Thread: Space elevator

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  1. #81
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    Ya the space elevator idea has been around for multiple decades.

    With carbon nanotubes it could potentially be possible. However building a long enough cable is a problem since it's not an easy material to work with.

    I don't think the cost would be much of a problem honestly. The ISS + shuttle program are/were pretty insane and it still got done. The investment risk factor is just pretty high.

    Also think about how much cheaper computer parts or superconducting wire is compared to 10 years ago. If the demand is there automatation will dramatically decrease the price.

    Though another thing would be the effects such a construct would have on earth itself. Even a small (in relation to earths mass) counterweight could imbalance earths rotational speed and posssibly orbit.
    I'm sure there are decent simulations about that but in the end you might have to abandon the project if the effect was greater than expected (butterfly effect so to speak). It's unlikely but in the end our understanding of the core of the earth is only a simulation without proof.

    Anyway if the human race hasn't killed itself off in a hundread years I think this could potentially be built. In our lifetime? Probably not.
    Last edited by mmocb100f50513; 2012-03-01 at 04:44 PM.

  2. #82
    Quote Originally Posted by Reeve View Post
    We probably could have had moon colonies by now, if we'd had the will to do it. But your point is taken, in that we probably lack the will to make something like a space elevator, even if the tech came into being.
    Quote Originally Posted by ita View Post
    It's because there is no profit in the space stuff. If it was possible to make a lot of money by going into space, we'd already have Mars bases by now or more. Sure there would be some rich tourists but on the long run, not enough to make it worth it.
    Yes, exactly. Space elevator belongs more to the list of stuff that's "awesome, but not nearly profitable enough to happen any time soon".

  3. #83
    Quote Originally Posted by Anakso View Post
    Unfortunately some students worked out how much it would cost to build a deathstar, it would cost $8.1quadrillion, which is 13,000 times the worlds gross product. No death star =(
    Ah, but you ignore the possibility of building the deathstar in the future.

    Some of the basic figures vary, but here is the math according to the figures i found on the original source:

    Cost to build - 852,000 Trillion dollars
    Current GDP - 63T

    which is approximately 13,500 times current GDP, varying on whose source of GDP you use. Lets not quibble on the basic estimation.

    GDP grows every year, lets assume on average the world's GDP grows at a decent, but not to fast rate of 2.5%.

    How long would it take before 1 years GDP = the cost to build the deathstar?

    852,000T= 63T *1.025^x
    852,000T/63T=1.025^x
    Ln (13,520) = x * Ln (1.025)
    x= 385

    385 years till we can build the deathstar in one year. So if under these assumptions of growth, and barring cataclysmic breakdown of world civilization, I think its safe to expect we might be building artificial moons, let alone a space elevator, within the next 500 years.



    What if we wished to build the deathstar straight, forgetting about all other forms of consumption?
    then: 852,000T= 0,x Σ 63T *1.025^x
    which leads to x=235
    so 235 years to build the death star if we devote all our efforts to it (bit illogical given investment spending is needed to boost economic output and consumption for human survival)
    Last edited by DraconusIX; 2012-03-01 at 07:57 PM.

  4. #84
    Quote Originally Posted by DraconusIX View Post
    Ah, but you ignore the possibility of building the deathstar in the future.

    Some of the basic figures vary, but here is the math according to the figures i found on the original source:

    Cost to build - 852,000 Trillion dollars
    Current GDP - 63T

    which is approximately 13,500 times current GDP, varying on whose source of GDP you use. Lets not quibble on the basic estimation.

    GDP grows every year, lets assume on average the world's GDP grows at a decent, but not to fast rate of 2.5%.

    How long would it take before 1 years GDP = the cost to build the deathstar?

    852,000T= 63T *1.025^x
    852,000T/63T=1.025^x
    Ln (13,520) = x * Ln (1.025)
    x= 385

    385 years till we can build the deathstar in one year. So if under these assumptions of growth, and barring cataclysmic breakdown of world civilization, I think its safe to expect we might be building artificial moons, let alone a space elevator, within the next 500 years.



