Fusion Update: The Turn of Direct Drive

Inertial confinement fusion, or ICF, is one of the two “mainstream” approaches to harnessing nuclear fusion in the laboratory.  As its name would imply, it involves dumping energy into nuclear material, commonly consisting of heavy isotopes of hydrogen, so fast that its own inertia hold it in place long enough for significant thermonuclear fusion to occur.  “Fast” means times on the order of billionths of a second.  There are, in turn, two main approaches to supplying the necessary energy; direct drive and indirect drive.  In direct drive the “target” of fuel material is hit directly by laser or some other type of energetic beams.  In indirect drive, the target is mounted inside of a “can,” referred to as a “hohlraum.”  The beams are aimed through holes in the hohlraum at the inner walls.  There they are absorbed, producing x-rays, which supply the actual energy to the target.

To date, the only approach used at the biggest ICF experimental facility in the world, the National Ignition Facility, or NIF, at Lawrence Livermore National Laboratory (LLNL), has been indirect drive.  So far, it has failed to achieve the goal implied by the facility’s name – ignition – defined as more fusion energy out than laser energy in.  A lot of very complex physics goes on inside those cans, and the big computer codes used to predict the outcome of the experiments didn’t include enough of it to be right.  They predicted ignition, but LLNL missed it by over a factor of 10.  That doesn’t necessarily mean that the indirect drive approach will never work.  However, the prospects of that happening are becoming increasingly dim.

Enter direct drive.  It has always been the preferred approach at the Naval Research Laboratory and the Laboratory for Laser Energetics (LLE) at the University of Rochester, the latter home of the second biggest laser fusion facility in the world, OMEGA.  They lost the debate to the guys at LLNL as the NIF was being built, but still managed to keep a crack open for themselves, in the form of polar direct drive.  It would have been too difficult and expensive to configure the NIF beams so that they would be ideal for indirect drive, but could then be moved into a perfectly symmetric arrangement for direct drive.  However, by carefully tailoring the length and power in each of the 192 laser beams, and delicately adjusting the thickness of the target at different locations, it is still theoretically possible to get a symmetric implosion.  That is the idea behind polar direct drive.

With indirect drive on the ropes, there are signs that direct drive may finally have its turn.  One such sign was the recent appearance in the prestigious journal, Physics of Plasmas, of a paper entitled Direct-drive inertial confinement fusion: A review.  At the moment it is listed as the “most read” of all the articles to appear in this month’s issue, a feat that is probably beyond the ability of non-experts.  The article is more than 100 pages long, and contains no less than 912 references to work by other scientists.  However, look at the list of authors.  They include familiar direct drive stalwarts like Bob McCrory, John Sethian, and Dave Meyerhofer.  However, one can tell which way the wind is blowing by looking at some of the other names.  They include some that haven’t been connected so closely with direct drive in the past.  Notable among them is Bill Kruer, a star in the ICF business who specializes in theoretical plasma physics, but who works at LLNL, home turf for the indirect drive approach.

Will direct drive ignition experiments happen on the NIF?  Not only science, but politics is involved, and not just on Capitol Hill.  Money is a factor, as operating the NIF isn’t cheap.  There has always been a give and take, or tug of war, if you will, between the weapons guys and the fusion energy guys.  It must be kept in mind that the NIF was built primarily to serve the former, and they have not historically always been full of enthusiasm for ignition experiments.  There is enough energy in the NIF beams to create conditions sufficiently close to those that occur in nuclear weapons without it.  Finally, many in the indirect drive camp are far from being ready to throw in the towel.

In spite of that, some tantalizing signs of a change in direction are starting to turn up.  Of course, the “usual suspects” at NRL and LLE continue to publish direct drive papers, but a paper was also just published in the journal High Energy Density Physics entitled, A direct-drive exploding-pusher implosion as the first step in development of a monoenergetic charged-particle backlighting platform at the National Ignition Facility.  An exploding pusher target is basically a little glass shell filled with fusion fuel, usually in gaseous form.  For various reasons, such targets are incapable of reaching ignition/breakeven.  However, they were the type of target used in the first experiments to demonstrate significant fusion via laser implosion at the now defunct KMS Fusion, Inc., back in 1974.  According to the paper, all of the NIF’s 192 beams were used to implode such a target, and they were, in fact, tuned for polar direct drive.  However, they were “dumbed down” to deliver only a little over 43 kilojoules to the target, only a bit more than two percent of the design limit of 1.8 megajoules!  Intriguingly enough, that happens to be just about the same energy that can be delivered by OMEGA.  The target was filled with a mixture of deuterium (hydrogen with an extra neutron), and helium 3.  Fusion of those two elements produces a highly energetic proton at 14.7 MeV.  According to the paper copious amounts of these mono-energetic protons were detected.  Ostensibly, the idea was to use the protons as a “backlighter.”  In other words, they would be used merely as a diagnostic, shining through some other target to record its behavior at very high densities.  That all sounds a bit odd to me.  If all 192 beams are used for the backlighter, what’s left to hit the target that’s supposed to be backlighted?  My guess is that the real goal here was to try out polar direct drive for later attempts at direct drive ignition.

All I can say is, stay tuned.  The guys at General Atomics down in San Diego who make the targets for NIF may already be working on a serious direct drive ignition target for all I know.  Regardless, I hope the guys at LLNL manage to pull a rabbit out of their hat and get ignition one way or another.  Those “usual suspects” among the authors I mentioned have all been at it for decades now, and are starting to get decidedly long in the tooth.  It would be nice if they could finally reach the goal they’ve been chasing for so long before they finally fade out of the picture.  Meanwhile, I can but echo the words of Edgar Allan Poe:

Over the Mountains
Of the Moon,
Down the Valley of the Shadow,
Ride, boldly ride,
The shade replied —
If you seek for El Dorado.

Interstellar Travel: Which Species Gets to Go?

