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Japanese Begin Working On Space Elevator
Posted by
CmdrTaco
on Mon Sep 22, 2008 08:57 AM
from the you-can't-get-there-from-here dept.
from the you-can't-get-there-from-here dept.
thebryce writes "From cyborg housemaids and waterpowered cars to dog translators and rocket boots, Japanese boffins have racked up plenty of near-misses in the quest to turn science fiction into reality. Now the finest scientific minds of Japan are devoting themselves to cracking the greatest sci-fi vision of all: the space elevator. Man has so far conquered space by painfully and inefficiently blasting himself out of the atmosphere but the 21st century should bring a more leisurely ride to the final frontier. Japan is increasingly confident that its sprawling academic and industrial base can solve those issues, and has even put the astonishingly low price tag of a trillion yen (£5 billion) on building the elevator. Japan is renowned as a global leader in the precision engineering and high-quality material production without which the idea could never be possible."
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Science: Future of Space Elevator Looks Shaky 486 comments
lurking_giant writes "In a report on NewScientist.com, researchers working on development of a space elevator (an idea we have discussed numerous times) have determined that the concept is not stable. Coriolis force on the moving climbers would cause side loading that would make stability extremely difficult, while solar wind would cause shifting loads on the geostationary midpoint. All of this would likely make it necessary to add thrusters, which would consume fuel and negate the benefits of the concept. Alternatively, careful choreography of multiple loads might ease the instability, again with unknown but negative economic impacts."
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Space Elevator Music (Score:5, Funny)
Just imagine fourteen hours of Japanese elevator music. I couldn't stand that much symphonic David Hasselhoff. And when you get to space and arrive at the Japanese Sky Deck, you can eat very expensive steak, while being entertained by a Max Headroom stylized recreation of David Hasselhoff, and groped by Hentai-motivated space-whores.
Re:Space Elevator Music (Score:5, Funny)
Could you cope any better with Music for Elevators by Anthony S Head though?
Being groped by space-whores could potentially be worth the wait anyway. ;)
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Re:Space Elevator Music (Score:5, Informative)
Being groped by space-whores could potentially be worth the wait anyway.
But remember, this is JAPAN we're talking about. They have tentacles.
Still, that amounts to $9.5 Billion USD at the moment. To put it in perspective, we're looking at spending $700B to bail out the banks this week. Over the course of the life of the shuttle, each launch as ended up costing $1.3B. So, for a little over a tenth of the bank buyout, or less than 10 shuttle launches*. Or, if you want to go with incremental costs ($60M), it'd be 158 launches - compared to the 115 launches as of Aug 2006. Still, I hardly think that it'd be fair to compare incremental costs of a dangerous platform with creating a new one with substantially lower incremental costs and hopefully greater safety.
Of course, the article does at least mention a number of issues - we need to industrialize a carbon nanotube production process that makes a cable that'd 4 times as strong as the best lab result to date. There's all sorts of issues with a pod that has to go 22k miles, straight up.
I heard a snippet of a speech by Reagan today about SDI and how we now finally have the missile defense stuff he proposed. They talked about him not realizing the difficulties and state of the art, at which I laughed a bit when, in the speech, he talked about it possibly taking 'into the next century'. Anyways - this topic reminded me of the SDI program - nice goal, but might end up being slightly out of our reach at the moment. Especially for a 'mere' 9.5B. Probably end up being 100B*, and an additional 40 years.
*Still cheap at the price.
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Re:Space Elevator Music (Score:5, Funny)
This is why my preferences are set to view low UID posters at higher point value than others. It is their keen insight from years in the tech arena that keeps me coming back.
I am going to go remove that preference now.
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Re:Space Elevator Music (Score:5, Funny)
You think that is bad, just wait until some wieseguy gets on and hits the buttons for every floor.
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Re:Space Elevator Music (Score:4, Funny)
Is it spelled "Whoosh" or "Woosh"?