    What if we wished to build the deathstar straight, forgetting about all other forms of consumption?
    then: 852,000T= 0,x Σ 63T *1.025^x
    which leads to x=235
    so 235 years to build the death star if we devote all our efforts to it (bit illogical given investment spending is needed to boost economic output and consumption for human survival)
    Wouldn't the cost also increase due to inflation...?

  5. #85
    Merely a Setback Reeve's Avatar
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    Quote Originally Posted by Purlina View Post
    Wouldn't the cost also increase due to inflation...?
    Not if that 2.5% increase per year is already inflation-adjusted.
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  6. #86
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    Quote Originally Posted by semaphore View Post
    Well, we can barter for goods, but the reason we use money now is because currency-based market is much more efficient than bartering. Sure it's a artificial concept, but that doesn't mean it's bad. It's still the best way to have a functional economy that we have.

    Also the food and housing and entertainment and medical needs for everyone building a space elevator is immense. No one can provide that much simply out of the goodness of their hearts.
    Kinda my point. Eventually we will probably need to find an alternative to our currency based system or stagnate in it. I was never saying it wasn't good or doesn't work. In fact i feel an industrialized society cannot work through barter due to how things are made. However i also feel that to go from an industrialized society to a "space"society if you will we will need to find an alternative.

    ---------- Post added 2012-03-01 at 09:13 PM ----------

    Quote Originally Posted by semaphore View Post
    Yes, exactly. Space elevator belongs more to the list of stuff that's "awesome, but not nearly profitable enough to happen any time soon".
    Proving the point even further that the currency system of good exchange may no longer be viable.

  7. #87
    Quote Originally Posted by Purlina View Post
    Wouldn't the cost also increase due to inflation...?
    yes the cost would increase with inflation. I should of noted this was all in Present day dollars, with 2.5% above and beyond inflation. To include inflation - (which would be extremely hard over that long of a time period) would mean inventing a lot more numbers I am guessing at. yes its a rough estimate. 2.5% may be too high of a rate. its a guess, but it gives you an idea how much compound growth adds up.

    It shows that it is quite feasible we COULD be building artificial moons, space elevators, and planetary bases elsewhere. No, I don't expect there to be bases on all planets. Some like mercury (to cold, to hot), venus (to hot, atmpospheric conditions) , and the interior Jovian moons (magnetic field and amount of radiation from jupiter) pose huge issues that might not be easily solved.

    It could be quite possible that we build a space elevator on the moon or mars before we build one for earth, given the gravitational differences.

    here is an interesting thought though - what happens if the space elevator breaks? You would have a huge object, (forget the length) that would basically encircle the equator. The mass is likely big enough that it would not all burn up in the atmosphere. Just like the WTC, the bigger it is, the harder it falls.
    Last edited by DraconusIX; 2012-03-01 at 10:25 PM.

  8. #88
    Quote Originally Posted by Sorrior View Post
    Kinda my point. Eventually we will probably need to find an alternative to our currency based system or stagnate in it. I was never saying it wasn't good or doesn't work. In fact i feel an industrialized society cannot work through barter due to how things are made. However i also feel that to go from an industrialized society to a "space"society if you will we will need to find an alternative.
    Well, maybe one day we will come up with something better. I don't know of anything even being suggested that can replace currency though.


    Proving the point even further that the currency system of good exchange may no longer be viable.
    Well not really, it's more of a reflection of the fact that space elevators provides too little benefits to justify the resources it would take to construct for the forseeable furture.

  9. #89
    Quote Originally Posted by DraconusIX View Post
    here is an interesting thought though - what happens if the space elevator breaks? You would have a huge object, (forget the length) that would basically encircle the equator. The mass is likely big enough that it would not all burn up in the atmosphere. Just like the WTC, the bigger it is, the harder it falls.
    If the rope itself breaks, it would simply fly off into space due to the outward acceleration. It would not fall down to Earth, again, due to the outward acceleration resulting in its centrifugal motion. The only way it could start to wrap around the Earth is if the mass suddenly came to a stop and was no longer moving in a geosynchronous orbit. Much like rolling a rope up on a rod, you need the rope to have a fixed position relative to the rotating pole in order to reel it inward. The only way that could happen is if space debris hit it hard enough to cause it to go out of its geosynchronous orbit, but that is a scenario that will be expected and prepared for (be it by readjusting its orbit or avoiding all debris all together).

