Japanese 2050 Space Elevator project (Obayashi Corporation)

[Justo Miranda]

That's just blatantly false since the concept of a tensile space elevator originated in 1959, and the idea of a compressive space tower from even earlier on in 1895.

Nice bait.

That stupid idea had occurred to a lot of people before, but Clarke is more guilty because of his scientific background.

 

[Orionblamblam]

And keep in mind it's NOT "one" tether but somewhere near a half to a full dozen so you can have traffic going both ways.

Assume a tether that tapers down to nearly nothing at sea level... a ribbon a millimeter thick and five inches wide, gradually expanding to several meters wide at the top, with a sizable asteroid in GEO for a countermass... and then another tether stretching tens of thousand of km out the other way. Great! You have your first tether. So... you want a half dozen? Fine. That means five more asteroids as well, or an asteroid five time the mass and size. Did you plan for that initially, or do you need to snag more and somehow expand the size of your baseteroid?

 

[Dilandu]

If beanstalks don't work, they don't work. And so far, they're interesting theoretically, but the engineering is extremely lacking.

Frankly, launch loops and laser launch systems looks like much more promizing concepts. But public imagination is captured by space elevators, because the whole idea looks "simple".

 

[martinbayer]

On the human engineering side of things, will there be a lift/elevator (wo)man/boy/girl/operator/servant with one of those snazzy/silly movie style uniforms and caps, or will you actually have to punch in a destination level button all by your lonely self and/or succumb to the almighty ai?

 

[Dilandu]

Agreed, though both remain pretty speculative

Yes, but they significantly less speculative than space elevators, since they do not require any unobtanium materials to operate. Of course, the road from "perfectly possible" to "actual design" is quite long and bumpy...

Rockets, on the other hand, we know work just fine. And they're getting cheaper.

True. Ironic, but it seems that chemical boosters may remain the main planet-orbit transportation even in distant sci-fi future; hard to find anything with similar thrust/weight without burning the launch pad into magma.

 

[publiusr]

What about two of them on some cosmic bodies?

I was thinking two would be attached to large statites/sails that crossed each other in an X?

The two wide sails use the pressure of sunlight to tack towards or away from each other.

This means the intersection where the two cables meet can raise or lower itself to the ground rather quickly.

Perhaps a flying windlass at the intersection that drops a tether straight down, let's it play out as the intersection falls, or spin up as it rises?

A large passing object going between the uprights snags this cable designed to detach quickly---this cable the only really rugged cable--+being only 100 miles or so in length...a skyhook.

The other cables just keep the third taut...

No train needed---all Archimedean.

 

[Prophet141]

nonces (a new word I learned from the Brits!)

Not On Normal Courtyard Exercises (or some similar variation). A label applied to those who defile the innocent young in society, so they don't get a stern talking to from the more conventional villains...

Back on topic, one of the main benefits of the space elevator is that it wouldn't require as much energy input to simply exist as a launch-loop, and effectively removes the gravity drag present in a laser launch system. Of course there'll likely be station-keeping or the odd manoeuvre that the tether has to undergo, but there are many methods through which that can be done (an electrodynamic tether being one that we could use on Earth) and they aren't as energy intensive as active support.

It would be interesting if there was a concerted effort to build a space-delivery megastructure today, I wonder which approach they would go for.

 

[publiusr]

As long as we are talking asteroid wrangling...perhaps a fly-by rotovator?

This need not be circularized.

You need a metal hunk or two for a bola...one end is back spun and deposits a good hunk with some rolls of cable...so you have a bit of time to attach the other end to a big floating metal structure preloaded as a station or base.


Rockets would be used with a hydroplane set-up to get the structure moving and to lessen the strain on the cables...that only need to be 200-1000 km or so.

 

[Nik]

Irony is that Earth seems 'just on the edge' of conditions for a practicable elevator..

If our day-length was significantly shorter, so rotation faster, geo-stand orbit would be much lower. Needing a shorter, less-strong elevator cable, lesser counter-weight etc

Likewise, if our day-length or Earth's gravity were some-what larger, elevator notions would require 'Oodles of Unobtanium'...

So, Mars is best candidate ??

 

[Scott Kenny]

Assume a tether that tapers down to nearly nothing at sea level... a ribbon a millimeter thick and five inches wide, gradually expanding to several meters wide at the top, with a sizable asteroid in GEO for a countermass... and then another tether stretching tens of thousand of km out the other way. Great! You have your first tether. So... you want a half dozen? Fine. That means five more asteroids as well, or an asteroid five time the mass and size. Did you plan for that initially, or do you need to snag more and somehow expand the size of your baseteroid?