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Re:Space Elevator Music (Score:5, Funny)
Are you kidding? This thing would be milked for every yen they can get. There'll be a food court floor, the stratosphere floor, ionosphere floor, the "Sunset Above the Troposphere" floor, the gift shop floor ("I rode the space elevator" T-shirts), the "Watch the aurora close up" floor...
Then there'll be sponsors. Just wait for "The Hello Kitty Space Elevator" sponsored by Sanrio.
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Re:Space Elevator Music (Score:5, Funny)
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That's Cheap! (Score:5, Funny)
Re:That's Cheap! (Score:4, Insightful)
It's not clear that the costs will be greatly reduced. There simply isn't that much demand (or foreseeable need for) "sending small unmanned craft to do [unspecified] things". Even with tourism (the likely largest market in the near term), you'll have a hard time charging enough to recoup your costs as well as operating expenses.
Not to mention that cost specified is almost certainly laughably low.
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Lift engine. (Score:5, Funny)
Reminds me of a quote... (Score:5, Informative)
"The first space elevator will be built about fify years after everyone stops laughing."
-Arthur C. Clarke
Largest is the nanotube problem... (Score:5, Interesting)
Bah... (Score:5, Funny)
I'll stick with PbZep (Score:5, Funny)
Wirri Wonka (Score:5, Funny)
If I find a golden ticket in my package of ramen noodles, do I get to ride the space elevator?
Missing from the article: (Score:5, Funny)
The elevators traveling speed will be measured in GFIp/t ("Girl from Ipanema" plays per transport).
Boffin (Score:5, Informative)
Re:No I didn't Read TFA (Score:5, Funny)
The concept of a space elevator, of course, requires a very very tall structure, or a pully of sorts from space. That would need to be a really damn strong system, to pull somebody up that high...
Yes, you instantly recognized the challenges of the project. Please, come, be a manager on the project!
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Re:No I didn't Read TFA (Score:5, Funny)
I have the solution though. To get around the problem with the long cable and pulley, we can use rocket propulsion on the bottom of the elevator cart.
Also since the shaft it will travel may encouter some problems with radial velocity and all that engineery stuff I know barely enough to be dangerous about, we should cut that out and just create a cart that doesn't need that.
Yeah, a rocket propelled shaftless space elevator. Where's my damn X-prize or whatever money for being so smart....
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Re:No I didn't Read TFA (Score:5, Informative)
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Re:No I didn't Read TFA (Score:4, Informative)
Technically, a weight in geosynchronous orbit would remain at the same altitude indefinitely with no other forces in effect. A space elevator will require a weight placed in an orbit which will supply tension — otherwise it'd be pulled out of orbit. It would probably be close to geosynchronous, but not quite.
(Actually, I'm not sure we even have a name for such an orbit. It would have to remain stationary above a point on the earth, but it would also have to hold up the cable and the car – in other words, without the tether it'd fly off into an entirely different orbit. Also, whenever the car accelerates it will put an additional tug on the cable – equal and opposite forces, you know. It'll be a tidy little equilibrium problem, and I'm glad I don't have to solve it!)
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Re:No I didn't Read TFA (Score:4, Insightful)
Technically, a weight in geosynchronous orbit would remain at the same altitude indefinitely with no other forces in effect. A space elevator will require a weight placed in an orbit which will supply tension â" otherwise it'd be pulled out of orbit. It would probably be close to geosynchronous, but not quite.
Couldn' this be achieved by moving a counter-weight downwards from space while the elevator moves up?
The total force on the weight in orbit would remain constant wouldn't it?
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Re:No I didn't Read TFA (Score:4, Informative)
The best counterweight is... another elevator car. If you have multiple tethers and superconducting cable (or another means of transmission), you can use a large fraction of the potential energy of the descending car to power the ascending car.
If you bring net mass down from orbit, you can actually make an energy profit (just on the elevator, I'm not saying that it would offset the costs of hauling propellant, etc, for asteroid miners and such).
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Re:No I didn't Read TFA (Score:4, Insightful)
If you bring net mass down from orbit, you can actually make an energy profit (just on the elevator, I'm not saying that it would offset the costs of hauling propellant, etc, for asteroid miners and such).
