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posted by martyb on Monday September 22 2014, @03:43PM   Printer-friendly
from the reach-for-the-sky-and-beyond dept.

Once the realm of science fiction, a Japanese company has announced they will have a space elevator up and running by the year 2050.

If successful it would revolutionise space travel and potentially transform the global economy.

The Japanese construction giant Obayashi says they will build a space elevator that will reach 96,000 kilometres [~60,000 miles] into space.

The company said the fantasy can now become a reality because of the development of carbon nanotechnology.

"The tensile strength is almost a hundred times stronger than steel cable so it's possible," Mr Yoji Ishikawa, a research and development manager at Obayashi, said.

"Right now we can't make the cable long enough. We can only make 3-centimetre-long nanotubes but we need much more... we think by 2030 we'll be able to do it."

Universities all over Japan have been working on the problems and every year they hold competitions to share and learn from each other.

What say you Soylents? After years of speculation, are we finally at a point where this has become an engineering problem of implementation? Is this just wide-eyed public-relations posturing? Given the gravity well of the earth is much greater than that of the moon or Mars, might they be a better starting point for implementation? What do you see as the greatest challenges blocking the construction of a space elevator?

Other non-rocket spacelaunch systems have been proposed: Launch Loop, Lightcraft, Space gun, and Strar Tram among others. Do one of these hold a brighter promise for getting things into orbit or even off this planet?

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  • (Score: 5, Funny) by hoochiecoochieman on Monday September 22 2014, @03:47PM

    by hoochiecoochieman (4158) on Monday September 22 2014, @03:47PM (#96798)

    I like my sushi rice cooked on... vapourware.

  • (Score: 4, Funny) by Alfred on Monday September 22 2014, @03:50PM

    by Alfred (4006) on Monday September 22 2014, @03:50PM (#96802) Journal

    By 2050 I will have gotten laid.

    I hope.

    • (Score: 2, Funny) by Anonymous Coward on Monday September 22 2014, @03:59PM

      by Anonymous Coward on Monday September 22 2014, @03:59PM (#96807)

      By 2050 I'd likely be laid.

      6 feet under.

    • (Score: 3, Funny) by davester666 on Monday September 22 2014, @05:51PM

      by davester666 (155) on Monday September 22 2014, @05:51PM (#96859)

      just what the world needs more of...optimists.

    • (Score: 2) by choose another one on Monday September 22 2014, @06:12PM

      by choose another one (515) Subscriber Badge on Monday September 22 2014, @06:12PM (#96872)

      This is /., nobody hear gets lai... oh wait...

      • (Score: 2) by nitehawk214 on Monday September 22 2014, @08:29PM

        by nitehawk214 (1304) on Monday September 22 2014, @08:29PM (#96915)

        The new meme for SN is: Everyone Gets Laid [hark.com].

        --
        "Don't you ever miss the days when you used to be nostalgic?" -Loiosh
        • (Score: 2) by Alfred on Monday September 22 2014, @09:31PM

          by Alfred (4006) on Monday September 22 2014, @09:31PM (#96936) Journal

          Soylent news ... is people! ... getting laid!

          So do I take a number or something?

  • (Score: 5, Insightful) by MrGuy on Monday September 22 2014, @03:56PM

    by MrGuy (1007) on Monday September 22 2014, @03:56PM (#96804)

    Sure, the idea of a Space Elevator has been the stuff of science fiction since it was originally thought up. But the main challenges are really all engineering ones, and the major ones (tensile strength, powering the climbers without wires) are ones that seem like we're sufficiently close to acceptable answers that this seems totally doable. The concept isn't terribly complicated.

    Yes, a space elevator requires a lot of "technology that hasn't been invented yet." But probably on the same order of magnitude as the first manned mission to the moon.

    Proposing that we could have a working implementation in 36 years doesn't seem outrageously ambitious, as long as someone (in this case, the Japanese government) is willing to invest significant resources in the effort.

    • (Score: 5, Informative) by MrGuy on Monday September 22 2014, @03:59PM

      by MrGuy (1007) on Monday September 22 2014, @03:59PM (#96806)

      Sorry for the self-followup. Clicked "Submit" prematurely.

      The American LiftPort group [liftport.com] has a similar mission and a considerably more ambitious goal (working space elevator by 2019). If you're interested in space elevators, their website is well worth a read - good info on the engineering challenges facing a space elevator project and what's still needed.

      Personally, I'm rooting for LiftPort, since if they get there first, heaven will permanently become part of America.

