The serious study of flight to the stars is a comparatively recent phenomenon. One of the early papers to take interstellar travel to a new level — and to my knowledge the first technical article on manned interstellar missions — was Leslie Shepherd’s ‘Interstellar Flight,’ which appeared in the Journal of the British Interplanetary Society in 1952. These days we all tinker with sociology and psychology, musing about what drives a society spaceward, but Shepherd, a British physicist and one of the godfathers of today’s interstellar work, thought the reasons were obvious. We’ll go to the stars out of scientific curiosity and the pure love of adventure.
Thus the view from a somewhat more optimistic 1952, at least where space was concerned. It was an era when what seemed possible far outweighed the budgetary and political concerns that would silence efforts like Project Orion and, eventually, Apollo itself. But Shepherd, who at the time he wrote the paper was technical director for the BIS, recognized other motives as well, including the need to communicate with the other species he assumed must inhabit other star systems, and the imperative to disperse humankind over many worlds to ensure its survival.
Image: The April, 1953 issue of Hugo Gernsback’s Science Fiction Plus, which contained a version of Leslie Shepherd’s ‘Interstellar Flight’ for a broad audience. The image shows what appears to be a hollowed out asteroid being used as a massive generation ship.
For all these reasons, the view from 1952 was startling to many who read Shepherd in JBIS or, in more popular form, in Hugo Gernsback’s Science Fiction Plus, where he wrote on the subject in 1953. Shepherd wasn’t much interested in probes in that era. He wanted to get not just a few humans but entire colonies of them across the interstellar gulfs. And after going to great pains to address the problems of distance and energy, and to explain them with the relevant mathematics, he went on to take a science fictional concept into the realm of the possible:
…the explorer or colonist setting out for some distant system may do so in the knowledge, not only that he will never again see his native planet, but that he will not even see the planet of his destination – a privilege reserved for his descendants. Thus the philosophy of the explorer may be that of the soldier or airman setting out on a suicide raid, doing so in the knowledge that for him there can be no personal gain, only the dying knowledge that some will survive to benefit from his action. Indeed, interstellar colonization may call for the sacrifice of whole generations in the lonely reaches of space. Colonies once established may have to exist for generations in a state of complete isolation and such communications as exists between systems may be a very tenuous and precarious matter.
When Starflight Becomes Possible
This is bracing talk because it assumes, as Robert Forward would do a decade later, that despite its incredible hardships, an interstellar journey is possible within the bounds of known physics. When would we begin to take the idea seriously? In Shepherd’s view, a journey to Alpha Centauri would start to resonate when we could reach velocities of up to 10,000 kilometers per second, a speed that gets you to the Centauri stars in a bit less than 130 years. The figures and mathematics he provides in his paper show how severe the power requirements would be with conventional rocketry, and why systems with low thrust and high exhaust velocity (an ‘ion rocket’) would be optimal.
Remember, this is in the pre-laser days, when the idea of a solar sail was just beginning to go from a theoretical fancy to a real possibility for space missions — here we think back to Carl Wiley (writing as ‘Russell Saunders’), who published ‘Clipper Ships of Space’ in the May, 1951 issue of Astounding Science Fiction. So sail configurations and in particular Forward’s ‘lightsails,’ with their laser beam push, have no place in Shepherd’s thinking. Nor did he have the benefit of our catalog of over 500 exoplanets to work with, though he did note the necessity of such observations before any interstellar departure.
And, of course, he captured the essence of the drama that various science fiction authors, including most recently Greg Bear in his novel Hull Zero Three (2010), have worked with. The ‘slowship’ to the stars becomes a sociological experiment on a grand scale, particularly when the destinations are so distant that travel times of a thousand years can be anticipated:
In the normal way, some thirty generations would be born and would die upon the ship. It would be as though the vessel had set out for its final destination under the command of King Canute and arrived with President Truman in control. The original crew would be legendary figures in the minds of those who finally came to the new world. Between them would lie the drama of perhaps ten thousand souls who had been born and had lived and died in an alien world without knowing a natural home.
Shepherd saw this ship as a kind of Noah’s Ark, one carrying everything, including the vast variety of Earthly life forms, that colonists would need to set up shop on another world. The vehicle would of course be gigantic, a small planetoid in its own right weighing at least a million tons excluding the weight of propellants and fuel. He recognized that on a journey of many generations even a million tons makes for a tiny living space, but assumed that sufficient care to design could make it bearable. All along the route, his crew would work to preserve order:
The community would be subjected to a degree of discipline not maintained in any existing community. This isolated group would need to preserve its civilization, hand on precious knowledge and culture from generation to generation and even add to the store of science and art, since stagnation would probably be the first step to degradation.
The Hope for Relativistic Flight
And if we could reach much faster speeds? Shepherd’s section on relativistic flight works through the benefits of time dilation and ponders the possibilities of antimatter to generate the energies required. But he also introduces, in one of the earliest discussions of the question, the consequences of the ship’s interactions with interstellar gas and dust, noting what the designers of Project Daedalus would wrestle with much more extensively 25 years later, that any spacecraft moving at a significant fraction of lightspeed would have to be well shielded.
Shepherd’s conclusion is straightforward, like his entire paper:
There does not appear to be any fundamental reason why human communities should not be transported to planets around neighbouring stars, always assuming that such planets can be discovered. However, it may transpire that the time of transit from one system to another is so great that many generations must live and die in space, in order that a group may eventually reach the given destination. There is no reason why interstellar exploration should not proceed along such lines, though it is quite natural that we should hope for something better. To achieve a more satisfactory performance, however, we should need sources of energy far more powerful than any utilized or known today.
Shepherd remains a seminal figure in the development of interstellar studies, and I notice that he is honorary symposium chairman for the 2011 interstellar sessions in Aosta, to be held this July. His sober analysis of generational starflight foreshadows Robert Forward’s attempts to ramp up velocities while remaining, as Shepherd did, within the realm of known physics and technologies that could be extrapolated from what we use today. His paper is well worth reading for its historical value in placing our dreams of the stars on a solidly scientific foundation.
Thanks to Kelvin Long for passing along a copy of this paper. The reference is Shepherd, “Interstellar Flight,” JBIS Vol. 11 (1952), pp. 149-167.
Enjoyed this post as a new year approaches. I’m in the middle of Bear’s “Hull Zero Three” which is an engrossing novel. I’ve figured that two things needed for interstellar travel would be genetic engineering (to create humans suitable for the new planet), artificial wombs, and robot nursemaids to bring up the new settlers. Bear adds much more including skill imprinting of new humans, etc. If anybody else has similar books to recommend I’d love to hear about them.
It may be possible to reach another planet, and it may even be possible that there are other planets with exactly the right conditions for humans. But such planets surely would not be devoid of life. On what moral basis could humans consider taking a planet from its current occupants?