Yeah of course you can't win overall, but nevertheless wouldn't it be totally awesome to bring back a load of minerals from an asteroid and get a "free" lift of your next load of fuel and supplies?
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Re:No I didn't Read TFA (Score:5, Interesting)
The problem is that even the *simplest* form is way beyond what we can produce in the present day, and you're wanting to do a form that's far harder.
In a space elevator, the tether has to be long. Very, very, very long. So much that even if you could build a cable with the density of graphite and a tensile strength of 100GPa, it'd still have to taper severalfold as it reaches toward the earth. With the taper requirement, pulleys are simply right out (can't have the pulley's cable change shape as it goes, now can you?), as is *anything* that can increase the weight of the fiber. You need elevator "climbers", powered by beamed power transmission.
The problem remains the cable. 100GPa with the density of graphite is just so far beyond anything that we can achieve today it's really just a sci-fi concept that people like to dream about. The last I checked, the strongest *individual single-walled carbon nanotubes* that people had directly measured the strength of broke at just over 60GPa. This is for single tubes, let alone bundles of tubes, let alone a bulk fiber, let alone an entire tapered cable. Tubes theoretically can be stronger, but I haven't seen any measurements confirming such extreme theoretical strengths. The strongest SWNT bulk fiber I've read about was planar sheets that were about 10GPa.
Yes, you can build a space elevator with a tensile strength of less than 100GPa. But your taper factor for the elevator rises *very fast* with decreasing tensile strength or increasing density, which means that its mass increases *very fast*, which rapidly puts it outside the realm of possibility. Honestly, something more like 120GPa would be much easier to build, but that's even further from what we can achieve today. I'm not even sure it's physically possible to achieve. SWNTs are pure graphene SP2 structures; how can you get stronger than that? The only thing I can think of that could help us best today's best strengths are complete perfection, every atom of the fiber all the way up, and I'm not sure that would do it.
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Re:No I didn't Read TFA (Score:5, Informative)
actually it's the center of mass that is relevant. The device would be considered in GSO because the center of mass would be there, or minimally lower (a few feet).
There would be roughly evenly distributed mass from earth to GSO, Maybe slightly increasing as it goes up to GSO, and then a large weight beyond GSO.
The idea is to not have it pull up on the ground, or press down (much). Last thing they need is to have a huge chunk of the terminal flung into space.
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Re:No I didn't Read TFA (Score:4, Interesting)
You're mostly right. A weight in geosync with a tether hanging down would fall, due to the weight of the tether. What you actually have is a system where the center of mass of the entire system is in geosynchronous orbit. There are two ways you can do this, one is to have a big chunk of mass just the other side of the orbit you want, the other is to have another tether extending outward from the geosynchronous midpoint. There are some advantages to that idea. If you want to go somewhere further than earth orbit, you can go out to the end of the outer tether and start off with a fairly healthy velocity, although constrained to being in the plane of the equator. (although, given that the plane of the equator varies considerably with respect to the plane of the ecliptic over the course of the year, you actually have a fair amount of, well, latitude for lack of a better term, with your initial vector if you have the ability to move around your launch date some.) Second, it makes it fairly easy to run masses up and down the external tether to counteract the mass/acceleration of the elevator on the inner tether. Third, if you for some reason want an environment with near-earth-normal gravity, but want it to be 70k km (that's an ugly nomenclature. and 70 Mm looks too much like 70 mm. How about 7E7 m?) away from the earth, there's a perfect place for it, just hang your lab off the end of the outer tether.
The disadvantage, of course, is that you have to make two long, expensive tethers, as opposed to making one tether and a big block of steel (or whatever) as a counterweight.
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Re:No I didn't Read TFA (Score:5, Interesting)
That's probably not how it would be done. You'd have a ribbon hanging down from geostationary to the equator, and your vehicle would actively climb up it, rather than being hauled up. The ribbon still needs to be incredibly strong and light, but it's not the component that's actually doing the work.
Exercise for the reader: work out how you're going to power the climber.