      • (Score: 3, Insightful) by darkfeline on Monday September 22 2014, @05:47PM

        by darkfeline (1030) on Monday September 22 2014, @05:47PM (#96856) Homepage

        >Personally, I'm rooting for LiftPort, since if they get there first, heaven will permanently become part of America.

        Really? I'd much rather Japan get there first, since Japan makes everything into cute little cartoon girls. On the other hand, let America have a go at it, and be prepared to spend eternity in heaven with your loving Big Brother.

        --
        Join the SDF Public Access UNIX System today!
      • (Score: 3, Informative) by mojo chan on Tuesday September 23 2014, @11:39AM

        by mojo chan (266) on Tuesday September 23 2014, @11:39AM (#97114)

        This is generally how Japan gets major new engineering projects done. They set a goal, figure out what is needed, and throw money at it with the expectation of profit in the long term. It's the same with the new linear motor shinkansen (maglev bullet train). As well as being insanely fast (550kph at first, rising to over 900kph by 2050) the track is making extensive use of tunnels to avoid gradients and go directly through the mountains. It's incredibly expensive and has required the development of many new technologies, but Japan Rail is happy to look at it as a long term investment that will not only pay off by transporting people but will keep them competitive with air travel and be sold around the world to other countries.

        Japan knows how to build big, expensive stuff.

        --
        const int one = 65536; (Silvermoon, Texture.cs)
    • (Score: 5, Interesting) by subs on Monday September 22 2014, @04:20PM

      by subs (4485) on Monday September 22 2014, @04:20PM (#96820)

      Yes, a space elevator requires a lot of "technology that hasn't been invented yet." But probably on the same order of magnitude as the first manned mission to the moon.

      Not even close. The engineering basis for pretty much the entirety of the lunar landing has been known for almost half a century before the actual mission took place (and the theory was resolved much earlier than that), it was all a question of tradeoffs and details. Certainly by the late 1930s (30 years ahead), the British Interplanetary Society (BIS) had designs for a solid-fuel rocket that could execute such a mission, even though it was crude by comparison to the actual thing - that's what the space race in the 40s & 50s did - fill in the details on how to do it practically.
      This space-elevator thing is much more in line with BIS's later Project Daedalus interstellar fusion-powered space probe proposal. In theory the rough physics is known, but in practice, even 40 years on we're still a very long way away from any engineering proposals even remotely approaching practicality. The space elevator has tons of problems with it, the cable tensile strength being just the tip of the iceberg.

      • (Score: 4, Insightful) by frojack on Monday September 22 2014, @05:09PM

        by frojack (1554) on Monday September 22 2014, @05:09PM (#96838) Journal

        Agreed, the whole concept assumes it into existence then marvels how cool it would be.

        At the time of Kennedy's buying into going to the moon the plan was already fleshed out in fairly good detail, satellites and ICBMs had already been launched, and vehicles has even reached the moon.

        Now we are told its possible to make 3 cm of the cable.
        Nobody has any believable plan on how to get a space elevator installed or keep in from falling until fully assembled.
        Everywhere you read about them they gush about how this will be so much easier to put an elevator on the moon or mars.

        The plan isn't even half baked. We don't have the ingredients let alone the cooking utensils. All we have is a vision of pie in the sky.

        --
        No, you are mistaken. I've always had this sig.
        • (Score: 0) by Anonymous Coward on Monday September 22 2014, @05:44PM

          by Anonymous Coward on Monday September 22 2014, @05:44PM (#96853)

          Wake me up when they can make a 6000 meter tall version (only 2000x bigger). At that point they will be somewhat closer. At that point we are talking maybe getting to the stratosphere. We can then maybe start talking about how to get to space with it.

          http://en.wikipedia.org/wiki/File:1000px-Atmosphere_layers-en.PNG [wikipedia.org]

          This is still in the lab/trying to figure it out stage. Not the 'well we mostly have a stab at it and need to work out a few details' stage.

          36 years out is not even worth talking about. Dream about maybe but thats it.

          hey gush about how this will be so much easier to put an elevator on the moon or mars
          That pesky air we use to breath :)

          And how they plan to make the thing not act like a giant piece of spaghetti flapping in the wind should be interesting. Also to be practical you would also want more than one train. So you would have to figure out power for the train as well as weight distribution to not put giant waves into the elevator itself causing it to break up. Also the moons affect could come into play as well with that much material being used to create the thing.

