Evacuate Earth!

By Eric M. Jones

THE EARTH WILL NOT LAST FOREVER. Perhaps the detection of a habitable exoplanet will spur the building of ships of exploration and colonization. Or some mega-disaster might happen that will make leaving the Earth the only conceivable choice to save a piece of the human race. “Colony Ships” or “Interstellar Arks” have been discussed for nearly a century. Perhaps a miniscule percentage of the Earth’s population will someday climb into a ship headed to possibly-habitable planets circling around other star systems.

Recently the National Geographic Channel ran a special on what Earth might do if a neutron star was on a collision course with Earth ... estimated time of arrival, 75 years. (I recently wrote a short story for “Perihelion” about what humans would do if an asteroid as big as the Earth itself was on a similar collision course.) In the National Geographic story, Earth decided to send one humongous colony ship containing 250,000 people towards a candidate star system with a candidate planet.

These ships have variously been portrayed as huge arks where the crew will live awake and tootling around for centuries, or sometimes ships where the crew is in some sort of suspended animation. Actually, suitable volunteers would be easy to find.

The National Geographic ship was roughly based on the 1958 project Orion spaceship (and later ones) which used tiny little nukes shot out the rear and exploded. This type of spaceship was the product of a group headed by the infinitely smart Freeman Dyson (a scientist whose random off-the-cuff speculations are probably better than most other expert’s carefully studied opinions. Freeman Dyson did math for Richard Feynman, and invented the Dyson sphere ... and, by the way, doesn’t believe in Anthropogenic Global Warming, either.

The best reason for supporting Stan Ulam-Freeman Dyson’s pulse-nuke approach is unexpectedly simple: It is known to work and provides the necessary thrust to do the job. Maybe we will see another way to do it in the future, but this is all we’ve got for now. There are many more sophisticated methods, but nothing else is known to work for high-thrust applications. They even tested a non-nuke, small-scale version. It was noisy and worked fine.

Now if nuclear bombs are dropped out the butt of a spaceship, putt-putt style, the acceleration could be severe. So the spaceship would be equipped with an absorber mass, springs, pistons, and sliding parts, or whatever is needed to dampen the shocks. Still, you have to wonder what being kicked by nuclear explosions for a very long time will do. People used to worry about internal combustion engines, (once called internal explosion engines)—and they worked it out.

It is important to note that the Orion data is all available, and the refinements are too. (See Project Daedelus.) It looks like about 400 billion dollars would be needed to get a ship full of 100 or so people to the closest star system. This would cost a contribution of $50 a head for every person living on the planet. About half what the Wall Street bailout cost us.

The significance of this seemingly-wild method of spaceship propulsion is that it was entirely achievable with the then-current technology, and even easier now.

All propulsion engineering boils down to what is called Specific Impulse of the fuel/rocket. The bigger the better. These are well known for virtually all materials and combinations:

• Estes E9-6 = 86 seconds. [Those toy rockets]
• LOX / RP-1 = 300 seconds. [High thrust]
• LOX/LH2 = 475 seconds. [High thrust]
• Ion thruster = 3,000 seconds. [Low thrust]
• Dual-stage 4-grid electrostatic ion thruster = 21,400 seconds. [Low thrust]
• Ulam-Dyson Nuclear Pulse Ship = >>50,000 seconds. [Very high thrust]

The second best method of long-term propulsion seems to be ion engines and their various cousins (there are many). Regardless of the type of ion engine, they all operate by accelerating atoms—almost always xenon ions because they are very heavy, nonreactive and easy to ionize—to extremely high velocities. Ion engines have been used in space for various spacecraft and satellite moving tasks for some years. Many newer versions are being studied and tested. Most of these engines are small, but there is every reason to scale them up to build very large engines.

How big would the Interstellar Colony Ship be? A single half-century old Saturn launch vehicle including the Apollo spacecraft and lander stood 111 meters and weighed nearly 3,000 metric tonnes or about eight fully-fuelled and loaded Boeing 747s. The International Space Station in comparison weighs 420 metric tonnes, or about one Boeing 747. The Saturn V could have accomplished this weight in two easy launches—it was rated to lift 240 metric tonnes to Low Earth Orbit (LEO).