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Re:No I didn't Read TFA (Score:5, Funny)
Exercise for the reader: work out how you're going to power the climber.
CowboyNeal as a counterweight?
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Re:No I didn't Read TFA (Score:5, Interesting)
In other words, their "space elevator" will probably more closely resember a sleeker rocket/airplane design, and less like an actual elevator...
Given the speed you'll want to haul cargos up to have them there in a reasonable time you'll want some areodynamics.
Even assuming you speed up once you reach upper atmosphere/vacuum, a 22k mile journey at an average speed of 100mph will take 220 hours, or just over 9 days.
I'd see a fuel cell system for in atmosphere lifting, shifting to battery/solar once you're over the atmosphere. Maybe even jettison the fuel cell to be recovered and reused.
Though there is a chance you could use the cable - electrical potential is generated if you string a conductive line through a chunk of the atmosphere, and CF is conductive. You still have the problem of how to utilize that differential at any given point of the cable though. You might end up using a double ribbon system and shipping electricity that way to the cars.
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Re:call me when they have something (Score:5, Interesting)
Absent any stunning advances in material sciences,
The TFA states that carbon nanotubes would require a 4x increase in strength compared to present-day materials, and that the past 5 years of research have already brought about a 100-fold improvement ... sounds to me like many stunning advances have already happened and we're well on track to fully-stunned status.
This is just a Popular Science article, i.e. "hey wouldn't it be neat if but it ain't happening so we're really just jerking your chain."
"Japan is hosting an international conference in November to draw up a timetable for the machine."
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Re:call me when they have something (Score:4, Insightful)
I thought a millionfold increase in length was also required?
Does not matter how strong they are if you cannot make them long enough.
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Re:call me when they have something (Score:5, Funny)
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Re:call me when they have something (Score:5, Funny)
Good thing you're anonymous. If I had a 'nanotube' I sure wouldn't want to admit it on slashdot. :)
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Re:call me when they have something (Score:5, Informative)
Well, no. Modern materials are within a factor of 3 or so of what's required for a space elevator, and known materials with sufficient theoretical strength exist, it just needs to be figured out how to build them. It would not be surprising to have those materials move from theory to reality within a decade or so.
AI, human-indistinguishable androids, and world peace, on the other hand, are not things that people have any idea how to achieve. And FTL drives are prohibited by currently accepted physical theory. To compare a space elevator to any of those is either deliberately being stupid, or a result of profound ignorance about either space elevators or all the other things you mentioned.
A space elevator is certainly not going to be as easy as a Popular Science article makes it sound. But on the other hand it's not anywhere near as difficult as the pipe dreams you named.
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Re:call me when they have something (Score:5, Insightful)
A space elevator essentially just needs certain advances in materials science. It's a big engineering project, but nothing more than that.
AI, on the other hand, is something that nobody in the world has any clue how to achieve. They're simply not comparable. We may very well see AI before a space elevator, but it will be because computer technology advances vastly more quickly than space technology.
And just for the record, I did not claim that FTL is impossible, merely that it's impossible according to accepted physical theory. And that statement is absolutely true.
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Re:call me when they have something (Score:5, Funny)
Actually, it would take a guy in the spacecraft a minimum of 4.3 years to arrive at Alpha Centauri. In Earth's reference frame it might take thousands of years. I'm saying that you're using the times in the wrong frames of reference.
How disappointing would that be? You get yourself all packed up and ready to go to Alpha Centauri. You're excited, the kids are excited, you're going to be the first humans to ever step foot outside the solar system. It's groundbreaking stuff, you are lauded as heroes as you step into your state-of-the art ship that travels at 60% of the speed of light.
After almost ten difficult years in a cramped interstellar ship, you and the other colonists can finally see your destination. You will forever own a place in the chronicles of human history. And then, you discover than the place was already colonized by humans centuries ago ... the ones who waited until FTL travel was invented back on Earth. They made the trip in a couple weeks. They've been waiting for you ever since.