Asimov also devoted a portion of his work _Extraterrestrial Civilizations_ to a treatment of the concept he referred to as a “free-world”, which was essentially the hollowed-out asteroidal generation ship. This was where I encountered the idea as a student, more decades ago than I care to dwell on.
New physics and or “magic propulsion” dreams aside, I think it very likely that this is ultimately how our species will spread to the stars – slowly, gradually, using in fact few technologies we do not already have, but a great deal more focus and applied willpower, at least on the parts of the teams of builders and colonists.
@ Istvan: The practical problem I can see with this approach relates to the “planetary Greenland” discussion we had earlier. Without rapid interstellar travel–and even a transit time of a couple of decades to Alpha Centauri might not be rapid enough–we’ll have to create durable, self-sustaining human and natural ecologies. How large will they have to be to be survivable and capable of growth on arrival in the system of destination? How large will be too large to move on any kind of practical timescale?
@ Bill: Interesting question. To what extent is an ecology sacrosanct, and to what scale? Is it OK to transport a species from one continent to another and not from one planet to another, or from one system to another, or … ?
How could we know a generation of humans who’ve known nothing but life on a ship would want to leave the ship and settle on a planet?
Their parents and grandparents and many generations before them would know only space travel. How would we know their goals would be our goals? In fact, I’m sure their priorities would be quite different from those who sent their vessel on its way.
The possibility of designing interstellar travel, let alone interplanetary travel, brings up many interesting questions. Chief among these is that it is a widely held belief, beyond these pages, that we are better off forcing ourselves to remain on the one planet. The idea is that this would in turn force us to look out for humanities prospects on this one planet and solving our current problems. It is insufficient to point out that this would doom us in the long term since these multitudes have no interest in humanities prospects beyond Earth anyway. To them people beyond Earth is a oxymoron.
As for the prospects of generation-ships, surely the mindset of the initial crew (if properly informed) would be either that of a renegade religious cult or that of supreme confidence that no further technical or scientific breakthroughs could provide us with practical relativistic travel within a century of their departure.
I think Bill Mead has a point, though given humans and their penchant for creating trouble it wouldn’t surprise me if the Powers That Be on a roving Space City would send dissidents into exile on natural planets. But the real life of such “Macrolife” communities, to borrow a term from Dandridge Cole, is amongst the stars, not stuck in the 2-D environment of planets.
Bill Osberg above asks “On what moral basis could humans consider taking a planet from its current occupants?” To me this is one of those realist details that is seldom seen in this discussion, but should be taken seriously. There is another that keeps recurring to me, and which may partly answer Bill’s question: I would think that by the time we reached the technological development and the ability to harness the kind of energies needed for regular intersteller travel (as opposed to just the initial probes), we will largely be living in space itself, not on the kind of surfaces that require no technological improvement at all, like parts of Earth today. In that case, there will be no great need to find and colonize those primitively perfect planets, and thus no need to take them from their natural inhabitants. On the contrary, we may just become curious observers.
When thinking of generational star ships I like to think what it would be like for the people that would be worst-off in the endeavor — those that would live and die entirely within the depths of interstellar space — the intermediate generations.
What would it be like to wake up and realize that you’re one of them? You’d have to be taught which star your ancestors came from and to which your descendants will go.
I can’t imagine you could live what we consider a fulfilling life; throughout your entire life, the ship would essentially be traveling at roughly the same speed and pointed in the same direction — except for minor course-corrections.
That’s a pretty pessimistic existence, I think. How do you make the intermediates feel that their lives are worth something? That’s a real problem. I’d like to help future generations, but I also want my own life to mean something… wouldn’t they?
@Randy: I do assume that a sufficiently large “colony” aboard an asteroidal generation ship would be likely to have some subset of members willing to colonize a planet. Some fraction of most human societies seek the novel. The problem will be whether their numbers are /viable/ to colonize a planet. I’ve read somewhere, years ago, that a minimum gene pool of 10K individuals is required for genetic viability…. that’s a lot, probably more than the likely population of a generation ship, unless it’s also carrying frozen fertilized ova. However, that number may also be in error. I also read recently about a bottleneck event in homo sapiens history, and the authors of that article suggested a vastly smaller survivor population than 10K individuals.
As to timescale, what timescale is impractical when the ship is a sustainable homeworld itself? In that event, I should think no one cares when they “get there”. However, Bill’s point about the future generations having the interest to actually colonize is admittedly relevant – but only to the designs of the builders of the ship. For purposes of species survival, it’s immaterial whether we have two planets or a dozen sustainable, potentially self-replicating asteroid “freeworlds”… in fact I’m sure it could be argued that by spreading the freeworlds around, we’re better off than just colonizing one or two other planets.
Keep in mind we’re assuming a lot of capability in a “freeworld”, though. Too far down this path and we’re speculating as broadly as we do when we dream of hyperdrives to get us elsewhere.
The more I think about interstellar flight/exploration/colonization the more I realize the analogy that most people use (i.e. the peopling of North America) breaks down, worthless to being utterly misleading. Sorry, but it’s usefulness, slight at best, is now a dead end. And the worst version of it, “white guilt to the stars,” aka the Cameron Movie, is just silly. In the vast reaches of the universe almost everything is certainly dead, dead, dead. Noble savages will not be an issue. And with RAN (“Really Advanced Nanotechnology”) we are free to do anything we want with that dead matter. Speculations regarding interstellar travel that avoid mention of nano-tech, as if it were something unseemly, are not to be taken seriously. In 1986 with Engines of Creation, the threshold was crossed; speculative thinking must look forward (see the above noted website).
SF book recommendations.
As for:
Genetic engineering as a crucial aspect of interstellar exploration etc., I recommend James Blish’s The Seedling Stars. It probably won’t happen this way, but who cares? I know of no other book quite like it.
Generation ships and their problems (e.g. Heinlein’s Orphans of the Sky; see also the link http://en.wikipedia.org/wiki/Generation_ship), there are too many to list. I do have a great fondness for Brian Aldiss’s StarShip (a.k.a Non-Stop). The take on the idea is so inventive that it remains my favorite of the genre.
The first interstellar travelers will probably be people already used to live in space. Space colonies in the outer reaches of the solar system already must have learned how to do without sunlight, and pushing out further into interstellar space will not be such a large step. Isolation from the rest of the system would be the worst problem, but perhaps not that bad if we are talking about a whole flotilla, or stream, or tendril. Once established in a new system, some will explore the surfaces of planets, and perhaps settle there. Or not, but does that really matter?
Gerard O’Neill was of the view that Earth like planets would have little value in humanity’s future, that most humans would eventually live in space habitats. The communities living in such habitats could make the choice between circular travel around the Sun or linear travel to the stars.
The largest habitats, depicted in T. A. Heppenheimer’s book Colonies In Space, were cylinders about 30km long and over 6 km in diameter, and would be able to each support a population in the millions, each colony would be a ready made interstellar ark, but I always thought it’d be really cool to build a colony ship 20 km in diameter and 200 km long by joining together 36 such habitats.
http://www.nss.org/settlement/ColoniesInSpace/index.html
There’s a number of conceptual hurdles that the idea of generation ships need to surmount. For one, the concept proposes societies that are essentially static over centuries, any yet still somehow maintain a spirit of exploration and possibly colonization. That’s a feat of social engineering that rivals the technical challenges of building a starship.