Popular Mechanics just published an article entitled How Many People Does It Take to Colonize Another Star System?  Apparently the number needed to maintain sufficient genetic diversity is very large indeed – 40,000 would be ideal!  Unfortunately, if you do the math, the amount of energy it would take to transport that many people to another star system, even allowing a couple of thousand years for the voyage, is enormous.  As several commenters pointed out, by the time our technology advances to the point that such missions are feasible, it will also be feasible to send the necessary “genetic diversity” along in the form of frozen eggs and sperm with carefully chosen DNA sequences, complete libraries of human alleles that can be fabricated and inserted into DNA sequences as needed, etc.  It might not even be necessary to send anything as bulky as fully formed humans on the voyage.  Self-replicating robots could be sent in advance to create housing, farms, and birthing facilities prepared to receive fertilized eggs.  The first humans born would have robotic “parents.”

It’s always fun to speculate on what we might be able to do assuming our technology becomes sufficiently advanced.  The question is, what can we do now, or at least in the foreseeable future with existing technologies, or ones that seem accessible in the near future?  “Existing technologies” means travel times of 25,000 years, give or take.  In other words, we must rule out our own species, at least for the time being.  It will be necessary for us to send some of our relatives.  For some of them – other species – such lengthy interstellar voyages are feasible now.  As I wrote in an earlier post,

The 32,000 year old seed of a complex, flowering plant recovered from the ice was recently germinated by a team of scientists in Siberia. Ancient bacteria, as much as 250 million years old have been recovered from sea salt in New Mexico, and also brought back to life. Tiny animals known as tardigrades have survived when exposed to the harsh environment of outer space. We might choose the species from among such candidates most likely to survive the 50,000 to 100,000 years required to journey to nearby stars with conventional rocket propulsion, and most likely to evolve into complex, land-dwelling life forms in the shortest time, and send them now, instead of waiting 100’s or 1000’s of years for the emergence of the advanced technologies necessary to send humans. Slowing down at the destination star would not pose nearly the problem that it does for objects traveling at significant fractions of the speed of light. The necessary maneuvers to enter orbit around and seed promising planets could be performed by on-board computers with plenty of time to spare. Oceans might be seeded with algae in advance of the arrival of organisms that feed on it (and breathe the oxygen it would release).

Why would we want to do such a thing?  Survival!  Morality exists only because animals equipped with it were more likely to survive.  We are one such animal.  There is no such thing as an objective “ought.”  However, given the reason that morality exists to begin with, the conclusion that nothing can be more immoral than failing to survive does not seem unreasonable.  It one accepts that logic, it follows that our first priority “should” be the survival of our own species, and our second should be the preservation of biological life.  It’s really just a whim, but I hope that many others will share it.  The alternative is to accept the fact that one is a defective biological unit, resigned to extinction, which I personally don’t find an entirely pleasant thought.

Let’s assume that a canonical voyage will last 25,000 years.  Conventional rockets are capable of reaching the nearest star systems in that time.  By using nuclear propulsion of the type that was successfully tested 50 years ago, we should be able to reach stars within a distance of a dozen light years or so within the same period.  As noted above, there are life forms that could survive the voyage.  The particular ones chosen would be those most compatible with the conditions existing on candidate planets.  Needless to say, the conditions of our own atmosphere, oceans, etc., have been drastically altered by the long existence of life on our planet.  Finding such conditions on reachable planets is most unlikely, and our biological voyagers must be chosen accordingly.

It will be necessary to develop certain technologies that we do not as yet possess.  Fortunately, they are all within reach, and nowhere near as demanding as, say, fusion or anti-matter propulsion systems.  For example, we will need a timing device that can keep “ticking” for 25,000 years, and, when necessary, signal the rest of the interstellar package to “wake up.”  The Long Now Foundation has made some interesting starts in this direction, in the form of giant mechanical clocks that are designed to run for 10,000 years.  Of course, those designs aren’t exactly what we’re looking for, but if one can conceive of a 10,000 year mechanical clock, than a 25,000 year digital clock must be feasible as well.  A similar problem was solved by John Harrison more than two centuries ago, in the form of a clock that kept time exactly enough to keep track of a ship’s longitude.  If he succeeded in solving the British Navy’s problem with the technology that existed then, we should be able to succeed in solving our own clock problem with a technology that is now far more advanced.

It will be necessary to develop systems that will perform reliably over extremely long times.  As it happens, that, too, is a problem that has already been taken in hand by earth-bound scientists.  The relevant acronym is ULLS (Ultra Long Life Systems), and some of the required technologies are discussed in a NASA presentation entitled, Technology Needs for the Development of the Ultra Long Life Missions.  Some of the ideas being considered include,

Generic Redundant Blocks – redundant components that are generic and can be programmed to replace any type of failed component.  An example might be field-programmable gate arrays (FPGA’s).

Adaptive Fault Tolerance – Working around failures instead of replacing failed components with spares.

Self-repair components – Including self-repair with nano-technologies and self-healing with biologically inspired technologies.

Regenerative systems – Modular regrow with biologically inspired technologies.

In interesting presentation on the subject by NASA scientist Henry Garrett, who happens to prefer Project Orion-type interstellar missions with propulsion by few kiloton nuclear devices, may be found here (sorry about the long-winded introduction).  Dave Reneke recently posted an interesting if somewhat speculative article  on various types of self-replicating interstellar probes entitled How Self-Replicating Spacecraft Could Take Over the Galaxy.

