Centauri Dreams

One of the things I love about writing Centauri Dreams is that I learn something new every day. Often this comes from the research needed for individual stories, but just as often it comes from readers suggesting new directions or seeing nuances in an earlier story that I had missed. Yesterday’s post on long-term thinking led to an exchange with Centauri Dreams regular NS, who questioned my ideas on longevity in the Middle Ages, and before long we were both digging up data to try to discover what the numbers really are. It’s an ongoing process, and if you’re interested in such arcana, you can follow it in yesterday’s comments thread.

If you’re just joining us and wondering why we’re discussing medieval longevity, it ties into what I was saying about long-haul construction projects like cathedrals, and the question of what a worker on one of these projects might have thought of his chances of seeing its completion. You can also chalk it up to a fascination with the Middle Ages that has always preoccupied me.

Of course, my interest in long-haul projects doesn’t mean I wouldn’t welcome much faster transportation methods to get to the stars than the worldships I sometimes write about. My friends at Icarus Interstellar have their own worldship study, Project Hyperion, in progress in the capable hands of Andreas Hein, but they also have as their centerpiece Project Icarus, which is an attempt to design a fusion starship that some of their members believe can fly in this century. This seems wildly optimistic to me but I would love to be proven wrong. Icarus Interstellar president Richard Obousy discussed all these matters at the recent workshop in Huntsville.

An Eye on Breakthrough Propulsion

“Interstellar Flight from Conception to Reality” was the title of his talk, and in it Obousy made the case that one of the drivers for the new enthusiasm for interstellar flight is the wildly accelerating pace of exoplanet discovery. He sees exploration as the ‘expression of a curious and energetic species,’ one also becoming aware of the need for planetary defense and the imperative for developing skills in deep space. But one of his key points — and I’ve heard him say this before — is that we tend to overestimate what we can do on a short time-frame, and underestimate what we can do over longer periods.

It’s a heartening thought for me because it means interstellar flight might take place sooner than the several centuries ahead I normally consign it to. Obousy ran through key discoveries at the atomic level, pointing out that it was no more than 70 years after we refined the model of the atom through the discovery of electrons, protons and neutrons that we developed the first nuclear thermal rocket. The history of flight tells the same tale. We have gone from theory to experiment to useful technology in a numbingly short time, from Kitty Hawk to the Moon landings.

Image: I don’t know why Richard Obousy would be difficult to photograph, but my shots of him from the conference all had one or another thing wrong with them, so I’m pulling this one from the Icarus Interstellar site.

While running through interstellar options from fusion to antimatter, Obousy told the Huntsville audience that he had a deep interest in breakthrough propulsion ideas, the kind of thing once actively studied at NASA through the Breakthrough Propulsion Physics project under Marc Millis. If we can go from Maxwell’s equations on electromagnetism to the world we see today in so short a time, what might we pull out of the theoretical physics of dark energy in another hundred years? In a way, it could be said that the Victorian era was the birthplace of the nuclear rocket, and Obousy wonders what string theory, supersymmetry, dark energy and dark matter may ultimately lead to as we take a similar path from theory to experiment to technology.

“Theoretical physics is the key to a future interstellar civilization,” Obousy said, suggesting that a world-class technical team could grow up around these ideas working one day with a breakthrough propulsion physics research lab. Icarus Interstellar obviously has such a project in mind as Obousy charts its future direction, and the beauty of the approach is that in gathering momentum, such an effort need not be costly, for the emphasis right now remains on theory rather than experiment as we chart the early stages of some of these concepts. We have much to learn. What constraints do the laws of physics place on advanced civilizations? What exactly is the dark energy field that evidently exerts negative pressure on spacetime?

Beginning of Interstellar Studies

Kelvin Long, president of the Institute for Interstellar Studies and editor of the Journal of the British Interplanetary Society, noted in his talk that a 2007 BIS conference had worked through many of the issues raised by Miguel Alcubierre in an often-referenced 1994 paper. It was Alcubierre who studied how spacetime could be warped to accelerate a spacecraft, identifying the basic physics problems that would have to be solved if such a thing were to happen (the conference identified nineteen of these, a daunting figure). The premise here is that while no object can move through spacetime faster than light, spacetime itself has no such restriction, as assumed through theories of cosmic inflation in the early moments of the universe.

