The Official Newsletter of the Washington Science Fiction
Association -- ISSN 0894-5411
Edited by Joe Mayhew
WSFA Minutes January 5th at Gilliland's
Space Colonization Chapter II
Edited by Joe Mayhew
Attending: Pres. Covert Beach, VP. Terilee Edwards-Hewitt, Sec. & 98 Chair Joe Mayhew, Treas. & 96 Chair Bob MacIntosh, Trust. Jim Edwards-Hewitt, Trust. David Grimm, Trust. John Pomeranz, Bernard Bell, Elspeth Burgess, Steven desJardins, Don Eastlake III, Christine Fatula, Alexis Gilliland, Lee Gilliland, Karl Ginter, Erica Ginter, Steven Glick, Chris Holte, Alan Huff, Eric Jablow, Bill Jensen, Judy Kindell, Samuel Lubell, Richard Lynch, Nicki Lynch, Keith Marshall, Walter Miles, Lance Oszko, Peggy Rae Pavlat, Sam Pierce, Rebecca Prather, Rachel Russell, John Sapienza, Tom Schaad, George R. Shaner, Steven Smith, William Squire, Michael J. Taylor, Kate Terrell, James Uba, Michael J. Walsh, Michael Watkins, Mike Zipser, Beth Zipser,
Covert Beach called the meeting to order at 9:20, there was no agenda of old business. Bob MacIntosh announced the WSFA treasury to have 6,934.99 in it, and that Dues for 1996 were due and payable.
DISCLAVE 1996 Joe Mayhew will be doing the flier and asked that anyone who needs information put in it see him asap. The origami party will take place at the February 2nd Meeting.
DISCLAVE 1997 Michael Nelson has found a GOH. Joe Mayhew, as requested by Michael, announced it as "P. Anthony." Waiting an appropriate pause, then announced that the "P" did not stand for "Piers" but rather for "Patricia." WSFA applauded the choice enthusiastically.
NEW BUSINESS: On behalf of FAST FORWARD: CONTEMPORARY SCIENCE FICTION, Producer Tom Schaad resquested that WSFA continue supporting the distribution of the program to the various networks which give it air time. He requested, and was granted without objection, $364.00 for that purpose.
ANNOUNCEMENT: WSFA was invited to a party on Monday, Jan 15th from 2pm to 10pm on the Martin Luther King holiday at the home of Rebecca Prather. She was also inviting people from Mensa, and her neighbors. The meeting was adjourned at 736.
In the preceding chapter we saw how humanity would get into the (potentially) rich and verdant pastures of space. In this admittedly self-indulgent chapter, consideration will be given to the furniture for our dream.
In The High Frontier Gerard K. O'Neill imagined three variations, "Island One" being a sphere 460 meters in diameter rotating at 1.97 rpm to provide earth gravity at the equator, in which he would house 10,000 people. Space suburbia is clearly what he had in mind; those people would commute to work and their food would be "trucked" in. Otherwise, you have 10,000 people inhabiting 665,000 square meters, and while an allotment of 66.5 square meters per person provides a large and spacious room, it is not enough to raise food as well. Or, more precisely, you can't feed yourself off a garden 6.65 by 10.0 meters (21.7 by 32.6 feet.) The much larger "Island Three" was to have been two counter rotating cylinders, each four miles in diameter and 20 miles long. Each cylinder would be divided into six sections; three great window bays, alternating with three great land bays, providing a total land area of 250 square miles. The land bays would be illuminated by mirrors set at 45 degrees to the axis, so that sunlight is reflected through the window bay, passing through four miles of air to fall on the opposing land bay. Day and night was provided by opening and closing the three great mirrors. O'Neill himself did not consider this arrangement as a proper engineering solution, but rather as an "existence proof", a conservative estimate to demonstrate how the thing could be done.
I've given the matter a lot of thought, he said modestly, and I would direct my robots to do the thing differently. Begin with the mirrors: Simple geometry shows that the mirrors would have to be 28.3 mile long to illuminate a 20 mile window. Opening and closing them every day to provide day and night would put a considerable strain on them, and since they are rotating with the cylinder, they will be under considerable stress. Far better to have stationary mirrors, even if you need twice as many. Ah, but how then do we achieve day and night, so deeply rooted in humanity's slow and laborious evolution?