Of course, none of this fine technology will work without a reliable power supply that needs to last, potentially, for upwards of 25,000 years.  It so happens that we have just the isotope – plutonium 239.  You might call it the ultimate dual use material – life or death.  It is ideal for making nuclear bombs or carrying life across interstellar distances.  Of course, another isotope of plutonium, plutonium 238, has already been used to power many spacecraft, including the Voyagers and New Horizons.  Unfortunately, with a radioactive half-life of only 87.7 years, there would only be a few atoms of it left after 25,000 years.  Pu-239, on the other hand, has a half-life of 24,100 years – just about what’s needed.  Of course, it could only provide a tiny fraction of the power of Pu-238 via radioactive decay.  Not much is required, though – only enough to keep the clock going.  At key points in the mission, of course, a great deal more power will be necessary.  And that’s what brings us to the reason that Pu-239 is ideal – it’s fissile.  In other words, it’s an ideal fuel for a nuclear reactor.  When high power is needed, the plutonium can be assembled into a critical mass, serving as either a conventional reactor or a space propulsion system.

I am convinced that all of the above can be accomplished in a matter of a decade or two instead of centuries if we can somehow again achieve the level of collective willpower we reached during the Apollo Program.  Of course, this old planet of ours could easily go on supporting high tech human civilizations until we master the art of interstellar travel on our own.  It might – but why take chances?


But Wait! There are More “Worries” from The Edge!

I won’t parse all 150+ of them, but here are a few more that caught my eye.

Science writer and historian Michael Shermer, apparently channeling Sam Harris, is worried about the “Is-Ought Fallacy of Science and Morality.”  According to Shermer,

…most scientists have conceded the high ground of determining human values, morals, and ethics to philosophers, agreeing that science can only describe the way things are but never tell us how they ought to be. This is a mistake.

It’s only a mistake to the extent that there’s actually some “high ground” to be conceded.  There is not.  Assuming that Shermer is not referring to the trivial case of discovering mere opinions in the minds of individual humans, neither science nor philosophy is capable determining anything about objects that don’t exist.  Values, morals and ethics do not exist as objects.  They are not things-in-themselves.  They cannot leap out of the skulls of individuals and acquire a reality and legitimacy that transcends individual whim.  Certainly, large groups of individuals who discover that they have whims in common can band together and “scientifically” force their whims down the throats of less powerful groups and individuals, but, as they say, that don’t make it right.

Suppose we experience a holocaust of some kind, and only one human survived the mayhem.  No doubt he would still be able to imagine what it was like when there were large groups of other’s like himself.  He might recall how they behaved, “scientifically” categorizing their actions as “good” or “evil,” according to his own particular moral intuitions.  Supposed, now, that his life also flickered out.  What would be left of his whims?  Would the inanimate universe, spinning on towards its own destiny, care about them one way or the other.  Science can determine the properties and qualities of things.  Where, then, would the “good” and “evil” objects reside?  Would they still float about in the ether as disembodied spirits?  I’m afraid not.  Science can have nothing to say about objects that don’t exist.  Michael Shermer might feel “in his bones” that some version of “human flourishing” is “scientifically good,” but there is no reason at all why I or anyone else should agree with his opinion.  By all means, let us flourish together, if we all share that whim, but surely we can pursue that goal without tacking moral intuitions on to it.  “Scientific” morality is not only naive, but, as was just demonstrated by the Communists and the Nazis, extremely dangerous as well. According to Shermer,

We should be worried that scientists have given up the search for determining right and wrong…

In fact, if scientists cease looking for and seeking to study objects that plainly don’t exist, it would seem to me more reason for congratulations all around than worry.  Here’s a sample of the sort of “reasoning” Shermer uses to bolster his case:

We begin with the individual organism as the primary unit of biology and society because the organism is the principal target of natural selection and social evolution. Thus, the survival and flourishing of the individual organism—people in this context—is the basis of establishing values and morals, and so determining the conditions by which humans best flourish ought to be the goal of a science of morality. The constitutions of human societies ought to be built on the constitution of human nature, and science is the best tool we have for understanding our nature.

Forgive me for being blunt, but this is gibberish.  Natural selection can have no target, because it is an inanimate process, and can no more have a purpose or will than a stone.  “Thus, the survival and flourishing of the individual organism – people in this context – is the basis of establishing values and morals”??  Such “reasoning” reminds me of the old “Far Side” cartoon, in which one scientist turns to another and allows that he doesn’t quite understand the intermediate step in his proof:  “Miracle happens.”  If a volcano spits a molten mass into the air which falls to earth and becomes a rock, is not it, in the same sense, the “target” of the geologic processes that caused indigestion in the volcano?  Is not the survival and flourishing of that rock equally a universal “good?”

Of the remaining “worries,” this was the one that most worried me, but there were others.  Kevin Kelly, Editor at Large of Wired Magazine, was worried about the “Underpopulation Bomb.”  Noting the “Ur-worry” of overpopulation, Kelly writes,

While the global population of humans will continue to rise for at least another 40 years, demographic trends in full force today make it clear that a much bigger existential threat lies in global underpopulation.

Apparently the basis of Kelly’s worry is the assumption that, once the earths population peaks in 2050 or thereabouts, the decrease will inevitably continue until we hit zero and die out.  In his words, “That worry seems preposterous at first.”  I think it seem preposterous first and last.

Science writer Ed Regis is worried about, “Being Told That Our Destiny Is Among The Stars.”  After reciting the usual litany of technological reasons that human travel to the stars isn’t likely, he writes,

Apart from all of these difficulties, the more important point is that there is no good reason to make the trip in the first place. If we need a new “Earth 2.0,” then the Moon, Mars, Europa, or other intra-solar-system bodies are far more likely candidates for human colonization than are planets light years away.  So, however romantic and dreamy it might sound, and however much it might appeal to one’s youthful hankerings of “going into space,” interstellar flight remains a science-fictional concept—and with any luck it always will be.