But Long paused only briefly on Alcubierre. His intent was to offer an overview of interstellar concepts, and in doing so he ran through the contribution made by the BIS not only with an early Moon mission design but also through Project Daedalus, the fusion starship that came out of late-night sessions in various London pubs back in the 1970s (particularly the Mason’s Arms, I’m told — is it still there?). At the party before the conference, Kelvin talked to me about his view that interstellar studies really began with Les Shepherd’s 1952 paper “Interstellar Flight” (JBIS, Vol. 11, pp. 149-167). I think it’s a reasonable assumption, because Shepherd’s was the first paper I know of to approach the question with true scientific rigor.

In fact, Shepherd did a little worldship building of his own, as I noted in an obituary of the man written about a year ago. I’ll run the same quote I did then to make the point:

It is obvious that a vehicle carrying a colony of men to a new system should be a veritable Noah’s Ark. Many other creatures besides man might be needed to colonize the other world. Similarly, a wide range of flora would need to be carried. A very careful control of population would be required, particularly in view of the large number of generations involved. This would apply alike to humankind and all creatures transported. Life would go on in the vehicle in a closed cycle, it would be a completely self-contained world. For this and many other obvious reasons the vehicle would assume huge proportions: it would, in fact, be a very small planetoid, weighing perhaps a million tons excluding the dead weight of propellants and fuel. Even this would be pitifully small, but clever design might make it a sufficiently varied world to make living bearable.

But the paper goes on to look at antimatter options that could take starships up to relativistic speeds and considers not only time dilation but also the problems of running into stray gas and dust along the way. It’s a classic that’s well worth re-reading today. And it’s worth remembering that the JBIS ‘red cover’ issues devoted to interstellar studies set the standard for innovative thinking on the topic for many years. Although the British Interplanetary Society has run into a host of problems in the past few years, it’s heartening to see how much Kelvin has achieved as the new editor of JBIS in getting the publication back on schedule. Well done, sir.

I won’t go through all the interstellar propulsion concepts that Long and Obousy presented because they’re already part of our continuing discussion in these pages. Instead, I’ve asked both for a Centauri Dreams contribution, Obousy to talk about where Icarus Interstellar now stands and Long to give us more about JBIS and its history, including the fascinating fact that Project Daedalus came about largely to make a point about the Fermi paradox. Calling Daedalus ‘a balance between being credible and being bold,’ Long noted that even the most improbable starship design — if it could be shown to be feasible for future engineering — would have ramifications for Fermi’s ‘where are they’? question.

More on this in coming days, along with a series of stories on a space power concept that would constitute an essential early step in our building of a system-wide infrastructure. I’m also hoping to discuss an idea that is making a comeback, the colony starships of Robert Enzmann. Consolidating ideas from the Huntsville conference should keep me busy for quite some time.

I conceived an early love for Tennyson, but it wasn’t until a bit later in life that I ran into his “Locksley Hall,” which contains lines many science fiction fans are familiar with:

Many a night I saw the Pleiads, rising thro’ the mellow shade,
Glitter like a swarm of fire-flies tangled in a silver braid.

When I dipt into the future far as human eye could see;
Saw the Vision of the world and all the wonder that would be.—

and so on. The poem is the lament of a soldier returning to the places of his boyhood and eventually turning his thoughts, and his resolve, on the future. When I read the line ‘the long result of time,’ I realized that it was here that I found resonance with the poet. The idea of a remote futurity and the need to build its foundations now was a powerful motivator.

Building Structures That Last

A sense of that futurity pervaded our recent sessions at the Tennessee Valley Interstellar Workshop in Huntsville. Several speakers alluded to instances in human history where people looked well beyond their own generation, a natural thought for a conference discussing technologies that might take decades if not centuries to achieve. We talked about a solar power project that might take 35 years, or perhaps 50 (much more about this in coming days).

The theme became explicit when educator and blogger Mike Mongo talked about getting interstellar issues across to the public, referring to vast projects like the pyramids and the great cathedrals of Europe. Cathedrals are a fascinating study in their own right, and it’s worth pausing on them as we ponder long-term notions. Although they’re often considered classic instances of people building for a remote future, some cathedrals were built surprisingly quickly. Anyone who has stood in awe at the magnificent lines of Chartres southwest of Paris is surprised to learn that it came together in less than 60 years (the main structure in a scant 26), though keep in mind that this was partly a reconstruction of an earlier structure that dated back to 1145.

Image: The great cathedral at Chartres.