My first answer, thriftily put to use in The End Of The Empire, my fourth book, was to arrange the two cylinders end to end on the same axis, while putting the mirrors between them like a great, circular venetian blind; the angle of the blind slats would reflect the light sharply forward for the sunward cylinder; changing the angle would obliquely reflect the same light to the outer cylinder. Thus, one complex mirror provides day for cylinder A and night for cylinder B, with only the smallest of motions. A 1995 afterthought is that the outside window surface would have to be cut like a Fresnel Lens to properly catch the sunlight, which would be coming in at an oblique angle.
My second answer, which I liked a whole lot better, was the "dragon scale" mirror array, thousands of small mirrors capable of being individually controlled. A tool and a weapon of considerable power, I used it to good effect in the Rosinante trilogy, refining metal and pumping huge, low power lasers. I even solved the question: How do you conquer a place defended by such a mirror array? My answer: Replace the enemy chips with your own chips, at which time surrender becomes the only option for those no longer in control of their mirror.
In both cases, however, the "Island Three" concept remained essentially unchanged; giant windows admitting enough light for agriculture, while day and night are provided by fiddling with the mirrors. Absent any compelling objection, O'Neill's idea remained both powerful and persuasive--although it didn't persuade Congress--and it was hard to visualize any useful alternative. An unsold story provided me with a variation of the basic concept: To wit, the mirrors don't move at all. Given totally static mirrors, how do we provide day and night? The answer: Use the whole of the inside of the cylinder instead of only half of it, and then roll the main deck in a spiral around the axis of rotation, so that there are two levels. This results in a conceptually inelegant space station, one in which the light path to the inside goes from *primary planar mirror* to *secondary parabolic mirror one* to *secondary parabolic mirror two* to an *optical glass light guide*, which takes the incoming sunlight, via a *switch*, to a *light pipe* on either level one or level two. A technical note may be in order here. A light guide is typically a bundle of very clear glass fibers that moves light where you want it to go with minimal losses. A light pipe is a glass tube whose inside has been cut with a series of right angle grooves parallel to the pipe's axis, with the result that it leaks the light over its 10-meter length.
There are some compensations for giving up O'Neill's elegant and beautiful design, however. The first is available space; in one cylinder of "Island Three" we have an interior area of 125 square miles of land area and 125 square miles of window. Rearranging the cylinder increases the available land fourfold, and it also gets rid of those big and fragile windows. Wunderbar! With one clunky design modification, our space station becomes four times more capacious and a whole lot more robust. The outside view of the cylinder's surface would be a hexagonal pattern of parabolic mirrors reflecting the sunlight inside as described in the preceding paragraph. We have windows, yes, in the form of tens of thousands of fiberoptic cables piercing the steel wall. Unaesthetic, perhaps, but functional.
Ideas evolve, and a subsequent change was provoked by the necessity
of having lots and lots of optical cables bringing in all that wild
sunlight to insolate our fields and meadows. It looked inelegant and
graceless, somehow. My first attempt was to
integrate the optical cables with the structural fabric of the space
station, thus getting them out of sight, like wires and pipes in
an office building. Which was all right, sort of, only it begged
the question. So in another unpublished story (I should get back
to writing stuff that sells, yes, I know.) I was thinking about
maximizing the size of the things, and rather than inventing a new
material, as Niven did in Ringworld , I stuck with conventional
materials. Which meant steel; and the optimum use of steel was to put
it under tension rather than compression, because steel is stronger
under tension. From which I came up with the idea of a central steel
core--which initially looked like the empty toiletpaper roll--from
which steel cables were hung. And since the core was rotating, the
steel cables would be normal to its surface, sticking straight out in
all directions. And since they are attached to the core, our cables
are also short, no more than the thickness of the two layers provided
by the spiral main deck. Which would be maybe 200 or 300 meters,
unless you needed a higher ceiling for some reason.
Later on, inspired perhaps by Buckminsterfullerene, if not Fuller himself, our core took on the look of rolled chicken wire, with hemispherical ends, not unlike the carbon fibers some labs have produced. (When these cargon fibers are alloyed with iron, you get "Rhodite steel" which has uncommonly high tensile strength.) Welding tubes produces a simple and strong structure, that is admirably suited for supporting what amounts to an huge area of double decker bridge. One nice thing is that the tensile strength and thickness of the cables is not critical; if you need more support, you add more cables or make them thicker.