In other words, he doesn’t want to go.  By all means, then, he should stay here.  I and many others, however, have a different whim.  We embrace the challenge of travel to the stars, and, when it comes to human survival, we feel existential Angst at the prospect of putting all of our eggs in one basket.  Whether “interstellar flight remains a science-fiction concept” at the moment depends on how broadly you define “we.”  I see no reason why “we” should be limited to one species.  After all, any species you could mention is related to all the rest.  Interstellar travel may not be a technologically feasible option for me at the moment, but it is certainly feasible for my relatives on the planet, and at a cost that is relatively trivial.  Many simpler life forms can potentially survive tens of thousands of years in interstellar space.  I am of the opinion that we should send them on their way, and the sooner the better.

I do share some of the other worries of the Edge contributors.  I agree, for example, with historian Noga Arikha’s worry about, “Presentism – the prospect of collective amnesia,” or, as she puts it, the “historical blankness” promoted by the Internet.  In all fairness, the Internet has provided unprecedented access to historical source material.  However, to find it you need to have the historical background to know what you’re looking for.  That background about the past can be hard to develop in the glare of all the fascinating information available about the here and now.  I also agree with physicist Anton Zeilinger’s worry about, “Losing Completeness – that we are increasingly losing the formal and informal bridges between different intellectual, mental, and humanistic approaches to seeing the world.”  It’s an enduring problem.  The name “university” was already a misnomer 200 years ago, and in the meantime the problem has only become worse.  Those who can see the “big picture” and have the talent to describe it to others are in greater demand than ever before.  Finally, I agree with astrophysicist Martin Rees’ worry that, “We Are In Denial About Catastrophic Risks.”  In particular, I agree with his comment to the effect that,

The ‘anthropocene’ era, when the main global threats come from humans and not from nature, began with the mass deployment of thermonuclear weapons. Throughout the Cold War, there were several occasions when the superpowers could have stumbled toward nuclear Armageddon through muddle or miscalculation. Those who lived anxiously through the Cuba crisis would have been not merely anxious but paralytically scared had they realized just how close the world then was to catastrophe.

This threat is still with us.  It is not “in abeyance” because of the end of the cold war, nor does that fact that nuclear weapons have not been used since World War II mean that they will never be used again.  They will.  It is not a question of “if,” but “when.”

Interstellar Travel Here and Now

The words “interstellar travel” seem to have generated some interesting data relevant to human behavior. Specifically, they generate a “good” moral intuition in some, and a “bad” moral intuition in others. There does not appear to be a linear relationship between the nature of the response, and the space occupied by the responder along the left/right political spectrum, or at least not yet. For example, Bill Clinton, who is identified, by conservatives, at least, as a “liberal,” recently gave a boost to DARPA’s 100 Year Starship Program. The similarly liberal editors of the New York Times, on the other hand, have just published a piece in their Op-ed section by astronomer Adam Frank heaping scorn on the very idea of travel to the stars. Perhaps the ideological divide will eventually become more focused, as the reasons given on the “bad” side tend to gravitate to the left. They include for example, the conclusion that only rich people will have the means to leave our home planet, leaving the poor, exploited masses behind on a planet they have polluted and despoiled, the belief that the result of interstellar distractions will be insufficient levels of alarm about problems such as global warming and overpopulation, diminished hopes of a peaceful world if there is some means of escaping the aftermath of the next world war, etc. The “good” reasons for interstellar travel tend to focus on existential threats, such as the possibility of a massive asteroid striking the earth, drastic swings in climate, whether natural or anthropogenic, and depletion of the earth’s resources. It has even been proposed that destructive humans be transplanted to other, less sensitive planets, leaving the earth as a “nature park” in space, presumably to be visited by interstellar tourists from time to time.

My own moral intuitions tend to favor survival as a prime virtue, so I support continued research towards enabling interstellar travel. After all, if we choose not to leave our home planet, our genetic descendants, whether in the long or the short run, are doomed to extinction. That said, I do not underestimate the difficulty of reaching the stars. Human interstellar travel will require massive amounts of energy stored in a much more concentrated form than chemical rocket fuels. The smaller the mass, the easier it is to accelerate to extreme velocities, so it may be that we will need to rely on seed ships to escape our home world. These would carry only eggs and sperm, or genetic material in a similarly compact form. Human beings would be born in artificial wombs, and raised by intelligent robots in prefabricated bases, perhaps constructed by self-replicating nano-robots at the destination planet.

All this, of course, assumes massive technological advances in many areas, and it is impossible to predict when and even if they will occur. In the meantime, I suggest we make a start with the technologies available now. We cannot leave the planet and expect to survive the trip across the vast interstellar voids at the moment, but other life forms, with all of which we share a direct, if distant ancestor, can. The 32,000 year old seed of a complex, flowering plant recovered from the ice was recently germinated by a team of scientists in Siberia. Ancient bacteria, as much as 250 million years old have been recovered from sea salt in New Mexico, and also brought back to life. Tiny animals known as tardigrades have survived when exposed to the harsh environment of outer space. We might choose the species from among such candidates most likely to survive the 50,000 to 100,000 years required to journey to nearby stars with conventional rocket propulsion, and most likely to evolve into complex, land-dwelling life forms in the shortest time, and send them now, instead of waiting 100’s or 1000’s of years for the emergence of the advanced technologies necessary to send humans. Slowing down at the destination star would not pose nearly the problem that it does for objects traveling at significant fractions of the speed of light. The necessary maneuvers to enter orbit around and seed promising planets could be performed by on-board computers with plenty of time to spare. Oceans might be seeded with algae in advance of the arrival of organisms that feed on it.

The travel time could be reduced significantly by using nuclear rockets similar to those which have already been built and tested decades ago. The nuclear reactors would be shut down during most of the journey. They would be activated again as the destination star was approached for deceleration and the necessary final maneuvers. During the journey, the small amounts of energy needed to power timing devices for signaling the nuclear reactors to resume operation when necessary, maintain minimal environmental life support conditions, etc., could be supplied using the same power source used by the Curiosity Rover. However, for such long voyages, plutonium 239 could be used instead of the plutonium 238 used on the rover. With a half life of over 25,000 years, it could supply a small but sufficient amount of energy during the long voyage and, perhaps, contribute power to the propulsion reactors at journey’s end.

