My favourite Space Elevator concept was from the Halo franchise.
There would be multiple elevators on the continents of the planets that were tethered to orbital platforms.
They didn't seem to survive the covenant well
Japan starts space elevator experiments
101–110 of 304 posts
Re: Japan starts space elevator experiments
#102Earlier quoted context omitted.
Centrifugal force would keep straightening it up.
Yes, but probably only in general (meaning only from a theoretical point of view without considering external forces)? E.g. as soon as the cable has headwind (in the opposite way of the planet's rotation) the cable would slack off, the thing in orbit would slow down & lower its altitude (how much? Would it anyway have to always skim the upper atmosphere?) => then as soon as the cable gets tailwind the opposite would…
For practical purposes the atmosphere ends at 500km altitude. The cable is going to have to be 36,000 kilometers long. Atmospheric effects are pretty much rounding error at that point - imagine trying to swing a 10 foot long pole by blowing on the first inch.
Re: Japan starts space elevator experiments
#103Earlier quoted context omitted.
That trip would only take an hour, but I don't think you could build a cable and drive system capable of operating at 18 km/s.
Not sure if this would work, but how about using a wire with evenly-spaced metal beads, then using a magnet (a large one like used in MRI machines) to pull up the cart? You'll probably have to turn the magnet on/off at a specific frequency, depending on the momentum of the cart, which could be a challenge.
Re: Japan starts space elevator experiments
#104The cars would travel at up to 200kph and arrive at the space station eight days after departure from Earth. These early cable experiments are important, but someone should also be working on the composing an 8 day Elevator Muzak score that won't drive you insane.
Re: Japan starts space elevator experiments
#105The cars would travel at up to 200kph and arrive at the space station eight days after departure from Earth. These early cable experiments are important, but someone should also be working on the composing an 8 day Elevator Muzak score that won't drive you insane.
I'd pick Max Richter. His Sleep¹, which is nearly 8.5 hours, would be a good start.
Re: Japan starts space elevator experiments
#106I saw a bunch of people throwing out good sci-fi space elevator examples and had to drop a reference to the space elevator in Neal Stephenson’s Seveneves. The descriptions are epic and do a good job of giving a real sense of placiness to the result of truly enormous engineering.
Re: Japan starts space elevator experiments
#107Earlier quoted context omitted.
Stairway to Heaven is about 8 minutes long, so they better work hard on speeding the elevator up to match that.
Only if they want this to be a fancy burial service where we slingshot your corpse into space for kicks.
Another version of the Euthanasia Coaster?
https://en.wikipedia.org/wiki/Euthanasia_Coaster
Re: Japan starts space elevator experiments
#108i remember reading here on HN someone explaining why space elevators are not possible. I can't recall why, but he/she had very convincing arguments. Anyone here remember that thread and can link it back here? Thanks
Kelly and Zach Weinersmith discuss space elevators in their book Soonish. The summary of the downsides is:
* If would need to be the most precisely engineered thing we've every produced just to stand a chance of being good enough.
* Because of that, it will be particularly sensitive to wear and tear. How the maintenance would work is an open question.
* It will probably attract terrorists like crazy.
* It needs to never get struck by lightning. It is a particularly attractive lightning rod.
* It generally should avoid bad weather. Whatever it is attached to on Earth needs to be able to move. When moving it you have to avoid not only the bad weather but everything in space, too.
* If the cable breaks, bad things could happen. Bad things can range from burning up in the atmosphere to it whipping around in space damaging satellites, or anything else.
Re: Japan starts space elevator experiments
#109The experiment sounds great. But should this work and a real cable to orbit is built, what happens when the cable snaps!? Can such a structure be made failsafe?
There are various simulations of what may happen. Here is one that demonstrates what may happen if the cable breaks at various points. http://gassend.net/spaceelevator/breaks/ In summary, if the cable breaks at the base, the elevator will fly harmlessly into space. If it breaks at the counterweight, a large portion of the cable (several thousand miles long) will collide with the Earth’s equator.
Harmless, except for the passengers.
Re: Japan starts space elevator experiments
#110Earlier quoted context omitted.
Most theoretical designs that have been proposed would require a very large counterweight, e.g. a captured asteroid.
Or you just build the cable out beyond geosynchronous orbit. The further out your counterweight mass is, the more force it exerts, so, AIUI, the most mass-efficient way to do it is an extension of the cable.
The problem is how you keep the tether from dragging behind the orbit when you do that. Space elevators require a fairly delicate balancing act to keep the mass directly over the base of the elevator, otherwise they turn into giant slings.