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Going Up? 567

Posted by michael
from the keep-arms-inside-the-car dept.
jmiyaku writes "The National Post is reporting that NASA has given a Seattle company a $570,000 grant to continue its investigation into constructing a space elevator. Coupled with some production-grade technology from a Japanese car company (carbon nanotube composites), this elevator could be a reality within 15 years..." The Highlift website has some more information.
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Going Up?

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  • Optimistic (Score:1, Insightful)

    by Fenresulven (516459) on Tuesday August 13, 2002 @09:33AM (#4060922)
    this elevator could be a reality within 15 years...

    Does anyone else think this is really really optimistic?
  • Re:Optimistic (Score:2, Insightful)

    by nick-less (307628) on Tuesday August 13, 2002 @09:40AM (#4060971)

    >>this elevator could be a reality within 15 years...

    Does anyone else think this is really really optimistic?


    I guess this is why he said "could" and not "will" ;-)
  • by barawn (25691) on Tuesday August 13, 2002 @09:42AM (#4060988) Homepage
    The Elevator in Red Mars fell down because it had an asteroid at the far end providing counterbalance. Separate the asteroid from the cable, and it's no longer a space elevator, but a really stupidly placed cable. Flop. Splat.

    The elevator they're proposing is not counterbalanced - this requires it to be even longer than if it wasn't counterbalanced, but it doesn't require a conveniently placed asteroid. :)

    Remember: you're asking what if it falls, right? It is falling. It just happens to be falling at exactly the same rate that the Earth is turning. It's in orbit. In order to make it fall, you'd need to break it.
  • by barawn (25691) on Tuesday August 13, 2002 @09:46AM (#4061010) Homepage
    It's not feasible to send waste into the sun - take a look through a few astronomy texts and you'll see why.

    Basically the problem is that any object we lift from the Earth has energy, and angular momentum. If you want to hit the sun, and not just put it in a very eccentric orbit, you need to remove a lot of energy from the object, and the space elevator wouldn't help - it pulls you out of Earth's gravity well, not out of Earth's orbit. You'd require massive amounts of fuel to get it there.
  • by barawn (25691) on Tuesday August 13, 2002 @09:55AM (#4061066) Homepage
    Dear God no. We can get across the Atlantic ridiculously easy: boats, planes, anything. There's no need to bridge it, and even if you did, then you've got stability against wind, gravity, anything else. It'd be engineering hell, and you can probably work out that it's impossible.

    A space elevator is a cute idea: it's quite safe, since, well, it's in orbit. It just happens to be in orbit above one spot over the earth (geosynchronous) and really long, so that one side of it touches Earth. And practical? Man. Launch costs go from "huge" to "free". The world would change in a year after this thing being built. Seriously. It'd look like science fiction in no time: space hotels, lunar bases, Martian missions - everything becomes easy.
  • is it just me... (Score:2, Insightful)

    by Drunken_Jackass (325938) on Tuesday August 13, 2002 @09:59AM (#4061102) Homepage
    ...or wouldn't you have to locate the anchor point to be at a location that makes sense for the "drop off" point of the satellites to establish a useful orbit?

    Why wouldn't we have a bunch of satellites in the same planar orbit?

    I'm assuming that the elevator gives the sats a ride up, and then simply releases them. Is there another release mechanism that "points" the satellite in the right direction?

    Also, could you use the elevator for geosynchronous orbit birds?
  • by virg_mattes (230616) on Tuesday August 13, 2002 @10:30AM (#4061307)
    > It seems to me that this project will never work. There are to many forces at play. The elevator would probable snap in half do to all the strain. If we did manage to build it there would be a HUGE problem: Earth's rotation would slow down, forcing us toward the Sun. Imagine the Earth as an ice skater in rotation. The person keeps their arms close to their body to rotate fast. What happens when the person's arms raise away from their body? They slow down. It is a simple concept of centripetal acceleration. The elevator would act as an arm of the Earth, thus causing it to slow down.

    Wow. There are so many scale errors here it's hard to tell where to start. First, What strain exactly would "snap the elevator in half"? It's a ribbon, and while it's certainly possible to break the ribbon, it's not likely to happen under normal operation, and the design specifies that they'll set it up in a location that minimizes the likelihood of high winds or lightning. Second, "Earth's rotation would slow down"?!? You can't be serious with this. The mass of this thing is so much less than that of the Earth that the slowdown would be indetectable with the most sensitive instruments we have, if we were actively looking for it. To take your example of the figure skater, imagine her spinning, then letting out a one inch long piece of the finest hair you can find. How much do you think she'll slow down? And last, why exactly would slowing Earth's rotation cause us to head for the Sun? The day would get to be more than twenty-four hours, but the speed the Earth moves around the Sun (that's "revolution", not "rotation") would not change in the least.

    Go buy a book on physics.

    Virg
  • Re:Great news, but (Score:5, Insightful)

    by LBU.Zorro (585180) on Tuesday August 13, 2002 @10:32AM (#4061325)
    Where to begin???