No, I believe the comment is multiple tethers kinda like a tall ship mast. You have one tether for holding the station. You then add another tether for up-bound trains, and a third for down bound trains. Got too much traffic for one tether each direction? Add another pair of tethers.

All going to the same GSO station.

For all intents and purposes, there are only two stops: top and bottom. Payloads could be carried externally and jettisoned at various altitudes, but the payloads will need propulsion systems to circularize their orbits. You'd have to be pretty high before something dropped from an elevator wouldn't have a perigee within the atmosphere.

A dandy way to deal with murderers, rapists, nonces (a new word I learned from the Brits!) and people who talk in theaters: haul them a few hundred miles up, toss 'em overboard. They'll plummet to a firey entry. Whatever's left plops into the sea for the sharks.

What did the poor sharks do to deserve that?

Irony is that Earth seems 'just on the edge' of conditions for a practicable elevator..

If our day-length was significantly shorter, so rotation faster, geo-stand orbit would be much lower. Needing a shorter, less-strong elevator cable, lesser counter-weight etc

Likewise, if our day-length or Earth's gravity were some-what larger, elevator notions would require 'Oodles of Unobtanium'...

So, Mars is best candidate ??

Or one of the Jovian or Saturnian large moons, yes.

 

[Orionblamblam]

No, I believe the comment is multiple tethers kinda like a tall ship mast. You have one tether for holding the station.

The station is a *requirement* of the tether. It anchors it in GEO. You need one for each tether, one one huge one for multi-tethers.

 

[Scott Kenny]

The station is a *requirement* of the tether. It anchors it in GEO. You need one for each tether, one one huge one for multi-tethers.

I think we're talking past each other on this one.

Again, picture the masts of HMS Victory. There's a mast going up to the fighting tops, then there's those net ratlines going up for people to climb up and down.

One tether going to the station is the mast, it's there to take extra loads from the other tethers. Then you have additional tethers like the net ratlines for the crew to climb up and down.

 

[Orionblamblam]

I think we're talking past each other on this one.

Again, picture the masts of HMS Victory. There's a mast going up to the fighting tops, then there's those net ratlines going up for people to climb up and down.

The tethers are straight up and down. Tethers that can hang off at any sort of angle would need to be stronger and would weigh substantially more, and would largely droop straight down most of the way anyway.

 

[Prophet141]

This entire debate is more or less based on how skeptical one is about the strength of future materials, or rather our ability to create such materials in usable lengths.

You two are likely to go around in circles.

 

[publiusr]

The reason I like skyhooks is that they can be shorter...have thinner, crossed tethers hold up the short, strong tether just out of the atmosphere, then have a passing body snag it.

 

[Nik]

Perhaps riding multi-mode 'Reaction Engines' jet/rockets ??

 

[Scott Kenny]

The tethers are straight up and down. Tethers that can hang off at any sort of angle would need to be stronger and would weigh substantially more, and would largely droop straight down most of the way anyway.

They don't have to be angled, they just need to be separated enough that the "ratline" tethers don't interfere with each other.

Somewhat poor analogy on my part, sorry.

 

[Orionblamblam]

They don't have to be angled, they just need to be separated enough that the "ratline" tethers don't interfere with each other.

Somewhat poor analogy on my part, sorry.

They all need to be anchored at top and bottom. The greater to total mass of tether, the greater the total mass of GEO anchor.

 

[Scott Kenny]

They all need to be anchored at top and bottom. The greater to total mass of tether, the greater the total mass of GEO anchor.

Right. And since GEO is right in the middle of a Van Allen belt, you need a crapton of shielding. Say, water.

I wasn't joking when I suggested a 100 million ton station at GEO, with something like 10 million tons of water for shielding. This is largely to allow people to spend a decent amount of time up there without radiation issues, including tourism. Spend a nice week going up the beanstalk, a week at GEO station, another week coming back down.

 

[PFJN]

This entire debate is more or less based on how skeptical one is about the strength of future materials, or rather our ability to create such materials in usable lengths.

You two are likely to go around in circles.

