spec fic: elevator going up

Good science magazines were few and far between in the boondocks where I grew up, so most of my early contact with new scientific ideas was in fiction. I first encountered science fiction in Madeline L'Engel's A Wrinkle in Time, which makes use of the concept of the tesseract (a four-dimensional cube) as a gateway between dimensions (something I later learned was more like a wormhole). The idea that science could do things like this—maybe not now, but in the future—gave me chills of excitement. I quickly looked for more books with these cool ideas, and wound up plunging right into the hard stuff, thanks to my dad, who was a long-time reader of the pulps. Before long, I had a shelf full of hard Science Fiction from the Golden Age.

For the uninitiated, the term hard science fiction refers to SF that takes pains to get the science right, often at the cost of characterization, unfortunately. But what hard SF lacks in character development, it makes up for in wow factor, tackling big ideas and making concepts like space travel and colonization seem plausible if not inevitable. In the days when science magazines for the public were limited to Scientific American and Popular Mechanics, this was a service of some magnitude.

Many writers of hard SF have degrees in the hard sciences or engineering themselves (Isaac Asimov, Ph.D. in biochemistry; Larry Niven, B.A. in math; Poul Anderson, B.A. in physics; Gregory Benford, Ph.D. in physics; Hal Clement, B.S. in astronomy, M.S. in chemistry; Joe Haldeman, B.S. in astronomy, Dean Ing, aerospace engineering; Jerry Pournelle, degrees in statistics and engineering, etc., etc.), so they do care about the science behind their ideas. But they're also interested in exploring not just the how but the social consequences of an invention or new technology—something scientific research rarely takes into account. Not just what if? but, what then? As Frederik Pohl said, "A good science fiction story should be able to predict not the automobile but the traffic jam."

Still, all that extrapolation and speculation is just pipe dreams if one doesn't get the science right—not necessarily the fine technical details, but at least the theory, and enough details to lend verisimilitude. Among hard SF writers, this is paramount, so much so that the resulting fiction is sometimes not just predictive but prescriptive. Take Arthur C. Clarke's body of work as an example. Clarke, who has a first class degree in math and physics from Kings College, London, is probably one of the most recognizable and influential authors to tackle hard science fiction. Clarke's Three Laws are often viewed as the recipe for formulating new technology:

1. When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong.
2. The only way of discovering the limits of the possible is to venture a little way past them into the impossible.
3. Any sufficiently advanced technology is indistinguishable from magic.

Cute, you might think, but Clarke's own track record should be impressive enough to prompt a further pondering. For instance, you may not know that a geostationary orbit (where an orbiting object remains over the same coordinates, following the earth's rotation) is also called a Clarke orbit. This is because Clarke was one of the first people to realize how useful this particular orbit could be for the placement of communications satellites. This observation influenced the Intelsat and Telstar programs, almost twenty years after his original paper was published in 1945.

 Now we're on the verge of seeing yet another of Clarke's popular predictions come true: the space elevator (also called a skyhook or beanstalk), described in his 1979 novel, The Fountains of Paradise. While Clarke is certainly not the first writer to describe this idea, he's one of the most eloquent and well-known, and the one most instrumental in putting the idea in the public eye. The original space elevator, as Clarke acknowledges, was first described by Russian engineer Yuri Artsutanov in 1960, in an article in Pravda called "To the Cosmos By Electric Train." Since then, it's apparently been independently "reinvented" at least three times: by a team from Scripps Institute of Oceanography and Woods Hole Oceanographic Institute (1966); in 1969 by A.R. Collar and J.W. Flower in the Journal of the British Interplanetary Society; and by Jerome Pearson of the Air Force Research Laboratory at Wright-Patterson Air Force Base (1975). It was hinted at, though not fully developed (for lack of a large enough envelope for calculations, he claims) by Clarke himself in 1963 in an essay for UNESCO on communications satellites.

No matter who's describing it though, the concept remains roughly the same. I'll let NASA's PR writers do the, uh, heavy lifting:

A space elevator is essentially a long cable extending from our planet's surface into space with its center of mass at geostationary Earth orbit (GEO), 35,786 km in altitude. Electromagnetic vehicles traveling along the cable could serve as a mass transportation system for moving people, payloads, and power between Earth and space. Current plans call for a base tower approximately 50 km tall — the cable would be tethered to the top. To keep the cable structure from tumbling to Earth, it would be attached to a large counterbalance mass beyond geostationary orbit, perhaps an asteroid moved into place for that purpose. Four to six "elevator tracks" would extend up the sides of the tower and cable structure going to platforms at different levels. These tracks would allow electromagnetic vehicles to travel at speeds reaching thousands of kilometers-per-hour.

