Japan To Test Mini 'Space Elevator' (phys.org) 114
Zorro shares a report from Phys.Org: A Japanese team working to develop a "space elevator" will conduct a first trial this month, blasting off a miniature version on satellites to test the technology. The test equipment, produced by researchers at Shizuoka University, will hitch a ride on an H-2B rocket being launched by Japan's space agency from southern island of Tanegashima next week. The test involves a miniature elevator stand-in -- a box just six centimeters (2.4 inches) long, three centimeters wide, and three centimeters high. If all goes well, it will provide proof of concept by moving along a 10-meter cable suspended in space between two mini satellites that will keep it taut. The mini-elevator will travel along the cable from a container in one of the satellites. The movement of the motorized "elevator" box will be monitored with cameras in the satellites.
That's fine for Japanese (Score:5, Funny)
6cm long, 3 cm wide, 3cm high, works for Japanese, that's the average size of a Japanese apartment, but what about the rest of us?
Typical, don't waste a moment to think about those damn gaijins.
Re: That's fine for Japanese (Score:3, Funny)
They rarely design for overweight Americans in space.
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So Americans then. They don't design for Americans.
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We're our own kind of overweight, eh?
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That's an optical illusion. Americans are so overweight that they SEEM like a continent.
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A ten meter tether is not a space elevator (Score:5, Informative)
A ten meter tether is not a space elevator, and is not really anything like a space elevator.
Twenty kilometer tethers have already been demonstrated in space, notably the NASA Small Expendable Deployer System Experiments
(SEDS and SEDS II): http://www.daviddarling.info/e... [daviddarling.info]
Re:A ten meter tether is not a space elevator (Score:4, Insightful)
They're not testing the tether, they're testing the wee little elevator cabin.
Be interesting to see how long it can keep running up and down....
it's bigger on the inside (Score:4, Funny)
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Be interesting to see how long it can keep running up and down...
The answer should be obvious: it will keep running up and down until it runs down.
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There is no Up in Space.
they need to godzilla size it! (Score:2)
they need to godzilla size it!
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Godzilla is just a regular lizard. Japanese people are really tiny [wikipedia.org].
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That's also a Japanese thing [wikipedia.org].
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Godzilla is a guy in a rubber suit stomping around models.
So they dropped depth charges on and electrocuted a guy in a rubber suit? Then fire on him with tanks and jet fighters? And finally asphyxiate him? What the hell is wrong with Japan.
People call Americans savages for the death penalty. But at least we don't make death row inmates dress in embarrassing rubber suits and continually fail at actually killing them. Jeez.
Obligatory Family Guy (Score:2)
https://www.youtube.com/watch?... [youtube.com]
Its not a "Space Elevator"... (Score:4, Insightful)
Unless its running from the surface to space. Between two satellites in space is more of a "Space Conveyor".
Re:Its not a "Space Elevator"... (Score:4, Interesting)
Not to mention Newton's Third Law necessarily puts a very harsh and unforgiving limit on possible payloads on those floating endpoints.
Ignoring material strength requirements, rotational physics alone dictates a functional space elevator has a minimum required size, and that's nowhere near where a label "mini" would be appropriate.
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It's comparable to geosynchronous orbit. It's a decent first-semester physics problem [wikipedia.org] (once you get rid of references to fictitious forces).
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once you get rid of references to fictitious forces
A sure sign of a smug pseudo-intellectual is the claim that "centrifugal force is not a real force". What nonsense. Centrifugal force exists in a rotating reference frame. When your talking about the physics of a rotating reference frame, only a pedantic jerk whines "centrifugal force is not a real force". Don't be that guy.
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And a sure sign of anti-intellectual pedant is someone who doesn't recognize the scientific term fictitious force [wikipedia.org].
In my classes, we avoid fictitious forces not because they are not "real", but because they are difficult—you shouldn't bring up centrifugal forces unless you are also ready to handle the Coriolis force, but that's more of upper-division level classical mechanics, where you are taught Euler-Lagrange equation on the first day.
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So, that "launch loop or space fountain" is at an unstable equilibrium with respect to Earth, right? Meaning it would need constant expenditure of fuel to maintain its "orbit".
They are both at science-fiction (and not that hard on the Mohs scale) level of feasibility, but I somehow think finding the magic material for space elevator will happen long before where we have such a well-established space-based economy that the astronomical maintenance of launch loop/space fountain would be practical.
P.S. The len
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You're the type of person who debates the meaning of the word "hole" with your wife. Giggidy.
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What is the BNP word for racist scum bag?
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Unless its running from the surface to space. Between two satellites in space is more of a "Space Conveyor".
