Carefully Timed Jerks Could Power Space Elevator 270
Hugh Pickens writes "BBC has an interesting article on the long-standing issue of how to power the 'climber' that would ascend a space elevator into space. Previous ideas have included delivering microwave or laser power to the climber beamed from the Earth's surface, but now European Space Agency ground station engineer Age-Raymond Riise has demonstrated a device that could provide a "lift into space" for cheaper space missions along a 100,000-km long tether anchored to the Earth. Riise demonstrated sending power mechanically by providing carefully timed jerks of the cable at its base with a broomstick to represent the cable held in tension, an electric sander to provide a rhythmic vibration to the bottom of the stick, and three brushes representing the climber with their bristles pointing downwards allowing the climber assembly to slide upward along the broomstick as it moved slightly downward, but grip it as it moved slightly upward. 'It would be possible to make a suspension system that completely decouples the cabin where the passengers are,' says Riise. 'For them it would be a linear movement with very little disturbance.' Riise says that he has been approached by commercial elevator companies, who are researching new ideas for elevators in superscrapers where the simplicity of the approach makes it attractive when compared to other ideas for powering lifts, such as compressed air."
"jerks" (Score:5, Funny)
Re:"jerks" (Score:5, Insightful)
Actually, this is something the average person can see at home. The idea he's describing is a ratcheting mechanism, and is an excellent idea easily seen to be of use in any amateur environment.
My only concern is what happens when those bristles get a little worn out after all that high intensity cyclic stress and an elevator load of passengers plummet to their doom from 100 km up. Gonna need a really good preventative maintenance regimen, not something commercial operations are typically known for in the industrial sector.
Re:"jerks" (Score:5, Funny)
What's next, Mr. Brainiac? Are you gonna tell us you read the article, too?
I think he was running with it... (Score:2)
Am I the only one who read that and understood he was worried about chafing?
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I certainly didn't read the article. I just came here to read all the "jerk" puns.
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You and me both...
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My only concern is what happens when those bristles get a little worn out after all that high intensity cyclic stress and an elevator load of passengers plummet to their doom from 100 km up.
It shouldn't be too hard to add a braking system.
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It shouldn't be too hard to add a braking system.
And if it is too hard, a couple more quick jerks and it should soften pretty quickly.
Has been seeing for decades, too (Score:5, Interesting)
> Actually, this is something the average person can see at home.
If anyone here had been a kid back in the last century, we could all have shared the memory of kite riders (no, I don't really know what they are called in english). While flying a kite, put a piece of paper on the string, and in a strong wind it will ratchet itself up. You could improve them, of course, one of the favorite mods being a release rod which would release the payload upon reaching the kite. You couldn't lift a lot of weight this way, but strategic stinkbomb bombardment was possible. Yes... Kids these days are sure missing out on a lot of things...
The power released during descent... (Score:2, Insightful)
...can be used to power the space kleenex dispenser.
Oh no! (Score:5, Funny)
Too...many...jokes... [head explodes]
Re:Oh no! (Score:5, Funny)
There's one additional joke to be made about the relevance of your username to this topic left as an exercise to the reader.
Re:Oh no! (Score:5, Funny)
And you, sir, are the (Score:5, Funny)
C-C-C-C-Combo breaker!
One other joke (Score:2)
Vision problems (Score:2)
Re:Oh no! (Score:5, Funny)
After all these years, I can't believe there's no +5 "Masturbation Reference" mod. C'mon Rob!
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Re:Oh no! (Score:5, Funny)
Do not try this at home!
Re:Oh no! (Score:4, Funny)
I think there's a Darwin award about that.
Hmmmmm. (Score:5, Funny)
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Y'know, this just might work, seeing that there is such a plentiful supply of jerks on the planet.
Yes, but as the summary states, it's all in the timing. We'll have to leave this up to the professionals: where are The Three Stooges when you need them?
Re:Hmmmmm. (Score:5, Funny)
Unfortunately, it's been my experience that most jerks have a horrible sense of timing, so they may not be all that useful
Re:Hmmmmm. (Score:5, Funny)
Y'know, this just might work, seeing that there is such a plentiful supply of jerks on the planet.
Since the Bush Administration is about to be unemployed, this timing is fortuitous indeed.
Slashdot: Setup lines for bad jokes... (Score:5, Funny)
Slashdot: Setup lines for bad jokes. Stuff that splatters.
Dude's name is Riise (Score:2)
Re:Slashdot: Setup lines for bad jokes... (Score:5, Funny)
please, google "begs the question".
