Don't get me wrong here and maybe I am being a bit slow here, but I have some issues that just keep bugging me about the concept of a space elevator.
1. How do you get it down in the first place. Upper atmosphere winds can move at over 150 MPH. How do you get a ribbon through that without it whipping so bad that it either tears itself apart or will be impossible to catch. A simple issue but one that is troubling. 2. What about the electrical discharge from something like that connecting to the earth. Over that distance the static charge alone could blow the thing apart when it connects to the ground. No one has ever explained how to solve this to me in a way that amde sense. 3. Orbital mechanics are pretty picky. Pertibations of the orbit alone will account for hundreds of meters of slack/tension. What do you do, spool it up when it goes slack? Now the anchoring system has to be able to wind up and down too? 4. This cable/ribbon will have to undergo a large amount of both tension and compression from multiple angles. I don't know that nanotubes are tested in a fabric mode that could provide for all of these forces. I have also heard that if the ribbon does snap, it will remain stationary and can be repaired. Stationary to what? Again the speeds involved with pertibation and wind forces, it will not remain stationary for very long. I really want to believe in the space elevator but so far, these questions are unanswered and untested. Anyone have ideas or am I just being a wet blanket? Joe L. On Wed, 2003-11-19 at 21:53, Michael Turner wrote: > My take on this: the right kind of space elevator need not compete for > orbital space with an Earth-Moon tether. A space elevator moving in the > equatorial plane of the Moon could be an enabling technology for building > the Earth-Moon tether, since it's probably the cheapest per pound way to get > both to Earth-Moon L1 and to the surface of the Moon. It makes sense to > think more in terms of how they might be complementary than competing. > > Designs I've seen so far for space elevators assume they are tethered to the > Earth, and have an equatorial orbit for their center of mass. However, > geosynchronous orbits don't have to be equatorial orbits. The Earth is > tilted with respect to the Earth-Moon orbital plane, so a space elevator > tethered to the Earth would either have to pendulum, or the tip of it would > have to travel north and south through the atmosphere, making a round trip > every 24 hours. > > A space elevator "ground floor" that travels thousands of miles a day is > still moving slowly enough for a jet plane, and maybe a helicopter, to reach > it, a small added cost. A pendulum approach might not work -- anchoring it > might be too hard, and might introduce angles that conflict with an > Earth-Moon tether. I don't this means we shouldn't do an anchored elevator, > starting with equatorial orbit. Just that it should be designed so that it > can be unhooked and moved to an Earth-Moon orbital plane later with > relatively little trouble. > > Having a space elevator in the Earth-Moon equatorial plane is the first > approximation to reducing the chance of an Earth-Moon tether and the space > elevator ribbon crossing. aking the elevator "ground floor" mobile rather > than fixed further reduces the intersection space. > > A second approximation might be to attach the Moon end of the Earth-Moon > tether to one of the Moon's poles. This introduces a small angle. > > Finally, there's the issue of whether the Earth-Moon tether can be attached > to the Earth, or whether it should just dangle outside the atmosphere. If > the tip of the Earth-Moon tether is near the equator, there's a relative > speed of about 1000 miles per hour. Consider, however, that once you're in > an aerodynamic regime of any kind, all the rules change. As you get further > into the atmosphere, you can use relative speed for aerodynamic lift, and > rudders can steer the tether away from the equator, moving the tip into > higher latitudes where the relative speed is much slower. The problems of > attachment appear at the poles -- a relative tether-tip/atmosphere velocity > that might become sub-aerodynamic. However, near those speeds, conventional > aircraft could rendezvous with the tip, an attachment to the Earth would be > unnecessary. One could imagine a standard cargo freight plane hovering over > a landing pad at near stall speeds, then just touching down -- you wouldn't > need something like an aircraft carrier dangling out there. > > The Earth-Moon's Earthside tether tip problems are further favored by being > in an aerodynamic regime, because, unlike the space elevator's center of > mass, the distance to the Moon is variable. The Earth-Moon tether tip would > spiral upward in latitude, and when the Moon was closer, the slack would be > taken up by drag forces within the atmosphere. > > How about the problem of pulling the Moon into the Earth? Well, maybe over > a very long time. However, a counterbalancing tether, hanging outward from > the Moon on its far side, would seem to take care of that problem. > > An Earth-Moon tether would be vastly more massive than a terrestrial space > elevator. For one thing, the distance is much greater. For another, over > much of that distance (past L1 toward the Earth), the forces of gravity > won't be significantly counterbalanced by sub-orbital centrifugal forces. A > space elevator's strongest point has to be at its center of mass in GEO. > The Earth-Moon tether's problem, not long after the growth of it has touched > down on the surface of the Moon, is in anchoring it strongly enough to the > Moon. > > -michael turner > [EMAIL PROTECTED] > > > ----- Original Message ----- > From: "Mark Schnitzius" <[EMAIL PROTECTED]> > To: <[EMAIL PROTECTED]> > Sent: Thursday, November 20, 2003 11:23 AM > Subject: RE: Nanotube cable will connect Earth and Luna > > > > Obligatory quote from It's a Wonderful Life: > > George Bailey: What do you want, Mary? Do you > want the moon? If you want it, I'll throw a > lasso around it and pull it down for you. Hey! > That's a pretty good idea! I'll give you the > moon, Mary. > Mary: I'll take