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Aerospace Space elevator ? How can it work?

  1. Nov 9, 2009 #1
    I have been reading about the so called "SPACE ELEVATOR" in various articles in the news
    papers and magazines and reading that in a contest recently a company won a $900,000.
    prize as their creation climbed a mile long cable suspended from a helicopter in under 4 min.
    I understand that this "Space Elevator" if it works is supposed to transport materials into
    space (The Space Station ?) The full size unit would be a cheaper way to send food,water and
    equipment into space ........but will someone explain how it would work ? IF the space Station
    were attached to the end of the cable and it is going at 17,000 miles an hour in Earth orbit, how can the Space Elevator be hooked up and have any chance of working ?

    Please forgive me if this subject has been talked about before this. I searched for SPACE
    ELEVATOR and only got " ? lifter".
     
  2. jcsd
  3. Nov 9, 2009 #2

    minger

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  4. Nov 9, 2009 #3

    Mech_Engineer

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    The point is that the winning design climbed the cable using power transmitted to it by a laser on the ground. Climbing the cable of a space elevator is fairly straightforward, but getting power to it can be difficult, and one possibility is a ground-based laser station which beams power to the elevator as it climbs the cable. This proof-of-concept showed it might be in the realm of possibility.

    As it is we don't have a way of creating a cable strong enough to act as a space elevator, and overall the elevator power system is a small one of many problems that need to be addressed before it becomes a possibilty.
     
  5. Nov 9, 2009 #4
    I would think maintenance/replenishment of the strand would be key.
     
  6. Nov 9, 2009 #5
    It wouldn't be hooked up to the station. It would be a geostationary platform from which the cargo were to be distributed.
     
  7. Nov 12, 2009 #6
    OK. Thanks for all the answers. I was thinking they were trying to get the thing from
    a parking lot up into something already in space.
     
  8. Nov 12, 2009 #7

    DaveC426913

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    No, they drop the cable from the orbiting satellite to the ground. It's stationary because the satellite is in geostationary orbit.

    Now that you've got the cable in place, you have to start getting payloads up it. That's where there's a lot of research. A payload that needs to climb 35,000km is going to be mostly motor. So they're looking at ways of keeping the motor on the ground. thus, lasers.
     
  9. Dec 19, 2009 #8
    It couldn't, as once the paylods arrived at the proper altitude, they'd be woefully shy of the ISS' orbital velocity.

    While that's fine for a 1 mile cable, the question is how well will this method work at 180 nmi distant?

    The motor? Or the power supply?

    With solar power and a worm drive, you could easily take your time, perhaps a couple of days, working your way up the cable.

    My concern involves the wear and tear on the cable!
     
  10. Dec 19, 2009 #9

    FredGarvin

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    How about the fact that the cable is still only available in La La Land? That seems like a pretty big concern to me.
     
  11. Dec 19, 2009 #10

    DaveC426913

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    As Arthur C. Clarke said: the space elevator will be built ten years after everyone stops laughing.

    A lot of people aren't laughing.
     
  12. Dec 20, 2009 #11
    Academic scientists and engineers don't care about such practical matters. They need to hype up their pet projects so they can get tenure and government funding.
     
    Last edited: Dec 20, 2009
  13. Dec 20, 2009 #12
    Do you have a source for this statement?
     
  14. Dec 20, 2009 #13

    FredGarvin

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    I have seen some pretty ridiculous things funded in my short time, so I can appreciate that aspect.

    Trust me Dave, the people who aren't laughing are the bean counters and the wackos that will have NOTHING to do with being responsible for trying to build this monstrosity. I have yet to see one credible source talk about its feasibility. It's a nice idea though.
     
  15. Dec 20, 2009 #14
    Arthur C Clark's The Fountains of Paradise gives a good description of how a space elevator might work.
     
  16. Dec 20, 2009 #15

    DaveC426913

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    No, what I'm trying to tell you is that there are whole communities of scientists and engineers that have banded together to solve these problems. I suppose if I directed you to these that would be pretty much the last word on the subject...
     
  17. Dec 20, 2009 #16

    FredGarvin

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    Yeah. Please do. When I see a credible engineering source, I'll believe it.
     
  18. Dec 20, 2009 #17
    I remember watching a seminar by a Ph.D physicist who claimed that we should put solar panels on the Moon and beam the energy back to Earth using microwaves. He didn't spend one second talking about practical economic or engineering realities. Projects like the space elevator and fusion power are being promoted by these kinds of people. They could care less if their pet projects ever materialize, as long as they can publish lots of papers and scam some money out of DARPA.
     
