Centauri Dreams

I’m looking forward to the upcoming Starship Congress hosted by Icarus Interstellar, which will take place in Dallas from August 15th to the 18th at the Hilton Anatole. With an audience of physicists, engineers and researchers of all kinds, this is a chance to catch up with old friends and firm up relationships that have in some cases been pursued solely through email. 2013 may be remembered as the year of the conference in interstellar terms, since we had the Tennessee Valley Interstellar Workshop in February, Starship Century in May, Starship Congress coming up in August, then the 100 Year Starship Symposium in Houston from September 19th to the 22nd.

This doesn’t include smaller events like the British Interplanetary Society’s excellent Philosophy of the Starship gathering in late May, and if you’re in range of BIS headquarters in London, it’s worth checking out what’s coming up on their always active schedule. But thoughts of indefatigable activity on the interstellar front always bring me around to Richard Obousy, president of Icarus Interstellar, who appears in a short piece titled Incredible Technology: How to Make Interstellar Spaceflight a Reality, along with Tau Zero Founder Marc Millis. Obousy is, in the best sense, an interstellar optimist.

Image: Richard Obousy, a tireless interstellar advocate now preparing for Starship Congress.

It was in Huntsville for the Tennessee Valley event that I heard Obousy use a phrase he repeated for Space.com’s Mike Wall: “I think a lot of people tend to overestimate what we can accomplish in the short term, in the next five to 10 years. But they also vastly underestimate what we can accomplish in the long term, decades or a century from now.” And that’s right on the money, because when we look ahead just a few years, we often see trends we think will accelerate, but over the long-term it’s often the factors we hadn’t yet considered that make all the difference.

I catch the same optimism in Marc Millis, who as former head of NASA’s Breakthrough Propulsion Physics project knows what it is like to be cut off at the knees by funding problems. Millis thinks the discovery of an Earth-like planet around another star will be a motivator for public engagement with space, resulting in the kind of interest that could spur demand for new exoplanet observatories and, we can hope, funding to support progress in propulsion. Advances in computer technology and the growth of commercial spaceflight, particularly through asteroid mining ventures that will extract resources and return them to Earth, should also help.

Obousy’s observation about underestimating what can happen over the long haul gibes with what David Deutsch argues in The Beginning of Infinity (Viking, 2011). Deutsch distinguishes between ‘prophecy’ and ‘prediction’ when talking about the future, prophecy being the discussion of things that are simply not knowable, whereas prediction involves conclusions that are based on good explanations. When we try to know the unknowable, we create a bias toward pessimism because we cannot know the shape or reach of future knowledge.

The growth of knowledge cannot change that fact. On the contrary, it contributes strongly to it: the ability of scientific theories to predict the future depends on the reach of their explanations, but no explanation has enough reach to predict the content of its own successors – or their effects, or those of other ideas that have not yet been thought of. Just as no one in 1900 could have foreseen the consequences of innovations made during the twentieth century – including whole new fields such as nuclear physics, computer science and biotechnology – so our own future will be shaped by knowledge that we do not yet have. We cannot even predict most of the problems that we shall encounter, or most of the opportunities to solve them, let alone the solutions and attempted solutions and how they will affect events. People in 1900 did not consider the Internet or nuclear power unlikely: they did not conceive of them at all.

Thus it may well be that the solutions we find in 2100 to problems that plague us today will come from directions we have yet to imagine. And I think the Icarus organizers are doing the smart thing by arranging their Starship Congress around time tracks: What can be done in the short-term to accelerate the progress of deep space research? What will be needed 20 to 50 years from now to achieve interstellar goals? And what can we say about longer timescales?

The interface between prediction and prophecy is a challenging place, demanding shrewd analysis and a mind open to possibility. Understanding how short-term prediction can turn into long-term prophecy reminds us of how easy it is to make blanket statements that are invalidated as new knowledge becomes available. Think of Albert Michelson’s address at the University of Chicago in 1894, when he argued that “The more important fundamental laws and facts of physical science have all been discovered, and these are now so firmly established that the possibility of their ever being supplanted in consequence of new discoveries is exceedingly remote… Our future discoveries must be looked for in the sixth place of decimals.”