Lifting parts and freight to LEO has, in fact, gotten cheaper and easier. So let’s say the interstellar ark ship could be the weight of two Saturn V launch vehicles, or 6,000 metric tonnes, of which the weight of fuel would be at least 5,000 metric tonnes.

Anything pushed out the back of a spaceship will thrust it forward. Our task is to push it out the back as fast as physics can make possible.

Chemical rocket engines usually use solid or liquid propellants that react violently, pushing the resulting gases out the rear of the engine.

The thermodynamic efficiency of any rocket engine—measured by how fast the exhaust goes out—is a function of how hot the reaction is. The temperature of the reaction is limited by what the construction materials will withstand, but in general a few thousand degrees is about the limit for chemical rockets. And even the best chemical rockets use fuel at tremendous rates.

Let’s design an ion engine for an interstellar ship:

For the ion engine we need, we start with some propellant material like liquefied xenon that we can turn into a gas then heat it up and accelerate it with techniques that can work at very high temperatures. Electricity and magnetism provide the only foreseeable tools to handle such propellant materials. Because the neutrally-charged xenon propellant material is hard to handle, the first thing to do is to charge it, then heat it up, and electro-magnetically accelerate it until it shoots out the rear.

So where does all the electrical power come from? For interstellar ships it comes from nuclear power or, for satellites and vehicles close to the sun, simple photoelectric arrays.

The details are what some very smart engineers are working on. None of the current ion-engine techniques can be used in the atmosphere. For now these engines only operate in space. But who knows what time will bring?

Lesbian Warriors From the Stars

The National Geographic program showed the final days of loading the giant 15 km long tubular ship loaded with happy Midwestern people. It rotated slowly to provide artificial gravity for some sort of small town suburban utopia, populated with children, parents, some clearly grandparents, and one hopes, rocking chairs, puppies and front porches.

But let’s cast aside the Norman Rockwell aspects of the spaceship idea and look at the facts based upon achieving the singular goal of landing the Human Race on some distant planet:

There really isn’t any reason for taking men along at all. Men have absolutely no special talents that provide them an automatic ticket to the stars. In fact, any such ship should be composed of a few liters of frozen sperm and a sufficient number of genetically selected females to give birth to genetically selected females. What happens if a male baby is born? Well, this can’t be tolerated if the mission is to have maximum chance of success. What happens if the voyage continues long enough so that more frozen sperm is needed?

A few liters should last longer than the ship, but I present to you the sad scene that a few males could be born for the sole purpose of frozen sperm replenishment—then they would be handed their hat. But that’s the likely reality of an interstellar colony ship.

But lest one think that women are the lucky ones: There really isn’t any reason for taking women along except to do spacecraft maintenance and give birth. After they are beyond in vitro breeding age (maybe 50?), they have outlived their usefulness. But it is even worse than that—after a single birth, or perhaps after the baby has been weaned, the mother should be disposed of. So it’s into the matter reprocessor, sorry.

This is a simple min-max calculus problem—how does one transport the Human Race to some distant point using the least energy? Let’s not be shy about this. The plan is how to get the Human Race to another star system. Wimps need not apply. Tough choices have to be made. Remember our premise that the Earth is going ka-boom?

Male-dominated society might never survive a trip as described. What is the biggest problem facing society? “Men,” says Helen Fisher, biological anthropologist. It is easy to surmise that Earth’s warfare, crime, and social disruption is caused by too much testosterone floating around men’s brains, whatever good this hormone does otherwise. Finally, women might have the opportunity to set things right. (Some readers will disagree with this statement.)

What might life be like aboard the Orion ship? [Artist’s rendering at right.]

Start: Liters of frozen sperm and a selection of about twenty very young, very petite, very healthy, genetically diverse females. This minimizes the mass.