          You also need to achieve escape velocity to make it interesting also. Which is cheaper energy wise further away from the earth. Meaning a taller tower...

          It is an interesting problem. But not a practical one at this point.

          • (Score: 3, Insightful) by bob_super on Monday September 22 2014, @06:03PM

            by bob_super (1357) on Monday September 22 2014, @06:03PM (#96866)

            > 6000 meter tall version (only 2000x bigger)

            You accidentally a couple zeroes, it currently is 3 cm.

            I personally want to know the stats on yearly particule collision probability if you have a 40000km cable (+/- 50%) 2cm wide (+/- 50%) sticking out past LEO layers known to harbor a decent amount of debris. One speck of paint from an old Soyuz, and your insurance company has to buy you a new fancy cable...

            • (Score: 0) by Anonymous Coward on Monday September 22 2014, @08:46PM

              by Anonymous Coward on Monday September 22 2014, @08:46PM (#96921)

              You accidentally a couple zeroes
              The best time to find mistakes is after submit :)

          • (Score: 2) by kaszz on Monday September 22 2014, @06:47PM

            by kaszz (4211) on Monday September 22 2014, @06:47PM (#96890) Journal

            "And how they plan to make the thing not act like a giant piece of spaghetti flapping in the wind should be interesting."

            Try putting a weight at one end of a rope and then swing it. You should be able to notice how the stabilization works.
            (hint centrifugal force)

            But nanotubes with sufficient length at a workable price is still not a reality and there's no predictable timetable.

            • (Score: 1, Interesting) by Anonymous Coward on Monday September 22 2014, @09:01PM

              by Anonymous Coward on Monday September 22 2014, @09:01PM (#96929)

              Perturbations in solids propagate at the speed of sound. At the macro scale it may be centrifugally stabilized, but that doesn't mean that it's going to be pulled perfectly taut all the way through. Local variations in tension could give it a substantial range of motion.

              (Not an engineer or physicist)

          • (Score: 0) by Anonymous Coward on Tuesday September 23 2014, @06:39PM

            by Anonymous Coward on Tuesday September 23 2014, @06:39PM (#97296)

            >Wake me up when they can make a 6000 meter tall version

            You're thinking upside down - space elevators almost certainly won't climb from the surface up, that would require enormous compressive strength and stabilization far beyond current technology. Most space elevator proposals have them begin in geostationary orbit (~36,000km) and then build simultaneously both towards and away from Earth to maintain orbital stability and keep the entire structure in tension until eventually the lower end reaches the planet's surface. As such a 6000m, or even a 6000km version would be far less useful*. As for length - I suspect that by the time we can make nanotubes a few meters long we'll be using a far more controlled technology than currently employed, and the extension to a few hundred thousand meters will simply be an engineering exercise. Besides which we don't necessarily need the individual nanotubes to be anywhere near that long - and in fact exposure to cosmic rays, solar wind, micrometeorites, etc. almost guarantees they wouldn't remain in one piece anyway. Fortunately nanotubes can also be formed into yarns that, while not quite as strong as continuous nanotubes, are far stronger than anything else we've created, and more fault-tolerant than a continuous-nanotube cable. And just as with more traditional yarns, as the length of the individual fibers increases we can reasonably expect the strength of the yarn to asymptotically approach that of the individual fibers.

            Besides which getting up into space is the easy part, it's only 100km away after all. The hard part is getting going fast enough to get into orbit instead of falling straight down again. For low earth orbit the energy breakdown is roughly 5% for altitude and 95% for speed. So a tower that reaches outside the atmosphere would, on it's own, be almost useless. You could launch rockets from it to save the trouble and waste of getting through the atmosphere, but your incredible feat of engineering would only save you a few percent on fuel costs.

            A more intelligent version would be to take your cable and put it in orbit, which brings us back to that * in the first paragraph:

            *a 6000km a space elevator would presumably have its midpoint orbiting at about 3000km altitude with the lower end stopping just outside the atmosphere which would imply an orbital period of about 2.5 hours, with the lower end moving at ~4500m/s. Considerably slower than the 7850m/s of an object orbiting at that altitude, enough to cut speed energy requirements to under 1/3 if you could manage to dock with it somehow - then the remainder of the energy could be potentially recovered as you can recover the energy descending the elevator that you expend climbing it.