Regardless what you call it is still an interesting experiment and important to know long before any real Space Elevator could realistically ever be proposed even assuming all other technical hurdles have been overcome.
Re: Its not a "Space Elevator"... (Score:2)
Space Elevator.... (Score:1)
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Space elevators are a lot older than anime.
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Space Elevators are from 1960, Anime is from 1917. (But yeah I know what you meant, the Space Elevators in Anime are newer than Space Elevators in scientific texts)
So Konstantin Tsiolkovsky had nothing to say in 1895?
Tsiolkovsky [Re:Space Elevator....] (Score:2)
Space Elevators are from 1960, Anime is from 1917. (But yeah I know what you meant, the Space Elevators in Anime are newer than Space Elevators in scientific texts)
So Konstantin Tsiolkovsky had nothing to say in 1895?
He had a lot to say. But his thought experiment was a tower, not a tether.
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Tether and Tower both describe Elevators. Int fact the tower concept is literally based on teh word "Elevator"
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If we're talking about towers, I think some guy named Nimrod might have him beat by a few dozen centuries.
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The idea of building a tower to Heaven predates history. But a tower is not a workable idea. "Space elevator" means something more specific.
Space elevators aren't problems for simple physics (Score:2)
They are materials science problems.
Newtonian physics does the job of predicting what will happen extraordinarily well and quite frankly you could do the experiment on earth, with a centrifuge apparatus and learn more, and cost less. Something like this https://www.roadsideamerica.co... [roadsideamerica.com] if you want to test your cable climber but you don't even need that.
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yeah that's what I was thinking. We have a pretty good idea what will happen if we build it. We just can't build it with current tech. I'd love to see one in my lifetime.
Wonder what the practical applications of this Japanese project are.
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It's probably Glico, I've heard they want to launch a new line of Space Pocky.
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One chap's kinetic bombardment is another chap's chocolate biscuits?
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"I'd love to see one in my lifetime". Not me. When, not if, it failed, it'd smash down a line of utter destruction all the way around the planet. Or maybe twice around.
Re:Space elevators aren't problems for simple phys (Score:4, Interesting)
We have a pretty good idea what will happen if we build it.
Yes: it will swing and bob wildy out of control, and eventually the counterweight will start zooming around the GEO station, if the station is massive. Then the cable will break and the counterweight will shoot off in a random direction, and inevitably destroy Tokyo.
The hard problem for a space elevator, even aside from needing unobtanium, is the lack of any way to damn the pendulum-like energy fed into the system with every payload lifted. Only half the energy needed to get to GEO is in lifting, the other half is in accelerating the payload laterally. That energy will be added to the system with every load lifted, and there's no obvious way to damp it.
And remember, this is not a Freshman Physics pendulum. It's both a spring pendulum and a double pendulum [youtu.be]. Each of which is a chaotic system. When combined, it's a mess.
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The hard problem for a space elevator, even aside from needing unobtanium, is the lack of any way to damn the pendulum-like energy fed into the system with every payload lifted. Only half the energy needed to get to GEO is in lifting, the other half is in accelerating the payload laterally. That energy will be added to the system with every load lifted, and there's no obvious way to damp it.
Oh way to dump on Elisha Otis.
counterweight. https://en.wikipedia.org/wiki/... [wikipedia.org]
Or there is the ever popular and very scenic funicular https://www.google.com/search?... [google.com]
If you are ever in Switzerland don't miss out it's a wonderful day trip to ride to the top of a mountain on one.
As to the double pendulum problem you solve that by making the anchor point large. Which is one of the reasons you need unobtanium to build the thing.
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Your reply was a bit of a non-sequitur.
When your start a normal pendulum swinging, or pluck a guitar string, the energy is eventually dissipated through interaction with the air and friction associated with bending the string (which is quickly lost as heat by conduction). That won't happen with a space elevator. A material suitable for making the cable will shed very little energy through internal friction (otherwise it will get quite hot, as radiative cooling in space sucks).
What that means is any energy
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Your reply was a bit of a non-sequitur.
The Elisha Otis reference should have been a dead giveaway that I was laughing my ass off.
When your start a normal pendulum swinging, or pluck a guitar string, the energy is eventually dissipated through interaction with the air and friction associated with bending the string (which is quickly lost as heat by conduction). That won't happen with a space elevator. A material suitable for making the cable will shed very little energy through internal friction (otherwise it will get quite hot, as radiative cooling in space sucks).
You aren't plucking this cable, you are applying a constant and relatively small force over a period of hours to days. The energy is going to go in and out of three reservoirs involved. The rotational speed of the earth, the orbital speed of the counterweight, and tension in the cable itself.
The complex pendulum will keep accumulating energy until it achieves "rapid unscheduled disassembly" in some unpredictable way.