Mid-voyage: These women must stay at minimum weight and propagate by in vitro fertilization to birth a single girl baby. Having a baby at age 50 is achievable. The baby must be female, which is also easy to achieve with today’s technology. Sorry, but the mother must be recycled. This—born, grow-old, give-birth cycle— continues while searching for, or approaching a habitable planet to colonize.

Arrival: A generation before the expected landing, determined by telescopic survey, the in vitro fertilization will switch to produce normal 50/50 male/female distribution. Some decisions are necessary here depending on the certitude of landing and colonization. But it is simply science fiction (and we’ll have none of that!) to believe that fuel and expendables will be adequate for either a return to Earth or to find another suitable home if the first one doesn’t work out. To do either of these would require technologies far beyond what we have so far imagined.

Sex and Society

After a while reading Bibles and playing canasta will get old and people will probably have sex. Did I mention the crew is entirely female?

Gay men and lesbians actually have completely different motivations. All responsible studies seem to conclude that gay men seem to be born that way. Straight men are known to act homosexually when confined in jails or in other situations where there are no women. But they strongly reject the notion that they are gay and return to strict heterosexuality when they can. While women who are confined for long periods of time with only women, such as in prisons or on our interstellar ship, might engage in homosexual behavior and never return to purely heterosexual behavior when the opportunity allows. Lesbians don’t seem to be born that way, they become “that way.” This is called the “plasticity of sexual desire between women.” [The evolution of plasticity in female-female desire, Journal of Psychology and Human Sexuality, volume 18, pp. 245-274, 2006.]

There might be very good reason to exclude homosexuals of either sex from a space voyage to reestablish the human race on another planet: It might just be a waste of time, since procreation is part of the reason we would go. Now, homosexuals also want to have children, but let’s be honest here ... the determined breeders are all heterosexual. The problem is that the women crew won’t start out lesbian and can’t be selected out.

For obvious reasons, homosexuality does not seem to be genetically encoded. So there might not be a way to exclude them, or at least their DNA from the voyage. If an individual had extremely valuable skills and happened to be homosexual, they could make the roster, but it seems unlikely.

So will women be the humans to populate the stars and men only sperm donors? Actually, I don’t think so. Women could have done something similar at any time, but it has always been men who want to undertake an adventure and accept enormous risk. That is how humans seem to be wired. Would a mixed male-female crew gradually evolve during the journey to be “women only?” My feeling is that it probably would, and that it would be impossible to prevent.

Passing the Time

I refuse to believe that someone won’t be making hooch with the leftover wheat husks or whatever. Some clever pharmacology will be employed to relieve the boredom that is sure to come. Rather than trying to prevent this, I suggest just making it standard to be unconscious or in virtual reality as long as one wished (or as long as time from tasks allowed). With only twenty or so women as crew, the need for a gigantic rotating cylinder with a Midwestern town inside it would be eliminated. Only a smaller (~1g) habitat would be required, assuming no solution to bone loss in microgravity is discovered.

Language

One item that is never discussed is that a 300-year journey would almost certainly force a rapid evolution of language among the crew. This might make the crew’s language incomprehensible to Earthlings after a time.

Religion

What religion or religions would the twenty women who leave on the voyage take with them? What religion or religions would remain after 300 years? Which way does one face to be aligned towards Mecca? The Mormon God lives near a planet called Kolob? Besides, what would the relevance of Jesus or Mohammed from the Bronze Age holy lands of Earth’s eastern Mediterranean be to a group of humans who have settled on a strange planet in the next star system? Can religious mythology stretch that far? It’s doubtful.

Albert Einstein said that: “Buddhism has the characteristics of what would be expected in a cosmic religion for the future: It transcends a personal God, Avoids dogmas and theology; it covers both the natural and spiritual, and it is based on a religious sense aspiring from the experience of all things, natural and spiritual, as a meaningful unity.”