Of course one way to simplify that social challenge is to extend the human lifespan. If people have a three-hundred year lifespan, then a 130-year long trip won’t need as much social engineering, though boredom would still be a factor. All that would require is a rewiring of the human genome (and possibly metabolism and any number of other things), and likely a large degree of social change to deal with the effects of massively extended lifespan.
One of the other factors can be dealt with as well- the size of the spacecraft. Mr. Shepherd was writing in the days before Gerald O’Neil and his 20 mile long “Island III” space colonies, so it seems like a million-ton starship may be conservative. In fact, given the amount of area needed for a properly redundant ecology, a minimal population of 100,000 may have a decent amount of space to work with.
But the big issue is this: if you’ve been on a journey of 13o years, why stop and colonize? The situation of a colony starship is not dissimilar to that of a colony in say, the Oort cloud, where really all the inhabitants need is to replenish resources and maintain a constant supply of energy. The colonists would likely not be interested in colonizing a planet at all, and given the population dynamics of modern societies, population pressure would be unlikely to be a factor. Even building a second colony would likely be a matter of taste (“We can make a better colony!”) or political schism.
I freely admit these are all questions that have been raised before, and various writers have proposed different solutions. But on the plus side, the recent discoveries of the sheer diversity of planetary systems could be an attractant to interstellar colonists. Why stay in a boring old Sol system, when one could travel to a star system with multiple close-in super-Jupiters?
Bill’s comment regarding the moral questions are reasonable and deserve a full airing. It would be easy to say that we have the right to do this, founded on the principle of self preservation. But, of course, if an alien race were to show up tomorrow saying the same thing, we would probably have something to say about that.
The question of the desire of future generations in a generation ship being willing to inhabit / occupy / invade a new world is similar, and likewise deserves consideration.
Even more speculatively (is that a word?), imagine a future where we become aware of an impending disaster, generate the will to launch a multi generational ship to save our species. Then suppose those who remain solve the problem, but those who left ultimately return. Would they be considered returning long lost members of our family, or potential invaders? Lots of different scenarios.
Even more interesting, perhaps, is the question of why these questions are not brought up more often. The technical questions are fun, but do not present any moral hazard.
Funny how the concepts of suspended animation or extended hibernation hasn’t been mentioned here as a way of dealing with the long travel times of interstellar flight. The crew sleeps through the voyage while the AI runs the ship, perhaps with a rotation of a few crew members standing watch a few years before waking their relief then heading back to the hiber-pods.
Not a new idea but still a very good way of dealing with long travel times and resource consumption. Has the possibility of cryo-storing people been proven to be impossible? Or just very difficult? Compared to interstellar engineering?
Is there a fundamental hitch preventing the extended hibernation of people comparable to the way basic physics forbids FTL travel?
I posted this in reponse to Scott Gs’ concern about restless intermediate generations finding little satisfaction in their predicament. A collapse of morale would lead to the collapse of the mission I would think.
Just freeze everbody and wake them at arrival 2 or 3 centuries later, fresh as daisys and ready to go to work!
Clearly the biggest stumbling block to an interstellar mission (and that’s really saying something considering the huge engineering challenges) is Human biology and Human nature given the best we could likely do is about 10% light speed if even that. You have to wonder if people could withstand it.
So if possible, sleep through the trip.
Why assume biological humans will make the journey? Perhaps we can either download our minds to machines, or grow our minds out into machines, allowing us to travel as machines, perhaps turned off or with very slow “clock rates”.
It wouldn’t surprise me if we create the bodies from local materials and therefore need very small ships that can store minds captured at the molecular storage level.
If we can make artificial people, then we can even subsequently create biological humans, as the key problems of first few generations of education and infrastructure creation will have been solved.
I appreciate we don’t have much of an inkling of how this could be done today, but the descriptions of transporting largest colonies of people in generation ships just seems remarkably quaint.
CHAS,
try reading, “voyage from yesteryear” by James Hogan.
as for all of the rest of you who might be on the new interstellar mission design team or are followers of your work,( I have been following your work since the 1970’s) I have noticed a pragmatism take hold over some of you :) and that would be lowering the speed for our star ships down to very low thresholds.We are now in the practical realm of the generation ship!
so I plead with those of you who are embarking on a new design for interstellar voyages to de facto divide your efforts but cross fertilize your ideas between low light speeds and that of a short generation ship mission.
a short generation ship mission would have to be off course, to a nearby system of any kind, knowing that the colonists may only have asteroids and comets to work with,but turning them into O,Niel colony’s.
So at .oo1 of light speed what is our journey time to Alpha Centauri system?
whatever the answer I thinks its important to give the generation ship no more then the lifetime of most nation states, and I do not mean cultural nation states such as China or Egypt, but politically democratic states such as our own or perhaps the progenitor states to the European union, these have lasted only a several centuries at best, and with an American civil war and the history of Europe before the EU,this record is spotty at best.
I believe that a future world organization made up of a hybrid organization made up of a NATO, EU and other democrats that include Russia could found a international council of scientists and cultural experts that would use peer review to assemble a generation ship crew.
I think we need to trade speed for crew,economy, and duration of the voyage
robotic probes will offer the best choice for the present effort for speed,but send mass and human culture on a voyage lasting just under 500 years just might work.
Hi Folks;
It is interesting to contemplate the notion of old hat interstellar propulsion concepts in new and ressurected forms.
The venerable interstellar ramjet was a concepts that we all know came out decades ago and which seems all but relegated to the proverbial trash-heap as of late.
Science fiction is familiar with the concept of a nuclear device that would involve exothermic proton fission where the binding energy of quarks would be released. Recall that protons and neutrons are each composed of different combinations of up and down quarks. The proton is composed of two up quarks and one down quark. The neutron is composed of two down quarks and one up quark. The electrical charge of the up quark is + 2/3 e and the electrical charge of the down quark is – 1/3 e, where e is the magnitude of the charge of an electron. The rest mass of the quarks is only on the order of 1 percent of the mass of these nucleons. The additional mass comprising the roughly 936 MeV/[C EXP 2] rest mass of protons and neutrons comes from the relativistic kinetic energy of the bound quarks as well as the gluon field binding energy acting between and on the quarks. I would love to see an ISR able the harness a reaction such as this. The accelerations of the ISR could well approach 12 Gs or more in such an instance.
We need to also consider of the potential for developing mechanisms to collect and exothermically process Cold Dark Matter. Cold Dark Matter makes up about 85 percent of the massive component of the universe. The remainder of the massive component exists in the form of ordinary baryonic matter of the form of protons, neutrons, and electrons, most of which exist in the form of interstellar and intergalactic gas and dust. The gas and dust is mostly composed of hydrogen and helium. The rest of the mass-energy component of the universe appears to take the form of Dark Energy. Dark Energy is a theoretical cosmological constant like property of space that appears to be causing an acceleration in the rate of the expansion of the universe.