Missions using such advanced nuclear technology could probably only be carried out by technologically advanced states. However, seeding of the planets around nearby stars with very simple life forms such as bacteria could be undertaken by private companies such as those now engaged in building rockets for missions such as resupplying the space station. The main problem they would need to solve would be how to bring the seed craft out of hibernation at the end of the voyage without access to a suitable radioactive material. Perhaps they could purchase enough americium 243 or some other radionuclide with a sufficient half-life to do the job. Solar panels would begin to generate electricity as the craft approached the target star, but none currently available are capable of surviving such a long voyage. Still, the amount of energy necessary to signal the propulsion and other systems to resume operation would be tiny, and this does not seem to be an insurmountable problem.

Why would this be “ethical”? Because it would enable the survival of the DNA-based life that has evolved on earth, to all forms of which we humans are related. There cannot be anything more immoral than failure to survive. Anyone who thinks otherwise lacks awareness of why morality exists to begin with.

Interstellar Transport: Freeman Dyson and Hydrogen Bomb Propulsion

And you thought I was crazy…  Check out this article by Freeman Dyson in the October 1968 issue of Physics Today entitled “Interstellar Transport.”  Dyson was an active participant in Project Orion, a program to build interplanetary space vehicles propelled by nuclear bombs.  After the program was ended by the 1963 nuclear test ban treaty, he decided to write a paper for a high visibility journal to insure that the idea was kept alive and people were aware of its potential.

People thought big in those days, and Dyson’s notional interstellar transports certainly reflected the fact.  The first was designed to absorb the blast of one megaton deuterium fueled bombs in a gigantic copper hemisphere with a radius of 10 kilometers weighing 5 million tons.  The fully loaded ship would have weighed 40 million tons, including 30 million of the one megaton bombs.  Assuming each bomb would require 10 pounds of plutonium (or about 60 pounds of highly enriched uranium), a total of 150,000 tons of plutonium would be required for the mission.

Dubious assumptions were made, as, for example, that 100% of the bomb’s energy would go into the kinetic energy of debris, even though it was known at the time (and certainly known to Dyson), that the actual fraction is much less than that.  The cost was calculated to be one 1968 gross national product, based entirely on the projected cost of the necessary deuterium fuel (3 billion pounds at $200 per pound in 1968 dollars, for a total of $600 billion.)  In other words, the cost of the plutonium, copper, and other building material wasn’t even factored in, nor was the cost of getting it all into earth orbit prior to launch.  In spite of all this, the massive ship, carrying about 20,000 colonists, would still take about 1300 years to reach the nearest stars.  Barring a “Noah’s ark” forlorn hope escape from a dying world, even Dyson considered this impractical for human travel, writing,

As a voyage of colonization a trip as slow as this does not make much sense on a human time scale.  A nonhuman species, longer lived or accustomed to thinking in terms of millennia rather than years, might find the conditions acceptable.

To obviate some of the objections of this “conservative” design, Dyson also proposed an “optimistic” design, which allowed some ablation of the surface of the vehicle nearest to the explosions, rather than requiring all the energy to be absorbed in solid material.  After removing this energy limitation, the main limitation on the ship’s performance would be imposed by momentum, or, as Dyson put it, “the capacity of shock absorbers to transfer momentum from an impulsively accelerated pusher plate to the smoothly accelerated ship.”  Basing his reasoning on the optimum performance of practical shock absorbers, Dyson calculated that such a ship could be accelerated at a constant one g, enabling it to reach the nearest stars in centuries rather than millennia.  The cost, again based solely on the value of the deuterium fuel, would be only $60 billion 1968 dollars, or a tenth of the GNP at that time.  The weight of the ship would be “only” 400,000 tons, a factor of 100 less than that of the “conservative” design.  Dyson concluded,

If we continue our 4% growth rate we will have a GNP a thousand times its present size in about 200 years.  When the GNP is multiplied by 1000, the building of a ship for $100B will seem like building a ship for $100M today.  We are now building a fleet of Saturn V which cost about $100M each.  It may be foolish but we are doing it anyhow.  On this basis, I predict that about 200 years from now, barring a catastrophe, the first interstellar voyages will begin.

I suspect Dyson wrote most of this paper “tongue in cheek.”  He’s nobody’s fool, has remarkable achievements to his credit in fields such as quantum electrodynamics, solid state physics, and nuclear engineering, and remains highly regarded by his peers.  Nobel laureate Steven Weinberg said that the Nobel Committee had “fleeced” Dyson by never awarding him the prize.  The objections to his designs are obvious, but for all that, bomb-propelled space vehicles are by no means impractical.  I suspect Dyson realized that other scientists would recognize ways they could improve on his “conservative” and “optimistic” designs as soon as they read the paper, and start thinking about their own versions.  Project Orion might be dead as a budget line item, but would live on in the minds and imaginations of his peers.  And so it did.

Why Not Start Interstellar Travel Now?

Google “interstellar propulsion” and you will find all kinds of speculative schemes for reaching the nearest stars with propulsion systems based on controlled fusion, harnessing of anti-matter, and any number of other speculative technologies that don’t yet exist.  Well, actually, fusion technology does exist and is, in fact, quite mature, in the case of thermonuclear explosives, and Project Orion was an entirely practical scheme for harnessing that technology, but that approach is probably ruled out by political considerations for the time being.  In any case, all these schemes are based on the assumption that travel times must be measured in decades or, at worst, a few centuries.  My question:  “What’s the hurry?”

We have already demonstrated the practicality of interstellar travel with Voyagers 1 and 2 and several other probes.  Reasonably achievable travel times to nearby stars using chemical rockets and payloads weighing on the order of a ton are around 50,000 years.  I suggest such voyages be launched with the purpose of seeding as many planets as possible with earth life forms.