    If worse came to absolute worse, I presume they would have a quick release switch to lower the elevator quickly with the help of gravity and then untether the wire from Earth. I doubt it would ever come to that, but if it was an absolute worse case...
    Last edited by Marksman79; 2012-03-02 at 06:33 PM.

  10. #90
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    Quote Originally Posted by semaphore View Post
    Well, maybe one day we will come up with something better. I don't know of anything even being suggested that can replace currency though.



    Well not really, it's more of a reflection of the fact that space elevators provides too little benefits to justify the resources it would take to construct for the forseeable furture.
    No my point was how so many things that could/would benefit all are blocked/not done due to money concerns whether that be loss of profit or percieved waste for those spending said money. Inshort money really helps support the me first thought process rather than a greater good thought process.

  11. #91
    well the whole cost problem is that if u make something free its not free it passes the cost on to someone else EVENTUALLY somebody is gonna pay for this thing and cool as it is u can't make the bottom chain pay for something the top wants.
    The world was just as bad when you were young as it is today. You only see it now because of your age.

  12. #92
    Quote Originally Posted by Marksman79 View Post
    If the rope itself breaks, it would simply fly off into space due to the outward acceleration. It would not fall down to Earth, again, due to the outward acceleration resulting in its centripetal motion. The only way it could start to wrap around the Earth is if the mass suddenly came to a stop and was no longer moving in a geosynchronous orbit. Much like rolling a rope up on a rod, you need the rope to have a fixed position relative to the rotating pole in order to reel it inward. The only way that could happen is if space debris hit it hard enough to cause it to go out of its geosynchronous orbit, but that is a scenario that will be expected and prepared for (be it by readjusting its orbit or avoiding all debris all together).

    If worse came to absolute worse, I presume they would have a quick release switch to lower the elevator quickly with the help of gravity and then untether the wire from Earth. I doubt it would ever come to that, but if it was an absolute worse case...
    The rope itself, even if built of carbon nano-tubes would likely have to be a huge structure both to manage the amount of goods that would need to travel along it and to withstand the forces, especially at the middle.

    Anything above the break is going to be on an interesting journey through the solar system, anything below the breakpoint is coming down to earth. Given the forces involved, it would actually need to thicken towards the middle. Without the counterweight, anything up top would fall prey to gravity and fall. The area devastated might well be less then a mile wide, but it would stretch likely for thousands of miles (unless the break occurred very near the bottom).

    The cost of such a structure is likely to be so huge it would take a hundred years to pay back the cost.

  13. #93
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    Sounds terrifying lol.

  14. #94
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    Quote Originally Posted by Archangel Tyrael View Post
    How can they make it cheaper?
    by not doing it i suppose

    corporations will not invest in space exploration

    they might invest in a gimicky trip into orbit or something like that, but actual exploration has no profit motive therefore its never going to be a capitalist's investment.

    and before you bring up richard branson he's not investing in exploration he's investing in allowing citizens to do what many astronauts have already done. not anything new.

  15. #95
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    Quote Originally Posted by McSpriest View Post
    by not doing it i suppose

    corporations will not invest in space exploration

    they might invest in a gimicky trip into orbit or something like that, but actual exploration has no profit motive therefore its never going to be a capitalist's investment.

    and before you bring up richard branson he's not investing in exploration he's investing in allowing citizens to do what many astronauts have already done. not anything new.
    We just need to convince someone that there's east Indian Spices and such out there if they'll just head UP instead of EAST. Worked for Columbus, right?
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  16. #96
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    Quote Originally Posted by Marksman79 View Post
    If the rope itself breaks, it would simply fly off into space due to the outward acceleration. It would not fall down to Earth, again, due to the outward acceleration resulting in its centripetal motion. The only way it could start to wrap around the Earth is if the mass suddenly came to a stop and was no longer moving in a geosynchronous orbit. Much like rolling a rope up on a rod, you need the rope to have a fixed position relative to the rotating pole in order to reel it inward. The only way that could happen is if space debris hit it hard enough to cause it to go out of its geosynchronous orbit, but that is a scenario that will be expected and prepared for (be it by readjusting its orbit or avoiding all debris all together).