Cold Dark Matter is about 6 times as plentiful as normal baryonic matter. As a result, there remains the possibility that 6 times more power can be extracted from the interstellar and intergalactic medium for a given ISR velocity relative to the case where some sort of proton fission reaction as conjectured about above would be utilized.
The rate of acceleration of an ISR for perfectly efficiently utilized interstellar and intergalactic fuel is proportional to the square root of the mass specific potential energy content of the fuel. Consequently, perfectly utilized or almost perfectly utilized cold dark matter fuel would enable accelerations as high as [(140)(6)] EXP (1/2) times that of fusion fuel alone or accelerations as great as 29 Gs or more. Accelerations as high as [(140)(6 + 1)] EXP (1/2) = [(140)(7)] EXP (1/2) = 31.3 Gs or greater should be obtainable when also including any hydrogen fission based energy production.
The reason for my assumming the effective “super-relativistic” effective energy content of any CDM based ISR fuel is that CDM will not impose a drag on the starship, except for perhaps a CDM processing apparatus which will necessarilly need to have a thermodynamic coupling to the natural CDM. So the energy derived from CDM may effectively almost appear as if it came from nowhere.
Regarding nuclear fusion powered ISRs, it became clear that perhaps there is not enough fuel density on average within the interstellar medium to achieve a net thrust when considerations of astrodynamic drag imposed on the craft by the magnetic scoop or other electrodynamic field scoop mechanisms are made. It is now sometimes suggested that perhaps the interstellar ramjet could choose specially mapped-out routes through the interstellar medium where interstellar gas and plasma concentrations would be adequate to permit the craft to accelerate at rates as great as 1 G or more.
Intergalactic dust lanes that appear to exist between and possibly connecting galaxies in a road like manner comprising primordial hydrogen may enable such vehicles to hop from galaxy to galaxy, ever increasing in velocity, to the extent that a net positive acceleration of the vehicle can be maintained in the presence of loss inducing astrodynamic drag.
Finding other reactions that liberate more energy than pure conversion of mass into energy would permit even higher accelerations but given a required paradigm change for such an as yet fanciful notion, I will not hold my breath on this one.
Another fusion reaction sequence was proposed by Physicist Daniel Whitmire that involves utilizing the CNO bi-cycle for producing the energy to power an ISR. The CNO bi- cycle starts with the fusion of hydrogen nuclei or 2 protons with a carbon 12 nucleus. This fusion reaction sequence transforms the Carbon 12 into a Nitrogen-14 nucleus. The Nitrogen-14 is then transformed into Oxygen 16 through the fusion of two protons with the Nitrogen-14. The result is a highly exited state of Oxygen 16 whereupon the Oxygen 16 nucleus undergoes fission to produce a carbon 12 nucleus and a Helium-4 nucleus and the process is repeated.
This process is often referred to as a Carbon 12 Catalyzed Fusion Reaction since the Carbon 12 is not actually used up in the process. Note that this process in not a chemical catalytic reaction, but is instead a nuclear catalytic reaction.
Since each of the above exotic ISR notions can be mathematically rationalized and can be cast in a lexocographically plausible matter, we do indeed need to remain open to the “old hat” interstellar drive concepts in spirit.
By the way, HAPPY NEW YEAR!
” How would we know their goals would be our goals? In fact, I’m sure their priorities would be quite different from those who sent their vessel on its way.”
An interesting point. Consider the episode on ST the original series where Kirk encounters just that- folks living in an astroid and at the behest of a computer.
Assuming that our intrepid sailors (what else?) remain keen and knowledgeable, what difference their choices far in the future? We’re all dead back here anyway, and the point of the entire exercise–spreading out- will have been achieved.
I wrote a novel with a similar theme mentioned above. I imagined ‘downloading’ millions into a craft, duplicating it several times with the same inhabitants in each, then sending each out in different directions. You have exploration and in a sense alternate realities, too. In the end (spoiler alert!), some determine to make the transition back to human form, some do not, and some–well, leave it there, shall we?
Happy new year everybody! May you all stay healthy and your wishes come true (as far as they are reasonably decent and not detrimental to others). And may the coming year see many fascinating new discoveries, planetary and otherwise.
There are refs above to humans living permanently in space in O’Neill like colonies. This discussion is already being conducted in the ‘Greenland risk’ post just before this post, so I will not carry it much further here (I will there though), and limit myself by stating that, though large space stations may definitely become part of our future, I do not believe that they will become our *primary* human habitat (i.e. in stead of planets) in any foreseeable fiture, because, summarizing:
1) those artificial habitats are and will always be extremely risky in the long run, I am not talking about years or decades here, but centuries, millennia to begin with, and longer. Major risks consist of e.g. technical and constructional failures, material failure (fatigue), natural disasters (such as impacts, diseases), serious internal accidents, social upheaval, … Even very small impacts or failures could result in serious loss of atmosphere and/or complete disaster.
2) we humans simply like planets, their spaciousness and (potential) abundance of life, it is in our mindset. Orcas (killer whales) can live in oceanarias, but it probably wouldn’t be their own first choice. Who would volunteer to live in such a space colony if (other) planets were also available?
3) planets are overwhelmingly abundantly available and , with some ‘modest’ modifications, ready for the picking, resulting in an enormous amount of pleasant and relatively safe and stable real estate. Hey, why keep living on a ship, if North Amercia and Australia are available?!
This brings us to a more relevant topic, brought up by Bill Osberg, the morality of colonizing other, already inhabited planets.
I would say to that, that probably the most ideal and ‘innocent’ planets are those that are potentially (near-)habitable, but not yet inhabited, i.e. earthlike planets in a primordial state and easily terraformable terrestrial planets. These categories are probably quite common.
Interesting question is what to do with terestrial planets inhabited only by primitive (single-celled, bacterial or equivalent) life? This category could also be rather common. We could probably not eradicate it, even if we wanted it, and it will most probably not be harmful to us, as it will be more alien to us than Dutchy Elm’s disease. But we may change the entire course of evolution of such a planet and its indigenous life and in the most extreme case we might even condemn such life for instance by altering the atmosphere.
Planets with any higher advanced life, I believe, must always be approached with the utmost respect and care, and even be largely left alone, mainly studied. (Maybe some others are already doing that with us?).
Since there are no resources of any kind en route, the need to “replenish resources and maintain a constant supply of energy” provides an excellent reason to stop. And about the colonizing: 1) It would take a lot of time to restock for another journey, you’d practically have to build a new ship. In the meantime, you’d be forced to settle down for all practical purposes, anyway. 2) Why leave again in a hurry if a whole new system (with resources) is waiting to be explored? You may not need or want a planet, but an Oort cloud or asteroid belt of some kind is absolutely required for growth, and nowhere to be found except orbiting around a star. It would be reasonable to assume that only a small fraction of the new population is going to want to go on another 130 year journey anytime soon, if they could even muster the resources to do so.
