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Japan To Test Mini 'Space Elevator' (phys.org)
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.
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.
We used to have a Bill of Rights. Now, with the rights gone, all we have left is the bill.
Unless its running from the surface to space. Between two satellites in space is more of a "Space Conveyor".
This reminds me their 00 Gundam series has some kind of space elevator or solar elevator or whatever they called it. They're trying to make the anime real! Kind of curious of how well this would actually work.
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... if you want to test your cable climber but you don't even need that.
We must take control of the aluminium supply and churn out some giant death robots!
"...will hitch a ride on an H-2B rocket"
Only 2041990 meters to go!!
They can just make the cable out of unobtanium, no problemo.
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.
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 can calculate how much of a gap I need in my door so it will open, but I will always give it an extra millimeter more because the wood may expand during different humidity, the cut may not be perfectly straight, pressure on the beams may cause a little bit of bowing.
If something is so important that you feel the need to post it on the internet... It probably isn't that important.
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/...
I am Slashdot. Are you Slashdot as well?
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...
http://www.geoffreylandis.com
they need to godzilla size it!
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.
http://www.geoffreylandis.com
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.
http://www.geoffreylandis.com
https://www.youtube.com/watch?...
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It's probably Glico, I've heard they want to launch a new line of Space Pocky.
#DeleteFacebook
Alright, so let's build this space elevator on the moon, then. Problem solved, once and for all.
#DeleteFacebook
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.
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/
http://www.geoffreylandis.com
"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.
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.
ONCE AND FOR ALL!
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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. Each of which is a chaotic system. When combined, it's a mess.
Socialism: a lie told by totalitarians and believed by fools.
"What is this, a space elevator for ANTS?!"
the preceding comment is my own and in no way reflects the opinion of the Joint Chiefs of Staff
I guess it's time to re-read "The Fountains of Paradise".
"Reality is that which, when you stop believing in it, doesn't go away." - Philip K. Dick
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/...
Or there is the ever popular and very scenic funicular https://www.google.com/search?...
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.
One chap's kinetic bombardment is another chap's chocolate biscuits?
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 put into swinging the pendulum will just stay there. And every payload lifted will add such energy. If it were an ideal pendulum, it would just start swinging with greater amplitude, and maybe you could try to send payloads up in such a way as to damp the swing. A complex pendulum doesn't work that way, however, it will swing and bob and vibrate like a plucked guitar string, and the counterweight will swing about the station. There's no way in such a system to damp that energy by sending payloads up cleverly, or by having some rockets at the station (or at the counterweight).
The complex pendulum will keep accumulating energy until it achieves "rapid unscheduled disassembly" in some unpredictable way.
Socialism: a lie told by totalitarians and believed by fools.
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!
Socialism: a lie told by totalitarians and believed by fools.
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 disassembly. The cable may well have some sort of material fatigue but this experiment wont tell you a damn thing about it, as it isn't even testing a material you would build such a cable out of.
Oh and no you don't need to be in space to test that either.
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 would start spinning around or slide off the desk.
That's they whole point: you have to damp the energy faster than you add it. A space elevator has little to work with for damping: energy must either be shed as heat, or lost to the atmosphere near the bottom (but that's such a small part of the length). Every ton lifted will mean finding a way to shed MWh of energy, and it's not at all obvious how that mechanical energy could be converted into heat via friction in any reasonable time.
Socialism: a lie told by totalitarians and believed by fools.
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 cycle would be zero.
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, pressing sideways. It will certainly have energy when you're done.
Socialism: a lie told by totalitarians and believed by fools.
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.
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.
Socialism: a lie told by totalitarians and believed by fools.
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...
Feel free to try and actually think about what you say in the future.
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?
Socialism: a lie told by totalitarians and believed by fools.
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.
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.
Socialism: a lie told by totalitarians and believed by fools.
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 ignorance, I can't tolerate willful stupidity.
Here's a free course in freshman physics
http://go.une.edu/sphp-program...
Reply again when you can say something intelligent.
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. But this is a chaotic system with many modes of oscillation: it's a spring pendulum, complicated by the weight of the station at GEO, that will hold massive energy in standing waves on the cable, as well as the counterweight itself rocking on the end of the cable (unless you have one amazing bearing where the cable connects, but why would you).
Given how well this would all be modeled, I could believe you could get some small damping effect from a payload going down, by timing against the pendulum swing (and only that mode), but even that's quite tricky as the pendulum period would just be a few hours, and the trip would likely take at least as long.
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 ?
Nothing is rigid at that scale: even for the hardest materials the length is thousands of "speed of sound seconds". The cable would need to have massive tensile strength, but it has no need to be rigid at scale - it's a cable, not an I-beam - and it can't be brittle. Sure, the unobtainium might have the highest spring constant of any known material, but push on it at one end and it will take thousands of seconds for the wave to reach the other end (where, absent some really impressive shock absorbers, the wave will bounce back down the cable).
Socialism: a lie told by totalitarians and believed by fools.
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.
You seem to have run out of arguments, leaving only name-calling. Sad.
Socialism: a lie told by totalitarians and believed by fools.
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.