Thus the view from 1894, with quantum theory and relativity looming in the near future. Deutsch would say that the physics of that year was not able to predict the content of its successors, that in fact it was not capable even of imagining the kind of changes quantum theory and relativity would bring. Comments like Michelson’s should keep us humble as we look ahead.

Millis makes much the same point in Mike Wall’s article. He’s been describing the kind of technologies under investigation for advanced propulsion, which include nuclear fusion, solar and beamed-energy sails, antimatter engines and interstellar ramjets. But as he tells Wall, none of these alternatives other than solar sails are even close to being flight-ready. Even the sails we’ve launched are experimental and far smaller than what would be needed for interstellar flight, nor have we any experience in accelerating actual sails in space through beamed energy.

But we want to move forward, and Millis thus advocates “a reasonable portfolio, a small amount spread over everything from the seemingly simple solar sails to the seemingly impossible faster-than-light [engines], and the things in between.” The goal should be to move forward through a series of achievable milestones to build momentum and attract funding. Or as Lao Tzu once put it, “You accomplish the great task by a series of small steps.”

Image: Interstellar researcher and Tau Zero founder Marc Millis.

We don’t know which propulsion option will be the one to take us to the stars, but as Deutsch would remind us, we don’t even know whether the one that actually succeeds is on our current list, because we may not have conceived of it yet. Something the philosopher Karl Popper once said sticks with me. This is from his The Myth of the Framework (Routledge, 1996):

The possibilities that lie in the future are infinite. When I say ‘It is our duty to remain optimists,’ this includes not only the openness of the future but also that which all of us contribute to it by everything we do: we are all responsible for what the future holds in store. Thus it is our duty, not to prophesy evil but, rather, to fight for a better world.

Martin Rees’ ideas on how humans will adapt to starflight, discussed here yesterday, offer plenty of ground for speculation and good science fiction. After all, the path ahead forks in many directions, one of them being the continuing development of artificial intelligence to the point where ‘artilects’ rather than humans become the logical crew for star missions. If decades or even centuries are needed to cross to another system, then this gets around the problem of keeping people sane and cooperating across what might be generations of voyaging.

Another fork is biological, with humans being gradually engineered to make them more adaptable to environments they’ll find at their destination. Here we can imagine crews sent out in some kind of deep hibernation, their biology tweaked to allow a ready transition to the new planet. Or perhaps cyborg solutions suggest themselves, with humans augmented by digital technologies to deal with problems and interface directly with critical shipboard computer systems.

I always think of Freeman Dyson when speculating about these things because back in 1985, he lectured in Aberdeen on a one kilogram deep space probe that would be as much biological as mechanical, a genetically engineered symbiosis of animal, plant and electronics. Dyson saw the animal component as providing sensors and nerves and muscles for basic operations and navigation, while electronics dealt with communications and data return. The plant component offered a closed-cycle biochemistry fed by sunlight. Artificial intelligence would integrate all operations in a probe he described as ‘agile as a hummingbird, with a brain weighing no more than a gram.’

You can read about the concept in Dyson’s Infinite in All Directions (Harper & Row, 1988), and you might pair it with Anders Hansson’s paper “Towards Living Spacecraft,” which ran in the Journal of the British Interplanetary Society in 1996. In the same Starship Century volume as the Martin Rees essay is Dyson’s latest thinking on the matter, a lively piece called “Noah’s Ark Eggs and Viviparous Plants.” Like Rees, Dyson is captivated with the tools that molecular biology is giving us and sees them as a way to seed the universe with life, turning inhospitable venues into living worlds [video].

After all, we are now learning the language of the genome and have sequenced the genomes of several thousand species. As the speed of such sequencing increases and the costs decline, it will take no more than twenty years or so to sequence the genomes of all species now existing on our planet. It turns out that describing the entire biosphere does not take up all that much space. In fact, Dyson writes, the information content of the biosphere genome comes to something on the order of one petabyte, which is less than the amount of data held by Google. “The biosphere genome,” he writes, “could be embodied in about a microgram of DNA, or in a small room full of computer memory disks.”

