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Canadians Vie for Space Elevator Victory

Posted by ryuzaki0 on from the to-the-moon-alice dept.

unc0nn3ct3d writes to mention a CBC article about some plucky Canadian teams planning to go for NASA's space elevator challenge. From the article: "Teams based in Saskatoon, Vancouver, Edmonton and Toronto are among thousands of space enthusiasts expected to converge on a desert site in Las Cruces, N.M., on Friday and Saturday for the X-Prize Cup, a festival mounted by the X-Prize Foundation ... The competitors are gearing up for the Spaceward Foundation's Space Elevator Challenge, which requires them to surmount technical obstacles in the development of a new type of vehicle that would take people and cargo from Earth into space."

14 of 99 comments (clear)

  1. Doesn't mention bringing them back though... by Channard · · Score: 5, Funny

    'Hey, how come there's no 'call space elevator' button at this end of the space station?'

    1. Re:Doesn't mention bringing them back though... by aussie_a · · Score: 4, Funny

      Sounds like my father. He's always more then happy to explain how to get somewhere (with instructions like "go to the end of road X and then turn left." And yet he never gives me instructions on how to get home, I think he's been trying to give me a hint for some time now.

  2. Canadian Laser Powered Climber by iendedi · · Score: 4, Interesting
    From TFA:
    The machine is being entered in one of the two parts of the elevator competition, known as the Power Beam Challenge, in which competitors build a machine that can climb at a rate of at least one metre per second up a ribbon suspended nearly 61 metres (200 feet) from a crane. The climber must be powered by a light source.

    "We developed a high-powered laser to power our climber," Ruszowski said.
    Which is all good and well, I suppose, for a cable suspended from a crane. But what happens when the space-elevator ribbon has to cut through the entire atmosphere of the earth, weather and all? Tracking the lateral movement of the elevator precisely in unpredictable weather does not seem trivial to me.

    Do any of you actually believe we are close to being able to produce one of these monsters? I am guessing we are still thirty years away from the appropriate tech.
    --

    It is your personal duty to fight for what is right on a daily basis. Ignoring injustice is identical to approving
    1. Re:Canadian Laser Powered Climber by oldelpaso · · Score: 4, Informative

      I'm highly sceptical about articles making optimistic claims about space elevators, of which there have been several of late, usually involving carbon nanotubes. Most of the time the theoretical strength of a cable constructed from carbon nanotubes is used, but this ignores the fact that the cable will inevitably have construction defects, as it would need to be about 10^5 km long. A decent analysis is provided in a recent paper I read: http://www.iop.org/Select/abstract/-group=subject/ -groupval=100/0953-8984/18/33/S14

    2. Re:Canadian Laser Powered Climber by afxgrin · · Score: 4, Informative

      The solution for powering a space elevator by laser certainly won't be trivial. It's not like you can just point a laser straight up and it'll hit the receiving dish/antenna/panel ... there will be lateral movement the climber will be undergoing. So there will need to be some type of optics required to guide the beam. These optics have existed for a long time, they just need to be adapted for higher powers and probably wider laser beams. To compensate for refractive index changes in the atmosphere, some form of adaptive optics will be needed. This type of research was done in previous atmospheric studies, and projects like the Airborne Laser.

      Right now the largest disadvantage for lasers is the inefficiency in creating electricity from photovoltiacs. The team i'm on - Punkworks is hoping to use a microwave rectenna array to convert 2.4 GHz RF energy into a few hundred watts of electricity. Right now we're lending our transmitter to another team, and have reached a deal to split the prize 50/50 if they win with our transmitter. The reason we're using microwaves is due to the conversion efficiency, there's lots of journal papers on microwave rectenna design indicating a maximum efficiency of 85%. This is a huge improvement over the ~30% you'd get from a solar panel.

      My team has yet to compete, and I'm eagerly waiting to hear how our climber performs. Right now they made us move to another location at the test site despite our approved application from the FCC. Apparently the airport doesn't like the idea of us beaming 13 kW of microwaves into the sky ...

      unfortunately I'm not in New Mexico for the competition, but a number of my teammates did the 44 hour drive.

    3. Re:Canadian Laser Powered Climber by mdfst13 · · Score: 4, Interesting

      The difference between an elevator in a skyscraper and a space elevator is that the elevator in the skyscraper has a building around it while the space elevator is just a big cable. The space elevator is held up by the fact that part of the cable (possibly with a counterweight at the end) is actually far enough away that angular momentum is pulling it *away* from the earth. It's the tension between gravity pulling it down and angular momentum pulling it up that makes it work. Break that into segments and some segments will go away from the earth while others go down. If you tie the segments together, then you just have one long cable again (with joins that are either heavier or weaker than the rest of the cable; if we had a lighter and stronger material, we'd just make the whole cable out of it).