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Re:call me when they have something (Score:4, Informative)
No, it's your references which are wrong: if you could get to C your trip (from your view) would be instantaneous, from Earth it would take 4.3years.
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Re:Just as a subnote... (Score:5, Informative)
And as a sub-subnote, this is approximately the cost of developing a complete conventional man-rated rocket launch system. I'm skeptical of the quoted price tag, but it would be extremely cheap if it could be achieved.
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Re:Just as a subnote... (Score:5, Interesting)
And as a sub-subnote, this is approximately the cost of developing a complete conventional man-rated rocket launch system. I'm skeptical of the quoted price tag, but it would be extremely cheap if it could be achieved.
That's not the actual price-tag, it's NIF [wikipedia.org] economics. You propose the project with a $9.5B price tag and spend your money providing whatever results you can. You then apologize for failing to complete, but assure the backers that you're nearly done, but need an additional $5B. When that's spent, you've hit a snag so complex that not even the top minds in the world could have seen it coming, but you can finish the project for only $8B more. After all, who wants to abandon a project that you've already spent several years and nearly $15B on when you're so close. Repeat until retirement.
It's amazing how well this seems to work in practice.
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Re:Just as a subnote... (Score:5, Funny)
would that work to finance the japanes space elevator:
1- take a subprime loan from a US bank
2- file for banckruptcy
3- let US treasury buy the debt back and cancel it
4- Profit !
I mean with that they could spend as much as 700 billions !
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To put the cost into perspective... (Score:4, Insightful)
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Re:Just as a subnote... (Score:5, Insightful)
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Re:Equal and opposite? (Score:5, Informative)
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Engineering efficiency (Score:5, Insightful)
A practical space elevator could use vehicles powered by electric motors, which would get about 70-80% efficiency. On the way down, the motors could be used as generators, getting back probably around 30-50% of the original energy supplied. The total energy consumption might only be a percent or so of that needed for a rocket. The design of the cable with electrical conductors on either side reaching all the way up to geostationary orbit is, of course, left as an exercise to the reader.
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Re:Equal and opposite? (Score:5, Informative)
You're thinking of making a big tower (like a really large skyscraper). That wouldn't work. You have to approach the problem differently.
A simplified explanation of a space elevator is to take a really long, really strong cable (nanotubes), hang a weight on the end (more cable, an asteroid, lots of metal, etc), and anchor it on the equator. The weight goes out beyond geostationary orbit, and the tension of your cable pulls in on the counterweight to keep it from flying away. The tension keeps your cable taut. You can then run "cars" or "trains" up and down the cable on motorized wheels, most likely with electric power (solar, beamed microwave, or conducted through the cable). Your car can travel nice and slow, and be more efficient than a rocket.
If this doesn't make sense, imagine tying a weight to the end of a string, holding on to the other end, and spinning in circles. The weight will be held out at the end of the string and appear stationary relative to (since you're spinning too). Now put a caterpillar on that string that walks to the counterweight and back to you.
In short, the advantage is that you can use electrical power (which you don't have to carry with you) converted to direct mechanical energy to climb into orbit, instead of expelling fuel (less efficient) that you do have to carry with you. Your vehicle ("car") structure is simpler, more robust, and cheaper than a rocket. The elevator itself would be quite expensive, and requires some advances in materials science, but isn't physically impossible.
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Re:a disaster waiting to happen (Score:5, Insightful)
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Re:a disaster waiting to happen (Score:5, Informative)
So don't tie it down. There's nothing about the design of the space elevator that requires it to be tied to the earth in any way. If there's a storm coming, pull it up (or fold it up) about a mile or so above the clouds.
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Re:Start from orbit. (Score:4, Informative)
This is exactly how all the people considering this intend to do it. The problem is that the strength of cable required to support its own weight for that distance is huge. It has been determined that a ribbon shaped like a giant flat golf tee (can't think of a better description) will be best.
In short, your plan is the same as the best plan that mankind has so far, but we still don't have a suitable material to make the cable from.
Justin.
(Incidentally, geostat tends to be much higher than 100 clicks (qv 'Low Earth Orbit').)
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