And what of the “ethics” of that endeavor?  To answer that question, one must have a clear understanding of what morality is, and why it exists.  The British philosopher David Hume discovered what it is centuries ago.  As he put it,

Morality is nothing in the abstract nature of things, but is entirely relative to the sentiment or mental taste of each particular being, in the same manner as the distinctions of sweet and bitter, hot and cold arise from the particular feeling of each sense or organ. Moral perceptions, therefore, ought not to be classed with the operations of the understanding, but with the tastes or sentiments.

Cast in more modern terms, that means that the ultimate source of morality, or the perception of objects and actions as good or evil, lies in human emotional traits.  Absent those traits, morality and, with it, good and evil, would cease to exist.  Like most of our other significant characteristics, moral emotions exist because they evolved.  The only reason they evolved is because they happened to increase the chances that creatures bearing those traits would survive and reproduce.  In other words, when it comes to ultimate Goods, nothing trumps survival.  I propose we seed nearby planets with life in order to survive.

Of course, our species is not capable of surviving a voyage of 50,000 years.  Other species, however, are.  There are no human beings on the planet identical to me.  All of them are more or less related to me.  I am somewhat more distantly related to every other life form on the planet.  We all share a common ancestor.  If my species cannot survive the voyage, let others go.  That works for me.  My overriding interest is that life survive.  How long it will do so on our home planet is uncertain.  However, the quality of the environment is deteriorating rapidly, and I prefer not taking chances.

What life forms shall we send?  Certain forms of bacteria have survived a dormancy of 250 million yearsTardigrades or “water bears,” far more complicated animals with tens of thousands of cells have survived the vacuum of space, cooling to near absolute zero, and heating to over 150 degrees centigrade.  We should choose the life form most closely related to ourselves that is likely to survive the voyage.  In the case of tardigrades, the oceans of target planets might first be seeded with plankton before their arrival to serve as a food supply.

At the end of the voyage, it would be necessary to make necessary adjustments to the craft’s trajectory, and then approach and perhaps enter orbit around the target planet in order to choose a favorable landing spot.  Sophisticated computers would be necessary to carry out these tasks, and a source of power would be necessary to run them.  A pure plutonium reactor might serve as the necessary power source.  Of course, plutonium 238 is currently used as a power source for deep space probes, but it only has a half life of 87.7 years, and would have decayed almost completely by the end of the voyage.  Plutonium 239, however, has a half life of over 24,000 years, and is fissile, meaning it could also serve as fuel in a very compact nuclear reactor.  Its decay heat could be used to power timers and other devices that require minimal power during the voyage, signaling the reactor to turn on during the final stages.

And what of our species?  I doubt that it will be possible to send full grown human beings to planets around nearby stars any time in the foreseeable future.  The energy requirements are just too great for achieving speeds sufficient for us to survive the journey.  Seed ships are another matter.  They might be sent with human embryos in suspended animation, to be cared for by robots at their destination, in prefabricated environments constructed in advance.  Google “Project Hyperion” to see this idea developed in more detail.  All this would require technologies that we have not yet developed.  In the meantime, I suggest we get started with the technologies we already have.

More on E. O. Wilson’s “The Social Conquest of Earth”: Let the Kerfluffles Begin!

Group selection isn’t the only hornet’s nest E. O. Wilson poked a stick into in his latest book. The interstellar travel fans at the Tau Zero Foundation are bound to take exception to this:

The same cosmic myopia exists today a fortiori in the dreams of colonizing other star systems. It is an expecially dangerous delusion if we see emigration into space as a solution to be taken when we have used up this planet.


Another principle that I believe can be justified by scientific evidence so far is that nobody is going to emigrate from this planet, not ever.

In my humble opinion, Wilson is wrong about interstellar travel.  I hereby predict that we will colonize planets in other star systems.  Our survival depends on it, and our species has a strong inclination to survive.  I suspect his opinion is motivated less by a sober assessment of the technological possibility of interstellar travel than by ideological concerns about the environment.  For example,

Surely one moral precept we can agree on is to stop destroying our birthplace, the only home humanity will ever have.  The evidence for climate warming, with industrial pollution as the principle cause, is now overwhelming.

I suspect a certain rather irascible Czech physicist may take exception to that comment.  In any case, while I admit to having a personal preference that the planet not be destroyed, but I would certainly not presume to elevate such idiosyncratic whims to the level of a “moral precept.”  Here, like so many other modern thinkers who should know better, Wilson is treating moral precepts as objective things.  In this case, he is suggesting that not destroying the planet can be legitimized as a “good-in-itself” by virtue of everyone agreeing on it.  Otherwise, his comment becomes pointless.  He probably wouldn’t agree, because he writes elsewhere,

There is a principle to be learned by studying the biological origins of moral reasoning… If such greater understanding amounts to the “moral relativism so fervently despised by the doctrinally righteous, so be it.

I can certainly sympathize with Wilson’s aversion to the doctrinally righteous or, as I would call them, the pathologically pious.  However, virtually in the same breath, he falls back into the same old fallacy, writing,

It is that outside the clearest ethical precepts, such as the condemnation of slavery, child abuse, and genocide, which all will agree should be opposed everywhere without exception, there is a larger gray domain inherently difficult to navigate.

Here we have the familiar “50 billion flies can’t be wrong” justification of the legitimacy of moral precepts.  Wilson’s comment begs the question of what qualitative difference exists between “clear ethical precepts,” and all the rest that lie in the gray area.  If, as he asserts, the origins of moral reasoning are biological or, in a word, evolved, in what way is it at all reasonable to claim that condemnation of slavery, child abuse, and genocide can have an objective existence as ethical precepts at all?  Presumably, the thought that there even was such a thing as “genocide” never occurred to those of our forebears among whom the “biological origins of moral reasoning” evolved.   Wilson’s implicit acceptance of an objective morality is evident elsewhere in the book.  For example,

For scientific as well as for moral reasons, we should learn to promote human biological diversity for its own sake insted of using it to justify prejudice and conflict.