            A potentially even smarter approach with no moving parts (and hence roughly 100% efficiency) is the so called "tumbling cable" elevator where you set the cable spinning so that the lower end matches speed with the Earth's surface (think of the cable as running through the hub of a giant imaginary wheel rolling around the Earth's surface.) Then all you have to do is get up to altitude, and catch the end of the cable, no extra speed required. You can then ride it to the high point where you are travelling at a ridiculously excessive speed and can let go to be at the lowest point of of a highly elliptical orbit. So long as you can manage to catch that insanely fast-moving upper cable end on the way down to transfer back the momentum you borrowed from it, it will stay in orbit indefinitely.

            In fact tumbling cables have the somewhat ironic property that they are more powerful the smaller you make them: A shorter cable allows a lower (and thus faster) orbit, and maximum release speed is roughly twice the orbital speed. The down side is that the smaller it is the faster it has to spin for the ends to to match speed with the surface, which means a lot more acceleration while you're riding it. Thanks to the lower gravity and lack of atmosphere on the Moon a tumbling cable solution is particularly viable there - with adjustable-length ends on the cable you could basically grab stuff right from the surface and, by coordinating with the Moon's own 1000m/s orbital velocity, hurl it on transfer orbits to either Mars or Venus.

            Of course all of these solutions have two major problems:
            1) You need to put an insane amount of material in orbit, to the point where you need to already have a high-efficiency launch system on Earth, or capture a decent sized carbonaceous asteroid into near Earth orbit for raw materials. (on the plus side, if you've already got an asteroid in orbit you can use it as a counterweight, reducing the necessary cable length by half or more)
            2) You render all other Earth orbits highly problematic - those in the same plane as the elevator will need to be swept almost completely clean as the elevator is moving at a radically different non-orbital speed at all altitudes except for it's center of mass, and almost everything orbiting in other planes will still have to have their orbits modified periodically to avoid colliding with the giant structure.

            Which sadly makes the potentially most-awesome long-term option extremely problematic: You could build a traditional "beanstalk" space elevator from the nearest point on the moon, through the Earth-Moon L1 point, until it's close enough to the Earth that the tip is moving at the same speed as our surface, so all you need to do is launch straight up from Earth and catch the tip, then ride an elevator either all the way to the moon, or to an L1 orbital station where everything is in free-fall. Then from the Moon you could catch the tumbling cable to Mars or Venus, assuming you could somehow manage to avoid tangling the tumbling cable and beanstalk as they pass each other. Meanwhile Earth's near orbits would be left clear for satellites of various stripes. Best of all, Lunar elevators would only be subjected to forces well within the tolerances of existing carbon-fiber cable, no new material science needed.

            --Immerman

    • (Score: 3, Insightful) by choose another one on Monday September 22 2014, @06:16PM

      by choose another one (515) Subscriber Badge on Monday September 22 2014, @06:16PM (#96874)

      s/Space Elevator/Fusion Power/ and go back 36 years.

      Space elevator is probably about 36 years after successful fusion power, which is 20 years away (always 20 years away...)

      • (Score: 1, Insightful) by Anonymous Coward on Tuesday September 23 2014, @01:45AM

        by Anonymous Coward on Tuesday September 23 2014, @01:45AM (#96993)

        Nobody wants to seriously invest in nuclear fusion properly, which is why it's always twenty years away. To develop workable fusion power costs a lot of money, but why spend on something like that when there are countries full of brown people to bomb?

      • (Score: 2) by mojo chan on Tuesday September 23 2014, @12:13PM

        by mojo chan (266) on Tuesday September 23 2014, @12:13PM (#97119)

        Fusion requires the development of new technologies that are only really of use to fusion, so there is a lack of funding and interest. A space elevator will be build on developments of existing technologies that have many other uses and are attracting interest. I imagine that Obayashi sees this project as a way to get ahead of the competition in developing and using these materials in terrestrial construction.

        --
        const int one = 65536; (Silvermoon, Texture.cs)
    • (Score: 2) by jdccdevel on Monday September 22 2014, @09:37PM

      by jdccdevel (1329) on Monday September 22 2014, @09:37PM (#96939) Journal

      Maybe I'm feeling cynical today, but I'd tend to disagree.

      With any new major advancement like this, the main barriers to getting it done seem always follow the same progression:

      1) Scientific (i.e. theoretical, can this be done?)
      2) Technical (i.e. it can be done, we just need to figure out how?)
      3) Bureaucratic (i.e. We can do it, do "we" have the will to?)

      People tend to overlook bureaucracy, or dismiss it entirely. In my experience, the Scientific and Technical challenges can pale in comparison to the bureaucratic ones.