The larger vision here is that we can’t talk about permanent human settlement away from Earth unless we learn how to grow complete ecosystems in remote places. Here’s the concept:

It is not enough to have hotels for humans. We must establish permanent ecological communities including microbes and plants and animals, all adapted to survive in the local environment. The populations of the various species must be balanced so as to take care of each others’ needs as well as ours. Permanent human settlement away from Earth only makes sense if it is part of a bigger enterprise, the permanent expansion of life as a whole. The best way to build human habitats is to prepare the ground by building robust local ecologies. After life has established itself with grass and trees, herbivores and carnivores, bacteria and viruses, humans can arrive and build homes in a friendly environment. There is no future for humans tramping around in clumsy spacesuits on lifeless landscapes of dust and ice.

But Dyson doesn’t stop at the kind of worlds we would consider suitable for humans. He’s talking about going well beyond this, designing biosphere populations that can survive in environments ranging from planetary moons to comets. He imagines future bioengineers designing biosphere genomes for such places (these are the Noah’s Ark Eggs of his title) and seeding them in venues like the outer Solar System, where warm-blooded plants that can collect energy from sunlight would begin the process of building an ecosystem. Many biospheres would fail but those that survived would evolve in unpredictable ways as they adapt to small, cold places without atmospheres. You can see that Dyson’s emphasis is on life at large, not just humans.

How would you engineer a warm-blooded plant? Dyson thinks even objects as distant as the Kuiper Belt could become homes for life if we can do something like this:

Two external structures make warm-blooded plants possible, a greenhouse and a mirror. The greenhouse is an insulating shell protecting the warm interior from the cold outside, with a semi-transparent window allowing sunlight or starlight to come in but preventing heat radiation from going out. The mirror is an optical reflector or system of reflectors in the cold region outside the greenhouse, concentrating sunlight or starlight from a wide area onto the window. Inside the greenhouse are the normal structures of a terrestrial plant, leaves using the energy of incoming light for photosynthesis, and roots reaching down into the icy ground to find nutrient minerals.

Comets have plentiful sources of carbon and oxygen along with nitrogen and other key elements. Sunlight at a distance of 100 AU is reduced by a factor of ten thousand, but even the human eye can concentrate incoming light onto a spot on the retina by a factor larger than a million. So Dyson is arguing that a mirror as precise as a human eye could keep a plant warm at distances even further out than the Kuiper Belt. These self-grown mirrors would, like sunflowers, track the Sun as it moves across the sky. Plants like these would also be viviparous, with the seeds developing into viable plants before being dispersed into the frigid waste around them.

Stop being provincial, Dyson is telling us: Instead of focusing on how to find or re-create exactly Earth-like conditions wherever you go, think about helping life itself to spread into environments where it does not now exist. Give life this chance and let evolution take over to lead where it will. Seeding the universe may lead to places utterly incapable of supporting people like us, but extend the tools of molecular biology far enough and the explorers of the far future may adapt themselves to the environments they have shaped. ‘A terrible beauty is born,’ Yeats once wrote about a different kind of transformation, but in that beauty may lie habitats for new beginnings.

How we’ll go to the stars is often a question we answer with propulsion options. But of course the issue is larger than that. Will we, for example, go as biological beings or in the form of artificial intelligence? For that matter, if we start thinking about post-human intelligence, as Martin Rees does in the recently published Starship Century, are we talking about reality or a simulation? As the Swedish philosopher Nick Bostrom has speculated, a supremely advanced culture could create computer simulations capable of modeling the entire universe.

Rees recapitulates the argument in his essay “To the Ends of the Universe”: A culture that could create simulations as complex as the universe we live in might create virtual universes in the billions as a ripe domain for study or pure entertainment, allowing a kind of ‘time travel’ in which the past is reconstructed and the simulation masters can explore their history. So there we have a play on the nature of reality itself and the notion that our perceptions are constricted — as limited, Rees says, “as the perspective of Earth available to a plankton whose ‘universe’ is a spoonful of water.’

It’s a mind-blowing thought and Rees uses it to point out that our concepts of physical reality may need adjustment. What engages him about post-human evolution, though, isn’t the simulation speculation as much as the idea that genetic modifications and a simultaneous advance in machine intelligence will allow the kind of ‘directed’ evolution we’ll need if we are to expand into colonies beyond Earth. Here’s the argument compacted into a paragraph:

Darwin himself realised that ‘No living species will preserve its unaltered likeness into a distant futurity.’ We now know that ‘futurity’ extends much farther, and alterations can occur far faster than Darwin envisioned. And we know that the cosmos, through which life could spread, offers a far more extensive and varied habitat than he ever imagined. So humans are surely not the terminal branch of an evolutionary tree, but a species that emerged early in the overall roll-call of species, with special promise for diverse evolution — and perhaps of cosmic significance for jump-starting the transition to silicon-based (and potentially immortal) entities that can more readily transcend human limitations.