One of the reasons that predictions fail (and look terribly silly after a time) is that great strides of technology might or might not happen. Here are some major technological leaps that might occur that could change everything regarding interstellar colony ships.

Artificial wombs. Nobody knows when, but women having babies the old-fashioned cave-women way is certainly on its way out. Dialysis and a feeding tube in one’s arm is technically not so far from having a tub of amniotic fluid and a growing embryo. It will certainly be done in this century. If guys had the babies, this would have been done a century ago! If this technology works out, pushing a freighter full of embryos to the stars with robots to take care of them and maybe a few teachers, might happen faster than you think. [Likelihood estimate 95 percent in this century.]

Faster-than-light spacecraft. It’s a real longshot, of course, but FTL spacecraft would simply rewrite the rulebook. [Likelihood estimate 0.000001 percent in this century.]

SETI comes through. The Hat Creek SETI folks might yet come up with that elusive alien radio contact. Maybe we’d be spurred to go and shake hands, or claws, or tentacles. [Likelihood estimate 0.01 percent in this century. I figure that makes me an optimist.]

Fusion drives. The technology that would enable hydrogen or deuterium to be fused into helium for thrust would open up vast areas for human exploration. But fusion drives are probably more likely to be used for higher-thrust applications over shorter times. [Likelihood estimate 60 percent in this century.]

Cryo-sleep and associated technologies. This technology has been nearly possible for a century. The problem is that freezing multicellular organisms usually destroys the organism because of the growth of ice crystals, which mechanically destroy the cells with little ice-crystal knives. That’s why they freeze sushi ... to kill the roundworms, hookworms, and whipworms which infect the body and give you the disease known as anisakiasis. Critics maintain that freezing the body produces similar changes as would cooking it. It is still a tantalizing idea, because some things can be frozen and revived. Furthermore, perhaps we can avoid freezing by cooling the body nearly but not quite frozen—then doing something to stop the dissolution of tissue. New England legend has it that the Hill People in the Green Mountains of Vermont give their old folks a really really really stiff drink, cover them with straw, and put them out in the cold to hibernate all winter long. So maybe it will work. [Likelihood estimate five percent in this century.]

Solution to bone loss in microgravity. Because bone growth by electric currents is easy and currently used in therapy, I would estimate that the problem of bone loss in microgravity will soon be solved. [Likelihood estimate 95 percent in this century.]

The Technological Singularity. And with it super-intelligent, perhaps conscious computers. We could just leave the problem to them (or it), although we might have to specify some parameters like “Best” or “Fastest.” Cyber-guru Ray Kurzweil is the present-day champion of this idea, but it originally goes back to Stanislaw Ulam and others, who noticed that technology was pointing to a time where humans would be outdistanced by their electronic servants. And then what? We’ll soon see. [Likelihood estimate 95 percent in this century.]

Big nuke-u-lar or biological war. If this happens civilization won’t be going anyplace for a long time. And a lot of post-apocalyptical science fiction scenarios will look pretty good in comparison to the putrid results of our own devices. [Likelihood estimate 30 percent in this century.]

Global pandemic or Zombie Apocalypse. [Likelihood estimate 3 percent in this century ... the pandemic not the zombie thing.]

New world order. The Rich take over and kill some large percentage of poor people. [Likelihood estimate 30 percent in this century.]

Let’s assume a habitable planet is discovered, and the colony ship has successfully achieved orbit around it. Descending to the surface is probably not a question, it is an imperative. Surface reconnaissance can be done from orbit and by dropping drones. The choices would have to be made a light-year out.

There is no certainty that the chosen planet will actually be habitable or inviting once the details are understood. We could well be the invaders and meet fierce resistance for which we would not be prepared. Surrender would be the only possible strategy. Enslavement is possible. Wildly incompatible DNA is possible. There is fodder for speculation in all these possibilities. Have at it. 

Eric M. Jones is the Associate Editor of “Perihelion.” He is an engineer, designer, consultant, and entrepreneur, working in the experimental aircraft community, NASA, space transportation companies, and the International Space Station.