      Any time the bureaucratic challenges go away, the technical challenges seem to follow soon after. (i.e. The Moon Landing.)

      In the case of a space elevator, you're talking a cable that is long enough to wrap around the world. Talk about a nightmare of red tape! Even though this company may be able to overcome the technical obstacles before 2050, I still don't see it getting built.

      Sorry for my cynicism today, maybe I need some caffeine.

  • (Score: 2) by Runaway1956 on Monday September 22 2014, @04:01PM

    by Runaway1956 (2926) Subscriber Badge on Monday September 22 2014, @04:01PM (#96808) Journal

    I really do love the idea of putting it up. But, this is something that you better get right the FIRST TIME! The engineers had best have the tech figured out to more than a couple decimal points. There had BEST be no foot to yards to meters mix ups. None of that "Wish we had known this six months ago" bullshit. The article makes no mention of the anchor point. Nanotubes, huh? Back when scientists and Sci-Fi authors started exploring the idea, there weren't any nanotubes.

    • (Score: 2) by c0lo on Tuesday September 23 2014, @02:54AM

      by c0lo (156) Subscriber Badge on Tuesday September 23 2014, @02:54AM (#97014) Journal

      Nanotubes, huh? Back when scientists and Sci-Fi authors started exploring the idea, there weren't any nanotubes.

      No, but they caught up quick enough [wikipedia.org] - including some technical problems: cable oscillations stabilization, conservation of momentum as the carriages go up, the anchor point, time of travelling...

      --
      https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
  • (Score: 0) by Anonymous Coward on Monday September 22 2014, @04:13PM

    by Anonymous Coward on Monday September 22 2014, @04:13PM (#96815)

    Blah blah by 2030/2050, they are all sci-fi.

  • (Score: 3, Insightful) by cmn32480 on Monday September 22 2014, @04:18PM

    by cmn32480 (443) <reversethis-{moc.liamg} {ta} {08423nmc}> on Monday September 22 2014, @04:18PM (#96818) Journal

    According to this article, http://www.businessinsider.com/the-8-fastest-elevators-in-the-world-2013-1?op=1 [businessinsider.com], the fastest elevator in the world went 37.7mph at the time of writing.

    60,000 / 37.7 = 1,591.511 hours.
    1591.511 = 66.312 days

    Actually, that isn't nearly as bad as I thought, but that is a lot of food and water crammed into that box!

    Perhaps I missed it in the article, did they give an actual speed they expect this thing to go?

    --
    "It's a dog eat dog world, and I'm wearing Milkbone underwear" - Norm Peterson
    • (Score: 2, Informative) by MorbidBBQ on Monday September 22 2014, @04:29PM

      by MorbidBBQ (3210) on Monday September 22 2014, @04:29PM (#96826)
      200kph
      http://www.wired.co.uk/news/archive/2012-02/22/space-elevator-2050 [wired.co.uk]
      Or, the speed of a raptor running on top of a flatbed truck on the highway.
      http://xkcd.com/526/ [xkcd.com]
      • (Score: 1) by soylentsandor on Monday September 22 2014, @08:59PM

        by soylentsandor (309) on Monday September 22 2014, @08:59PM (#96927)

        That would only be marginally less awkward:

        36000 / 200 = 180 hours
        180 / 24 = 7,5 days

    • (Score: 4, Informative) by SlimmPickens on Monday September 22 2014, @04:30PM

      by SlimmPickens (1056) on Monday September 22 2014, @04:30PM (#96827)

      I think people will still go up the old fashioned way, it's for fuel and cargo.

    • (Score: 4, Informative) by VLM on Monday September 22 2014, @05:19PM

      by VLM (445) Subscriber Badge on Monday September 22 2014, @05:19PM (#96844)

      Its essentially a monorail pointing up, so how fast would you like to go? You've got something to supply power from the ground and to push against, eventually a non-contact maglev would be possible, and with no atmosphere beyond the first 1% or so of the climb...

      This is a big problem WRT stability, if you're climbing at 20 fps, a modest disruption in the cable barely wiggles you, but at 2000 fps that same wiggle might exceed survivability. And with no atmosphere the only way for "wiggle" to dissipate, unless someone sets up an active stabilizer system, is internal friction turning to heat.