On what, exactly, are we to base the legitimacy of these “moral reasons”?  In what sense was the “promotion of human biological diversity” relevant to the australopithecines?  Wilson has some other comments on the origin of moral precepts that are bound to make the detractors of group selection see red, such as,

An unavoidable and perpetual war exists between honor, virtue, and duty, the products of group selection, on one side, and selfishness, cowardice, and hypocrisy, the products of individual selection, on the other side.

At the risk of committing lèse-majesté, I must admit that I find such sweeping generalizations somewhat over the top.  Turning to less controversial subjects, Wilson mentions the concept of a superorganism in several places, such as,

The queen and her offspring are often called superorganisms…

This circumstance lends credence to the view that the colony can be viewed as an individual organism or, more precisely, an individual superorganism.


In this sense, I have argued, the primitive colony is a superorganism.

It would have been nice if Wilson had mentioned the great South African, Eugene Marais, who first proposed the idea of a superorganism in the context of his studies of termites, in the course of these discussions.  Readers of today will find some remarkably modern insights in books such as The Soul of the White Ant and The Soul of the Ape.  To say Marais was ahead of his time is an understatement.

In any case, I hope all the controversy Wilson’s latest is bound to inspire won’t have the unfortunate effect of toppling him from his exalted state as the “father of evolutionary psychology.”  The field has enough unpersons as it is.  Regardless, some rewriting of textbooks will likely be in order.  For example, in David Buss’ Evolutionary Psychology he refers to the “bulk of the theoretical tools” in Wilson’s Sociobiology as “inclusive fitness theory, parental investment theory, parent-offspring conflict theory, and reciprocal altuism theory.”  Might it not, perhaps, be best, to avoid “confusing” young undergraduates, to just let Wilson’s group selection faux pas pass in silence?  If not, and his head must indeed roll, I hereby nominate Charles Darwin as the new “father of evolutionary psychology.”  At least he will be a safe choice.

Space Colonization and Stephen Hawking

Stephen Hawking is in the news again as an advocate for space colonization.  He raised the issue in a recent interview with the Canadian Press, and will apparently include it as a theme of his new TV series, Brave New World with Stephen Hawking, which debuts on Discovery World HD on Saturday.  There are a number of interesting aspects to the story this time around.  One that most people won’t even notice is Hawking’s reference to human nature.  Here’s what he had to say.

Our population and our use of the finite resources of planet Earth are growing exponentially, along with our technical ability to change the environment for good or ill. But our genetic code still carries the selfish and aggressive instincts that were of survival advantage in the past. It will be difficult enough to avoid disaster in the next hundred years, let alone the next thousand or million.

The fact that Hawking can matter-of-factly assert something like that about innate behavior in humans as if it were a matter of common knowledge speaks volumes about the amazing transformation in public consciousness that’s taken place in just the last 10 or 15 years.  If he’d said something like that about “selfish and aggressive instincts” 50 years ago, the entire community of experts in the behavioral sciences would have dismissed him as an ignoramus at best, and a fascist and right wing nut case at worst.  It’s astounding, really.  I’ve watched this whole story unfold in my lifetime.  It’s just as stunning as the paradigm shift from an earth-centric to a heliocentric solar system, only this time around, Copernicus and Galileo are unpersons, swept under the rug by an academic and professional community too ashamed of their own past collective imbecility to mention their names.  Look in any textbook on Sociology, Anthropology, or Evolutionary Psychology, and you’ll see what the sounds of silence look like in black and white.  Aside from a few obscure references, the whole thing is treated as if it never happened.  Be grateful, dear reader.  At last we can say the obvious without being shouted down by the “experts.”  There is such a thing as human nature.

Now look at the comments after the story in the Winnipeg Free Press I linked above.  Here are some of them.

“Our only chance of long-term survival is not to remain lurking on planet Earth, but to spread out into space.”  If that is the case, perhaps we don’t deserve to survive. If we bring destruction to our planet, would it not be in the greater interest to destroy the virus, or simply let it expire, instead of spreading its virulence throughout the galaxy?

And who would decide who gets to go? Also, “Our only chance of long-term survival is not to remain lurking on planet Earth, but to spread out into space.” What a stupid thing to say: if we can’t survive ‘lurking’ on planet Earth then who’s to say humans wouldn’t ruin things off of planet Earth?

I will not go through any of this as I will be dead by then and gone to a better place as all those who remain and go through whatever happenings in the Future,will also do!

I’ve written a lot about morality on this blog.  These comments speak to the reasons why getting it right about morality, why understanding its real nature, and why it exists, are important.  All of them are morally loaded.  As is the case with virtually all morally loaded comments, their authors couldn’t give you a coherent explanation of why they have those opinions.  They just feel that way.  I don’t doubt that they’re entirely sincere about what they say.  The genetic programming that manifests itself as human moral behavior evolved many millennia ago in creatures who couldn’t conceive of themselves as members of a worldwide species, or imagine travel into space.  What these comments demonstrate is something that’s really been obvious for a long time.  In the environment that now exists, vastly different as it is from the one in which our moral predispositions evolved, they can manifest themselves in ways that are, by any reasonable definition of the word, pathological.  In other words, they can manifest themselves in ways that no longer promote our survival, but rather the opposite.

As can be seen from the first comment, for example, thanks to our expanded consciousness of the world we live in, we can conceive of such an entity as “all mankind.”  Our moral programming predisposes us to categorize our fellow creatures into ingroups and outgroups.  In this case, “all mankind” has become an outgroup or, as the commenter puts it, a “virus.”  The demise, not only of the individual commenter, but of all mankind, has become a positive Good.  More or less the same thing can be said about the second comment.  This commenter apparently believes that it would be better for humans to become extinct than to “mess things up.”  For whom?

