What's wrong with moving cables for a Space Elevator?

Ok, Space Elevators have fallen out of the limelight, sorry for them, but the concept is intriguing just the same, so here it goes.

One of the worst problem space elevators face is the fact that they are not elevators at all; they are structures, instead, that allow a "crawler" to climb them, with endless problems about how to feed energy to it, the need for motors, etc, etc.

The reason for this is that the cables need to be thicker (more resistant) near the geostationary orbit than elsewhere. A moving cable (a loop) would need to have a cross section instead.

There are, of course, many other structural problems, but I'm not trying to address them all with a single question.

Let us assume the cable itself can be made. It will have to be "tapered", which means it needs to be thicker near center of gravity (geosynchronous orbit) where everything is suspended.

This is standard S.E. design.

In this design you need a "crawler" autonomously climbing the cable and you need to give it enough power to arrive at GSO.

Doing without a crawler would mean having a true elevator, with moving cables, but a cable loop (chairlift-style) needs a cable of uniform diameter, thus it's necessary to break the distance into suitable legs.

What I propose is to:

• subdivide the whole length into sections where the cable can reasonably be of constant section/strength.
• make each "leg" of the trip with one loop of cable (the thinnest possible) between two wheels and have it run at constant speed; so the tract would be connected by two cables, one going up and one going down.
• add a number of static cables (the same size as the moving one) to connect the wheel rig to the "upper station" to make up for increased cable strength needed.
• have "crawlers" be simple cabins that will accelerate and hang on to the cable "going in the right direction".
• add more cables for redundancy.
• add space platforms at the wheel rigging to have nice platforms for scientific/touristic purposes (and to dampen Coriolis); to hold them in place it might be necessary to add some more static cables.

This rigging has multiple benefits:

• you get "station platforms" (almost) for free.
• all cables are the same section, so manufacturing is way simpler.
• the structure can be built incrementally and enlarged at will.
• multiple cables are less vulnerable to all kinds of incidents.
• if (some of) the static cables are conductive you get free electricity.
• motors to keep the moving cables running can have minimal power and rely on cable inertia for "crawler" acceleration.
• different "legs" of the trip may be done at different speeds (e.g.: first, in atmosphere, leg should be slower than long-distance to geostationary).
• crawler can be really simple and lightweight.

As requested I have added an image (sorry, I'm not really able to draw!):

What is wrong with this scheme?
Why is this not taken into account (at least I haven't found references to it)?
Please cross-check my proposed design.

posted over 6 years ago

ZioByte‭

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