      The World Trade Center system worked because the building was there and they attached the segments to the building. A space elevator is problematic because we simply don't have the ability to build a building that tall to hold up segments (if we did, we'd just make the building the cable and crawl up the side). Each segment would have to be self-supporting.

      The minimum cable length (to be self supporting) is determined by the angular velocity of the earth, the radius from the center of the earth to the cable mount, and the mass of the earth. There is no way to make a shorter cable that is self supporting.

      Your solution requires something to hold up the segments. We don't have that something. We are somewhat closer to being able to build a single cable of that length than we are to building a segmented solution (which requires something like anti-gravity). Further, if we did have the tech to build a segmented solution, we probably wouldn't need to do so. With anti-gravity, we'd just float up -- no elevator cable needed.

      I think that what's confusing you is that in buildings, the cable pulls up the car (which is just a big box). In a space elevator, the "cable" has a role more like that of the elevator shaft or the rails of an incline. The elevator "car" is propelled by something else. Maybe they should change the name to something more static, like pillar, shaft, or stem.

  3. Comment removed by account_deleted · · Score: 4, Funny

    Comment removed based on user account deletion

  4. Welll..... by MrAnnoyanceToYou · · Score: 5, Funny

    If you lived next to 300 million Americans, you'd want off this stupid rock too.

    --
    My little site.
    1. Re:Welll..... by Kjella · · Score: 4, Insightful

      Actually, that would be 100 million Americans, and 200 million illegal immigrants.

      I didn't know there were so many native Americans left.

      --
      Live today, because you never know what tomorrow brings
  5. Re:So......when will it be? by kbox · · Score: 5, Funny

    Not long, There are only three.. Earth, Menswear and space.

    --
    God Be Gone
  6. I was there! by apsmith · · Score: 4, Interesting

    It was pretty cool seeing the teams trying to climb the tether. I only saw a couple make it to the top (200 ft), but several got part way. I don't believe anybody beat the 1-minute time limit to meet the goal.

    One interesting thing is that, having to power the climbers from beamed power, they had to make them as light as possible, relative to the area of solar panels trying to capture energy. So these were pretty flimsy looking devices, and you could see wind causing trouble. Stripped bolts and computer glitches also caused their share of failures...

    It was also nice to see all those young teams of excited people trying to do this - mostly undergraduate engineering students, but there were even some high school students participating.

    And having John Carmack hanging out chatting with the crowd while his crew was trying to get his "hover" craft back in shape was fun. They had jumbotron displays for their challenge attempts, but you could also see it just hovering there a hundred feet up (not too close to the crowd, but quite visible). Of course the crashes had a bit of a car-wreck interest too... The most successful things seemed to be some straightforward high powered rocket launches. But there was a big enthusiastic crowd, and lots of sideshows. Definitely worth a trip to the El Paso area if they do this again!

    --

    Energy: time to change the picture.

  7. Re:Space elevator by GTMoogle · · Score: 4, Informative

    Uhm, you can put the rockets on the earth side, actually, and by rockets I mean a large mass sitting on the earth's surface. The other end of the tether can have a constant outward pull that is more than capable of counteracting any and all mass sent up the line.

    As for the ionosphere, they've actually done a lot of research entirely unrelated to the space elevator including physical tests. From what I've read on it, they're not ignoring the problem, it's just not significant. The proposed carbon nanotube cable isn't really conductive and would only be affected by the very local area anyway. That doesn't ammount to much. They've even bothered to calculate whether having a conductive cable could generate any useful power. The answer was no, there's just not enough energy there to do anything useful with. Even if the cable could act as a lighting rod, lighting is the result of built up potential. Having a lightning rod to the clouds would prevent any potential from building!

    A concern you didn't raise, that's nonetheless of interest (to me anyway) is the scale of the project. IIRC, the individual wires that make up the cables of the golden gate bridge if placed end to end would actually be as long as the space elevator. Probably heavier as well. Since the cable has so much surface area, and most likely would be cut very very close to the ground (ie still in atmosphere), the cable would flutter harmlessly to earth. So disaster situations are unlikely.

  8. Canadians will lead the way by duh+P3rf3ss3r · · Score: 5, Funny

    'Cause if there's one thing Canadians are good at, it's getting an entire carload of people high.

    --
    Give a man a match: warm him for an instant. Douse him in petrol and set him aflame: warm him for the rest of his life.
  9. Re:Space elevator by GTMoogle · · Score: 4, Informative

    No, the structure of carbon nanotubes (there are many variations) determine its electrical properties, as well materials that the tubes can be doped with. You can make them insulators or conductors.

    In addition, the current idea is that the cable will be made of short filaments of carbon nanotubes glued together in some as-yet-to-be-developed fashion. The glue alone would probably make the cable non-conductive.

    As a material, nanotubes have very flexible properties. By the time we're able to produce the quality and quantity necessary to make a feasible cable, we'll probably have the technology to pick and chose its attributes.