In his treatment of self-replicating star probes (http://www.rfreitas.com/Astro/ReproJBISJuly1980.htm), Robert A. Freitas Jr. allows 500 years for the construction and provisioning of a new ship, and that is for a single-minded robotic probe. A human society would presumably be much less focused on this task, and likely to delay it indefinitely until the new system is thoroughly explored and populated.
@Chas and others.
I also read Hull Zero Three and enjoyed it. I think that big generation ships would probably take some of the characteristics described in that book.
There’s no need for the crew to be continuously present if it could be manufactured custom-ordered (in skills, personality, and physical attributes) to meet certain needs. So in that book, a full blown community and supporting ecology don’t need to be sustained for centuries on end.
Of course, if ships had such abilities to radically remake people, I’m not sure why they’d bother looking for so hard for planets to colonize. Why not just hop from ice-body to ice-body, since there are uncounted trillions of those a lot easier to reach? It seems the critters best suited for interstellar travel will probably find Oort-cloud bodies as perfectly suitable habitats.
Am I the first to mention that Interstellar Travel proposals have made the front and center magazine racks at American bookstores of late? The Magazine is “Science Illustrated”, and the cover story, beautifully illustrated, is “Destination: Alien Stars – Riding a Black hole to Alpha Centauri”
Granted, that lame title is a “hook.” The article itself is better, basically it mentions various possibilities, in the following order of likely development:
– Space sails
– Nuclear Power (Project Orion, so… Fission)
– Antimatter
– Nuclear Fusion
– Black holes + Lasers ( per Louis Crane, Kansas State)
It also picks our likeliest destinations, in order:
– Alpha Centauri
– Barnards Star
– 40 Eridani
– Gleise 581
– 18 Scorpii
Sorry if this is a bit off-topic, Paul, but I RAREly see this subject matter front and center in the public eye. Ok I’m new here so I’ll pipe down, just wanted to make ya’ll aware.
Steven, thanks! I wasn’t aware of this title and will go out tomorrow and find a copy.
@all
Isn’t it likely that an obscure, or yet unknown, technology will, in time, present itself and solve some of these issues? John Q, above, mentioned Really Advanced Nanotech. That’s one such possibility.
The Singularity is another that comes to mind. Such things as man (animal)-machine hybrids, Avatars and downloadable consciousness would impact long term Space Travel as much as a workable fusion drive. At least it seems so to me. I am not a devotee of Victor Vinge. My belief system was drawn by Doc Smith, shaded by E.R. Burroughs and inked by Mr. Heinlein (would somebody, please, start writing juveniles of his caliber? kudos to Rowling, btw) .
Thank you, Mr. Gilster.
Hi Folks;
I just had to throw this one in since we are contemplating high specific impulses and mass specific energy densities for space craft here. I will not normally attempt to post such long comments on TZ CD, but the concepts expressed below ring true to my heart.
Now consider the possibility that 20,000 Coulomb charge could be instilled within a 100 femtometer thick neutronium sphere having a diameter of 0.01 meter. The surface area of the sphere would be equal to 4 pi (R EXP 2) = 4 pi [(0.005 meter) EXP 2] = [3.1416 x (10 EXP – 4)] square meters. The mass of the sphere would be equal to [3.1416 x (10 EXP – 4)](100) metric tons = 31.416 kilograms because the density of high end density neutronium is estimated to be 10 EXP 15 metric tons per cubic meter. Therefore, a one square meter lamicon of 100 femtometer thick neutronium would have a mass of (10 EXP 15)(10 EXP – 13) metric tons = 100 metric tons.
The electrostatic potential energy contained within this sphere would be equal to F = [1/[(4 pi) (epsilon naught)]][[(10 EXP 4) Coulombs] EXP 2]/(0.01 meters) = 10 EXP 20 Joules = 23,800 megatons. A one metric ton rest mas space car powered by such a decompressed charge where the charge is gradually released from an opening within the sphere would obtain a kinetic energy of roughly 10 EXP 20 Joules and a relativistic gamma factor of 1 + {{(1,000 kilograms)[C EXP 2]}/{(1,000 kilograms)[C EXP 2]}} = 2 assuming that all of the thrust energy would be converted into ship based relativistic kinetic energy. In reality, although we could expect a specific impulse of about 1 C due to the inertia produced by the electrostatic potential energy’s inertial mass equivalence or the bound electrostatic energy, the space car would most likely obtain a velocity of Delta V = C tanh [(Isp/C) ln (M0/M1)] = C tanh [(1C/C) ln 1] = C tanh [ 1 ln 1] = 0.866 C which yields a gamma factor of about 2.
The force pushing outward on the 0.01 meter neutronium sphere would be a whopping F = [1/[(4 pi) (epsilon naught)]] [(q1)(q2)/(r EXP 2)] = [1/[(4 pi) (epsilon naught)]] [(10,000 Coulombs)(10,000 Coulombs)]/[(0.01 meter) EXP 2] = [(10 EXP 10) (10 EXP 8)/(10 EXP – 4)] = 10 EXP 22 Newtons = 10 EXP 18 metric tons.
Now consider the possibility that the 200,000 Coulomb charge could be instilled within a 1,000 femtometer thick neutronium sphere having a diameter of 0.01 meter. The surface area of the sphere would be equal to 4 pi (R EXP 2) = 4 pi [(0.005 meter) EXP 2] = [3.1416 x (10 EXP – 4)] square meters. The mass of the sphere would be equal to [3.1416 x (10 EXP – 4)](1,000) metric tons = 0.31416 metric tons or 314.16 kilograms because the density of high end density neutronium is estimated to be 10 EXP 15 metric tons per cubic meter. Therefore, a one square meter lamicon of 1,000 femtometer thick neutronium would have a mass of (10 EXP 15)(10 EXP – 12) metric tons = 1,000 metric tons.
The electrostatic potential energy contained within this sphere would be equal to F = [1/[(4 pi) (epsilon naught)]][[(10 EXP 5) Coulombs] EXP 2]/(0.01 meters) = 10 EXP 22 Joules = 2,380,000 megatons. A one metric ton rest mas space car powered by such a decompressed charge where the charge is gradually released from an opening within the sphere would obtain a kinetic energy of roughly 10 EXP 22 Joules and a relativistic gamma factor of {(100,000 kilograms)[C EXP 2]}/{(1,000 kilograms)[C EXP 2]} = 100 assuming that all of the thrust energy would be converted into ship based relativistic kinetic energy. In reality, although we could expect a specific impulse of about 1 C due to the effective mass produced by the electrostatic potential energy’s inertial mass equivalence or the bound electrostatic energy, the space car would most likely obtain a velocity of Delta V = C tanh [(Isp/C) ln (M0/M1)] = C tanh [(1 C/C) ln 100] = C tanh (ln 100) = 0.9998 C which yields a gamma factor of about 50.
