I’ve recently started reading the “Mars” series of books by Kim Stanley Robinson. In Red Mars, Robinson makes mention of a space elevator used on the red planet. A couple things come to mind:
Is a space elevator only existant on low-gravity planets where the weight of the cable wont tear itself apart?
How are payloads/passengers carried up and down the space elevator? In the book, it mentions cable car type modules continually going up and down the cable. I picture a rather odd way of transporting payloads similar to two people holding a string and applying force in the middle to make the string vibrate.
And as for the second question, any method would work. You could grab the elevator shaft with rubber wheels, or some other type of mechanical contact. You could use a cable and winch system and just pull the capsules up from the top, but that would be very tricky because of the enormous amount of slack in the long cable. A linear motor system would probably be the best bet. Basically, you attach magnets of some sort (electromagnets, most likely) along the entire length of the elevator shaft. The magnets on the capsule/car pull it up. It’s the same system used on maglev trains, and is already used (experimentally?) on elevators in some buildings. That’s what Arthur C. Clarke used in his novel “Fountains of Paradise” (one of my favourites).
I think we’re about an order of magnitude away from a material with enough tensile strength to make a ‘space elevator’ while still having a reasonable mass and circumference.
BTW, the trip to and from Orbit is very cheap. It takes energy to climb up, but on the way down you can generate electricity which can be used to power the vehicles going up. All you’re losing are the frictional losses.
I think that buckytubes/nanotubes (basically, diamond) have much greater tensile strength than is needed, and could be amassed and shaped into an elevator. Unfortunately, right now they cost several million dollars a kg to produce. Which makes a space elevator a proposition costing more than the combined GNPs of every nation on Earth.
Hey, if they can make TWO alien transport systems in Contact, we can make a friggin’ diamond elevator 200 miles high. THAT’d really cheese King Solomon.
“Man, my temple was the greatest, nobody can beat it…”
Don’t forget “The Web Between the Worlds”, which has an intro by Clarke noting the eerie similarities between it and “Fountains of Paradise”. By the time Heinlen wrote “Friday” all he had to do was mention “The Beanstalk”, the idea had been so fully explained. For a more recent take, see Robert L. Forward’s “Indistinguishable from Magic”
And the official way to test when an idea has passed into SF cliche–when it appears on “Star Trek.” “ST: Voyager” did an episode a season or two back titled “Rise” that had to do with a space elevator.