      Of course you could play games by tossing smart pigs up before the crewed car goes up. You can build 50 G force missiles, and a herd of them actively stabilizing the cable before the humans fling past might help with stability. So stabilizer car 1 experiences 50 G force sideways due to a wiggle and fires its maneuvering engines to stabilize out the wiggle, bringing it down to 45 G. Then stabilizer car 2 experiences 45 G force sideways due to the partially dampened wiggle, so it fires it maneuvering engines to dampen oscillations down to 40 G... repeat. Another strategy other the brute force is to launch stabilizer cars up the think constantly plus or minus real cargo. Assuming the cable can handle the load of course.

      There may be scheduling implications where heaving up bulk cargo carriers with 20G side load ratings might require a couple days (weeks?) of stabilizing before humans can survive.

      And there's various interesting "crack the whip" phenomena to think about where a perfectly static loaded cable might be safe but under wiggle tension with just the wrong load that might snap it because the total load due to weight and wiggle might exceed the tensile limit.

      Launch loops are a lot simpler because centripetal force tends to dampen them into circles (plus or minus standing wave nodes) and the launch is really simple, just clamp a variable magnetic brake on and when there's no braking force its because you're in orbit. They're not so simple when a loop snaps, of course. That could be quite a mess indeed.

    • (Score: 2) by Snotnose on Monday September 22 2014, @06:42PM

      by Snotnose (1623) on Monday September 22 2014, @06:42PM (#96886)

      "It's a dog eat dog world, and I'm wearing Milkbone underwear" - Norm Peterson

      This quote precedes Cheers by at least a couple decades. We used to say that in Jr High back in the 70s.

      Are you a turtle?

      --
      Why shouldn't we judge a book by it's cover? It's got the author, title, and a summary of what the book's about.
      • (Score: 2) by cmn32480 on Monday September 22 2014, @08:38PM

        by cmn32480 (443) <reversethis-{moc.liamg} {ta} {08423nmc}> on Monday September 22 2014, @08:38PM (#96919) Journal

        What, exactly, are these 70s you speak of?

        For certain they happened before I was born.

        Now, if you will excuse me, I'll get off your lawn. :-)

        --
        "It's a dog eat dog world, and I'm wearing Milkbone underwear" - Norm Peterson
    • (Score: 0) by Anonymous Coward on Tuesday September 23 2014, @08:01AM

      by Anonymous Coward on Tuesday September 23 2014, @08:01AM (#97069)

      You probably don't want to go all the way to the end. The thing will need to be a balanced configuration around geostationary orbit (to keep the bottom end from dragging over the ground). That's "only" 36000 km or 22000 miles.

      And that's assuming you want to go to a geostationary satellite, the ISS is much lower than that - but at a completely different speed, so using a space elevator to get there may not actually be an advantage.

  • (Score: 3, Informative) by VLM on Monday September 22 2014, @04:54PM

    by VLM (445) Subscriber Badge on Monday September 22 2014, @04:54PM (#96834)

    I think there's some careful editing for maximum humor

    "Japanese construction giant" Godzilla

    "the fantasy can now become a reality" It is, after all, a giant tentacle. And we're surprised the Japanese will be first to deploy it. Yeah.

    "We can only make 3-centimetre-long" The jokes keep rollin

    "Universities all over Japan have been working on the problems and every year they hold competitions to share and learn from each other." Yes tentacle pr0n. I've seen it on the internets.

    "Launch Loop" Slightly more seriously one of my infinite spare time ideas is trying to make really big launch loop. Like 100s of feet. In my infinite spare time (aka it aint happening any time soon) Dynamic stability and stability during bootup / shutdown are non-trivial, which is why I like the idea and occasionally sketch out ideas. This is definitely an "empty rural land" kind of hobby. Other than being a complete waste of time (aka, a hobby), I'm thinking it would make an interesting RC sailplane launcher.

    • (Score: 2) by Fnord666 on Tuesday September 23 2014, @05:07AM

      by Fnord666 (652) on Tuesday September 23 2014, @05:07AM (#97036) Homepage

      Other than being a complete waste of time (aka, a hobby), I'm thinking it would make an interesting RC sailplane launcher.

      It's just a scaled up discus launch, right?

      • (Score: 2) by VLM on Tuesday September 23 2014, @11:16AM

        by VLM (445) Subscriber Badge on Tuesday September 23 2014, @11:16AM (#97101)

        A rope discus. Or a lasso, I guess.

  • (Score: 2) by BradTheGeek on Monday September 22 2014, @05:43PM

    by BradTheGeek (450) on Monday September 22 2014, @05:43PM (#96851)

    What about escape velocity? It is my (admittedly limited) understanding that you can climb as high as you like, but if you're moving at less than escape velocity, you will come back down.

