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Japan starts space elevator experiments

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Re: Japan starts space elevator experiments

#151

Post by DoreenMichele »

tambourine_man wrote: post #146
DoreenMichele wrote: post #17

Earlier quoted context omitted.

Most humor can be categorized as "insubstantive comments" and those are discouraged. It is possible to crack a joke here and get it upvoted, but it's hard to pull it off. I even once had a joke upvoted by quite a lot,* like 50 points or something, but most jokes are downvoted not because humor is forbidden, but because insubstantive comments are discouraged. Some humor is downvoted for being uncivil because a lot of…

Can I ask why you retired your previous handle?

The short version is that I made the leaderboard and it looks like a feminist handle. There's more factors involved, but that's the crux of it.

Re: Japan starts space elevator experiments

#152

Post by maxxxxx »

theothermkn wrote: post #117
jandrese wrote: post #110

Earlier quoted context omitted.

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.

The center of mass of the cable-counterweight system orbits at geosynchronous height. Also, the gradient of gravity will Stabilize the attitude in the desired orientation. None of this should be construed as an endorsement of space elevators, though. They will never happen on Earth as it exists now. Over and above the material science, you have to clean out LEO of all satellites before you even start construction. It…

I thought the base station would be a ship that can be moved to avoid collisions with satellites.

Re: Japan starts space elevator experiments

#153

Post by sandworm101 »

DoreenMichele wrote: post #17
newnewpdro wrote: post #11

Earlier quoted context omitted.

Is humor against HN rules? I regularly see such posts being downvoted and it doesn't make sense to me.

Most humor can be categorized as "insubstantive comments" and those are discouraged. It is possible to crack a joke here and get it upvoted, but it's hard to pull it off. I even once had a joke upvoted by quite a lot,* like 50 points or something, but most jokes are downvoted not because humor is forbidden, but because insubstantive comments are discouraged. Some humor is downvoted for being uncivil because a lot of…

But if you note my "joke" actually illustrated a point of physics about which at least one person was confused: the expected g-forces. So it wasnt insubstantive, certainly not as insubstantive as the parent comment about elevator music.

Re: Japan starts space elevator experiments

#154

Post by cptaj »

TheSpiceIsLife wrote: post #140
mortenjorck wrote: post #73

It’s cool that any kind of space elevator experiment is happening at all, but temper your expectations with the numbers: this is a 10m cable. It is literally a 1:9,600,000 scale model of a real space elevator.

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.

Re: Japan starts space elevator experiments

#155

Post by sandworm101 »

craigmi wrote: post #53
thanatos_dem wrote: post #22

Earlier quoted context omitted.

No, it’s not against the rules, but downvotes aren’t there to enforce the rules. It’s just a culture thing. HN tends to be more news and factually focused than reddit/Twitter/etc. People here just prefer to stay on topic, especially since humor is very different between people and can be very hit or miss.

yup, coming here and the top comment actually being something insightful or some point worthy of discussion instead of some sarcastic comment or joke like elsewhere is what makes this place.

The use if my joke is evident in the immediate reply, the confusion over g forces. There is no reason an informative comment cannot also be funny.

Re: Japan starts space elevator experiments

#156

Post by gammatrigono »

zepearl wrote: post #91
comboy wrote: post #86

Earlier 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…

Have to love seeing computer programmers feebly attempt to understand physics despite being completely ignorant. It's like seeing a ballerina try competitive swimming.

Re: Japan starts space elevator experiments

#157

Post by reustle »

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…

It's an elevator to _space_. There are going to be some comfort compromises, especially on these early iterations.

Re: Japan starts space elevator experiments

#158

Post by BurningFrog »

curiousgal wrote: post #45
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…

How much space would they get on the ISS either ways? It'd be a good practice.

There is - and I don't mean to pun - plenty of space in space. Space stations could be quite roomy.

Re: Japan starts space elevator experiments

#159

Post by knodi123 »

mLuby wrote: post #28
ourmandave wrote: post #3

The 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.

Weird to me that they aren't accelerating till the midpoint and then breaking till the destination at a constant 1g. Gets around the space sickness by providing artificial gravity and should take ~hours rather than ~days.

you're already experiencing a constant 1g right now :-)

Re: Japan starts space elevator experiments

#160

Post by snowmaker »

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.spaceward.org/elevator-when. Basically, we would need to find a material that is at least 10x, probably 25x as strong as any cable today.

Carbon Nanotubes are theoretically strong enough, but no one knows how to manufacture them. The longest carbon nanotube tether that has ever been manufactured is only a few inches long, a millimeter in width, and not particularly strong due to imperfections in the manufacturing process.

Obayashi is planning a 10m cable. Even building a 10m cable made of carbon nanotubes would require a Nobel Prize worthy breakthrough.

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