With unstinting public support, such things could happen even with the engineering of the day, creating what historians now view as the high point of French Gothic art. Each cathedral, of course, tells its own tale. Salisbury Cathedral was completed except for its spire in 45 years. Other cathedrals took longer. Notre Dame in Paris was the work of a century, as was Lincoln Cathedral, while the record for cathedral construction surely belongs to Cologne, where the foundation stone was laid in 1248. By the time of the Reformation 300 years later, the roof was still unfinished, and later turmoil pushed the completion of the cathedral all the way into the 19th Century, with many stops and starts along the way.

Remember, too, that the cathedral builders lived at a time when the average lifespan was in the 30s. The 15-year old boy who started working on the foundation of a cathedral might have hoped to see its consecration but he surely knew the odds didn’t favor it. Humans are remarkably good at this kind of thing, even if the frenetic pace and short-term focus of our times makes us forget it. Robert Kennedy pointed out to me at the conference that the Dutch dike system has been maintained for over 500 years, and can actually be traced back as far as the 9th Century. The idea of technology-building across generations is hardly something new to our civilization.

The ‘long result’ context is an interesting one in which to place our interstellar thinking. Naturally we’d like to make things happen faster than the 4000-year plus journeys I talked about on Friday with worldships, though my guess is that as the species becomes truly spacefaring and begins to differentiate, we’ll see colonies aboard O’Neill-class cylinders holding thousands, many of the colonists being people who will spend less and less time on a planetary surface. At some point, it would be entirely natural to see one of these groups decide to head into the interstellar deep. They would be, after all, taking their world with them, a world that was already home.

Evolutionary Change in Space

Gerald Driggers is a retired engineer and current science fiction author who worked with Gerald O’Neill in the 1970s. I see him as worldship material because he has chosen for the last seventeen years to live on a boat, saying “It was the closest thing I could get to a space ship.” Driggers believes we can begin our interstellar work by getting humans to Mars, where they will be faced with many of the challenges that will attend much longer-term missions. We must, after all, build a system-wide infrastructure, mastering the complexities of power generation and resource extraction on entirely new scales, before we can truly hope to go interstellar.

And what happens to humans as they begin working in extreme environments? Evolution doesn’t stop when we leave the planet, as Freeman Dyson is so fond of pointing out. These are changes that should be beneficial, says Driggers. “Evolutionary steps toward becoming interstellar voyagers reduce the chances for human failures on these journeys. We’re going to change, and we will continue to change as we look toward longer voyages. The first humans to arrive around another star system probably won’t be like anybody in the audience today.” Responding to evolutionary change, Martians may make the best designers and builders of interstellar craft.

Image: Gerald Driggers discussing a near-term infrastructure that will one day support interstellar missions.

Get it right on Mars, in other words, and we get it right elsewhere and learn the basics of infrastructure building all the way to the Kuiper Belt, with active lunar settlements and plentiful activity among the asteroids. Along the way we adapt, we change. Driggers’ worst-case scenario has Martian settlements delayed until the mid-22nd Century, but he is hopeful that the date can be moved up and the infrastructure begun.

All of which brings me back to something Mike Mongo talked about. We are not going to the stars ourselves, but we can inspire and train people who will solve many of the technical problems going forward, just as they train the next generation. One of these generations will one day train the crew of the first human interstellar mission, or if we settle on robotics, the controllers who will manage our first probes. Placing ourselves in the context of the long result acknowledges our obligation to future generations as we begin putting foundation stones in place.

It’s surprising but gratifying that we can now talk about the ‘interstellar community.’ Just a few years back, there were many scientists and engineers studying the problems of starflight in their spare time, but when they met, it was at conferences dedicated to other subjects. The fact that the momentum has begun to grow is made clear by the explicitly interstellar conferences of recent memory, from the two 100 Year Starship symposia to the second Tennessee Valley Interstellar Workshop. Icarus Interstellar is mounting a conference this August in Dallas, and the Institute for Interstellar Studies plans its own gathering this fall in London.

Of course the Internet is a big part of the picture — Bob Forward and his colleagues could use the telephone and the postal service to keep in touch, but the energizing power of instant document exchange and online discussion was in the future. All this was apparent in Huntsville for the Tennessee Valley event, from which I have just returned. There was an active Twitter channel open and video streaming of the talks, and although I had little time to answer them, I was getting emails from many interested parties who couldn’t attend. Getting copies of papers and presentations after the conference closed can be managed in hours on the Net.

Starflight challenges not only everything we know about propulsion but also our understanding of human nature. If we are seriously considering human travel to such distant destinations, we are looking at decades of travel time at a bare minimum, or the possibility of a generation ship in which people live their lives entirely aboard the craft, which could take hundreds or even thousands of years to reach its destination. Astronaut Jan Davis, who gave the keynote in Huntsville, talked about the various problems of even short duration spaceflight based on her own experience of multiple Shuttle missions.