In the asteroid belt, which is where we are building, iron is about 46 percent of everything, so it is only common sense to use iron and its alloys to construct our space stations. Once the remotely-directed and/or computer-controlled construction machinery, aka our loyal and faithful robots, are up and running, iron is not something we will likely run short of. Given the certainty that we will be doing all sorts of computer assisted designing, it is also probable that in a very short time the basic design will evolve into an elegant standard pattern, very much as I have described it here. This pattern can then be replicated indefinitely, or to our hearts content, whichever comes first.
Another nice thing about this design is that the cables are not so long that they end up supporting mostly their own weight. (I had considered cables many miles long, at one point, sort of like bicycle spokes.) Once we have decided to configure our spacious vistas with main deck to ceiling cables, life becomes a lot simpler in many ways. For instance, the weight supporting cable provides a natural conduit for all those optical glass (fiberglass, if you wish) light guides, taking them to the ceiling where the sunlight is dispersed to the environment via lightpipes, or through it, to insolate the upper level. To give our interior a light and airy look, the glass and steel cables would be enclosed in a stainless steel mirror. Where we wish to build, oh, say, a palace, or a large office building, the vertical supports are everywhere in place for it.
Finally, the main deck freely lends itself to the purposes of one's imagination.
One could design it to contain roads, subways and power lines in a ten-meter space enclosed by three-meter utility decks, the upper deck containing communication and electric utilities while the lower deck contains gas, water and sewage. On top, two or three meters of carefully composed topsoil for plants to grow in. In passing let me note that the spiral design solves the drainage problem, which I found rather troublesome in a rotating cylinder, and which is properly ignored by everyone. Since the deck is pierced at regular intervals by the support cables, the openings could be enlarged for elevators or whatever. Why do I mention such trivia? In a very old structure, one could find the most bizarre mazes imaginable, hidden palaces or secret gardens, a useful consideration for the writer of fiction.
Which leads us to ask, he-ey, how big are these cylinders we're talking about, anyway? Well, "Island Three" was four miles in diameter by 20 long, not counting its hemispherical ends; it had a non-glass inside area of about 125 square miles. Our double wrapped cylinder could easily be seven miles in diameter by 63 miles long, with an inside area of 2772 square miles. True, it might well be bigger, but seven is a magic number, and a cylinder nine diameters long looks about right. Anyway, the unit we have is big enough to serve as a basic building block that can be strung together like pop beads to produce states, nations, and even, you should pardon the expression, "cantinents." Four of our pop beads (11,088 sq. mi.) would be about the area of the state of Maryland (10,460 sq. mi., including the Chesapeake Bay, an amenity we might well want to imitate.) while Texas, at 266,807 sq. mi., would require an array of "only" 96.
Let us leave the arithmetic that guesstimates how many states of Texas could be fabricated from the asteroid Ceres as an exercise to the reader. The point is: A rack of habitats, naturally abreviated as a hatrack, will provide would-be authors with a convenient planet-substitute, in which air, gravity and temperature are all earth-normal. Travel from one hat to another can be by rail, in a matter of a few hours. As a matter of convenience, for those like myself that are unhappy on roller-coasters (Oh, why did I ever let them talk me into going on the Magic Mountain at Disney World?) it is a simple matter to hook up six cars around a suitably designed engine, and spin the whole thing around the monorail it will ride from point 1 to point 2. Why? To provide the passengers with the creature comfort of gravity; they might even be able to eat dinner.
Why do we put our hats on a rack? Housekeeping, mainly. To stop them from drifting together under the pull of gravity, for one thing. For another, to cancel out the rotation of our contra rotating cylinders. For a third, to facilitate the precession of our suite of gyroscopes, so that all the axes of all the hats spinning on our little rack will be aligned with the sun as they precess around their collective orbit. If there is an asteroid involved, our rack can keep its hats safely out of that asteroidal gravity "well"--a distance of about 30 asteroid diameters should be adequate in most cases (On earth, that is about where the geostationary orbit is. On 2155 Wodan, diameter 29.5 km., that would be a mere 900 km., an easy commute. (Did I hear someone say that 30 x 29.5 = 885? Gimmeabreak. The diameter of Wodan is plus or minus 2.6 km.)
