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Japan starts space elevator experiments

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Re: Japan starts space elevator experiments

#291

Post by marcosdumay »

jimmcslim wrote: post #252
ridgeguy wrote: post #179

I'm curious about space elevator phenomena related to lateral ∆V. At Earth's equator (zero altitude - i.e., on the ground), an object moves spinward at about 0.46 km/sec. In geosynchronous orbit, an object has to move at about 3.07 km/sec. A space elevator car ascending from stationary on the equator to a terminal at geo altitude would require a tangential (lateral) ∆V of 2.61 km/sec. This is in addition to the energ…

Wouldn’t payloads travelling up the space elevator and departing for the rest of the solar system and beyond ultimately deprive the earth of angular momentum and send it hurtling towards the Sun?

It does remove some momentum from the elevator, and sends it down towards Earth.

The system is not connected to Earth, so it doesn't change the planet's orbit.

Re: Japan starts space elevator experiments

#292

Post by tomatotomato37 »

cptaj wrote: post #154
TheSpiceIsLife wrote: post #140

Earlier quoted context omitted.

This isn't a scale model of a real space elevator at all. From the article: Shizuoka University and contractor Obayashi aim to launch two small (10 sq cm) satellites connected by a 10m steel cable from the International Space Station. I don't see any ways in which this is a space elevator related experiment.

They're testing the cart pulley system in space. Sure, the cable itself is the core technology needed for this, but you still have to work on the rest of it. These nanosats are a good, cheap way to move the TRL forward a bit.

I actually wonder if that is the true purpose and not what the media glued together out of "thing moving on cable." It could just as well be a test for a space tether or cable centrifuge, with any space elevator research being a secondary thing

Re: Japan starts space elevator experiments

#293

Post by nabla9 »

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…

Astronauts wear diapers, painfully lose their fingernails when working in spacewalks. Having to bunk in submarine style accommodation for little over week is nothing.

Re: Japan starts space elevator experiments

#294

Post by BurningFrog »

jessaustin wrote: post #288
BurningFrog wrote: post #216

Earlier quoted context omitted.

The slightly counter intuitive point is that you only have to transport wall material. An inflatable "house" is conceptually completely possible. Airplanes have to be small because of air resistance. Space stations have no such constraints.

Inflatable, sure, but not a balloon. Micrometeors/space junk are a threat, and more so for bigger inflated objects.

Yeah, the walls need to be strong enough. Whatever that means long term.

The mathematical argument of 2D vs 3D still holds.

Re: Japan starts space elevator experiments

#295

Post by spydum »

nabla9 wrote: post #293
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…

Astronauts wear diapers, painfully lose their fingernails when working in spacewalks. Having to bunk in submarine style accommodation for little over week is nothing.

okay i had never heard of the fingernail thing. that sounds awful. I wonder if later designs helped? My immediate thought is: fill those finger spaces with clay like material -- to spread the load across the whole surface of the finger, not just the nail.. but yowtch. glad I never chose that career.

Re: Japan starts space elevator experiments

#296

Post by grozzle »

salutonmundo wrote: post #145
toyg wrote: post #46

Earlier quoted context omitted.

You forget this is Japan, where tons of people sleep on trains almost every day - often on their feet.

Not to mention the existence of 'capsule apartments'...

There's one practically derelict building of capsule apartments, it was a failed experiment. Capsule hotels are a thing, but not apartments.

Re: Japan starts space elevator experiments

#297

Post by picsao »

roryisok wrote: post #279
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…

Seveneves is a great read!

The first part

Re: Japan starts space elevator experiments

#298

Post by retromario »

mac01021 wrote: post #198
djsumdog wrote: post #195

Earlier quoted context omitted.

Also the Mars Trilogy (Red Mars, Green Mars, Blue Mars) by Kim Stanley Robinson. Honestly that's my favorite Sci-Fi novel series of all time. Just give Red Mars a try and I prosome you won't be able to put it down.

Gave it to my father after reading it. He thought it was too slow and didn't have enough of a narrative arc, and he opted not to finish reading. I loved the trilogy, though.

It is really slow in places. Robinson loves to flesh out the environment of Mars. Beautiful trilogy, really enjoyed it, but it is an occasional slog.

Re: Japan starts space elevator experiments

#299

Post by [deleted] »

roryisok wrote: post #279
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…

Seveneves is a great read!

[deleted]

Re: Japan starts space elevator experiments

#300

Post by ataturk »

rapnie wrote: post #229
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…

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…

The quoted price is what makes me think it is a publicity stunt. $4Billion? That's not a lot of money to Uncle Sam. We're counting a $3Trillion federal budget or some such nonsense now. Inflation is rampant, even if not officially counted.
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