Right away, sir. To whom shall I send the results?
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At the risk of _being_ a jerk.....
The commonly used phrase is "for all intents and purposes", and please, google "begs the question".
Whoosh! BIG whoosh!
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But you agree that "whom" isn't a word?
Either you're not getting his joke, or I'm not getting yours.
I don't think this will work (Score:4, Insightful)
Consider how much energy it would take to move this massively long cable. There is no way in hell that is going to be efficient. You're going to be wasting a massive amount of energy as you move the entire cable the whole time the thing is climbing.
To the naive this approach seems workable because it looks simple. The fact is that it takes a certain amount of energy to do things and this is probably a very poor method that will become quite obvious at the scale we are talking about. In this house we obey the laws of thermodynamics and all that...
Then you have to consider the wear and tear on the mechanical parts, especially that really expensive long cable into space. This just seems like a bad idea all around.
Re:I don't think this will work (Score:4, Insightful)
Seth
Re:I don't think this will work (Score:4, Informative)
For every 'yank' performed on the cable, you pull the anchor lower in orbit.
This is wrong - the transmitting end (ground station) can and would "push" just as readily as it would "pull". Then the vehicle would absorb this wavefront as it converts it to potential energy, such that there is very little energy propagating past it up the cable. You have to consider that this cable is very very long, and at such a scale it becomes more like a slinky, or a piece of string with a cup on each end.
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Your assuming that the cable is rigid... most designs for this that I have seen are usually a ribbon/cable that can flex in either one or two dimensions. This would mean that you could not push it, only pull.
Also, we are having enough trouble creating a cable that can withstand the incredible force required for a simple tether... now they want to add vibration on purpose? This has disaster written all over it.
Re:I don't think this will work (Score:5, Insightful)
Your assuming that the cable is rigid... most designs for this that I have seen are usually a ribbon/cable that can flex in either one or two dimensions. This would mean that you could not push it, only pull.
Actually I'm assuming precisely the opposite - nothing could be considered rigid at this scale. I'm further assuming that the wavelength of the vibrations is vastly shorter than the length of the cable. The cable has very high tensile strength and is under constant tension by centripetal force - this gives it a low enough mechanical impedance to be able to transmit meaningful force.
Also, we are having enough trouble creating a cable that can withstand the incredible force required for a simple tether... now they want to add vibration on purpose? This has disaster written all over it.
This does not necessarily introduce transverse oscillation, which would indeed be a problem. The net added tension on the cable would be zero, we're only talking an incredibly tiny variance in comparison.
I think you need to give this some more consideration before dismissing it. We don't know much from TFA how much research has gone into this, but I'd venture a guess that the inventor spent more time thinking about this than the few minutes you've had to noodle the idea since it made slashdot.
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are usually a ribbon/cable
Would that be ATA100 or ATA133?
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Re:I don't think this will work (Score:5, Insightful)
Consider how much energy it would take to move this massively long cable. There is no way in hell that is going to be efficient. You're going to be wasting a massive amount of energy as you move the entire cable the whole time the thing is climbing.
That was my initial reaction too, but then I thought about it for a minute and it occurred to me that this is probably analogous to an electrical/RF transmission line. The cable has some (very low) impedance in the sense that it is quite rigid, but it's not zero. You're not "moving the whole cable" by jerking on it, what you're really doing is transmitting a wavefront along a medium. Provided the whole system is impedance matched, nearly all the power could be delivered to the vehicle.
I'm not sure how well this holds up when you consider internal friction of the cable and other inefficiencies, but I wouldn't dismiss it off hand. The simplicity of it in that it works purely on kinetic energy makes it pretty intriguing. It may even have applications besides a space elevator.
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Some things you should consider:
1. you'll need either high amplitude or high frequency to get up to a useful speed
2. the design of a space elevator is already constrained by tension in the cable, and this scheme will lead to more tension, plus risk of fatigue fracture
3. how to power more than one vehicle at a time
4. what to do about the person who confuses vibration with jerking
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I would guess the energy in the cable would dissipate quite readily before making it even part way up the cable (try throwing a jolt down a long garden hose and see how far it goes), unless they build this cable out of buckyballs or something, which was an idea I read in Popular Science I believe a few years ago. I think it would need tensile strength off the charts.
The tether needs that tensile strength anyway. For me, I just don't how to transmit that much energy via vibration. Maybe it can be done, but sounds pretty iffy to me.