Hi,
I suspect that you are probably right about the debate on materials strenght. My big concern though is that when people suggest that we may potentially be on or near the verge of developing materials with adequate properties, alot of that appears to me based on only accounting for "some"of the loads that such a cable/ribbon/tether may have to withstand and when you consider additional things like wind shear loads, particle/object impacts, wear, tear, abrasion, local loads from whatever the object is that is "crawling up the tether" and other such things, that others have posted above, plus the needs for factors of saefty and such, then it appears to me that instead of some theorectical materials being potentially very close to being suitable, that there material properties may in fact still be off by orders of magnitude/factors of ten or more. And such some of the loads that a ribbon/tether/cable must withstand increase as the physical weight of the cable increases you can kind of end up chasing your tail, in that efforts to strengthen the tether tends to lead to the need for more tether "cross section" to support the increased weight, etc.

Regards

Pat

 

[publiusr]

The big thing would probably be icing loads and lightning strikes.

You have the ITCZ along the equator...where storm clouds are tallest. That's how the Air France flight was lost---frozen up pitot

Columbia was hit by a hunk of icy foam (I know, at speed).

An elevator car can expect a hailstorm.


One more reason I push for a scissor lift scheme...only expose the load carrying tether when you have to.

 

[Scott Kenny]

The big thing would probably be icing loads and lightning strikes.

You have the ITCZ along the equator...where storm clouds are tallest. That's how the Air France flight was lost---frozen up pitot

Columbia was hit by a hunk of icy foam (I know, at speed).

An elevator car can expect a hailstorm.


One more reason I push for a scissor lift scheme...only expose the load carrying tether when you have to.

I'm not sure how much lighting protection would be necessary, the tethers would basically passively drain charge out of a whole column of air.

Edit: and if you can build on traincar scales of mass instead of airplane or aluminum confetti rocket, you don't need to worry about any of the first 30km of travel up the beanstalks.

 

[Adventurer104]

Nobody's touched….
Rouge states/individuals crashing aircraft / drones into the beanstalk.
24/7 no fly zone? Enforced by which nations Air Force?
Two intercepters in air 24/7 is costly. Ground alert…..just might not make it in time….

 

[Prophet141]

Hi,
I suspect that you are probably right about the debate on materials strenght. My big concern though is that when people suggest that we may potentially be on or near the verge of developing materials with adequate properties, alot of that appears to me based on only accounting for "some"of the loads that such a cable/ribbon/tether may have to withstand and when you consider additional things like wind shear loads, particle/object impacts, wear, tear, abrasion, local loads from whatever the object is that is "crawling up the tether" and other such things, that others have posted above, plus the needs for factors of saefty and such, then it appears to me that instead of some theorectical materials being potentially very close to being suitable, that there material properties may in fact still be off by orders of magnitude/factors of ten or more. And such some of the loads that a ribbon/tether/cable must withstand increase as the physical weight of the cable increases you can kind of end up chasing your tail, in that efforts to strengthen the tether tends to lead to the need for more tether "cross section" to support the increased weight, etc.

Regards

Pat

This is a good point, but I can't see those forces being significantly greater than the primary tensile forces acting upon the cable, so I doubt that it would need to be as much as an order of magnitude greater. There are materials which appear to have a good margin over the necessary strength, such as Carbyne. Of course, there may be materials over the horizon which we haven't even predicted yet that could be yet stronger. We'll have to play the waiting game.

 

[Prophet141]

Nobody's touched….
Rouge states/individuals crashing aircraft / drones into the beanstalk.
24/7 no fly zone? Enforced by which nations Air Force?
Two intercepters in air 24/7 is costly. Ground alert…..just might not make it in time….

If you have microwaves/laser arrays at or near the base to power your climber, they could either pull double duty, or you could have the spare power necessary for an array of more specialised combat lasers.

Drastic, but not impossible, and very effective. Given that a space elevator is the kind of thing that we will Optimistically be building in, say, 50 years time, and the fact that lasers are already reaching hundreds of kilowatts in power, it's likely that such lasers would be more than powerful enough to destroy a rogue aircraft.

Also, if a space elevator is in use, it would likely be representative of a large industry, and in any case would be a vital resource for the country or countries which operate it. This might justify an array of defensive measures.

 

[publiusr]

I think where cables would be the most useful would be in asteroid mining.

Extrude metal cables and webbing...and it may be easier to move mass back to Earth...charged, you have starwisps so you can make like some spiders that fly with.....streamer recovery Estes called it.

Maybe discharge some of the HAVOK near gas giants to allow safer exploration.

Cables cut the Kursk--maybe nickel-iron slugs...cables allow astronauts to zip-line...but the best use might be in bagged contact binaries to turn them into bolas such that artificial gravity can be had on the inner facing surfaces.

