Forgot your password?
typodupeerror
Transportation Space

Carefully Timed Jerks Could Power Space Elevator 270

Posted by ScuttleMonkey
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."
This discussion has been archived. No new comments can be posted.

Carefully Timed Jerks Could Power Space Elevator

Comments Filter:
  • "jerks" (Score:5, Funny)

    by Anonymous Coward on Monday January 05, 2009 @07:25PM (#26336875)
    Something tells me the average slashdotter might be able to offer assistance in this "scientific research"
    • Re:"jerks" (Score:5, Insightful)

      by biryokumaru (822262) * <biryokumaru@gmail.com> on Monday January 05, 2009 @07:41PM (#26337057)

      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)

        by uniquename72 (1169497) on Monday January 05, 2009 @08:11PM (#26337395)
        Great - you've ruined a perfectly good joke with a bunch of "information".

        What's next, Mr. Brainiac? Are you gonna tell us you read the article, too?
      • 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.

        • 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.

      • by Chemisor (97276) on Monday January 05, 2009 @08:45PM (#26337693)

        > 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...

  • by Anonymous Coward

    ...can be used to power the space kleenex dispenser.

  • Oh no! (Score:5, Funny)

    by HaveNoMouth (556104) on Monday January 05, 2009 @07:27PM (#26336897) Homepage

    providing carefully timed jerks of the cable at its base

    Too...many...jokes... [head explodes]

  • Hmmmmm. (Score:5, Funny)

    by Oloryn (3236) on Monday January 05, 2009 @07:28PM (#26336921)
    Y'know, this just might work, seeing that there is such a plentiful supply of jerks on the planet.
  • by istartedi (132515) on Monday January 05, 2009 @07:32PM (#26336965) Journal

    Slashdot: Setup lines for bad jokes. Stuff that splatters.

  • by Cthefuture (665326) on Monday January 05, 2009 @07:47PM (#26337105)

    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.

    • by SethJohnson (112166) on Monday January 05, 2009 @07:58PM (#26337235) Homepage Journal
      Your point about the energy is spot-on. Additionally, this concept totally ignores the orbiting anchor for the space elevator. For every 'yank' performed on the cable, you pull the anchor lower in orbit. The anchor then has to reposition itself USING ENERGY. Probably rocket fuel, I'd imagine. Either that, or the anchor releases the cable to allow it to go downwards, then has to pull it up again. That's the "lift" for the elevator- the pulling up of the cable.

      Seth
      • by seanadams.com (463190) * on Monday January 05, 2009 @08:17PM (#26337445) Homepage

        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.

        • Re: (Score:3, Informative)

          by Q-Hack! (37846) *

          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.

          • by seanadams.com (463190) * on Monday January 05, 2009 @09:01PM (#26337823) Homepage

            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.

          • Re: (Score:2, Funny)

            by ScrewMaster (602015) *

            are usually a ribbon/cable

            Would that be ATA100 or ATA133?

      • Re: (Score:3, Insightful)

        by Tubal-Cain (1289912) *
        If you put the anchor far enough out there that centripetal force pulls it away harder than the base station's vibrations pull it, it should work.
        • by meist3r (1061628)
          Actually, as far as I know about the research for a cable solution that is one of the hard-to-solve problems. The force that pulls on the cable because the anchor wants to fly off is so strong that even if you could work out this mechanical energy transfer you'd still lack the ability to manufacture a cable that is strong enough. Isn't that why they started trying weave nano tubes into wires?
      • by tokabola (771071)
        Actually, the counterweight (which, unlike the article states, is farther out than Geostationary,) would pull any slack out of the cable with centrifugal force. Read up on space elevators - they require no added energy to stay in place. The only energy needed is to move the payloads.
      • by smoker2 (750216)
        You don't have to yank the cable first. You have the ground based tether jump slightly to initiate a wave which travels up the cable. The elevator rides the waves. It's the same principle as the whip really, in that you throw the whip out first then back to make the crack.
    • by seanadams.com (463190) * on Monday January 05, 2009 @08:00PM (#26337261) Homepage

      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.

      • Re: (Score:2, Interesting)

        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

    • by Plekto (1018050)

      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)

    by phrostie (121428) on Monday January 05, 2009 @07:50PM (#26337145)

    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.

    • Sounds to me like this is turning a problem into a solution.
    • it's like a 300 mile long guitar string

      Twang! the Drink of Astronauts!

    • 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.




  • 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!
  • by DanWS6 (1248650) on Monday January 05, 2009 @07:54PM (#26337205)
    That would take a while to get up. Then again, with enough jerking I'm sure anything is possibly.
  • 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.

  • by werdnapk (706357) on Monday January 05, 2009 @08:03PM (#26337305)
    Jerking at the base is ok, but jerking at the top works much better.
  • ObFarSide (Score:4, Funny)

    by HiVizDiver (640486) on Monday January 05, 2009 @08:06PM (#26337335)
    Jerks. [photobucket.com]
  • by The Breeze (140484) on Monday January 05, 2009 @08:06PM (#26337339) Homepage

    After all, he is a jerk with an impeccable sense of timing.

  • Ok, that's a cool little video clip... Notice how the ad in front of it was longer than the clip itself, though?

    OMGWTFBBC?

  • power Slashdot

  • For a moment I wasn't sure if I was reading /. or penthouse...

    ...providing carefully timed jerks of the cable at its base...
    ...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...
  • by I_Can't_Fly (1442225) on Monday January 05, 2009 @08:16PM (#26337441) Homepage
    2:00 A.M Somewhere on a lonely street near the outskirts of Des Moines.

    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?"

  • it might be necessary to power manually: "You, jerk!" "What?! I didn't cut the power!"
  • But will it scale? (Score:2, Insightful)

    by merreborn (853723)

    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

    • Ahem... at first brush, it sounds ridiculous.
    • 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

    • by ceoyoyo (59147)

      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.

    • 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.

  • So... (Score:2, Funny)

    by pondermaster (1445839)
    ...from take offs to jerk offs? Evolution!
  • when you make a jerk tick?

    Yeah, I'd much rather have them manually triggered than timed.

  • 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.

    Clearly this man has a calling in erotic literature.
  • 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.

  • Surely with the world's mean unemployment rate, they could just hook up huge engines to millions of treadmills...
  • And afterwards the Lord of the Rings Trilogy, The Seven Samurai, The Uncut Frost/Nixon interviews and every Episode of Seinfeld ever made.

    *DING* *crackling speaker* "First floor: Radiation, Vacuum and Anti-Gravity Masturbation"
  • ... a diode?

  • Did the elevator move?

  • by Jane Q. Public (1010737) on Tuesday January 06, 2009 @02:38AM (#26339939)
    ... on the count of THREE! ...

Repel them. Repel them. Induce them to relinquish the spheroid. - Indiana University fans' chant for their perennially bad football team

Working...