The force pushing outward on the 0.01 meter diameter, 1,000 femtometer thick neutronium sphere would be a whopping F = [1/[(4 pi) (epsilon naught)]] [(q1)(q2)/(r EXP 2)] = [1/[(4 pi) (epsilon naught)]] [(100,000 Coulombs)(100,000 Coulombs)]/[(0.01 meter) EXP 2] = [(10 EXP 10) (10 EXP 10)/(10 EXP – 4)] = 10 EXP 24 Newtons = 10 EXP 20 metric tons.
Now consider the possibility that 200,000 Coulombs of charge could be instilled within a 1,000 femtometer thick quarkonium sphere having a diameter of 0.00001 meters. The surface area of the sphere would be equal to 4 pi (R EXP 2) = 4 pi [(0.000005 meter) EXP 2] = [3.1416 x (10 EXP – 10)] square meters. The mass of the sphere would be equal to [3.1416 x (10 EXP – 10)](1,000,000) metric tons = 0.00031416 metric tons or 0.31416 kilograms because the density of high end density quarkonium is estimated to be 10 EXP 18 metric tons per cubic meter. Therefore, a one square meter lamicon of 1,000 femtometer thick quarkonium would have a mass of (10 EXP 18)(10 EXP – 12) metric tons = 1,000,000 metric tons.
The force pushing outward on the 0.00001 meter diameter, 1,000 femtometer thick neutronium sphere would be a whopping F = [1/[(4 pi) (epsilon naught)]] [(q1)(q2)/(r EXP 2)] = [1/[(4 pi) (epsilon naught)]] [(100,000 Coulombs)(100,000 Coulombs)]/[(0.00001 meter) EXP 2] = [(10 EXP 10) (10 EXP 10)/(10 EXP – 10)] = 10 EXP 30 Newtons = 10 EXP 26 metric tons.
The electrostatic potential energy contained within this sphere would be equal to F = [1/[(4 pi) (epsilon naught)]][[(10 EXP 5) Coulombs] EXP 2]/(0.00001 meters) = 10 EXP 25 Joules = 2,380,000,000 megatons. A one metric ton rest mass space car powered by such a decompressed charge where the charge is gradually released from an opening within the sphere would obtain a kinetic energy of roughly 10 EXP 25 Joules and a relativistic gamma factor of {(100,000,000 kilograms)[C EXP 2]}/{(1,000 kilograms)[C EXP 2]} = 100,000 assuming that all of the thrust energy would be converted into ship based relativistic kinetic energy. In reality, although we could expect a specific impulse of about 1 C due to the effective mass produced by the electrostatic potential energy’s inertial mass equivalence or the bound electrostatic energy, the space car would most likely obtain a velocity of Delta V = C tanh [(Isp/C) ln (M0/M1)] = C tanh [(1 C/C) ln 100,000] = C tanh (ln 100,000) = 0.9999999998 C which yields a gamma factor of about 50,000.
Let us go one step further and consider the situation where 200,000,000 Coulombs of charge could be instilled within a 1,000 femtometer thick Higgsinium sphere having a diameter of 0.00001 meters. The surface area of the sphere would be equal to 4 pi (R EXP 2) = 4 pi [(0.000005 meter) EXP 2] = [3.1416 x (10 EXP – 10)] square meters. The mass of the sphere would be equal to [3.1416 x (10 EXP – 10)](1,000,000,000) metric tons = 0.31416 metric tons or 314.16 kilograms because the density of high end density Higgsinium is estimated to be 10 EXP 21 metric tons per cubic meter. Therefore, a one square meter lamicon of 1,000 femtometer thick high end Higgsinium would have a mass of (10 EXP 21)(10 EXP – 12) metric tons = 1,000,000,000 metric tons.
The electrostatic potential energy contained within this sphere would be equal to F = [1/[(4 pi) (epsilon naught)]][[(10 EXP 8) Coulombs] EXP 2]/(0.00001 meters) = 10 EXP 31 Joules = 2,380,000,000,000,000 megatons. A one metric ton rest mass space car powered by such a decompressed charge where the charge is gradually released from an opening within the sphere would obtain a kinetic energy of roughly 10 EXP 31 Joules and a relativistic gamma factor of {(100,000,000,000,000 kilograms)[C EXP 2]}/{(1,000 kilograms)[C EXP 2]} = 100,000,000,000 assuming that all of the thrust energy would be converted into ship based relativistic kinetic energy. In reality, although we could expect a specific impulse of about 1 C due to the effective mass produced by the electrostatic potential energy’s inertial mass equivalence or the bound electrostatic energy, the space car would most likely obtain a velocity of Delta V = C tanh [(Isp/C) ln (M0/M1)] = C tanh [(1 C/C) ln 100,000,000,000] = C tanh (ln 100,000,000,000) = 0.9999999999999999999998 C which yields a gamma factor of about 50,000,000,000.
The force pushing outward on the 0.00001 meter diameter, 1,000 femtometer thick Higgsinium sphere would be a whopping F = [1/[(4 pi) (epsilon naught)]] [(q1)(q2)/(r EXP 2)] = [1/[(4 pi) (epsilon naught)]] [(100,000,000 Coulombs)(100,000,000 Coulombs)]/[(0.00001 meter) EXP 2] = [(10 EXP 10) (10 EXP 16)/(10 EXP – 10)] = 10 EXP 36 Newtons = 10 EXP 32 metric tons.
Since the Planck Pressure = Fp/(Lp EXP 2) = [C EXP 7]/[(h/ 2 pi) (G EXP 2)]= [4.63309 x (10 EXP 113)] Pascals where Fp is the Planck Force, Lp is the Planck Length, h is the Planck Constant, and G is the Universal Newtonian Gravitational Constant, I feel somewhat free to speculate about such extreme forces acting over small surface areas.
We can go one to contemplate microscopic spheres constructed of monopolium, however, first we need to learn how to produce macroscopic mass quantities of stabilized neutronium, then stabilized quarkoniums comprised of up quarks, down quarks, charmed quarks, strange quarks, botton quarks and even top quarks if top quarks can somehow be induced to enter stable bound relations. Then it is off to Higgsiniums perhaps followed by monopolium and maybe even raw space time foam or perhaps small wormhole wall material samples in wormholes that would be held open by the charge contained within.
To make these ultracompressed electrostatic potentials work, we will need to find suitably strong materials that will not be pulled apart by the extreme forces developed within by the compressed electrical charge. To use a phrase from a good science fiction star ship novel, perhaps the “mathematical Johnies” in the decades and centuries to follow will provide the solutions.
