Japan to build Space Elevator

Discussion in 'General Science & Technology' started by madanthonywayne, Sep 22, 2008.

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  1. NGM Registered Member

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    Opps, I wasn't thinking in that direction, but taking that into consideration, the existing satellites that are or were in geostationary orbit have to also be considered. As of 1 January 2005, there were 1,124 objects with a cross-section of more than 1 m catalogued in the geostationary region and its immediate vicinity. Of these, only 346 are operational satellites. Two thirds of them are equipped to jet out of their current orbit upon their end of life tour but a full one third of them will remain to end with natural conclusions. That conclusion could be by contact with other objects. Hope it's not an elevator.
    "Look Ralph, doesn't that look like something coming awful fast towards us?"

    Hey, I'm full of pizza and I'm going to call it a night.

    Thanks for the discussion this evening.
     
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  3. Walter L. Wagner Cosmic Truth Seeker Valued Senior Member

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    Wouldn't it be easier/better to build it on the moon first? Much shorter cable, much less tension required, existing nano-tube technology would suffice? And, no icing/wind/crazy-religionists to worry about.
     
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  5. Sciencelovah Registered Senior Member

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    Rrr, no. What Japan is trying to do is to build the space elevator until the
    geostationary orbit, i.e. 36,000 km up. The cable needed is twice than that
    (72,000 km) so that the length will be centered in the geostationary point for
    the reason which has been explained by Nasor (post #32). On the other hand, the
    distance from earth to the moon (center to center) is 384,403 km.
     
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  7. Nasor Valued Senior Member

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    I think he meant build an elevator to go from the moon's surface to lunar orbit. It would be a lot easier, but also a lot less useful.
     
  8. Sciencelovah Registered Senior Member

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    Oops, you are right, he said on the moon, I thought to the moon.

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    Even though so, how is that easier? For instance, you are going to have to transport
    all the materials to the moon first. Also the machines, the manpower, etc.
     
  9. orcot Valued Senior Member

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    Average it"s worse in reality with the moon ellips orbit and the fact that it doesn't rotate the earth around it's centre.

    And not to hijack a threat
    but here is a nice link abouth a martian space elevator
    That amongs many things say that Mars would need only 42 GPA stong nanotubes far a cable weighting 2 000 000kg. Meaning it would weight the construction facility send to Phobos to construct it.
     
  10. Sciencelovah Registered Senior Member

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    Draqon would be really excited to read that one

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    It looks really interesting as the cable length would be 'only' 6000 km.

    From that source:
     
  11. Sciencelovah Registered Senior Member

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    Btw, in the above post you mentioned the necessity of the center of the
    cable to be in the geostationary orbit. This is to make sure the stability
    of the cable, right? So that it would look like a satellite, i.e. hanging on
    the geostationary orbit, maintained by centripetal force. The total weight
    of the cable would be around 100 kg, whereas the mass of the elevator and its
    load (human, supplies) will outweigh it. So, when the elevator is attached into
    it, isn't it going to make the center of the mass changing?
     
  12. Nasor Valued Senior Member

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    Easier in terms of technology. Since the moon's gravity is lower the cable doesn't have to be nearly as strong, so you could build one today using a variety of commercially available materials like spectra or zylon (or probably a bunch of others that I don't know of off the top of my head).

    In addition to making it a lot easier to maintain a moon base, there are several kinds of rocket fuel that can be made from lunar materials, and such an elevator would allow you to bring up an unlimited amount of fuel from the moon for use elsewhere, more or less for free. Or aluminum, which you can also get from the moon. You could imagine it being very helpful if you ever wanted to do any sort of large-scale manufacturing in space.

    The actual cost of building it wouldn't be as high as you might think, because you could launch the cable in one piece from earth in a moderately big rocket. The main costs would be associated with setting things up on the moon, but it's assumed that you're already planning to have a colony or some industry or something there, otherwise there's no point in building it in the first place.
     
  13. orcot Valued Senior Member

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    give me a example the moon has virtually no hydrogen
     
  14. Nasor Valued Senior Member

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    There might or might not be water on the moon - the jury is still out. A slurry of aluminum nanoparticles suspended in a liquid oxygen also makes a reasonably good rocket fuel, and there is plenty of both on the moon. If you're using nuclear thermal engines, liquid oxygen can be used as a propellant by itself.
     