    • (Score: 4, Informative) by HiThere on Monday September 22 2014, @06:09PM

      by HiThere (866) Subscriber Badge on Monday September 22 2014, @06:09PM (#96871) Journal

      You are moving at the Earth's rotational speed. (More complex if you aren't starting at the equator.) As you lift higher in the elevator your angular velocity WRT the earth remains constant, which means your angular speed increases. This is a part of what the elevator does. At 35,786 km up your angular velocity will reach escape velocity. At that point you won't come back down. If you keep climbing, then you'll have a powered launch to ... somewhere. Just where depends on when you let go.

      --
      Javascript is what you use to allow unknown third parties to run software you have no idea about on your computer.
  • (Score: 3, Insightful) by tftp on Monday September 22 2014, @05:55PM

    by tftp (806) on Monday September 22 2014, @05:55PM (#96862) Homepage

    What do you see as the greatest challenges blocking the construction of a space elevator?

    How about the fact that only geostationary satellites will be safe? Every other satellite will eventually hit the elevator.

    • (Score: 0) by Anonymous Coward on Monday September 22 2014, @08:26PM

      by Anonymous Coward on Monday September 22 2014, @08:26PM (#96913)

      We have a winner! Unless we clear the equatorial orbit up to the height of the elevator, the tower/cable will be a hazard to all satellites in orbit--and vice versa. Good luck convincing every space-faring country on earth to abandon their satellites there, deorbit them safely, and not launch any more.

      • (Score: 2) by nitehawk214 on Monday September 22 2014, @09:01PM

        by nitehawk214 (1304) on Monday September 22 2014, @09:01PM (#96928)

        And they are claiming the thing will be 90,000km up. Since geosync is only 36,000km up, this would include being an obstruction to effectively every man-made thing orbiting the earth.

        I think that space elevator theory is that you have a combination of the anchor being able to move around to avoid debris, and any other object capable of maneuvering to avoid the thing. And any impacts are bound to be very high energy ones. [wikipedia.org]

        As awesome as a space elevator would be, I just don't see how someone could make it able to dodge all the unguided stuff out there..

        --
        "Don't you ever miss the days when you used to be nostalgic?" -Loiosh
        • (Score: 0) by Anonymous Coward on Monday September 22 2014, @10:38PM

          by Anonymous Coward on Monday September 22 2014, @10:38PM (#96952)

          nd they are claiming the thing will be 90,000km up.

          Which means they will be building it at 2500km per year until 2050... Or 7km per day, every day... They should start now! Go Go! If it's not 7km high tomorrow, they will miss their deadline.

          • (Score: 2) by nitehawk214 on Tuesday September 23 2014, @04:19PM

            by nitehawk214 (1304) on Tuesday September 23 2014, @04:19PM (#97208)

            Or to put it another way... It needs to be long enough to wrap around the earth... twice.

            --
            "Don't you ever miss the days when you used to be nostalgic?" -Loiosh
        • (Score: 1) by tftp on Tuesday September 23 2014, @12:53AM

          by tftp (806) on Tuesday September 23 2014, @12:53AM (#96981) Homepage

          I think that space elevator theory is that you have a combination of the anchor being able to move around to avoid debris, and any other object capable of maneuvering to avoid the thing.

          The anchor (beyond the orbit) would be hard to move for two reasons. First, the anchor wants to fly away along the radius, and the tether holds it in place. It is resistant to being moved anywhere except the elevator's anchor on Earth. Second, moving of the anchor will create waves in the tether - ultimately you will get a standing wave, with 100% (or close) reflections from the Earthed anchor. This is dangerous. Forces in that "string" may exceed the limit of structural integrity of the material; high frequency acceleration may throw climbers off the tether. (Try to climb up a giant guitar string while someone is playing.) That also reminds me about hurricanes, as they are common around the equator - they pack a lot of power. What is the resonant frequency of the tether, and how exactly that energy will be dissipated? (I see no obvious mechanisms.)

          On top of that, what is the speed of propagation of that wave? It may be not fast enough to skip that speck of paint. Even worse, you have to not only calculate in static how much you want to deflect the tether, but also calculate the waves that run along it, dynamically, as they will deform the tether more than the anchor is moved. It may be that you move the anchor left, the wave bounces the tether right, and it gets hit.

          In addition to that, movement of the anchor can protect only against one or two, maximum three objects that fly through it within some time. If you have many objects - say, a cloud of debris from that Chinese satellite - wherever you go you are in a bad spot. Unlike spacecraft you have only two axis (X, Y) to move along.