Renormalization techniques are used to cancel out infinities that crop up in quantum field theory calculations involving quantum-electro-dynamics phenomena. These calculations are necessary if one assumes that electrons and quarks are point charges, an assumption that still has not beeen replaced by any yet to be validated string theories or quantum-gravity theories that propose a finite size of fundamental particles as strings or loops having a size on the order of the Planck Length or of about 10 EXP – 35 meters.
One of the paradoxes of quantum field energy is the notion that perhaps electrons possess an infinite self-energy which would be interpretable as the infinite energy required to bind an electron’s charge into a geometric point. If the quantum field theory QED calculations end up requiring renormalization of infinities to produce a finite electron or quark rest mass energy, we can only speculate about the potential of somehow reifying the otherwise infinite self energy of an electron or a quark and releasing it fully or in part on demand.
Regardless, the electromagnetic force is awesome as is the even stronger strong nuclear force. We now have the heuristic and lexicographical tools to eventually harness the power of light and the atomic nucleus to do our bidding of travel among the stars. With this great power comes great responsibility. Let us look forward to the wonders of the New Year ahead and contemplate the impossible. With peace, all things are possible.
Steven Colyer:
“It also picks our likeliest destinations, in order:
– Alpha Centauri
– Barnards Star
– 40 Eridani
– Gliese 581
– 18 Scorpii
”
When people mention suitable stellar destinations, I get highly interested. I am somewhat puzzled though by some of the top destinations mentioned:
– Barnard’s Star is of course a close neighbor, but not very suitable: very low metallicity, variable and flare star.
– Gliese 581 is famous by now, because of its planetary system, but this consists of hot close-in planets and one or two super-earths in or near the HZ.
Not too bad, but I think there are better targets available;
Up to 30 ly:
– 82 Eridani (though rather low metallicity)
– Delta Pavonis (though gradually moving off the main sequence, becoming sub-giant)
– Beta Canum Venaticorum
– 61 Virginis
– Zeta Tucanae
– Gliese 442A
Maybe also Beta Comae Berenices (though on the hot side)
Between 30 and 50 ly:
– Alpha Mensae
– Zeta 1 and 2 Reticuli
– Gliese 302
– 58 Eridani (young solar analog)
– 18 Scorpii, indeed
– Nu 2 Lupi
To mention a few promising candidates.
Responding to Bill Osberg..
No ‘Moral basis’ to colonize alien planets ??
We don’t need one. Our kind of primate animal have colonized one valley, one continent , one island after another. That’s how we got here today. We have probably out competed a dozen other ‘human’ sapiens. Maybe you need a moral basis, but I and half the human race won’t stop at anything to settle a suitable new world. I am sure desperate times will call for desperate measures, as always. Outwards and onwards. This is the natural primal urge. All animals and plants on Earth and on other worlds grow and compete for ‘their’ patch of sunlight. Or die. Look in your garden. That’s nature.
It’s true that morality is a human concept. We have gone beyond nature in many respects however. When all you have is rocks and sticks and the largest social unit is the tribe, the natural “might makes right” morality doesn’t lead to great catastrophe.
But if our morals are primitive while our nuclear and biological weapons are capable of nearly instantaneous mass destruction, then our survival as a species is in great danger. If we want to survive long enough to reach the stars, it is imperative that we grow morally as we grow technically and scientifically.
I strongly agree with Bill Osberg that we as humans do need a sound morality when it comes to colonizing other planets. And with this I mean more and other than just ‘survival of the fittest’, no matter how real that also is.
It is, without denying biological reality, precisely our ability to see and go beyond those primeval urges and drives that makes us human and an intelligent civilization, our ability of self-control, self-constraint, appreciation of beauty and letting live.
And we will need those abilities to ever make it to the stars and to make it there. Though we need a certain aggressive drive, an overly aggressive, selfish and violent species and civilization probably won’t survive long enough to pass that ultimate test, extinguishing itself before reaching the stars.
Though probably imperative for our long-term survival, I disagree with Tarmen that our primary drive to reach the stars should be despair or competition, but rather hope and the spreading of life, beauty and intelligence. And I repeat that if we ever find (higher) lifeforms there we must treat them with the utmost care and respect, as we would also wish to be treated ourselves. If we cannot even observe that simple but essential morality we are probably not worth reaching the stars.
If Tarmen and “half the human race won’t stop at anything to settle a suitable new world”, I sincerely hope that Tarmen and half the human race will never make it to the stars.
Every time we catch a cold, we kill billions of viruses. Every time we boil water, we kill innumerable microorganisms.
Not colonising a planet because it’s inhabited by an intelligent/sentient species – of course.
Not colonising a planet because it’s inhabited by microorganisms, maybe plants or animals that will most likely coexist with what humans will bring – that’s unjustified.
According to these morals, one should kill oneself in order to prevent killing millions of microorganisms daily.
You only need to look at the differences in social moral codes in human societies over the last few hundred years to see that what is and is not moral can’t be defined in any objective sense. If you think Western society is more moral – in some object sense – today compared to past societies here’s something to think about; If our civilization collapsed tomorrow and we all became as poor as many past societies, many of the moral codes that those past societies lived by would come back into fashion. Richer societies can afford to be more tolerant of individuals behaving in ways that are costly to the society as a whole.
In addition to the social moral codes humanity has moral codes that are based in our evolved instincts, (you can witness other species of animals on this planet displaying their own instinct based moral codes in their own behaviour, though people often don’t recognise such instinctive behaviour as forms of morality) sentient species on other planets would have instinctive moral codes based in their evolved instincts, and, depending on their biology and instinctive aspects of their sociology, their own instinct based moral codes would differ from our own.
Presumably if future human societies have the wealth to travel to the stars, their moral codes will be those of wealthy human societies.
ProtoAvatar, I am sorry I have to say this, but apparently you did not think before responding this time, because your response is just plain silly:
of course there is no (moral) comparison at all between our daily and even inevitable dealing with microorganisms here on earth and the willful introduction of our kind of life into an alien ecosystem.
I was not even saying that we should never ever settle inhabited planets, but rather that we should do so with the utmost care, having a comprehensive ‘code of conduct’ beforehand, how to deal with various situations: varying from terraformable uninhabited planets, via planets with only the most primitive life (single-celled, maybe undifferentiated cell colonies), planets with higher life (multicellular, specialized organs, etc.), to planets with sentient life.
Of course morality is a very fluid and time/culture dependent concept, but our basic guiding principle could be to let live, to cause as little disruption to indigenous life and its course of evolution as possible. And not just the frontier/conquest mentality expressed by some.
Undoubtedly, this will in turn be partly or largely determined by what we will find in the neighboring galaxy (by telescopic research and maybe probes later): are easily terraformable and primeval earthlike planets common? Or are planets with primitive lifeforms common? And planets with higher life very rare? In that case we would probably go for the terraformable and primeval planets and leave the rare planets with higher life alone as reserves, maybe for study.
If, however, any kind of inhabitable planet appears to be extremely rare and the few that we manage to find and reach are already fully inhabited, also by higher life (e.g. principle of movie Avatar), we may face a new challenge, change our moral standards and still go for it.
