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Japan starts space elevator experiments

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Re: Japan starts space elevator experiments

#91

Post by zepearl »

comboy wrote: post #86
zepearl wrote: post #82

Thinking about a "counterweight" orbiting a planet to which it is connected by a cable: as the cable offers resistance to the planet's atmosphere, and as the planet's atmosphere is active/changing, the "thing orbiting" would still have to have an excellent aerodynamic shape to survive the planet's atmospheric effects, right? (as e.g. the lower part of its cable would probably soon or later be "pushed" by winds theref…

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 happen, with relative slingshot-effect.

Re: Japan starts space elevator experiments

#92

Post by black6 »

cryptozeus wrote: post #90

If they build this from japan, how would they deal with earthquakes ? Last thing you want is to be flying off to space in 18 x 7 m car

FTA:

> Obayashi envisages a space elevator using six oval-shaped cars, each measuring 18m x 7.2m holding 30 people, connected by a cable from a platform on the sea to a satellite at 36,000 kilometers above Earth.

36000 km is GEO, so it would be near the equator, away from land and safe from quakes.

Re: Japan starts space elevator experiments

#93

Post by Keyframe »

p1mrx wrote: post #89
Keyframe wrote: post #77

Earlier quoted context omitted.

So far, for humans, that lives within same realm that warp drives occupy in science fiction.

If bears were capable of warp drive, then I would agree with you.

If bears will be the ones to take space elevator trips, then we're set.

Re: Japan starts space elevator experiments

#94

Post by zepearl »

yohann305 wrote: post #78

Someone patented space elevators in 2015. http://patft.uspto.gov/netacgi/nph-Parser?patentnumber=90858... No comments...

Thanks for the link. I'm personally very conflicted about patents. In this specific case I classify it as a "speculative" patent => I'm totally against this it.

Patents should be allowed only for something that exists / can be demonstrated (which would ensure that patents are something somebody invested in, and therefore at least believed in).

Re: Japan starts space elevator experiments

#95

Post by cantagi »

tristanj wrote: post #23
rietta wrote: post #4

The 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.

The piece that falls to Earth ends up wrapping faster and faster, this causes centrifugal force on the tip, increasing the tension in the ribbon. Often the ribbon breaks on its way down and some fragments go flying out of Earth's gravity well. I didn't expect this at all.

The space elevator would become a space whip. I wonder whether this has a use case, like getting hardened unmanned space probes to speeds required for interstellar missions, or just much faster missions to other planets in the solar system.

Re: Japan starts space elevator experiments

#96

Post by worldsayshi »

zepearl wrote: post #94
yohann305 wrote: post #78

Someone patented space elevators in 2015. http://patft.uspto.gov/netacgi/nph-Parser?patentnumber=90858... No comments...

Thanks for the link. I'm personally very conflicted about patents. In this specific case I classify it as a "speculative" patent => I'm totally against this it. Patents should be allowed only for something that exists / can be demonstrated (which would ensure that patents are something somebody invested in, and therefore at least believed in).

Yeah, I wonder if anyone has patented human teleportation...

Re: Japan starts space elevator experiments

#97

Post by skookumchuck »

blahedo wrote: post #29

> "...six oval-shaped cars, each measuring 18m x 7.2m holding 30 people, ... eight days ...." Whooooa. Let's think about this for a second. Eight days means people need to sleep (and not just sitting up in a chair, no matter how comfy). At 1m x 2m per bed that would be a 15m x 4m space even without aisles to walk between the beds or down the middle or any sort of privacy separators. Also, a bathroom and actual washin…

Don't actually need much for 8 days. Provide video games, pizza, and a relief tube. People do it all the time.

Re: Japan starts space elevator experiments

#98

Post by Turbots »

Orbital rings would be a much better and more feasible option with our current technology, although I would love to see a space elevator in my lifetime as well. Check out the fantastic series called upward bound by Isaac Arthur who goes over the many options on leaving our planet: Upward Bound: https://www.youtube.com/playlist?list=PLIIOUpOge0LsGJI_vni4x...

Re: Japan starts space elevator experiments

#100

Post by Turbots »

Atheros wrote: post #80
zadler wrote: post #64

Earlier quoted context omitted.

Perhaps unless you decide to detach the cable at the earth end? You might be able to react to a break faster than the cable can fall.

Even if you could react and cut the cable in 1 ms, if the counterweight is disconnected, the rest of the cable is coming down to Earth.

And most of it will probably burn up at reentry, although some of it will fall into the ocean. Isaac Arthur runs over all the options to prevent this from even happening in his Upward Bound series, eg. automatically breaking up the cable in parts by blowing fuses and having parachutes on all the parts to slow them down.
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