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Japanese Begin Working On Space Elevator
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."
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."
If libertarians are so opposed to effective government, why don't they all move to Somalia?
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.
Real Daleks don't climb stairs - they level the building.
...No space elevator is going anywhere without the necessary nanotube manufacturing breakthrough, and that includes the Japanese.
If it truly that cheap it is an amazing thing though.
This could be huge.
If the cost to get away from earths gravity, and back into it can be reduced greatly you can suddenly start sending small unmanned craft to do things. It could pay for itself (in savings) very quickly, and perhaps in real money by charging to use it.
As far as major breakthrough public works it is also a bargain. Though at that low a price, and the potential to make money on satellite launches, it almost looks like a company should be starting it anyway.
Wow, sent an e-mail as suggested when clicking on "use classic" banner, and got a fast response that addressed my msg
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.
I don't read AC A human right
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 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.
He's getting rather old, but he's a good mouse.
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.
Pound! Bang! Bin! Bash! is this a shell script or a Batman comic?
NASA with the the Italian Space Program tried long (up to 5 km) space tethers several times. Either cable fries and breaks from huge electrostatic charge breakup or the satellite fries. Anyone whose flown a kite with a metal wire knows the problem is even worse in the atmosphere.
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.
You don't exist. Go away.
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'.
It was an NPR story, I heard it too and had the same reaction you did. The speech they played had him not only mention that it could well take into the next century, he specifically mentioned that the technical challenges were immense, but the state of the art had reached a point that it was time to begin trying to solve the problem by funding research. Pretty much everything they played supported the opposite conclusion to that offered by the NPR commentator. Funny.
No... First: any mass at ANY [circular] orbit will remain at the same altitude indefinitely. (You don't see the GPS satellites leaving orbit do you?) A mass in geosynchronous orbit has the additional property that it also stays fixed relative to the earth.
Second, the orbit doesn't need to supply [significant] tension. For every newton of mass you lower towards the earth you simply place an equal newton of mass equally farther out into space. As long as the center of mass remains at the geosynchronous orbit all forces cancel out and the object still stays fixed relative to the earth. The item could reach all the way down and tickle the surface of the earth and yet wouldn't be pulled out of orbit in either direction.
Third, you don't need to solve "the tidy little equilibrium problem." Simply attach the tether to the earth (Ecuador is an excellent spot for this) and place the center of mass slightly beyond geo orbit. This will place a permanent tension on the tether. You can climb with any weight that is less than the amount of tension. You may accelerate with a force that keeps the combination less than or equal to the tension. You can do this without any regard to maintaining any equilibrium. And even if you did it is easily achieved. Simply attach the tether to a winch. Want less tension? Reel the whole thing in. More? Reel it out. The servo control for this would take something like a day to setup.
You need to retake Newtonian Mechanics my friend. The mechanics of this system are easy, well known and have been around since the beginning of the twentieth century. The material sciences is the main thing holding this from being a reality. Carbon nanotubes are the first, and so far only, material which promises the performance we need. (currently 10% of required strength and insufficiently long)
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