Yes the same way people are being killed all over the place by executive desk toys that are spontaneously undergoing rapid disass
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You aren't plucking this cable, you are applying a constant and relatively small force over a period of hours to days.
The fundamental frequency of the cable would be very low indeed, given it's high mass and low proportional stiffness. If it's enough longer than the transit time of the payload, you are indeed plucking it. OK, that's a bit of an oversimplification - you're inducing a wave that will need to damp a bit to become a standing wave, but that's just an even more complex system.
Yes the same way people are being killed all over the place by executive desk toys that are spontaneously undergoing rapid disassembly.
They have a lot more friction (and air resistance, and they make noise, etc). Plus, people don't just keep adding energy to them, or they
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That's they whole point: you have to damp the energy faster than you add it.
Yes that is the whole point which is exactly what having balanced counterweights accomplishes. Once again the system is not the cable it is the cable the earth and the endpoint weight
They have a lot more friction (and air resistance, and they make noise, etc). Plus, people don't just keep adding energy to them, or they would start spinning around or slide off the desk
You failed physics I take it ? Or reading comprehension ?
"The energy is going to go in and out of three reservoirs involved. The rotational speed of the earth, the orbital speed of the counterweight, and tension in the cable itself."
Even if you didn't use a counterweight the net kinetic energy imparted to the system over a cycl
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Yes that is the whole point which is exactly what having balanced counterweights accomplishes. Once again the system is not the cable it is the cable the earth and the endpoint weight
Do you understand what "damping" means? The "cable the earth and the endpoint" is basically a pendulum, from the frame of reference of the rotating earth. As energy is added, the pendulum starts to swing, and to bounce, and the cable vibrates at each harmonic. The only way that energy is reduced is to somehow covert it into heat.
Even if you didn't use a counterweight the net kinetic energy imparted to the system over a cycle would be zero.
Cycle of what? Lifting a ton to orbit means MWh of energy added to the system as it laterally accelerated the payload, as if you ran your finger down the length of a pendulum, p
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Do you understand what "damping" means?
Do you understand how big the earth is ?
Cycle of what
What goes up comes down. It's a loop not a one way move.
Really you would do much better if you actually tried reading.
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Yeah, you don't understand what "damping" means.
Try stopping a swinging pendulum, with a flexible string, from the point it hangs from. There's no way to do that - you have to wait for the pendulum to slow down due to friction and air resistance. If your string is almost perfectly elastic, and you're in a vacuum, that pendulum will keep swinging for a long, long time.
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Yeah, you don't understand what "damping" means.
Seeing as I spent a good deal of my life dealing with tuned circuitry, I probably have a better idea than you.
Try stopping a swinging pendulum, with a flexible string, from the point it hangs from.
That's nice all you are doing showing is you don't understand where the forces are being applied, which would be the climber and the descender respectively.
I would suggest you just get a rope and spend a few hours to build a climber so you could see the dynamics are nothing like you are describing but it seems other people have already done this
https://youtu.be/a8xduff1yyM?t... [youtu.be]
Feel free to try and a
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That experiment did not involve a centripetal pendulum. When you move a weight to the station, the pendulum must swing "backwards" to conserve angular momentum. No way around it: you've given the pendulum a kick. Of course, it will swing back to directly above the ground station, but it won't stop there, it will keep being a pendulum.
Why is that confusing?
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When you move a weight to the station, the pendulum must swing "backwards" to conserve angular momentum
And when you simultaneously move a weight down the station the opposite happens. Really ring up whoever taught you physics and demand your money back.
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When you lower a weight (the same weight? unlikely) you give the pendulum another kick. Sure, this one's in the other direction, but that doesn't really help - this isn't an ideal, rigid pendulum where you could actually "brake" it that way. You'll be adding energy to the system in either direction.
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When you lower a weight (the same weight? unlikely)
Yes because ballast and dead weight aren't things that are well understood / sarcasm
you give the pendulum another kick.
You aren't kicking much of anything. For someone who keeps going on about dampening this is a relatively small force applied over a relatively long time across the entire elevator.
Sure, this one's in the other direction, but that doesn't really help
Conservation of angular momentum is on the phone for you.
- this isn't an ideal, rigid pendulum where you could actually "brake" it that way.
Actually that is exactly what it is. Very nearly Ideal and rigid. What did you think would be needed to reach from the surface of the earth to geosynchronous orbit ?
You'll be adding energy to the system in either direction.