    If worse came to absolute worse, I presume they would have a quick release switch to lower the elevator quickly with the help of gravity and then untether the wire from Earth. I doubt it would ever come to that, but if it was an absolute worse case...
    I'm sorry to call you out as you are not the only one, but stop saying centripetal. its centrifugal not centripetal. centripetal as a natural force does not exist with the exception of a counter force holding an object along a circular path.
    an object orbiting earth has a centrifugal velocity and is constantly falling.
    YES i know it sounds strange but satellites are constantly "falling" to earth. what keeps them aloft is the centrifugal velocity alowing them to travel forward faster than they fall.

    physics explanation time:

    <-o <this is a satellite circling in counterclockwise
    O <this is earth
    the small o is a satellite as it circles earth it falls towards it. its CENTRIFUGAL velocity is shown as an arrow. but while moving forward the earth's curve, curves away from it. to maintain altitude it must move fast enough to have the earth curve away from it faster than it can fall.

    still don't get it, please look in a physics textbook for a better explanation

    sorry for the rant, but its a pet peeve of mine, and i find it hard to trust the validity of someone's "scientific" statement when they demonstrate a lack of basic understanding of physics


    TLDR: its not centripetal, its centrifugal
    Last edited by McSpriest; 2012-03-02 at 05:22 PM. Reason: fixed my crude drawing

  17. #97
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    Usually I hate to quote myself, but in this case I'll make an exception, since there are many more promising concepts (at least as promising as a space elevator) on Wikipedia alone when researching the following category:
    http://en.wikipedia.org/wiki/Non-rocket_spacelaunch

    The one I found to be the most intriguing is the Launch Loop, which basically simply serves to allow for an orbital launch at relatively low altitude (~8 km) with an acceleration that would also be suitable for manned spacecraft (3g).

    Quote Originally Posted by Krostas View Post
    As for the promised alternatives (yeah, even more alternative than a space lift):
    http://en.wikipedia.org/wiki/Space_fountain
    http://en.wikipedia.org/wiki/StarTram

  18. #98
    Stood in the Fire McSpriest's Avatar
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    Quote Originally Posted by Krostas View Post
    Usually I hate to quote myself, but in this case I'll make an exception, since there are many more promising concepts (at least as promising as a space elevator) on Wikipedia alone when researching the following category:
    http://en.wikipedia.org/wiki/Non-rocket_spacelaunch

    The one I found to be the most intriguing is the Launch Loop, which basically simply serves to allow for an orbital launch at relatively low altitude (~8 km) with an acceleration that would also be suitable for manned spacecraft (3g).

    seems like it would take a bit to get up to 17,500 Mph

    Edit: just in case anyone was wondering why 17,500 that is the approximate orbital velocity of earth. meaning in order for any object to orbit earth it must travel at 17,500 Mph. to leave earth's orbit it must break 17,500 Mph. this speed can be reduced through efforts of the Bernoulli principle (like in an airplane which utilizes a unique wing shape to create lower pressure above the wing than below it thus creating lift)
    Last edited by McSpriest; 2012-03-02 at 05:52 PM.

  19. #99
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    Well, with a proposed length of 2000 km and a constant acceleration of 3g, it should take only 639 seconds (= 10 minutes 39 seconds) to reach a top speed of about 18800 m/s, which is roughly 67653 km/h or 42000 mph. I'm guessing that such a high speed is neither required nor being aimed at, since at 8 km altitude factors as atmospheric friction cannot be disregarded that easily and acceleration should be slowed down somewhat upon reaching supersonic speed.

    This would of course lead to a considerably higher launch time and an even more so lower launch speed - even though it should be sufficient to reach the speed required to enter orbit around earth. Some measures for gaining additional altitude are planned to reach LEO or even GEO. This could function similar to current rocket propulsion technology, but would require vertical velocities of an hundredth or a tenth of those a conventional rocket requires.

  20. #100
    The Unstoppable Force DeltrusDisc's Avatar
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    Have they considered a meteor or the like flying into the elevator pathway thinger? =S
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    yeh but lava is just very hot water

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