Suppose we put our four hat rack on Wodan; what would it look like? Begin with the individual hat, its axis normal to the sun. Around the hat are its primary mirrors, collecting the sunlight for the secondary parabolic mirrors, and since these primary mirrors are set at 45 degrees to the hat, they are 89 miles long and extend 63 miles in all directions from the hat they insolate. Or maybe not. The power of O'Neil's "Island Three" influences our thinking still. Originally, there were three rotating mirrors; with a brilliant conceptual leap the three were transformed into six non-rotating mirrors. So you reflect twice as much sunlight as you can use, so what? Consider that we wish to insolate only one half of the 2772 square miles inside the hat, 1386 square miles, and assuming a 1:1 ratio between mirror and main deck--which ought to be jes' fine in the Asteroid Belt--we only need 1386 square miles of mirror. Which may be contained in a circle 21.00 miles in diameter. Allowing for the 7 miles in diameter hat in the center, our circle expands to 21.29 miles; cut ourselves a little slack and round it up to 22.00. These smaller mirrors can then be arranged in two or three sets, or maybe a spiral, around the hat to insure its uniform insolation.
Which gives us four hats, arranged in a parallelogram 22 miles on a side with inside angles of 60, and 120 degrees. Viewed from the side, there are the four rotating cylinders, asteroid ends mounted on the non-rotating rack, which also supports the compact mirror array and the monorail connections between the hats, and whatever else is convenient for an author to imagine. This rack extends down 900 km. (Yeah, I know, I should pick miles OR kilometers, but I figure if it's Americans colonizing space we'll be using both.) to Wodan, which is rotating. Which means that the base of the rack will be mounted on pivots set at Wodan's poles.
Why bother with a dinky little asteroid like Wodan? Because it is the raw material for future expansion, containing 3200 cubic miles of stuff. Of which 46 percent by weight figures to be iron, so that the 54 percent remaining is less dense silicates and metal oxides, generally rock stuff suitable for processing into dirt. If our main deck is supporting 10 feet of soil, dirt enlivened with water and organic matter, a conservative estimate would be that Wodan would eventually provide an additional (Hmm, conservatively, 0.54 x 3200 cubic miles x 5280 feet per mile/10 feet = 912,384 square miles) 329 habitats. Maybe we would run out of iron after all, eventually, but it is clear that a habitat associated with an asteroid has far more potential than one orbiting in splendid isolation.
So how do we get around, travel being an essential component of adventure, and by extension adventure fiction? Intra-hat, walking or riding in the usual late-20th Century manner, except airplanes and helicopters would not be available--the ceilings would be high enough, but all those cables would be troublesome. Inter-hat would be by rail, very much the same as riding the subway in a big city, or, in a large rack, riding a sleeper train across the many time zones between points A and B. Inter-rack travel will be something else.
Well, inter-rack travel deserves its own paragraph and maybe its own chapter. One part of the problem is that moving a given number of people in space requires a much larger investment in life support than moving the same number of people on earth. The second part of the problem is the distances involved are, shall we say, astronomical. Even in the Solar System. We have, with great difficulty, sent men to the Moon and back, a round trip of half a million impressive miles, or a puny 0.005 AU. The classical science fictional solution is to travel under constant acceleration, which greatly reduces time t. Even so, imposing the mass costs of life-support (including proper sheilding) on a space ship means that achieving constant acceleration will become increasingly difficult and expensive. Using a million tons of iron as reaction mass to move the first colonists to a new habitat should be acceptable; but nobody is likely to pay that sort of price for commuting.
Before expanding on inter-rack travel, it should be noted that moving any significant number of people from Earth into those asteroid belt habitats is not a trivial problem. In the first chapter, we suggested that the likely means for such transport would be rather like floating islands rather than speedy airliners. The realization of such an idea would involve several things, such as a destination in the asteroid belt, and the construction of a small, mobile habitat which would have its perihelion at Earth's orbit, and its aphelion at the orbit of Ceres, or thereabouts. Slow and inconvenient as such a floating island would be, it might be the only way to move thousands of people into space. Perhaps some of the inconvenience could be alleviated by putting dozens of them in the same family of orbits, so that a floating island will be leaving every month or so on a one-way trip taking maybe 18 months or two years.