 

[Scott Kenny]

Nobody's touched….
Rouge states/individuals crashing aircraft / drones into the beanstalk.
24/7 no fly zone? Enforced by which nations Air Force?
Two intercepters in air 24/7 is costly. Ground alert…..just might not make it in time….

Given tether material strengths, the likely result of a nutjob crashing a plane into the tether is one wing ripping off the airframe and then we all point and laugh at the idiot as the wreckage of the plane falls to earth.

 

[Prophet141]

I think where cables would be the most useful would be in asteroid mining.

Extrude metal cables and webbing...and it may be easier to move mass back to Earth...charged, you have starwisps so you can make like some spiders that fly with.....streamer recovery Estes called it.

Maybe discharge some of the HAVOK near gas giants to allow safer exploration.

Cables cut the Kursk--maybe nickel-iron slugs...cables allow astronauts to zip-line...but the best use might be in bagged contact binaries to turn them into bolas such that artificial gravity can be had on the inner facing surfaces.

The cables used for a space elevator wouldn't use any known metal alloy. With that being said, the materials they would likely be made from tend to be very conductive, such as graphene, so electrodynamic tethering is possible.

Sorry, what does HAVOK refer to? Is it a specific electrodynamic tether concept?

 

[Archibald]

Irony is that Earth seems 'just on the edge' of conditions for a practicable elevator..

If our day-length was significantly shorter, so rotation faster, geo-stand orbit would be much lower. Needing a shorter, less-strong elevator cable, lesser counter-weight etc

Likewise, if our day-length or Earth's gravity were some-what larger, elevator notions would require 'Oodles of Unobtanium'...

Hey, same exact feelings about chemical rocketry and SSTOs. Earth mandates 9000 m/s to orbit, but single stage chemical rocketry collapses at 7000 m/s, into impossible propellant mass fractions. Same for isp. 465 ain't enough but 500- something would do it.
All this because Earth is just a touch too big and dense.
Even Venus planetary body would help: lighter, less dense.
Because those parameters directly impact the depth of the gravity well... and the velocity it takes to climb it and eventually exit it to travel into the Solar System.
We are trapped at the deep end of a steep gravity well.

 

[publiusr]

The cables used for a space elevator wouldn't use any known metal alloy. With that being said, the materials they would likely be made from tend to be very conductive, such as graphene, so electrodynamic tethering is possible.

Sorry, what does HAVOK refer to? Is it a specific electrodynamic tether concept?

Auto correct used the Venus airship caps

Space elevators wouldn't be metal---but metal cables could drain Van Allen belts, provide power, etc.

 

[Scott Kenny]

Auto correct used the Venus airship caps

Space elevators wouldn't be metal---but metal cables could drain Van Allen belts, provide power, etc.

Carbon fiber is conductive.

 

[martinbayer]

We are trapped at the deep end of a steep gravity well.

We are not. We have been successfully escaping this particular gravity well ever since October 4, 1957.

 

[Archibald]

Not economically (I should have added)

 

[southwestforests]

We have been successfully escaping this particular gravity well ever since October 4, 1957.

Not economically (I should have added)

Okay, but have we at least been doing it ergonomically?

 

[martinbayer]

Not economically (I should have added)

Yes we are. ComSats are *big* business and booming, not to mention Earth imaging platforms. But I believe you may be confusing/conflating *economically* with *affordably* for the average Jane/Joe to take a hop into (sub)orbit?

 

[martinbayer]

Okay, but have we at least been doing it ergonomically?

What would be your particular metrics? You can easily find statistics of astronaut/cosmonaut deaths on the job online, but if you're looking for say specific mission induced lumbar injuries or some such, feel free to do your own online research.

 

[Archibald]

But I believe you may be confusing/conflating *economically* with *affordably* for the average Jane/Joe to take a hop into (sub)orbit?

Screw english language.

 

[Scott Kenny]

Screw english language.

You don't want to do that, Lord only knows what strange diseases English has contracted over the years from visiting every other language and mingling for stray vocabulary.

 

[martinbayer]

Screw english language.

That really doesn't help a rational discussion. For your enlightenment, English is only my third language after German (my mother tongue) and Latin (which I thankfully only retain basics from), but before French as my fourth language, which I found to be terribly inefficient and clumsy, mostly due to the liberal use of not one or two, but *three* different types of accents. As a German born aerospace engineer residing in Southern California, English rules. English is the language of Shakespeare, as well as the lingua franca of science and engineering, and it has the highest information density, meaning it is the simplest (no umlauts) as well as the most efficient and elegant means of communication on this planet.

 

[Archibald]

I will stop this conversation right here before being rude...