I'm done, I can tolerate i
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s because ballast and dead weight aren't things that are well understood / sarcasm
You're going to, what, mine the counterweight for ballast? Won't work - a space elevator becomes economical when it launches payloads that collectively exceed the mass of the counterweight. So you'd be, what, dragging asteroids over to mine for ballast? Seems unlikely (well, eventually a space elevator would help enable asteroid mining, but it would be some time).
Sure, this one's in the other direction, but that doesn't really help
Conservation of angular momentum is on the phone for you.
As I said, that just means a kick to the pendulum in the other direction. Now it has twice as much energy, unless you do something very clever
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You're going to, what, mine the counterweight for ballast? Won't work - a space elevator becomes economical when it launches payloads that collectively exceed the mass of the counterweight. So you'd be, what, dragging asteroids over to mine for ballast? Seems unlikely (well, eventually a space elevator would help enable asteroid mining, but it would be some time).
Too stupid for words.
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You seem to have run out of arguments, leaving only name-calling. Sad.
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You seem to have run out of arguments, leaving only name-calling. Sad.
Well unlike you, I can't bring myself to predict economic details of civilization hundreds of years removed from now. I also have a pretty good idea of the limits of my knowledge and would never make the claims you do without actually doing the math. Then there is the fact I can't bring myself to ignore the laws of physics the way you do.
Must be nice to think you know everything.
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Well Newtonian physics doesn't factor in long term strain on a material. Radiation, wear, friction. Simple physics has a everything in a uniformed mass frictionless ball in a perfect vacuum.
Now these are good for the laws of physics, and its values will apply in general. However there are billions of tiny forces following these same rules just at different directions that makes engineering for the values more complex, and often will require over engineering a product to deal with this degree of entropy.
I c
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Alright, so let's build this space elevator on the moon, then. Problem solved, once and for all.
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Alright, so let's build this space elevator on the moon, then. Problem solved, once and for all.
Do a Google search. While we have strong enough material to build it, it would have to be much, much longer than a Earth elevator. Earth rotates once ever 24 hours, the Moon once every 28 days. IIRC it would reach beyond the first Lagrange point.
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ONCE AND FOR ALL! [imgur.com]
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Fun fact: the Moon-synchronous orbit height is actually closer to Earth than the moon.
Of course, we could just build it on Mars! Except, well, there's this damn moon that actually orbits lower than Mars-synchronous orbit, and our elevator would have to dodge it every few hours. But that's a minor problem for the engineers, let's not get side-tracked. Mars Elevator!
So they're going for a science victory? (Score:1)
Space Visa? (Score:2)
"...will hitch a ride on an H-2B rocket"
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AFAIK, they still haven't done the tests ti show that carbon nanotubes are actually strong enough to be used for the elevator cable ?
Anyone know if/when those tests will be done ?
Because without a cable material, this is all pure speculation.
My understanding is that there currently is no material suitable for an Earth-LEO space elevator. However a few years ago I did see someone saying that current materials technology could build a Moon based space elevator.
Seems like wikipedia agrees with me https://en.wikipedia.org/wiki/... [wikipedia.org]
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AFAIK, they still haven't done the tests ti show that carbon nanotubes are actually strong enough to be used for the elevator cable ?
Anyone know if/when those tests will be done ?
They've done tests to show that carbon nanotubes are NOT actually strong enough to be used for the cable.
But there may be variant materials that solve the problem.
Ultimate strength of nanotubes yet to be seen (Score:5, Informative)
The problem is that CNTs are strong enough, if manufactured perfectly. Flaws in the manufacturing process, even ones that lead to only a few atoms being misaligned, reduce tensile strength by 100x or more.
Not clear. The predicted high ultimate strength of nanotubes is entirely theoretical, it has yet to be experimentally demonstrated.
Carbon nanotubes are strong enough in an idealized theory that doesn't allow bonds to shift. If you include the fact that the hexagonal rings spontaneously shift the bonds to form pentagonal rings or heptagonal rings under stress, they don't reach that ideal strength. It's not clear that you can stabilize the hexagon only structure.
https://www.newscientist.com/article/2093356-carbon-nanotubes-too-weak-to-get-a-space-elevator-off-the-ground/
Yes! (Score:3)
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Virtual +1 Funny.
Sounds kind of pointless (Score:3)
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What exactly is the experiment meant to prove? Moving little devices over a 10 metre taut wire isn't exactly pushing the boundaries of science.
From the article:
"It's going to be the world's first experiment to test elevator movement in space," a university spokesman told AFP on Tuesday.
I'm not sure what you're saying. Do you think they should push a larger device over a longer distance for their first attempt? Or do you think they should skip this test entirely and just assume it will work fine?
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This seems more like a pointless stunt than anything of real scientific value.
We've had geostationary sattelites for a while now (Score:2)
I guess it's time to re-read "The Fountains of Paradise".