Humanity’s Special Moment?

Rees thinks we are at a special moment in time, a century that is the first occasion when the fate of the entire planet is in the hands of a single species. It’s also the century when we have the capability of starting the expansion of human life into the rest of the Solar System and beyond. This thought will recall Rees’ 2003 book Our Final Century (published in the US as Our Final Hour), whose subtitle says it all: ‘A Scientist’s Warning: How Terror, Error, and Environmental Disaster Threaten Humankind’s Future In This Century – On Earth and Beyond.’ There follows a study of the risk factors that hang over our culture’s head.

Which do you think would be the most likely cause of our demise? The possibilities are legion, ranging from environmental collapse to biological terrorism or the inadvertent results of using new technology, perhaps in the release of nanotechnology that goes out of control. The argument in the essay is similar to the book, that we have the ability to surmount these problems if we are wise enough to expand the frontiers of science and of exploration. The outcome is by no means certain but I think the picture may look darker than it really is, for while we can see the problems Rees outlines emerging, we cannot know what new knowledge we will gain as we confront them that will make solutions possible. Put me, then, on the more optimistic side of Rees’ speculations, a space the Astronomer Royal dwells on in this essay.

Let’s assume, then, that the outcome is indeed human survival and movement into space. That calls for near-term solutions to re-energizing the global space effort. How do we avoid the blunders of the past, the failure to follow up the Apollo landings with a credible and sustained program to continue manned exploration? The answer may well lie in private funding:

Unless motivated by pure prestige and bankrolled by superpowers, manned missions beyond the moon will need perforce to be cut-price ventures, accepting high risks — perhaps even ‘one-way tickets.’ These missions will be privately funded; no Western governmental agency would expose civilians to such hazards.

Here, of course, we think of Inspiration Mars, the plan to send a crew of two on a Mars flyby with launch in 2018, or the Dutch Mars One program, in which settlers would go to Mars knowing they would not be returning. Rees continues:

There would, despite the risks, be many volunteers — driven by the same motives as early explorers, mountaineers, and the like. Private companies already offer orbital flights. Maybe within a decade adventurers will be able to sign up for a week-long trip round the far side of the Moon — voyaging farther from Earth than anyone has been before (but avoiding the greater challenge of a Moon landing and blast-off). And by mid-century the most intrepid (and wealthy) will be going farther.

On Risk as Necessity

That scenario winds up with human outposts scattered through the Solar System, beginning with Mars or, perhaps, the asteroids. The post-human era may begin as we bring genetic engineering to bear on making ourselves more adaptable to such radically alien environments. A parallel development in artificial intelligence will make it an open question whether our forays beyond the Solar System are conducted by human or machine or a mixture of both. Given the time-scales involved in interstellar journeys, any human crews would be heavily modified, but it’s more likely that they will be non-biological entities altogether, adapted for long and solitary exploration.

Is interstellar travel possible? The answer may well be yes, but for whom? Rees’ point is that the options will grow as we gain experience with the new environments we explore. SETI may help us find extraterrestrial intelligence, but maybe not. Either way, evolution into the post-human era will be driven by the imperative to protect — and extend — the species. Whether or not such extension leads in the course of millennia to a Kardashev Type III civilization, actively shaping the fate of its entire galaxy, will depend at least in part upon our ability to transcend the kind of existential risks Rees discusses in Our Final Century.

Where I disagree with Rees is in the implication that, the risks of our century being solved, we will have transcended them. Risk survival is a continual process activated by the very breakthroughs in technology and exploration the astrophysicist here explores. We can only imagine what kind of dangers a rapidly growing starfaring culture would expose itself to purely in terms of its own engineering, not to mention its possible encounters with other civilizations.

Our encounter with risk has always been a precondition for our encounter with life, making the 21st Century a bit less unique than Rees would have it, but no less significant for the opportunity it offers to re-evaluate and once again engage the inevitable risks of growing starward.