Slashdot Log In
Carefully Timed Jerks Could Power Space Elevator
Posted by
ScuttleMonkey
on Mon Jan 05, 2009 06:22 PM
from the pull-harder-and-faster dept.
from the pull-harder-and-faster dept.
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."
Related Stories
This discussion has been archived.
No new comments can be posted.
The Fine Print: The following comments are owned by whoever posted them. We are not responsible for them in any way.
Full
Abbreviated
Hidden
Loading... please wait.
"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.
Parent
Re:"jerks" (Score:5, Funny)
What's next, Mr. Brainiac? Are you gonna tell us you read the article, too?
Parent
Re: (Score:3, Funny)
I certainly didn't read the article. I just came here to read all the "jerk" puns.
Re: (Score:3, Funny)
You and me both...
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...
Parent
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.
Parent
Re:Oh no! (Score:5, Funny)
Parent
And you, sir, are the (Score:5, Funny)
C-C-C-C-Combo breaker!
Parent
Re:Oh no! (Score:5, Funny)
After all these years, I can't believe there's no +5 "Masturbation Reference" mod. C'mon Rob!
Parent
Re: (Score:3, Funny)
Re:Oh no! (Score:5, Funny)
Do not try this at home!
Parent
Re:Oh no! (Score:4, Funny)
I think there's a Darwin award about that.
Parent
Hmmmmm. (Score:5, Funny)
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
Parent
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.
Parent
Slashdot: Setup lines for bad jokes... (Score:5, Funny)
Slashdot: Setup lines for bad jokes. Stuff that splatters.
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?
Parent
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
Parent
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.
Parent
Re: (Score:3, Informative)
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.
Parent
Re: (Score:3, Insightful)
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.
Parent
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.
100,000-km (Score:5, Funny)
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.
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?"
Okay, all you jerks... (Score:4, Funny)
Re: (Score:3, Insightful)
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.
Parent
Re: (Score:3, Insightful)
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.
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.
Parent
Re:frist (Score:5, Funny)
Parent
Re:frist (Score:5, Funny)
Parent
Re:frist (Score:5, Funny)
Yeah? Well, I had sex with your wife!
Parent
Re:frist (Score:5, Funny)
Parent
Re:frist (Score:5, Funny)
Parent
Re:frist (Score:4, Informative)
Parent
This is slashdot (Score:5, Funny)
The jerk store called. They want the third derivative of the position function back.
Parent
Re:frist (Score:5, Funny)
So if I'm reading the title correctly, Lawyers with rolexes could get us into space?
Are those crickets?
Parent
Re: (Score:3, Funny)
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 :)
Parent
Re: (Score:3, Interesting)
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]
Re: (Score:3, Informative)