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Consider how much energy it would take to move this massively long cable. There is no way in hell that is going to be efficient. You're going to be wasting a massive amount of energy as you move the entire cable the whole time the thing is climbing.
****
If the entire system is powered from the ground, we have essentially unlimited power available. Just build a couple of reactors nearby to power it exclusively. The major problem with getting materials up to space isn't a lack of power, it's a lack of space t
Vibration (Score:5, Funny)
although i like the beauty of it's simplicity, wasn't vibration in the tether already a problem?
it's like a 300 mile long guitar string with a slide going up and down.
one of these days we'll have a /. story about the music of the space elevator.
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it's like a 300 mile long guitar string
Twang! the Drink of Astronauts!
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it's like a 300 mile long guitar string with a slide going up and down.
More like a 300 mile long air guitar string, the way it's going.
But don't worry about acquiring sufficient power, you can consider the elevator is a long resonant conductor cutting magnetic field lines. Or the world's largest bloody Van De Graff Generator [wikipedia.org], one or t'other.
Carefully Timed Jerks Could Power Space Elevator (Score:2)
C'mon now. I know hourly workers in the high tech industry can be a pain sometimes, but that's no reason to slander them!
100,000-km (Score:5, Funny)
The Headline (Score:2)
Carefully timed jerks could power space elevator? Hmmm...I'm not too sure about that. I've been to frat parties and those guys can't even play beer pong all that well.
Jerking the wrong end... (Score:5, Funny)
ObFarSide (Score:4, Funny)
We need to get Steve Jobs on this right away. (Score:5, Funny)
After all, he is a jerk with an impeccable sense of timing.
Mod me offtopic, but... (Score:2)
Ok, that's a cool little video clip... Notice how the ad in front of it was longer than the clip itself, though?
OMGWTFBBC?
Carefully time jerks (Score:2)
power Slashdot
dirty minds prevail (Score:2)
Sign Me up Ma! All that practice was for somethin' (Score:5, Funny)
Mom: "Hello"
Me: "Mom, uh mom, I know it is late but.."
Mom: "Oh hi honey..."
Me: "Hey Mom, do you remember those sincere times when you tearfully told me to quit playing with myself and stop using so much water back in the day and how no good would come of it?"
Mom: "Honey.. It was in your best interest..."
Pause for dramatic effect, a little static on the line, the sound of dad snoring and breathing heavy..
Me: "Mom, NASA just called. They need an expert. I am going to space Momma!..."
Mom: "Oh Darling! I never knew you would succeed like this.. Your father will be so proud! What...what time is it? 2 o'clock?">BR> *rustling covers* *wierd pause* Space? I thought you were happy bagging groceries...
Me: "Well they needed an expert. That's what us experts do. I just got a call on the emergency line. I am gonna have step up training, and need to get started. Tell Dad I love him Mah. Tell dad I love him. If I don't make it.. you can have the cats..."
Mom:" What will you be doing again?"
In case of power failure (Score:2)
But will it scale? (Score:2, Insightful)
It's one thing to vibrate a broomstick in that manner, and quite another to do so with a 36,000 km space elevator. No matter what material you're using, you're looking at a very large mass; wikipedia estimates "a minimal, very low payload space elevator 'seed ribbon' could have a mass of at least 18,000 kg." -- or just shy of 20 tons. For hauling passengers and goods, you'll need much more. Now, we're talking about accelerating and decelerating this mass of at least 20 tons multiple times per second.
Think
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If you could translate side-to-side motion of the tether into upwards motion for the payload, then you could create a standing wave on the tether pretty efficiently.
As for exerting force on the passengers, I'm sure as TFA mentions, a suspension mechanism can be designed to at least make it bearable.
The ratcheting mechanism itself is probably the hardest part. How to make it so it survives at least one full ascension will be an interesting challenge.
All in all, I think it is great to look at problems
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Take a hammer. Find a big rig and hit it with the hammer. Congratulations, you've just caused it to accelerate and decelerate many times per second.
Now run away. That truck driver doesn't want to shake your hand.
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It's one thing to vibrate a broomstick in that manner, and quite another to do so with a 36,000 km space elevator...
Isn't the tether going to be vibrating anyway? There's a lot of atmosphere moving past the part that's in the atmosphere.
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Consider that the anchors could be springs with 1 meter play...