Ronald
“ProtoAvatar, I am sorry I have to say this, but apparently you did not think before responding this time, because your response is just plain silly:”
Silly?
Quite the contrary – my respnse makes of sense, as you yourself had to acknowledge:
“of course there is no (moral) comparison at all between our daily and even inevitable dealing with microorganisms here on earth and the willful introduction of our kind of life into an alien ecosystem.”
It’s just that comparing (morally and otherwise) earth microorgaanisms and
alien microorganisms is quite valid.
And an alien microorganism is NOT morally superior to an earth organism just because it’s alien.
As for the rest of your post, is is an exercise in rhetoric that manages to avoid responding the very simple question: Should we colonise planets inhabited by microbial/plant/animal life?
“utmost care” and “comprehensive ‘code of conduct’” do not constitute a response, Ronald. What code of conduct?
I agree with Bill and Ronald on the need for morality. Without morality, we would have bombed ourselves back into the stone age last century. Perhaps we still will. It is not clear that, should we ever happen upon others, we could make friends. But I do think the chance is greater than that of H. Sapiens making friends with H. Neanderthalis (They didn’t, although some individuals apparently did), due to the increased sense of morality that the lack of struggle for survival affords us (a point made above by Andrew).
If the others happened to be on the same level of capability, we might stand off for mutual benefit, like we did in the cold war. If there is a large difference, the superiors may treat the inferiors with respect (most of the time), like we treat whales or dolphins or apes. However, “might” and “may” are the operative words, here. There is no guarantee that cockroaches or cattle aren’t the more apt comparison.
Eniac makes the common mistake of stating that we did not get on with H. Neanderthalis. It is true that this is possible, but it may also be true that our individual relationships with them were exemplary. Unfortunately it is a principle of ecology that two species can not stably occupy the same niche. It is thus possible that to cohabitate without harm we would have to coordinate our societies in unparalleled ways. Perhaps this was almost managed with the result being the Chatelperronian culture. The issues of demise, morality and guilt are thus complex.
I admit I was jumping to conclusions, because they are extinct and we are not. Perhaps this happened without genocide, somehow. Peaceful coexistence, but eventual extinction due to gradual population shifts. Possible, but likely?
ProtoAvatar: to settle this dispute and start the new year in a reconciliatory fashion ;-)
I fully agree with you that alien microorganisms are not (morally) superior to earthly microorganisms, as individuals.
Besides, it seems unlikely that we would even be able to eradicate an alien microorganism on its own turf. Though I can imagine that our tinkering with an alien atmosphere and climate in an attempt to further terraform a primeval planet, possibly also by means of introduction of our own microorganisms (e.g. cyanobacteria, algae) could ultimately even affect the indigenous microlife. And we would inevitably be changing the course of evolution on such a planet.
My objections and moralizing were not so much directed toward planets with exclusively microorganisms, but rather with regard to our dealing with planets with higher developed lifeforms. The latter are probably much rarer than the former anyway. Just going by presence through time here on earth, it is quite well possible that at least 80 – 90% of all inhabited planets only have microbial life, and most of these only the more primitive varieties more or less equivalent to Prokaryotes (Bacteria, Cyanobacteria, etc.) here on earth.
You are asking me a pertinent question, which I will try to answer: “Should we colonise planets inhabited by microbial/plant/animal life?”
Though the ultimate decision with regard to this is of course not entirely up to me alone ;-)
I would suggest, with regard to various categories to consider:
– Terraforming and colonizing uninhabited planets: definitely!
– (Further terraforming and) colonizing planets with only microorganisms/single-celled life: in most cases OK. When not?: if and when we would have a wealth of choice of (other) planets and our meddling with the planet would be so far-reaching that it would likely result in the wholesale extinction of the indigenous ecosystems (not a very likely scenario anyway).
– Colonizing planets with higher life: preferably not full-scale colonization if this means transformation of the planet and likely extinction of indigenous life. I suppose this would also depend on the availability of alternatives. I would rather see a limited settling for scientific research and sampling. This is what I meant with ‘utmost care’.
– Colonizing planets with intelligent/sentient life: preferably not or very limited, again limited to study.
I trust you understand that this is just a very, very initial attempt to a ‘code of conduct’.
Ronald:
I agree with most of what you said. As for the rest, I find it quite reasonable.
Of course, given that O’Neill colonies will always present humans with arbitrarily large real-estate for colonising, a code along the lines of the one you sketched (with which I mostly agree) will mean humans will almost never colonise planets.
ProtoAvatar: thanks, but aren’t you being a bit too gloomy now?:
“a code along the lines of the one you sketched (…) will mean humans will almost never colonise planets”.
Apart from the undoubted attractiveness of O’Neill colonies ;-), and purely with respect to such a code of conduct, wouldn’t it be most likely that (by far) most terrestrial planets that we will find are either still lifeless (part of which will be the uninhabited terraformable category) or inhabited with primitive microbial life only?
In other words, even with a rather strict code of conduct, I would rather expect by far most terrestrial planets to be ready for the picking.
(And even if not, this would imply that higher life is apparently common, also not bad news).
Right: Either there is life, and we have something interesting to study, or there is not, and we have plenty of living space. Win-win all around, as long as we can steer clear of the evil aliens. :-)
Eniac: yes, that’s what I have always said: either there is life out there or we will bring it, indeed win-win :-)
The evil aliens: real but very small risk, in fact one of the least of our problems. They must be exceedingly rare or we would already have noticed them and they us. Most probably very little competition for the galactic pecking order.
Ronald
“ProtoAvatar: thanks, but aren’t you being a bit too gloomy now?:
“a code along the lines of the one you sketched (…) will mean humans will almost never colonise planets”.
Apart from the undoubted attractiveness of O’Neill colonies ;-), and purely with respect to such a code of conduct, wouldn’t it be most likely that (by far) most terrestrial planets that we will find are either still lifeless (part of which will be the uninhabited terraformable category) or inhabited with primitive microbial life only?
In other words, even with a rather strict code of conduct, I would rather expect by far most terrestrial planets to be ready for the picking.”
Yes, most terrestrial planets we’ll encounter will probably be either lifeless. How often will we find planets inhabited by microorganisms is uncertain – and a very good question:
-on one hand, microbial life evolved on Earth almost as soon as the conditions could support it;
-on the other hand, life evolved on Earth only once despite bilions of years in which the conditions were favourable (there’s no ‘shadow biosphere’).
In either casse – lifeless or microbial-inhabited planets – building domes/settlements there will have significant disadvantages over building O’Neill colonies in space.
And terraforming the planets will be far morexpansive and will take far more time than building O’Neill colonnies.
All this points to the fact that humans will almost always choose to build O’Neill colonies.
The only cases in which a planet could compete with O’Neill colonies is when life – plants/animals – exists on it, when the planet is already, more or less, earthlike.
And in these cases, according to the code you sketched, humans will not colonise.