In Clarke's vision, the elevator could also be used as a "cosmic sling" to send payloads off into space without the use of rocket power.

The engineer in Clarke's novel calls it both a vertical subway and "a bridge to the stars." There are numerous advantages to lifting space-bound payloads this way, instead of using rockets or shuttles. In comparison, the space elevator uses relatively little power to move even the largest payloads, keeping costs low. Bradley Edwards, of HighLift Systems (part of the LiftPort Group; see below), estimates the cost could be as low as "about $100 a kilogram" while a shuttle lift costs "$10,000 to $40,000 per kilogram." The elevator's descending cars, in fact, can be designed to feed power back into the system, so it's virtually self-contained. Because it uses electromagnetic power, there are no environmental effects from any chemical rocket exhaust. It's quieter than rocket launches or re-entry, and both adaptable and expandable. The trick is building the thing.

The only places on the earth's surface suitable for this type of project lie roughly along the equator, where satellites line up correctly in geostationary orbits, and where there are few hurricanes or tornadoes to give a 35,786 km cable whiplash. Check a map and you'll see that much of this area is deep ocean. So finding a suitable chunk of land, or engineering a stable ocean-going platform for the anchor is the first problem.

The next is one of logistics. Moving the counterweight into position requires rockets that, in 1960, were only being developed for the Russian and American space programs, or better yet, by a space shuttle that wasn't quite a gleam in anyone's eye. There's also the difficulty of herding structures of this size through space. The construction of the space station (and fixing the Hubble Telescope) taught us a fair amount about working in space, but controlling something as enormous as these structures is a leap in magnitude. Even once the American, Russian, and European space programs were in full swing, the problem of materials remained. What do we make the cable out of?

At the time Artsutanov's article was published, there was no material strong enough to withstand the tensions inherent in the design of such a mode of transportation. Steel would snap under its own weight if spun into a cable this long, and the means of making a cable of that length didn't exist. To solve this problem, Clarke's engineer introduces, cannily enough, a "pseudo one-dimensional diamond crystal" with some trace element impurities for strength, grown in zero-g labs. Sound familiar? It should. The clever Ms. Ouellette and her faithful sidekick, Jen-Luc, have written about it here. The real-world equivalent is another form of carbon called graphene, which looks to be the best carbon nanotube (CNT) material for the job. The tensile strength of CNTs is enormous—making steel and even diamond look positively brittle in comparison—but only graphene has the requisite electromagnetic properties, i.e., the consistency of size necessary to produce consistent conductivity. Other forms of CNTs (Clarke mentions the Buckminsterfullerene) might also be suitable, depending on the final design of the elevator.

Still sound like a pipe-dream to you?  Keep in mind that there's a consortium of companies working on the project right now, the LiftPort Group. Their goal is liftoff by April 12, 2018 and they're gearing up for it by beginning commercial production of carbon nanotubes for other industries at a plant in Millville, NJ. There's also Elevator 2010, the annual space elevator contest, patterned after similar engineering competitions like the X Prize. This year's competition is coming up on October 20th, with two types of entries: one for tether strength and one for the "climber" or elevator car, based on speed and payload weight. And NASA is fully behind the idea.

It's hard to say how many people now involved in the space elevator project first heard of it in Clarke's book, but The Fountains of Paradise certainly captured the imagination of readers when it was published, me included. To my mind, the real difficulty is not the technology or the cost, both of which are factors humans have overcome before to make great technological leaps, but the raison d'être. In Clarke's book, Earth already has space colonies and industry in space. Rockets make a racket lifting expensive payloads to them. The time has clearly come for better, faster, cheaper. But here and now we're still taking tentative steps into space. What do we need this thing for?

Mars. And the Moon. More on this in another post.

The beauty of fiction is that there's frequently a happy ending. (Spoiler alert: read no further if you want to read for yourself how it turns out.) Clarke's engineer's dream comes true and by the Epilogue, Earth is encircled by a ring city stabilized by several space elevator structures, the lower halves of which have become vertical cities themselves. Here, indeed,is not just the automobile, but the traffic jam.

And that ring city . . . hmmm . . .