You need to ensure that the downward motion of the ribbon would accelerate at a rate such as to be faster than the cabin falling (Equations for a Falling Body [wikipedia.org]). The springs would have to be quite strong to shift 20 tons one meter that quickly. Composition and cooling of the springs would be an interesting bit of engineering.
Another question to consider -- will the resonant frequency necessary to raise the cabin change with altitude? Considering the mass of the cabin would be constant, I'd think a lower
So... (Score:2, Funny)
Don't you hate it (Score:2)
when you make a jerk tick?
Yeah, I'd much rather have them manually triggered than timed.
This man is in the wrong field (Score:2)
Clearly this man has a calling in erotic literature.
April Fools or bad material science? (Score:2)
They still have to figure out how to build the actual ribbon - even carbon/fullerene nanomaterials have not achieved the required tensile strengths. lasers or some guy with a broomstick doesn't matter if the cable snaps on deployment.
This is why honest ROCKETS make so much more sense - proven tech that gets cheaper as frequency of flight increases.
Manual Labour (Score:2)
Elevator music played by Symphonic Orchestra (Score:2)
*DING* *crackling speaker* "First floor: Radiation, Vacuum and Anti-Gravity Masturbation"
Electronic equivalent... (Score:2)
... a diode?
How's my timing? (Score:2)
Did the elevator move?
Okay, all you jerks... (Score:4, Funny)
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EVER is a long time.
The Space Elevator is something an advanced civilization with a few hours to kill might whip up.
Re:What a dumb idea... (Score:4, Funny)
an advanced civilization with a few hours to kill
There isn't any evidence that such things exist, of course... :-) "Advanced civilizations," that is.
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I was talking about us.. in a few thousand years.. hopefully after all the dickwads who think making the earth a utopia is achievable have buggered off.
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"we'll be more advanced" suggests some kind of progression of the liberal arts sense.. I was just referring to technological advancement.
Re:What a dumb idea... (Score:4, Informative)
It's worse than that actually. The distance to Geosynch is 36000 km. Moving at a 100 km/h (about 55mph) you'd still be underway for 360 hours. There's no way any climbing-mechanism that depends on mechanical transfer from the ribbon will be able to climb even close to fast enough to make the thing practical.
The demonstration shows a climbrate of around 0.1m/s at which speed it'd reach geosynchornous orbit after about 15 years of climbing. Dumbest idea ever.
Re:frist (Score:5, Funny)
Re:frist (Score:5, Funny)
Re:frist (Score:5, Funny)
Yeah? Well, I had sex with your wife!
Re:frist (Score:5, Funny)
Re:frist (Score:5, Funny)
Re:frist (Score:4, Informative)
This is slashdot (Score:5, Funny)
The jerk store called. They want the third derivative of the position function back.
Re:frist (Score:5, Funny)
So if I'm reading the title correctly, Lawyers with rolexes could get us into space?
Are those crickets?
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Try it as a verb. Pretty sure that all slashdotters carefully time their jerks late at night.
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With criticism like this, I would say this idea is destined to succeed.
I call bullshit (Score:5, Insightful)
"Why is everyone so obsessed with this terrible idea? Even if we got it to work, there's no way we'd be able to afford the maintenance and energy costs. It just isn't viable."
This guy just copied and pasted his post. I found this same post about plane flight, the space shuttle, the hubble, the mars rover, and the lightbulb.
ok, i lied, but you get the point :)
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I never found Bozo the Clown particularly funny. Of course, the fact that Carl Sagan, who originated that quote, laughed is fairly easy to explain. [druglibrary.org]
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Um what? Why is this moderated insightful? Arguing that it doesn't work because you have to hold it up shows as poor an understanding of physics as claiming it's turtles all the way down [wikipedia.org].
Of course, the cable needs to be made out of a material that we don't yet know how to make -- but that our understanding of materials science suggests is entirely possible.
(OTOH, I don't think the elevator will be a useful idea for a long, long time, but that's for different reasons.)
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I didn't say it lightly [slashdot.org] Maybe you should read a few more articles. The problem is not with the material. It is with the system as a whole.
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I've read it. Requiring active control for stability when a car is in transit is hardly something that makes it impossible. Nor is it even remotely related to "suspension." There are plenty of systems that fail catastrophically without active stabilization.
The fact that there are several problems to solve does not mean the whole thing should be thrown out. If you seriously think the right answer to a hard but interesting problem is to give up as soon as you realize it's hard, I think you're on the wrong
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I wish I could find the article that showed how the system was not stable and would require thrusters to keep the "cable" taunt yet unbroken.
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