Slashdot Mirror


Carefully Timed Jerks Could Power Space Elevator

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."

40 of 270 comments (clear)

  1. "jerks" by Anonymous Coward · · Score: 5, Funny

    Something tells me the average slashdotter might be able to offer assistance in this "scientific research"

    1. Re:"jerks" by biryokumaru · · 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.

      --
      When you're afraid to download music illegally in your own home, then the terrorists have won!
    2. Re:"jerks" by uniquename72 · · Score: 5, Funny

      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?

  2. Oh no! by HaveNoMouth · · Score: 5, Funny

    providing carefully timed jerks of the cable at its base

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

    1. Re:Oh no! by IthnkImParanoid · · Score: 5, Funny

      No, there's really only two: one involving rude people and one involving masturbation. Of course, the second one makes the [head explodes] tag all the more understandable.

      There's one additional joke to be made about the relevance of your username to this topic left as an exercise to the reader.

      --
      It's nothing but crumpled porno and Ayn Rand.
    2. Re:Oh no! by mkiwi · · Score: 4, Funny

      After all these years, I can't believe there's no +5 "Masturbation Reference" mod. C'mon Rob!

    3. Re:Oh no! by GodlikeDoglike · · Score: 5, Funny

      People like you are why we can't have nice things.

    4. Re:Oh no! by Al+Al+Cool+J · · Score: 4, Funny
      What about:

      an electric sander to provide a rhythmic vibration to the bottom of the stick

      Do not try this at home!

    5. Re:Oh no! by MadnessASAP · · Score: 3, Funny

      I think there's a Darwin award about that.

      --
      I may agree with what you say, but I will defend to the death your right to face the consequences of saying it.
  3. Re:frist by Anthony_Cargile · · Score: 5, Funny

    Yeah? Well the jerk store called and they're running out of you!

  4. Hmmmmm. by Oloryn · · Score: 5, Funny

    Y'know, this just might work, seeing that there is such a plentiful supply of jerks on the planet.

    1. Re:Hmmmmm. by R3d+M3rcury · · Score: 4, Funny

      Unfortunately, it's been my experience that most jerks have a horrible sense of timing, so they may not be all that useful

    2. Re:Hmmmmm. by rhizome · · Score: 4, 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.

      --
      When I was a kid, we only had one Darth.
  5. Re:frist by l3ert · · Score: 5, Funny

    What's the difference? You're their all-time best seller.

    --
    per dolorem ad astra
  6. Slashdot: Setup lines for bad jokes... by istartedi · · Score: 5, Funny

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

    --
    For all intensive purposes, "whom" is no longer a word. That begs the question, "who cares"?
  7. Re:Just give up already... by Anonymous Coward · · Score: 3, Funny

    With criticism like this, I would say this idea is destined to succeed.

  8. I call bullshit by deft · · Score: 4, 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 :)

    --

    There's nothing Intelligent about Intelligent Design.
  9. I don't think this will work by Cthefuture · · Score: 3, 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.

    --
    The ratio of people to cake is too big
    1. Re:I don't think this will work by SethJohnson · · Score: 3, Insightful

      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

    2. Re:I don't think this will work by seanadams.com · · 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.

      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.

    3. Re:I don't think this will work by seanadams.com · · Score: 3, 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.

    4. Re:I don't think this will work by seanadams.com · · Score: 4, 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.

  10. Vibration by phrostie · · Score: 4, 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.

  11. Re:frist by Anonymous Coward · · Score: 5, Funny

    Yeah? Well, I had sex with your wife!

  12. Re:frist by Anthony_Cargile · · Score: 3, Informative

    This is not flamebait - its a classic seinfeld episode: Synopsis full episode.

  13. This is slashdot by ciaohound · · Score: 5, Funny

    The jerk store called. They want the third derivative of the position function back.

    --
    Oh, yeah, it's not easy to pad these out to 120 characters.
  14. Re:frist by geekmansworld · · Score: 5, Funny

    His wife's in a coma...

  15. 100,000-km by DanWS6 · · Score: 4, Funny

    That would take a while to get up. Then again, with enough jerking I'm sure anything is possibly.

  16. Re:frist by philspear · · Score: 4, Funny

    So if I'm reading the title correctly, Lawyers with rolexes could get us into space?

    Are those crickets?

  17. Jerking the wrong end... by werdnapk · · Score: 5, Funny

    Jerking at the base is ok, but jerking at the top works much better.

  18. Re:frist by Anthony_Cargile · · Score: 4, Funny

    (mumbles to self) Well the life support machine called... Wait! Thats it! You just screwed yourself Riley!

  19. ObFarSide by HiVizDiver · · Score: 3, Funny
  20. We need to get Steve Jobs on this right away. by The+Breeze · · Score: 4, Funny

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

  21. Re:What a dumb idea... by TerranFury · · Score: 3, 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.

  22. Sign Me up Ma! All that practice was for somethin' by I_Can't_Fly · · Score: 5, Funny
    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?"

    --
    Is this thing on? Check. Check.
  23. Re:Slashdot: Setup lines for bad jokes... by Bromskloss · · Score: 5, Funny

    please, google "begs the question".

    Right away, sir. To whom shall I send the results?

    --
    Swedish plasma phys. PhD student; MSc EE; knows maths, programming, electronics; finance interest; seeks opportunities
  24. Has been seeing for decades, too by Chemisor · · 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...

  25. And you, sir, are the by Failed+Physicist · · Score: 5, Funny

    C-C-C-C-Combo breaker!

  26. Okay, all you jerks... by Jane+Q.+Public · · Score: 3, Funny

    ... on the count of THREE! ...

  27. Re:What a dumb idea... by Eivind · · Score: 3, 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.