Life requires a lot of cosseting. Inorganic stuff doesn't complain about the food or service, and the principal use of inter-rack travel would necessarily be moving freight; cubic kilometers of stuff, or megasteres if you'd prefer. Perhaps the well made cores from which a habitat could be hung could be sent with their robot work crews, to sites like Wodan where they could establish themselves and wait for the arrival of us higher life forms. Or perhaps from the Oort Cloud would be captured a comet full of volatiles, steered by heroic robots to provide air and water to those hats deprived of such necessary amenities. My initial thinking was that clearly humans would not be doing much, if any, such traveling.
I could be wrong, he said, considering that such a restriction is surely antithetical to the needs of adventure fiction. Floating islands may do for spreading the biosphere and the humans it contains, but once there are well established destinations, it is clear that there will be a demand for travel between them. Using O'Neill's mass driver to propel computer ships has this unhappy side effect: They spray high velocity matter opposite the direction of thrust. Initially, this is not a problem, but as targets increase, and habitats are repeatedly perforated by the reaction mass of the rich and famous en route to the latest watering hole, it is probable that lawyers will stop that particular mode of travel.
The Gilliland solution to inter-rack travel is to have the vehicle propelled, not by its own efforts, but by the rack from which it is departing. In simple form, imagine Steamboat Willie in a rowboat. Instead of oars or a sail be has a cannonball catcher, and he is moved towards his destination by cannonballs fired from his home port. The astute observer will observe that, If This Goes On, the home port is very likely going to be pushed around by the recoil. Aha! Sensitive to environmental concerns, such as precessing gyros and racks getting bent out of shape, we have mounted the cannon on a circular track, where it fires to Willie when tangent to the track. The recoil sends the cannon backwards, while it is reloaded and turned around 180 degrees; when it is on the opposite side of the track, it again fires a cannonball at Steamboat Willie, and the effects of the recoil are cancelled out with every shot. As Willie approaches his destination, he catches cannonballs fired from there to slow down.
Scaled up for inter-rack commuting, this gives us a pair of magnetic cannon shooting pellets into a magnetic bottle that catches them. The recoil mechanism feeds the recoil energy into a flywheel, speeding it up or slowing it down, so that the net recoil from the magnetic cannon is zero. Thus do we get an action without a reaction, thereby refuting Newton. Meanwhile, the ship with the magnetic bottle is accelerated until it approaches its destination, when it begins decelerating.
To save weight, our ship might be powered by beamed microwaves, and it might even be that the field of the magnetic bottle would provide some protection from Solar flares. One drawback here is that our vehicle, which can hardly be called a "ship", travels on rails as surely as any trolly car. "Oh damn! At last I perceive what I am/ I'm a creature that moves In predestinate grooves/ I'm not even a bus, I'm a tram."
The conventional idea of space travel, at least the pre-Star Trek idea, is zooming around at one gee to get anywhere in the Solar System in a few days. Mandated by story requirements, the old idea will sort of work with this system, but some modification will be required. What sort of modifications? Consider that if our gunnery robots can keep the stream of pellets focussed and on target for 0.1 AU, an impressive 9.2 million miles, that will be a whole lot. Coasting at top speed afterwards will add substantially to the range of the ship, a range limited only by the constraints of the life support system. To paraphrase Kipling: "He travels the furthest who travels alone." However, inter-rack travel time is likely going to be measured in weeks, if not months; the Solar System is BIG. This is an improvement over the floating island mode, of course, if not quite up to Star Trek technology.
Note also the communications technology, relying in the main on radio, laser, or what not, is entirely limited by the speed of light. Which means that if you are out by Diomedes, a largish Trojan Asteroid, there will be an hour and a half time lag while light makes the trip from Diomedes to Earth. No snappy dialog between Capt. Buzz Lightyear and Admiral Eor; only e-mail messages, as in email@example.com to firstname.lastname@example.org flickering back and forth. The time delay is not an unmixed evil; it might even prevent flaming, as people paused to think about what was being said.