  19. Dec 20, 2009 #18
    That's certainly a major issue, Fred!

    I would offer that no systems are developed once all the technology is in place. From the SR-71 to Apollo to the Space Shuttle, Pegasus... Much of the technology was developed along with the system. Most of the time that involved refinement of existing technology until it worked as designed and met specs.

    Not always, however, particularly with R&D efforts. Often, there's no specific project in mind, but someone gets an idea, and runs with it so long as funding holds out. They often shelve whatever they have at that point, but occasionally a need will surface, either inside or outside the firm, and the technology is used/rented/sold.

    Carbon nanotubes are real. They do exist. However, we have not yet developed any appreciable means of making them into high-tension cabling. We're not even certain that nanotubes are the best solution. Time will tell.
     
  20. Dec 20, 2009 #19

    DaveC426913

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    That does not detract from respectable organizations working on it.

    There are crackpots working on space flight too. Does it then follow that "space flight" is crackpottery?
     
  21. Dec 20, 2009 #20

    DaveC426913

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    On the other hand, looking around, I'm not finding as much as I thought I would.

    ISEC seems to be the biggest organization, and it's just a half-dozen guys. Maybe interest has died away in the intervening years.

    This makes me sad.
     
  22. Dec 20, 2009 #21

    russ_watters

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    The steps from one to the other there are not that big and the SR-71 used a surprising number of off-the-shelf components. It was innovative, but a space elevator would require a quantum leap in materials technology. It is akin to suggesting the Wright Brothers should have tackled supersonic flight for the Flyer II.
    I know it sucks to have your bubble burst, but Fred really is talking about reality here. The idea of a space elevator is just science fiction. Even when people "research" the idea or do these little demos with cables hanging out of helicopters, serious scientists and engineers know that they are just publicity stunts. There isn't anything coming anywhere near to approaching reality in these ideas.

    I'd be surprised if we get a space elevator in my lifetime (I'm 34) and if we get one in the next 20 years, I'll eat my telescope.
     
    Last edited: Dec 20, 2009
  23. Dec 20, 2009 #22

    DaveC426913

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    On the contrary, it would require a large leap in materials technology...:tongue2:




    Sorry Russ. I hadda. :smile: Someone on TV used this the other day but my yelling at the screen didn't cause them to retract it.


    Perhaps there's some confusion about timelines here. I wasn't suggesting it would happen in the next 20 years. Not even the next 40.

    I suppose, upon reflection, an engineering feat that is 40 years in the future is hardly distinguishable from science-fiction.
     
    Last edited: Dec 20, 2009
  24. Dec 20, 2009 #23

    russ_watters

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    You yelled at your TV over a bit of slang? Ok... :confused:

    How 'bout this: we're light years away from having the this type of technology. :tongue:
    Indeed, if a piece of technology lies 40 years in the future, is science fiction because you can't schedule scientific advances. The horizon of technology just isn't that far. Consider how long people have been saying that fusion is right around the corner! (at least fusion is forgivable since it could so profoundly change society - it would be a real game changer)

    So if you see that this is that far over the horizon, I don't get how these little publicity stunts seem worthwhile to you. No money should be spent on the issue right now. Carbon nanotubes are going to advance whether the space elevator is on the table or not. In 20 years, maybe they'll have come far enough to start considering the question.
     
  25. Dec 21, 2009 #24
    Well, there I was in 1969, watching Star Trek, Superman, action-adventure movies, dreaming of rockets, airplanes, new materials, and putting them all together in a science presentation called "Moonopolis."

    Original, huh?

    I'm still doing much the same.
     
  26. Dec 21, 2009 #25

    FredGarvin

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    Be specific. Apollo and the SR had much of the ideas in place. Yes, things had to be figured out, but, in the case of the SR, there was no new materials being dreamed up. They pioneered manufacturing of titanium, but it was already in existence. There was nothing on the SR that required the leap in technology that the elevator would require. Apollo was built off of a lot of small, incremental improvements from the Mercury program.

    Trust me, ESPECIALLY with R&D efforts (I work in R&D), to get funding there has to be more than an idea. One has to have a clear road map for what they are looking at and supporting theory. This is not R&D. This is fantasy that some people are tying wishes to. Not that I have been scouring data, but I can not recall anyone posting something to do with the elevator that is technologically feasible right now or in the next 20 years.

    There is absolutely NO experience in using nanotubes. We have some small scale materials testing with limited details. We have no way of manufacturing in sight and we have no methods of forming things from those materials. We had a thread while back in which we calculated the required amount of time to manufacture a small cable for an LEO elevator. It was not a nice number. That is a very far cry from what level of knowledge is required to actually implement it in a design. The materials area alone will require huge money and time investments. It will most likely happen, not in ours or my kids' lifetimes though.
     
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