    Point 1: Neo to attach to. Unnecessary. You can achieve the same thing with a really long teather and a 1 kg weight on the end. Did you not notice that the cable was 100,000 km long, when geosynch orbit is only 36,000 (miles or km I can't remember, but even if it is miles that would make it 57odd thousand km up, far less then the 100,00 required) the extra thousands of km are used to provide leverage and a decent ratio for the mass to be lifted.
    Although I am curious to know what you mean by strong enough. All you need to do is get an object, in geosych orbit, move it to an outer orbit but keep it at the same angular velocity (how long it takes to orbit the earth) and the resulting centripetal force can be used to pull against when pulling up mass. 'Strong' neos aren't needed, a collection of cotton wool would do it, if there was enough and it was far enough out.

    Point 2: Constant height. Not actually necessary, the water level is pretty flat (aside from tidal variations due to the moon and the sun) BUT the cable is under constant tension thus would forgive a certain amount of play. In fact the cable has to be at over 5 tonnes of tension at the base to be able to lift the mass required.

    Point 3: Energy required for lift. Actually you are wrong again, the energy required is less. When you use a reaction engine fully half the energy required to boost you is wasted throwing mass out in the opposite direction. HOWEVER along with this is the fact that they are going to be using lasers to drive photovoltaic cells to drive electrical motors, and this could (in theory) be purely sunlight driven.

    Point 4. Location. The ocean isn't too bad, a simple cargo ship deliver the cargo and it lifts. Sure its not rail or lorry but its good enough. Most of the oil the US needs is shipped via tankers, why can't a few satelites?

    Point 5. Anti-gravity. (Ignoring the racist angle) this is an unproven experiment, and it should be noted that 2% is a little different to lifting the item into orbit.

    As an aside, the cable itself will weigh in at a stunning 750 tonnes. Of that 480 tonnes (metric) will be above geo-synch orbit (assuming 36k km or should that be Mm???) and not likely to crash down.

    I applaude them, but hope it does all work even though I have my doubts...

    The tensile strength of the cable needs to be huge.. 7.5 kg per km, and that needs to hold around 270 tonnes, its a hell of a challenge....

    Z.
  • According to the article, the power source is a laser shot from the platform, aimed at collectors on the bottom of the car. There, it's converted to electricity, and drives motors with wheels on the cable. Since intertia should keep the cable perfectly straight, it seems like a really good use of laser-powered propulsion.
  • by Oculus Habent (562837) <oculus@habent.gmail@com> on Tuesday August 13, 2002 @10:54AM (#4061475) Journal

    The subducting seafloor idea sounds much better to me. Drop in into a hole in the ocean floor, and it is pushed into the mantle. No loss of mass for the earth, no huge expenditure of energy, and the waste is taken care of.

  • by mikeee (137160) on Tuesday August 13, 2002 @11:52AM (#4061900)
    59,800,000,000,000 trillion tons into space to affect the aforementioned change. Again, a tremendous amount, right?

    Well, yes, actually.

    Consider this: New York city alone produces 13,000 tons of residential waste a DAY, and they've run out of places to put it (Again, Source [fathom.com])... It adds up REALLY quickly.

    You're using your intuition, and it's wrong, wrong, wrong.

    It doesn't add up. Assume everyone in the world produces as much trash as a New Yorker City resident, and that we double that for non-residental, and that we send all of the trash in the world into space.

    That's 13K*(1/.002)*2= 13 million tons of trash a day. To achieve the slowdown you mention (.1 second/day) would take about 1.2*10^16 years. Tidal effects are slowing the earth much faster than that. More to the point, the sun will have blown up by then, making the rotation of the earth moot. Hell, I'm not sure all our protons won't have decayed by then - anybody know the numbers on that one?

  • by WolfWithoutAClause (162946) on Tuesday August 13, 2002 @12:51PM (#4062393) Homepage
    I think realisticaly, the elevator has to deal with reentry anyway- the cable can get cut at any time because of micrometeorites. If you were on the way up at the time, then you would need the system to allow you to land safely from any altitude.
  • by shess (31691) on Tuesday August 13, 2002 @12:56PM (#4062443) Homepage
    It's not going to be for free, if only because most of your mass is being sent up there for a reason (ie, you send the satellite into orbit, you slingshot the Mars mission to Mars, etc).

    In fact, when you come down to it, with this system it probably costs as much to bring stuff down (in a controlled fashion) as to take it up, so you would want to minimize how much to bring back. Maybe delicate things like results from zero-G experiments, or people, ride the elevator back down, while other items might be ejected to reenter in more traditional fashion (if the cost of carrying the heat shield up is cheaper than the cost of carrying the payload down).
  • by surfcow (169572) on Tuesday August 13, 2002 @01:31PM (#4062801) Homepage
    >...shoot the radioactive waste into the sun...

    The romans dumped lots of crude oil into the sea. They were certain it had no practical use for anything. Today we use it for many things from plastics to medicines to fuel.

    And we also have a irritating substance to deal with. I hope we have the imagination to see it's potential future uses.

    =brian
  • by blablablastuff (577458) on Tuesday August 13, 2002 @01:40PM (#4062861)
    NO NO NO, sending nuclear materials out into the vastness of space, or the sun, where we can never hear from it again, is absolutely pointless. Radioactive matter is a source of energy. Some of these substances could conceivably have many uses we just haven't figured out yet.

    Throw it all in a big pile on the moon. When we need it, we'll know exactly where it is. A few solar powered robots can help dig through it when we need some and set it aside for collection, as well as protect us from the Terrible Secret of Space.

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