very different and outright weird. Because no descendants remain of the others (by definition of LUCA), we will never know what they were like.

  • ljk November 30, 2016, 18:27

    Pausing Life: Mouse Embryos Placed in Suspended Animation Can Survive for Weeks

    Scientists have developed a means of making suspended animation possible by using a protein inhibitor.

    This has far reaching implications for many fields, one such moonshot is the ability to “freeze” cancer cells to stop them from grown.

    Full article here:


    Sadly, the article does not mention the possibility for “freezing” the passengers and crew of a future interstellar vessel in case we can only do STL propulsion. However, the upcoming science fiction film Passengers is focused around this very topic, so fear not:


    • Alex Tolley November 30, 2016, 22:01

      I don’t see how that technique is going to work with whole organisms with brains. The experiment was done on embryos at the bastocyst stage, not even fully functioning organs, let alone animals.

      • ljk December 1, 2016, 10:33

        This is perhaps why it is more efficient that an interstellar vessel be entirely automated. Humans going to the stars would only be for colonization purposes, assuming such things are even required by the time we are able to launch such a starship.

        Of course none of this stops, say, a wealthy individual or group from making the attempt in a form of WorldShip just the same.

    • J. Jason Wentworth December 1, 2016, 10:32

      Thank you for posting the links to the article–and to the upcoming movie! Now:

      This unexpected protein inhibitor method for achieving stasis (suspended animation) might, one day, make possible the “Type II Suspended Animation Starship,” in which only fertilized ova and/or embryos would be sent, instead of–as in a Type I ship of this kind–adult people (and other adult organisms) who would be in stasis by means of drugs, low temperatures, or other techniques. Also:

      Suspended animation starflight (using either Type I or Type II starships, and particularly the latter) would be a relatively inexpensive and easy (as compared with relativistic-velocity starships) to spread Earth life far and wide. I freely admit, though, that the moral implications of doing this–unless our Sun was about to go nova, or the Earth was soon to become sterile for some other reason–make me cringe! But:

      Type II suspended animation (involving adult crew members) might be practical for long voyages *within* the solar system, enabling smaller and slower spaceships to travel to and from the outer solar system (and the Kuiper Belt) using chemical rocket (“thrust and then coast”) propulsion with minimum-energy Hohmann transfer orbits, or electrical propulsion with spiraling orbits. (Even solar sail spaceships could be used, with spiraling orbits. As Dr. Louis Friedman pointed out in his book, “Solar Sails and Interstellar Travel,” solar sail propulsion is practical even as far out as Saturn, although the acceleration rates are pretty low in that relative gloom. He also covered an earlier-proposed solar sail-driven manned Mars expedition, whose ships’ round-trip duration was comparable to that of chemical propulsion spaceships.) Plus:

      A reliable suspended animation system (it would have back-up systems and “emergency awakening” systems to facilitate quick repair by the crew in case of malfunctions [or other problems with the ship, of course]!) would greatly simplify the radiation shielding, life support, and food & water storage systems’ requirements for deep-space interplanetary spaceships, in addition to making the use of lower-powered propulsion systems practical. In addition:

      Experience using such suspended animation systems for interplanetary travel would result in continual improvements and refinements in them, which should eventually make practical Type I systems that could be used, with confidence, by the crews of suspended animation starships.

    • Eniac December 2, 2016, 20:33

      Embryos are routinely frozen and revived. This article talks about arresting cell division temporarily, without any actual freezing. Totally different thing, only arrests growth, not metabolism, and is unlikely to be useful for cryo-preservation.

  • Micky Badgero December 1, 2016, 16:31

    The whole concept of Kardashev levels of civilization seems flawed. If the Kardashev civilization level are ‘inevitable’, does that mean that eventually only humans and the plants they eat will exist on Earth? Or only humans and synthetic foods? We do not utilize 100% of the energy available on Earth, in part, because it is utilized by other species, and in part because we have not, and may never, figured out how to utilize energy with 100% efficiency.

    • J. Jason Wentworth December 2, 2016, 4:57

      I have a philosophical objection (a partial one, anyway) to the Kardashev “civilization scale,” although I see the scientific reason why he formulated it thus:

      Using more and more energy does not necessarily indicate a greater level of civilization (although it makes societies increasingly easy to detect at greater and greater distances). Using increasing amounts of energy is an index of cleverness, but cleverness and intelligence are not at all the same thing. Humanity was clever enough to invent gunpowder, the rocket, the gun, the airplane, nuclear bombs, and many other things, but their uses of these things do not–in great part–suggest intelligence or a growing level of civilization. The Amish and the Conibo Indians are more civilized than many if not most of their modern technology-wielding counterparts, but their presence isn’t detectable even as close by as the Moon.

  • Charley December 1, 2016, 20:07

    The problems that I see that I keep coming back to for the purposes of future starships is the fact that any common mechanism that we can build is going to have tremendous amounts of flaws in it from the standpoint that there is going to be a tremendous amount of unexpected environmental challenges that a spaceship will have to face.

    A case in point is the recent announcement by Jet Propulsion Laboratory of the creation of metallic glasses that are going to be formed into gears that don’t require anything such as lubricants to allow them to operate various mechanisms. The people who developed these type of metallic glasses that they plan to use in gear trains for planetary explorers is the fact that such mechanisms do not have to use energy to heat up lubricants to allow them to flow on gears that are used in the robotic mechanism, thus saving energy is the benefit they point to.

