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plutherusAt 5pm Saturday was another panel "Building the Giant's Beanstock".
This one I took notes on in the program book, next to the grid. That's how I know that.
Mostly it concerned the Space Elevator, one of my favorite subjects.
Although it did touch a bit on the concept of the long roatating tether. The way that works is you have a huge tether, say a hundred kilometers long, in orbit and rotating around a large center weight. Actually, you may not even need the center weight, as the tether has quite a bit of mass on its own. Each end dips down almost to the edge of our atmosphere once each rotation. By putting a sort of "wobble" into it, you can make it basically pause at that point for possibly up to a minute. Which is more than long enough to attach something to, which you fling up on a suborbital trajectory from Earth. Using this same wobble function, you can also make it dodge out of the way of other satellites or space debris by introducing all sorts of beautiful harmonics.
The beauty of this is that it's far, far cheaper and easier to do a suborbital trajectory to the edge of space than it is to put something all the way up into orbit. Once the tether's in place, going from the edge of space to orbit is essentially free (for large values of zero). As for getting to the edge of the atmosphere, we already have commercial vehicles capable of doing that.
The big news was Japan's new investment into space elevator technology. The article linked there is pretty good, though not quite flawless. For one, their "artists conception" doesn't include the actual "elevator" itself, which would be a series of ribbons, probably 5-12cm wide and paper-thin. A whole series of them so that if something happens and one breaks, it's not a major problem.
It also mentioned that "breakthroughs" have to be made, which is no longer true. The last breakthrough needed was in 1994 with the invention of the carbon nanotube. From here on out, it's just an engineering problem.
One of the problems is shielding. Anybody in this thing would be sitting in the Van Allen belt for far longer than any astronaut ever has. Hours, possibly days, instead of seconds. Water, fortunately, makes an excellent shield. Gold is good, too, and lighter (for the amount you would need.) Since you need to take water with you anyway (we're talking up to a week go get to orbit), just put the tank on the outside of your ascent pod, people inside. You can even flood the windows, as water is fairly easy to see through. Or have a shutter that closes while needed. Whatever. The point is, engineering problem not major scientific breakthrough.
Oh, yeah, and Arthur C. Clarke was not the first to come up with the concept. Tsiolkovsky was. I can still recommend Clarke's book The Fountains of Paradise, though, for some great discussions on how the whole thing works.
NASA has also done some research into the concept, their 2003 report is available online.
One of the problems would be where to anchor it. At the equator is best, though, for various reasons, not strictly necessary. Another advantage of the equator is that there's a lot of water there, and it tends to be fairly calm. Someone mentioned the need to defend it from terrorist attacks which, I suppose, would sadly be necessary. It wouldn't really be that great a target for terrorists, as the damage it would cause coming down is nothing like what most SF would have it. Unless you planted a bomb in the ascent pod itself, you'd be unlikely even to kill the occupants (it would be far safer to ride than, say, a space shuttle. Even if all the ribbons were cut, you would have minutes to hours, depending on how far up you were, to escape. Put some wings, a parachute, and inflatable pontoons on the pod and you wouldn't even have to evacuate it in case of catastrophe.) But as a symbol it would be a valuable target.
But, as was pointed out, if the US government builds something like this, I know where they can find a very large floating platform, complete with nuclear reactors, armaments, and room for a battalion or two of marines. You could probably even get them to throw in a few fighter planes, but you'd probably want to declare a 50-mile or so radius around it to be a no-fly zone, even for friendly aircraft. The view as you approach it by boat over the open sea would be worth the $500 or so you'll be paying for a ticket to the top.
Of course, you still have to worry about the smartass kid who gets on and pushes every button...
This one I took notes on in the program book, next to the grid. That's how I know that.
Mostly it concerned the Space Elevator, one of my favorite subjects.
Although it did touch a bit on the concept of the long roatating tether. The way that works is you have a huge tether, say a hundred kilometers long, in orbit and rotating around a large center weight. Actually, you may not even need the center weight, as the tether has quite a bit of mass on its own. Each end dips down almost to the edge of our atmosphere once each rotation. By putting a sort of "wobble" into it, you can make it basically pause at that point for possibly up to a minute. Which is more than long enough to attach something to, which you fling up on a suborbital trajectory from Earth. Using this same wobble function, you can also make it dodge out of the way of other satellites or space debris by introducing all sorts of beautiful harmonics.
The beauty of this is that it's far, far cheaper and easier to do a suborbital trajectory to the edge of space than it is to put something all the way up into orbit. Once the tether's in place, going from the edge of space to orbit is essentially free (for large values of zero). As for getting to the edge of the atmosphere, we already have commercial vehicles capable of doing that.
The big news was Japan's new investment into space elevator technology. The article linked there is pretty good, though not quite flawless. For one, their "artists conception" doesn't include the actual "elevator" itself, which would be a series of ribbons, probably 5-12cm wide and paper-thin. A whole series of them so that if something happens and one breaks, it's not a major problem.
It also mentioned that "breakthroughs" have to be made, which is no longer true. The last breakthrough needed was in 1994 with the invention of the carbon nanotube. From here on out, it's just an engineering problem.
One of the problems is shielding. Anybody in this thing would be sitting in the Van Allen belt for far longer than any astronaut ever has. Hours, possibly days, instead of seconds. Water, fortunately, makes an excellent shield. Gold is good, too, and lighter (for the amount you would need.) Since you need to take water with you anyway (we're talking up to a week go get to orbit), just put the tank on the outside of your ascent pod, people inside. You can even flood the windows, as water is fairly easy to see through. Or have a shutter that closes while needed. Whatever. The point is, engineering problem not major scientific breakthrough.
Oh, yeah, and Arthur C. Clarke was not the first to come up with the concept. Tsiolkovsky was. I can still recommend Clarke's book The Fountains of Paradise, though, for some great discussions on how the whole thing works.
NASA has also done some research into the concept, their 2003 report is available online.
One of the problems would be where to anchor it. At the equator is best, though, for various reasons, not strictly necessary. Another advantage of the equator is that there's a lot of water there, and it tends to be fairly calm. Someone mentioned the need to defend it from terrorist attacks which, I suppose, would sadly be necessary. It wouldn't really be that great a target for terrorists, as the damage it would cause coming down is nothing like what most SF would have it. Unless you planted a bomb in the ascent pod itself, you'd be unlikely even to kill the occupants (it would be far safer to ride than, say, a space shuttle. Even if all the ribbons were cut, you would have minutes to hours, depending on how far up you were, to escape. Put some wings, a parachute, and inflatable pontoons on the pod and you wouldn't even have to evacuate it in case of catastrophe.) But as a symbol it would be a valuable target.
But, as was pointed out, if the US government builds something like this, I know where they can find a very large floating platform, complete with nuclear reactors, armaments, and room for a battalion or two of marines. You could probably even get them to throw in a few fighter planes, but you'd probably want to declare a 50-mile or so radius around it to be a no-fly zone, even for friendly aircraft. The view as you approach it by boat over the open sea would be worth the $500 or so you'll be paying for a ticket to the top.
Of course, you still have to worry about the smartass kid who gets on and pushes every button...
