Monday, June 26, 2006

Elevating Spirits

The Liftport Group, whom I have mentioned before, are a private consortium dedicated to bringing about what will easily be one of mankind's more amazing engineering achievements: a space elevator.

Partially as a way of raising operating funds but, more importantly, as a method of raising their profile and informing people about the project, they have released a book: The Space Elevator—Opening Space To Everyone, which can be ordered here.

The book consists of technical articles, written by various experts, interleaved with fiction articles. The latter sees new authors alongside the expected and established (e.g. Arthur C Clarke and Charles Sheffield, both of whom coincidentally wrote stories about a space elevator in 1979). Also present is Kim Stanley Robinson whose book, Red Mars, features the collapse of such an elevator; the cable, sabotaged, falls to the planet with devastating consequences, a scenario which has worried many.

Luckily, the technical section of the book, which held far more fascination for me, explains—amongst other things—why the scale of destruction envisaged by these authors would not happen (essentially, the ribbon from which the elevator would be built would not only mostly burn up in the atmosphere, but would also be so light that it would float down to earth). But I am getting ahead of myself.

The basic idea of the elevator can be described like this: imagine swinging a weight around on the end of a piece of string. As you spin faster, the weight will swing out further and further to 90 degrees and the string will become taut. You are the earth, the weight is a counterbalance (this could be a space station, for instance) and the string is the ribbon of the elevator, reaching 100,000 km into space. "Lifters" would crawl up and down the elevator, hauling materials into geostationery orbit (and down again) for a fraction of today's costs.

The elevator would make breaking free of the earth's gravity well, a process which consumes the major part of any space rocket's power, a relative cinch. The inner solar system, and all of its resources, would be opened up to us in a way that simply isn't possible today, if only because of the current payload limits.

The Liftport group estimate current costs to be about US$10 billion, or about ten space shuttle launches. But how would the first ribbon be built? What could provide the tensile strength to build the ribbon, whilst remaining light enough not to be a threat (here's a clue: carbon nanotubes)? How would the Lifters be powered? How would the installation cope with—or rather better avoid completely—space debris, tropical storms and terrorist attacks? And what social and political changes might be needed to bring this project about?

The experts in this book answer all of these questions, and more, in a friendly, easy-to-understand way. The technical articles are comprehensive enough for anyone acquainted with the physics and engineering worlds, but comprehensible to the layman. In short, this is an excellent guide to man's next great project, and definitely worth looking at.

You can buy The Space Elevator here.

(Cross-posted at Nightcap.)

4 comments:

MatGB said...

This, is good to read. We thank you sir!

One thing I've never really seen discussed - would such an elevator be good for disposal of radioactive waste, or too risky security/safety concern wise?

Also good to know that KSR's falling elevator disaster wouldn't be that bad, although what about the modules &c that would be attached to it?

Devil's Kitchen said...

Mat,

Think about the swinging string; if, whilst you are spinning around, you cut the string in the middle, would the weight at the end come back at you? No. The weight would be carried out into space, leaving only the ribbon below the severance to fall to earth.

DK

Brian Dunbar said...

One thing I've never really seen discussed - would such an elevator be good for disposal of radioactive waste, or too risky security/safety concern wise?

Risk is a factor we really will have no evidence on until we have a few thousand hours of flight (lift?). Which may not be what the PR folks want to hear but oh well. It should be safer than conventional rocketry.

This may not be saying much, granted.

Security - it would be as secure going up an SE as it is now being hauled around the country.

Our attitude about this is that for us to use this - or any dedicated purpose - as a 'must have' is sub-optimal. We're open to anyone who wants to use our SE and can pay the bills and can meet or exceed applicible rules and regulations. If you can form a viable company around 'hauling nuclear waste' and tossing it into the Sun, go right ahead.

Or, you know, convince the government to do this for you.

There are some problems associated with this. You'll need to haul it to a port and put it aboard ship for shipment to the SE head. Which will add to the bill. You'll need a carrier once it gets to the top that has enough oomph to break loose and careen into the sun. Will all of this exceed the costs for a Yucca Mountain site? If it does it will be a non-starter.

My own take is that nuclear waste disposal is such a political issue (which is foolish but there you go) that doing anything is going to involve an enterprise in much legal wrangling and will require the enterprise to devote a signifigant amount of captial to lawyers and court time. It also doesn't lent itself to much rational discussion which is a pity.

Anonymous said...

You neglect to mention that the far tip of the elevator would be moving at way above escape velocity so providing a free slingshot to anywhere in the solar system. Put another one at Mars for instance and you've got a/. an orbital capture system and b/. two way travel at minimal energy expenditure

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