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Japan starts space elevator experiments

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Re: Japan starts space elevator experiments

#261

Post by TeMPOraL »

Keyframe wrote: post #233
adrianN wrote: post #224

Earlier quoted context omitted.

No, we don't even know if warp drives are allowed by the laws of physics. We have a pretty good idea how to do hibernation: Saturate the tissue with some cryoprotectant and freeze it very quickly. The problem is that we don't have a cryoprotectant that is sufficiently non-toxic and we can't freeze anything as big as a human quickly enough.

Of course we know. Bend space and don't travel faster than light. We JUST need exotic matter of sufficient energy density to carry around.

And some way of resolving the resulting time travel paradoxes.

Re: Japan starts space elevator experiments

#262

Post by mrhappyunhappy »

de_watcher wrote: post #240
rapnie wrote: post #229

Earlier quoted context omitted.

I agree on the publicity stunt feeling. Space elevators are thought-provoking stuff of science fiction. It would be fantastic if we could build them. Most I've read on the subject (this article included) are very thin on details, or point out the great scientific hurdles and breakthroughs that still need to be overcome / made. This article made me think of the publicity stunt some years ago to build a mountain of 3,5…

There is a very good youtube channel by Isaac Arthur where they look at different options. There is better stuff like the orbital ring which looks very expensive but actually feasible with current technology.

I watched that entire video on space elevators - very fascinating.

Re: Japan starts space elevator experiments

#264

Post by tripzilch »

codethief wrote: post #257
toxik wrote: post #234

Earlier quoted context omitted.

I’m not sure but I think since angular momentum is conserved, and angular velocity remains constant at all distances to Earth’s center here, then there will not be any lateral forces due to Earth’s rotation about its own axis.

While total angular momentum is certainly conserved in any rotationally invariant system (read: Earth + space elevator + objects traveling upwards + atmosphere), the situation only for an object traveling to space in the elevator is different: Angular momentum is given by L = I * ω where I is the moment of inertia and ω is the angular velocity. Let's assume that we put the internet ( https://m.youtube.com/watch?v=iDb…

> Let's also say that the internet has a mass m

silly, the Internet doesn't weigh anything! ;-)

Re: Japan starts space elevator experiments

#265

Post by blahedo »

misja111 wrote: post #249
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…

Comparing to a typical submarine, it's three times as much space per person. Submarines typically have 30 square feet pp, 18m x 17.2m for 30 people is 93 square feet.

7.2, not 17.2, so about 46 sqft per person. Point taken, but if a submarine is the point of comparison... yeah, that's really really not a lot of room.

Re: Japan starts space elevator experiments

#266

Post by Yizahi »

lugg wrote: post #260
adrianN wrote: post #223

Earlier quoted context omitted.

Those regulations are there for a reason. Safety is important. You don't want your space elevator climbers to fall down. A ripped cable would also be a pretty expensive accident.

Imagine untangling it.

Stanley Kim Robinson has very colorful description of space elevator falling on Mars. Basically it should loop around the planet accelerating during the fall, likely supersonic in the end and flatten everything in its path.

Re: Japan starts space elevator experiments

#267

Post by zengid »

ghaff wrote: post #30

For those looking for a popular culture examination of space elevators--albeit from a number of decades back--check out Arthur C. Clarke's The Fountains of Paradise. It also deals with some of the engineering issues, though again it's quite old.

The Three Body Problem Trilogy (officially named the Remembrance of Earth's Past trilogy) by Cixin Liu goes into space elevators a good bit. The Three Body Problem sets up the technology involved, while the other books develop the subject further.

Re: Japan starts space elevator experiments

#268

Post by aedron »

tripzilch wrote: post #264
codethief wrote: post #257

Earlier quoted context omitted.

While total angular momentum is certainly conserved in any rotationally invariant system (read: Earth + space elevator + objects traveling upwards + atmosphere), the situation only for an object traveling to space in the elevator is different: Angular momentum is given by L = I * ω where I is the moment of inertia and ω is the angular velocity. Let's assume that we put the internet ( https://m.youtube.com/watch?v=iDb…

> Let's also say that the internet has a mass m silly, the Internet doesn't weigh anything! ;-)

Seriously, the whole description became needlessly opaque by using the internet, of all things, as the example.

Re: Japan starts space elevator experiments

#269

Post by baby »

samstave wrote: post #219
snowmaker wrote: post #160

It's unclear to me if this is real or the continuation of a publicity stunt from Obayashi (who has been getting press about their plans to build a space elevator for years). I'm as excited about the theoretical concept of a space elevator as anyone. But the problem remains that no one can produce a cable even close to strong enough. This article has a good description of the material science problem: http://www.space…

The fact that we are talking about a japanese company called Obayashi making a carbon nanotube elevator to space is very cyberpunk to me. Reminds me of Ono Sendai making wetwire jacks to the internet.

Makes me think of Gunmm/battle angel alita

Re: Japan starts space elevator experiments

#270

Post by chris_st »

timonoko wrote: post #237

The Giant Space Wheel (of Seveneves) is so much more attractive than space elevator. That is a large mass on geostationary orbit having smaller pods rotating at the end of ropes. Those pods can be lowered to atmosphere and synchronized with earth rotation. Elevator pod comes down and can stay down maybe couple of hours and then jerked back to heavens. All energy comes from the sun - collected at the center station. S…

Does it need similar cable strength as the space elevator (as mentioned elsewhere in this discussion), or are its requirements easier to hit?
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