it! Then what? > George Bailey: Well, then you can swallow it, and > it'll all dissolve see, and the moonbeams would > shoot out of your fingers and your toes and the > ends of your hair... am I talking too much? > > Seriously, you could put a terminal at the Earth- > moon L1 Lagrange point, but that's closer to the moon > than it is to Earth. The pole idea might work. > It wouldn't come close to crossing paths with any > space-elevators that way too. I'm sure this crazy > idea will fizzle for some other practical reason, > though. To be replaced by something even crazier, > no doubt. > > > --Mark > > --- [EMAIL PROTECTED] wrote: > > Has anyone heard of this idea before? How would it > > work? The Moon doesn't > > revolve around the Earth at the same rate the Earth > > rotates, so how could > > such a cable be attached? (Through some sort of > > swiveling mechanism at the > > north or south poles, perhaps?) Would there be a > > danger of this cable > > getting tangled up with some Space Elevator cables > > that may have previously > > been built between the Earth's Equator and > > synchronous orbit? If the cables > > got tangled, could they pull the Earth and Moon into > > each other? :-) > > > > > > > > John Sheff > > Cambridge, MA 02139 > > [EMAIL PROTECTED] > > > > -----Original Message----- > > From: [EMAIL PROTECTED] > > [mailto:[EMAIL PROTECTED] Behalf Of LARRY > > KLAES > > Sent: Tuesday, November 18, 2003 9:59 AM > > To: setipublic > > Cc: BioAstro; europa > > Subject: Nanotube cable will connect Earth and Luna > > > > "NANOTUBE CABLE WILL CONNECT THE EARTH AND THE MOON" > > > > Andrew Yee <[EMAIL PROTECTED]> > > > > InformNauka (Informscience) Agency > > Moscow, Russia > > > > Contact: > > > > A.N. Redkin > > or > > L.V. Maliarevich > > Institute of Problems of Microelectronics Technology > > and > > Extra Pure Materials > > Russian Academy of Sciences > > Chernogolovka, Moscow Region > > + 7 (095)962-80-74, + 7 (095)962-80-47 > > [EMAIL PROTECTED] > > > > 14.11.2003 > > > > THE NANOTUBE CABLE WILL CONNECT THE EARTH AND THE > > MOON > > > > Researchers from the Institute of Problems of > > Microelectronics Technology > > and > > Extra Pure Materials (Russian Academy of Sciences) > > have designed and tested > > a > > new device for production of a new promising > > material -- nanotubes. The > > researchers believe that it is exactly the material > > a transport cable can be > > produced of to connect the Moon and the Earth. > > > > Back at the beginning of the last century, the idea > > was born to build a > > transport cable between the Earth and the Moon to > > deliver goods from our > > planet > > to the Moon. Until recently, there has been no > > material enabling to make > > this > > idea a reality. Polymers would not stand cosmic > > radiation, and the steel > > cable > > would have enormous weight. The most durable > > material as of today -- Spectra > > 1000 -- would allow to produce a cable of only 315 > > kilometers long, as the > > longer cable is simply unable to bear its own > > weight. > > > > Carbonic nanotubes would very well suit the role of > > a structural material > > for > > such a cable. According to the researchers' > > estimates, a lightweight cable > > of > > required length can be produced from this material, > > the cable being 50 times > > stronger than the current most durable materials. > > The problem is that the > > researchers have not learned yet to produce high > > quality nanotubes in large > > quantities: that is either too expensive or feasible > > only in the laboratory > > environment. Therefore, this material is still > > pretty exotic, its price > > varying > > from $60 through $100 per gram. > > > > The scientists from Chernogolovka have designed a > > device that allows to > > produce > > pretty large amounts of high quality nanotubes. The > > device is based on a > > rather > > simple scheme: spirit, glycerin or their mixture > > gets from a specially > > cooled > > chamber into the zone of graphite heater bar, where > > the temperature reaches > > 1000-2000 degrees C. That results in ultraspeed > > heating and substance > > combustion. The products precipitate on a special > > carbonic glass bell > > covering > > the device, or they are removed outside together > > with vapors and gases, thus > > allowing to protect the product from various > > unnecessary impacts. > > > > Precipitations of such kind normally contain > > amorphous carbon, soot and > > various > > particles covered by a shell of carbon, as well as > > carbon fibre and > > nanotubes. > > However, in this particular case the researchers > > came across a surprise: the > > precipitations obtained in the device turned out to > > contain only nanotubes > > and > > carbon fibre. No other admixtures were found. It > > means that a laborious > > procedure is not required for rectification from > > unnecessary compoments. The > > fibres are 30-150 nanometers thick, and nanotubes > > are 20-50 nanometers > > thick, > > their length being several micrometers. > > > > The growth of nanotubes can be accelerated with the > > help of catalysts -- > > iron, > > nickel, cobalt and gold. If the surface where > > nanotubes are to be > > precipitated > > is covered with a thin film of such catalyst in the > > form of some pattern, > > then > > nanotubes will precipitate only upon the pattern, > > the other parts remaining > > clean. > > > > In principle, such devices may lay the foundation > > for industrial production > > of > > nanotubes. Maybe, a nanotube cable will soon connect > > the Moon and the Earth. > > > > > __________________________________ > Do you Yahoo!? > Free Pop-Up Blocker - Get it now > http://companion.yahoo.com/ > == > You are subscribed to the Europa Icepick mailing list: [EMAIL PROTECTED] > Project information and list (un)subscribe info: http://klx.com/europa/ > > > > == > You are subscribed to the Europa Icepick mailing list: [EMAIL PROTECTED] > Project information and list (un)subscribe info: http://klx.com/europa/ == You are subscribed to the Europa Icepick mailing list: [EMAIL PROTECTED] Project information and list (un)subscribe info: http://klx.com/europa/