          In addition to that, you can move anchor only in response to known objects. But there are many that are unknown. They don't even have to be man-made. I'd guess there are many small pieces of Moon rock that got kicked out of Moon and captured by Earth. We even have such rocks from Mars. Who is going to watch for every grain of sand around Earth, from sea level to 90,000 km? With what?

          A space elevator can work in a highly advanced world, where there are no LEO satellites in orbits, but there are plenty of stationary relays and other objects that are held in place by engines (say, gravity drives.) However such a world does not need a space elevator.

          • (Score: 2) by romlok on Tuesday September 23 2014, @08:32AM

            by romlok (1241) on Tuesday September 23 2014, @08:32AM (#97071)

            The anchor (beyond the orbit) would be hard to move for two reasons.

            You're confusing your nomenclature here. The anchor is at the bottom of the tether. Rather like a ship's... anchor. As commonly conceived, the anchor is an ocean-based platform, with the ability to move around (under its own power, or via tugs) so it can guide the ribbon to avoid weather/space-junk/etc.

            The opposite end of the tether from the anchor is the counterweight, whose only requirement is to raise the centre of mass of the tether above GEO. The counterweight could be a space station, captured asteroid, or simply consist of more tether of appropriate mass - the longer the tether, the greater "launch" velocity can be attained upon releasing a payload/craft from the end.

            • (Score: 1) by tftp on Tuesday September 23 2014, @05:46PM

              by tftp (806) on Tuesday September 23 2014, @05:46PM (#97267) Homepage

              You're confusing your nomenclature here. The anchor is at the bottom of the tether.

              I see... I guess I do, thanks! Still, that doesn't resolve the problem. I don't know what will be the speed of sound in the tether, but even in solid metals this figure is about 5000 m/s. It would take 90000/5 = 18000 seconds, or 5 hours, for the wave to propagate (in ideal conditions, assuming a certain vibrational mode) and 10 hours to reflect from the open end (the counterweight) and return back - and that is for the fastest wave mode. Climbers and winds in the atmosphere will be creating additional disturbances; previous movements of the anchor (if it is a floating one, not a stationary island) will be adding up and causing the tether to carry all kinds of waves up and down.

      • (Score: 3, Insightful) by Non Sequor on Tuesday September 23 2014, @03:08AM

        by Non Sequor (1005) on Tuesday September 23 2014, @03:08AM (#97016) Journal

        I'm the first to criticize things, but this scenario doesn't seem likely.

        Economically, the space elevator would be worth substantially more than all of the satellites in orbit. If the construction plan is credible (huge if), contracts for elevator usage could be sufficient to convince satellite operators to voluntarily deorbit (or allow to be deorbited).

        --
        Write your congressman. Tell him he sucks.
  • (Score: 0) by Anonymous Coward on Monday September 22 2014, @06:47PM

    by Anonymous Coward on Monday September 22 2014, @06:47PM (#96889)

    http://en.wikipedia.org/wiki/Warsaw_radio_mast [wikipedia.org]

    What a screwup that became.
    What makes them think they can do this with a 96,000 km cable?

    What about biologic growth on said cable?
    And what about "stuff" hitting the cable?

    And from 3cm to 9,600,000,000cm
    Wow!

  • (Score: 0) by Anonymous Coward on Tuesday September 23 2014, @03:14AM

    by Anonymous Coward on Tuesday September 23 2014, @03:14AM (#97018)

    yes, this is pure PR BS - i hope. i would rather we took our first shot at this on the moon. really gonna suck if this modern version of the Tower of Babel falls to earth.

    • (Score: 2) by isostatic on Tuesday September 23 2014, @07:13AM

      by isostatic (365) on Tuesday September 23 2014, @07:13AM (#97058) Journal

      Yes, if it breaks it will collapse, reaching terminal veolcity of nearly 5mph, and may knock butterflies off their branches when it crashes down!

  • (Score: 2) by Freeman on Tuesday September 23 2014, @06:02PM

    by Freeman (732) on Tuesday September 23 2014, @06:02PM (#97274) Journal

    The StarTram actually looks reasonable. I for one wouldn't feel particularly safe with a cable that could wrap itself completely around the earth, if something went extremely wrong. On the other hand I would trust a slingshot from a maglev track into outerspace.

    --
    Joshua 1:9 "Be strong and of a good courage; be not afraid, neither be thou dismayed: for the Lord thy God is with thee"