  15. Walter L. Wagner Cosmic Truth Seeker Valued Senior Member

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    A moon base would ideally have nuclear reactor technology for energy production. No one complaining about messing up the environment [which is minimal anyway - radioactive materials decay away - chemical pollutants tend to be stable and remain indefinitely]. The energy could be used to extract aluminum and other useful materials, propel 'moon-buggies', and power a space-elevator for transporting aluminum, etc. to high orbit for subsequent production of a mars shuttle. If we're going back to the moon, we ought to do it right.
     
  16. Sciencelovah Registered Senior Member

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    Ok, thanks for the reply. What about my question in post #48? Am I right in
    thinking that the elevator load will influence the center of the overall mass, so
    the center won't be in the geostationary orbit anymore, but somewhat lower?
     
  17. cosmictraveler Be kind to yourself always. Valued Senior Member

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    But the concept has been stuck on the ground floor for decades, not least because constructing a tether strong enough for the job is beyond current technology. Nanotubes might be up to the task, but they would have to be made longer and with fewer defects than any that can be fabricated today.
    A new study makes the prospects appear even gloomier.

    Even if a space elevator could be built, it will need thrusters attached to it to prevent potentially dangerous amounts of wobbling, says Lubos Perek of the Czech Academy of Sciences' Astronomical Institute in Prague. The addition would increase the difficulty and cost of building and maintaining the elevator.


    Previous studies have noted that gravitational tugs from the Moon and Sun, as well as pressure from gusts of solar wind, would shake the tether. That could potentially make it veer into space traffic, including satellites and bits of space debris. A collision could cut the tether and wreck the space elevator.

    http://space.newscientist.com/article/dn13552-space-elevators-face-wobble-problem.html
     
  18. Nasor Valued Senior Member

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    Sorry, I somehow missed that before. Even though the cable is very thin and relatively low density, there is a LOT of it, plus the mass of the counter-weight (or extra length of cable). The mass of the elevator car+payload is probably going to be very, very small compared to the over all mass of the system, so the overall change in the center of mass will be very small - probably on the order of just a few tens of meters. But if you're really worried about it, you can always just have another mass located near GEO that you move up the cable right before you attach the car, so that the center of mass stays in the right place.
     
  19. Nasor Valued Senior Member

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    This has already been addressed. There are ways to cancel oscillations in the tether, including moving the base slightly or carefully timing the ascent and decent of the elevator cars. So far as I know, no one has ever shown quantitatively that the elevator cable could not be stable.
     
  20. Syzygys As a mother, I am telling you Valued Senior Member

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  21. Stryder Keeper of "good" ideas. Valued Senior Member

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    It would make more sense to be build only half an elevator. Basically you dangle the overall shaft from a space platform over the earth and use Airships to lift containers to the shafts base platform which is suspended at a point high in the atmosphere but not too high that an Airship can't reach.

    If the "shaft" is a cable, then it can be retracted and moved and then redeployed at a new location. I'd suggest having something like a Solar Drone (Similar to the drones the military uses) at the base of the shaft to control the end which can be dis-attached during redeployment.

    Using this method would mean that with thrusters it would be possible to move the shaft/Platform around the globe, so any country could potentially use it for a duration.

    Using a "container" system would work quite well, especially if the actual "lift/elevator" mechanism was individual per container (Namely inbuilt), so there is no lift/elevator to fail due to an over extended lifespan, as each container could contain their own lift/elevator mechanism.
     
  22. orcot Valued Senior Member

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    The cable would not be able to feed on earth angular momentum and would slow down in our atmosphere until it crashes.

    A better method would be to find a reasenable massed NEO (at least 10E16kg)and bring it in orbit at 10 000 km (that around 3 times the altide of the ISS and abouth 1/7 the lenght of a traditional space elevator.
    This rock comparable to phobos would apart from the estetical (it would apear to be half the size of the moon) have little to no tidel effect on the earth but the earth would have a mayor effect on this new moon tidal locking it.
    if you would attach the cable to this new moon and hang the lower end in our upper atmosphere then the energy will be transfert to the new moon changing it's angular momentum, however earth gravitational lock would then speed it up to keep it tidal lock and the moon would loose minimal altitude altough it would probably crash with the earth in between 1000- 10 000 years but by that time we could have imported enough fuel trusters and power plants to launch it to alpha centauri. So it would never crash.
     
  23. Michelle Redford Registered Member

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    As someone said above, I don't think space elevators will ever be possible. They are just too futuristic... Sci-fi in my humble opinion.
     
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