Image: Rockets dominate the Huntsville skyline in this shot I took from the Calhoun Community College on the final night of the workshop.

Some of these issues are well identified, including the lack of privacy and the loss of muscle and bone mass due to prolonged weightlessness. The privacy issue balances oddly with a sense of isolation, Davis said, as you are cut off from all aspects of your normal life. “You hear a lot of voices, but they’re not the voices you take for granted every day. I missed my dog. I missed sounds like wind, waves hitting the shore. You’re busy, but you’re also isolated.” As medical officer on her two flights, Davis trained on emergency procedures in case a crewmember became incapacitated. The main issue was to stabilize a patient long enough that he or she could be swiftly returned to Earth.

The conclusion from all this is that humans are adapted for Earth, not space, yet they have key advantages over robotic systems, including the ability to discern, judge and learn on a fine-grained basis. Swiftly changing conditions in an on-board experiment she was managing led Davis to alter the schedule on the fly, making changes that would have been difficult for the current generation of robotics. The astronaut sees a combination of the two paradigms as the most likely possibility for long-term missions, perhaps aided by medical breakthroughs in hibernation that would allow the crew to spend most of a long mission in stasis while automatic systems ran the ship.

Robert Hampson (Wake Forest University) extended thinking in this direction by talking about what we need to learn about the human brain before we can contemplate long-duration spaceflight with an interstellar reach. Hampson is an associate professor of physiology and pharmacology with a passion for neuroscience and biology. Given what we know today about risk factors like stroke, epilepsy and Alzheimer’s disease, he notes that if we launch 100 people on a 100 year journey, 25 of them will be incapacitated by the time they arrive even if we can extend their lifetimes significantly. Interstellar flight, then, demands that we learn to predict and prevent degenerative diseases, keeping the brain healthy through entertainment and intellectual stimulation.

One way to do that is with a direct human/machine interface, a kind of TiVo wired into the brain. Hampson told the audience that to fix the brain for long-duration spaceflight, we have to find a way to interface with it, and that means we have to understand its language and coding. It’s a challenge that demands the help not just of the medical community but of mathematicians, physicists and engineers. As to the hibernation that Jan Davis talked about, Hampson asks how much we know about brain activity during hibernation. Is an astronaut under hibernation for fifty years going to have a fifty-year long dream?

I’m jumping around in the schedule here to tie thematic ends together, so I’ll add that my own talk, called “Slow Boat to Centauri,” got into long-duration mode by discussing worldships and how they could sustain themselves along the way. The idea was to show how many resources are available between the stars, suggesting as many space researchers have that our expansion might not involve a direct mission to another star, but rather a step-by-step progression of colonies that gradually moves the human sphere outward. Gradual exploration like this might take thousands of years.

We can all hope for fast propulsion, but suppose the engineering is intractable. Would we still go to the stars if limited to speeds much less than ten percent of c? One-tenth of one percent of lightspeed gets you to Alpha Centauri in about 4300 years, which is also (very roughly) the extent of human history in terms of recoverable documents and written language. A worldship moving at this speed, in other words, recapitulates the human historical experience aboard a craft that would have to be engineered to be a living world, a vast O’Neill cylinder with propulsion.

The right kind of worldship — and Gordon Woodcock (L5 Society) worked through the engineering problems of creating such a vessel in a first-day talk — would have to be one large enough to sustain a population of thousands in conditions that were eminently livable, the complete antithesis of the cramped quarters Jan Davis experienced aboard the Shuttle. We’re all on a worldship of our own, following our star in its 230 million year journey at 220 kilometers per second around the galaxy, so perhaps a livable worldship engineered by the future Kardashev type 1 civilization we hope to grow into would be an acceptable interstellar ark.

Image: A worldship designed to hold generations of humans, as imagined by space artist Adrian Mann.

Putting the speed issue in perspective, one tenth of one percent of the speed of light is 300 kilometers per second, compared to the 17 kilometers per second that our fastest deep space probe, Voyager 1, has attained. There are ways of moving that fast that we can calculate today, but the engineering needed to produce a worldship — and the vast issues raised by creating a closed-loop ecology aboard the craft — demand a multi-disciplinary approach that takes us into biology, philosophy, sociology and the humanities as well as physics. The long-term perspective needed for such thinking was frequently discussed in Huntsville, about which more on Monday.