As for the third commenter, survival in this world is unimportant to him because he believes in eternal survival in a future imaginary world under the proprietership of an imaginary supernatural being.  It is unlikely that this attitude is more conducive to our real genetic survival than those of the first two commenters.  I submit that if these commenters had an accurate knowledge of the real nature of human morality in the first place, and were free of delusions about supernatural beings in the second, the tone of their comments would be rather different.

And what of my opinion on the matter?  In my opinion, morality is the manifestation of genetically programmed traits that evolved because they happened to promote our survival.  No doubt because I understand morality in this way, I have a subjective emotional tendency to perceive the Good as my own genetic survival, the survival of my species, and the survival of life as it has evolved on earth, not necessarily in that order.  Objectively, my version of the Good is no more legitimate or objectively valid that those of the three commenters.  In some sense, you might say it’s just a whim.  I do, however, think that my subjective feelings on the matter are reasonable.  I want to pursue as a “purpose” that which the evolution of morality happened to promote; survival.  It seems to me that an evolved, conscious biological entity that doesn’t want to survive is dysfunctional – it is sick.  I would find the realization that I am sick and dysfunctional distasteful.  Therefore, I choose to survive.  In fact, I am quite passionate about it.  I believe that, if others finally grasp the truth about what morality really is, they are likely to share my point of view.  If we agree, then we can help each other.  That is why I write about it.

By all means, then, let us colonize space, and not just our solar system, but the stars.  We can start now.  We lack sources of energy capable of carrying humans to even the nearest stars, but we can send life, even if only single-celled life.  Let us begin.

DARPA’s “100 Year Starship” and Planetary Colonization

DARPA seems to have its priorities straight when it comes to space exploration.  The agency is funding what it calls the “100 Year Starship” program to study novel propulsion systems with the eventual goal of colonizing space.    Pete Worden, Director of NASA’s Ames Center, suggests that Mars might be colonized by 2030 via one-way missions.  It’s an obvious choice, really.  There’s little point in sending humans to Mars unless they’re going to stay there, and, at least from my point of view, establishing a permanent presence on the red planet is a good idea.  My point of view is based on the conclusion that, if there’s really anything that we “ought” to do, it’s survive.  Everything about us that makes us what we are evolved because it promoted our survival, so it seems that survival is a reasonable goal.  There’s no absolutely legitimate reason why we should survive, but, if we don’t, it would seem to indicate that we are a dysfunctional species, and I find that thought unpleasant.  There, in a nutshell, is my rationale for making human survival my number one priority. 

If we seek to survive then, when it comes to planets, it would be unwise to put all of our eggs in one basket.  Steven Hawking apparently agrees with me on this, as can be seen here and here. In his words,

It will be difficult enough to avoid disaster on planet Earth in the next hundred years, let alone the next thousand, or million. The human race shouldn’t have all its eggs in one basket, or on one planet. Let’s hope we can avoid dropping the basket until we have spread the load.

Not unexpectedly in this hypermoralistic age, morality is being dragged into the debate.  The usual “ethics experts” are ringing their hands about how and under what circumstances we have a “right” to colonize space, and what we must do to avoid being “immoral” in the process.  Related discussions can be found here and here.  Apparently it never occurs to people who raise such issues that human beings make moral judgments and are able to conceive of such things as “rights” only because of the existence of emotional wiring in our brains that evolved because it promoted our survival and that of our prehuman ancestors.  Since it evolved at times and under circumstances that were apparently uninfluenced by what was happening on other planets, morality and “rights” are relevant to the issue only to the extent that they muddy the waters.

Assuming that others agree with me and Dr. Hawking that survival is a desirable goal, then ultimately we must seek to move beyond our own solar system.  Unfortunately there are severe constraints on our ability to send human beings on such long voyages owing to the vast amounts of energy that would be necessary to make interstellar journey’s within human lifetimes.  For the time being, at least, we must rely on very small vessels that may take a very long time to reach their goals.  Nanotechnology is certainly part of the answer.  Tiny probes might survey the earth-like planets we discover to determine their capacity to support life.  Those found suitable should be seeded with life as soon as possible.  Again, because of energy constraints, it may only be possible to send one-celled or very simple life forms at first.  They can survive indefinitely long voyages in space, and would be the logical choice to begin seeding other planets.  Self-replicating nano-robots might then be sent capable of building a suitable environment for more complex life forms, including incubators and surrogate parents.  At that point, it would become possible to send more complex life forms, including human beings, in the form of frozen fertilized eggs.  These are some of the things we might consider doing if we consider our survival important.

Of course, any number of the pathologically pious among us might find what I’ve written above grossly immoral.  The fact remains that there is no legitimate basis for such a judgment.  Morality exists because it promoted our survival.  There can be nothing more immoral than failing to survive.

The Daedalus Starship

Earthlike Worlds…

The Kepler Mission has now identified more than 700 suspected new planets, some of them earthlike, in interstellar space.  As Insty would say, “faster please.” We should be searching for life forms on earth that are most likely to survive on these worlds and working on the technology to get them there as quickly as possible. At first these will be limited to single celled or simple multi-celled species that are small enough to accelerate to the speeds necessary for interstellar travel. While we’re doing that, we can work on the nano-technology required to self-assemble human nurseries on alien worlds capable of nurturing single human cells through birth to adulthood. The energy cost of sending fully developed human beings is prohibitive, and probably impossible at the moment. However, the technology required to send single living cells is within our grasp.

Every other challenge we face and all the great political, religious, and ideological issues that have captured our imaginations and whipped us into self-destructive frenzies since the dawn of human existence pale in significance compared to the ultimate challenge of carrying life into interstellar space.  Unless we meet the challenge, all our pompous babbling about morality and ethics will be as meaningless as the life of a soap bubble.  There can be nothing more immoral than failing to survive.