    Now multiply such a development with practically an infinite number of unknowns that will face both people and the mechanisms they take with them in going to other stellar systems and expect these systems to operate in the face of such environmental dirt and dust, noxious vapors, as well as a whole host of other toxic externalized problems and you wonder how ANY system could ever be devised that will be able to handle what’s thrown at it. These machines may of course possibly be repaired from time to time, but they may be also of such a nature in which repair may have to be carefully metered out to permit timely revamping of the mechanism.

    In the case of the moon voyages, spacesuits worn by the astronauts on the moon began to almost INSTANTLY began to abrade the spacesuit surfaces by the sharp and almost glasslike particles that made up the moon’s dust. The moon dust worked its way into the fabric and into the joints of the spacesuit and had they stayed even a little bit longer. They might have had a spacesuit worn through and exposed the occupants to the vacuum of space. And that’s just with regards to our nearest neighbor ! How much more alien will other star systems be with regards to our materials and what can we do to meet the challenges. None of these interstellar voyages are in any way shape or form going to be simple as depicted in these movies, and I imagine that we are in for some very unpleasant surprises when we go.

  • Jens Knudsen December 2, 2016, 12:22

    Phycisist Gerald Jackson just got his kickstarter effort funded for continuing work on the design of an antimatter production facility. He says an antimatter fueled thruster can propel a probe to Proxima b at 5% of the speed of light, and decelerate it into orbit there with a total transit time of 90 years. It might be worth it. Preparing for the unknown is, of course, not completely possible, but if we do our homework, odds will improve. I realize this is not the hole picture.

  • Jens Knudsen December 3, 2016, 10:05

    Hm.. Informative.

  • ljk December 5, 2016, 15:49

    A note on the possible impending death of human space exploration

    As NASA continues to efforts to eventually send humans to Mars, studies are showing a wide range of health issues that long-duration spaceflight poses to astronauts. Roger Handberg wonders of those issues, and the increasing capabilities of robotic spacecraft, may close the window on human spaceflight.

    Monday, December 5, 2016


    • Eniac December 6, 2016, 10:11

      What I learned from this article is that zero gravity is a solved problem, that and that the conclusion is that artificial gravity is not needed. Health effects can be controlled well by exercise. Also, that observed effects on vision are not known to be from low-gravity, but are alternatively suspected to be from high CO2 instead. It turns out the air aboard the ISS has ten times the CO2 level of normal air.

      Much of this, actually, I learned from this other articles cited in that one: http://www.thespacereview.com/article/3094/1

      Besides all that, it is obvious that humans can survive long space voyages, because many have done so.

      • ljk December 7, 2016, 11:56

        The longest any single human being has stayed in space so far is 437.7 days by cosmonaut Valeri Polyakov:


        That wouldn’t even get us to Mars one way. We – meaning NASA – have yet to really get beyond the early days of the Space Age where highly trained astronauts and cosmonauts spent relatively brief times in the Final Frontier – the vast majority staying in Low Earth Orbit – conducting controlled experiments and such. We have yet to establish one real space colony either circling Earth or on another world, let alone see what happens when couples and families start spending years in space and reproduce.

        I recommend this online NASA book which I reviewed a while back. As you will see, NASA and the Russians did not even really start sharing data on human physiology in space until the 1990s, even though both nations had space stations since the early 1970s and been placing humans in orbit since 1961:


        Exercise may combat microgravity conditions on the human body, but as we see every day on this planet, not everyone exercises regularly, even if it is good for them or necessary. I do not expect people to change too much even in space once they are on really long-duration missions or colonization efforts, especially the ones not sponsored by a government space agency.

        Of course this won’t stop people from sending other people into space any time soon, if ever, but let us not pretend we have solved all the issues of living beyond Earth when we have barely done so even after five decades. Machines are still better and cheaper at exploring space and they are only becoming more efficient all the time.

        • Jens Knudsen December 8, 2016, 15:25

          We need a different kind of ‘staying’, or ‘living’ in space. The high tech story we are seeing at present is necessary, but it can’t give us ‘homes’ away from Earth. High tech and high performance is delicate. We need rugged vessels, or habitats, where life is reasonably uncomplicated – and then use some high tech when we need to do some ‘stunts’.

  • Douglas Dwyer December 6, 2016, 8:33

    “prime directive.”
    Exists because we do.
    The same would apply to any evolved intelligence that by definition would randomly develop within any niche i.e appear to search for such a niche..
    We can assist this natural process by designing simple rugged life forms and seeding our neighbourhood.
    Inevitably Robot vehicles will assist in the process. Every time a vehicle incorporating a human is destroyed by impact on a surface this will still be part of the process.

  • ljk December 30, 2016, 14:44

    Of course the most interesting and plausible “stars” of the new science fiction film about interstellar travel, Passengers, are the robot and the vessel itself:


  • ljk January 3, 2017, 16:05

    We need “people person” astronauts for future manned deep space missions:


    To quote:

    “In the early days of space exploration, it really was important to just have the ‘right stuff.’ If you don’t get along very well with people, you can suck it up for a couple weeks,” says Doug Vakoch, the president of Messaging Extraterrestrial Intelligence International, a nonprofit research institute and author of Psychology of Space Exploration: Contemporary Research in Historical Perspective. “But when you’re talking about a mission that’s going to last for a year, and you don’t have a safe way to vent, thats going to be a big problem.”