XPost: sci.space.policy, sci.physics   
   From: invalid@invalid.com   
      
   On 6/19/2018 2:45 AM, Fred J. McCall wrote:   
   > Sergio  wrote on Mon, 18 Jun 2018 22:17:21 -0500:   
   >   
   >> On 6/18/2018 8:06 PM, Alain Fournier wrote:   
   >>> On Jun/18/2018 at 2:45 PM, Sergio wrote :   
   >>>> On 6/16/2018 8:54 AM, Alain Fournier wrote:   
   >>>>> On Jun/15/2018 at 11:34 PM, Fred J. McCall wrote :   
   >>>>>> JF Mezei  wrote on Fri, 15 Jun 2018   
   >>>>>> 22:13:01 -0400:   
   >>>>>>   
   >>>>>>> On 2018-06-15 19:21, Alain Fournier wrote:   
   >>>>>>>>   
   >>>>>>>> Yes. But I think I am a little less optimistic than you about it   
   >>>>>>>> becoming practical in the future. If we have fantastic materials   
   >>>>>>>> in the   
   >>>>>>>> future, maybe an elevator will become more practical,   
   >>>>>>>>   
   >>>>>>>   
   >>>>>>> Apart from lifting geostationary satellites to just below orbit and   
   >>>>>>> then   
   >>>>>>> let them use their own thrusters to position to their assigned   
   >>>>>>> slot/longitude, what other use would a space elevator have ?   
   >>>>>>>   
   >>>>>>   
   >>>>>> You go above the GEO point on the cable and get flung on   
   >>>>>> interplanetary trajectories.   
   >>>>>   
   >>>>> Yes!   
   >>>>>   
   >>>>> You would also likely put at least one cable above GEO rotating in a   
   >>>>> plane perpendicular to the main cable. So you can give an extra push for   
   >>>>> interplanetary trajectories and to fine tune in which direction you   
   >>>>> depart for said trajectories.   
   >>>>>   
   >>>>> You can also jump off at an altitude of about 15000 km (that figure is   
   >>>>> from the top of my head, it might be more or might be less). From there   
   >>>>> after a few passes of aero-braking you can reach LEO with very small   
   >>>>> thrusters.   
   >>>>>   
   >>>>> For polar orbits, you use the rotating cable above GEO mentioned above.   
   >>>>> But instead of using it for extra push you get off while it is   
   >>>>> subtracting some speed but not quite in the direction of rotation of the   
   >>>>> cable. So you subtract some speed in the direction of rotation of the   
   >>>>> cable and give some speed in the north-south axis. You then use   
   >>>>> aero-braking again to lower apogee, and a small thruster to raise   
   >>>>> perigee. Note however that using the elevator to reach polar orbits in   
   >>>>> this way isn't obvious. You would want a long and fast rotating cable   
   >>>>> and you would want it far above GEO, it might not be practical to do so.   
   >>>>>   
   >>>>> Building an elevator, with current technologies, is outrageously   
   >>>>> expensive. But if you have one, it can be very useful.   
   >>>>>   
   >>>>   
   >>>> we don't have one, and never will.  It is a joke among Engineers.   
   >>>>   
   >>>> What would is the monthly insurance payment for it?  if it fell over ?   
   >>>   
   >>> You put the cable on an east coast. You also put a system to cut the   
   >>> cable at something like 10000 km high. If the cable breaks below that   
   >>> 10000 km the upper part doesn't fall it goes up, the bottom part falls   
   >>> in the ocean, where it isn't likely to cause damage. If the cable breaks   
   >>> higher than 10000 km, you cut it at 10000 km, the bottom 10000 km falls   
   >>> once again in the ocean. The two other parts won't fall to the ground,   
   >>> the lower part will probably be in an elliptical orbit, the higher part   
   >>> might be in an escape trajectory. So the damage from a cable breaking   
   >>> doesn't have to be high. It might be a little difficult to explain that   
   >>> to an insurance company, but if you can pay for the cable, you should be   
   >>> able to cover the damages.   
   >>>   
   >>   
   >> how much does 10,000 of cable weigh?  100,000 #   
   >> the center of gravity is directly over the support, so you have 100,000#   
   >> of steel cable crashing onto it.   
   >>   
   >   
   > Nope.  The Earth spins, you know.  And STEEL?  That's cute.   
      
   earth spin is red herring, do the math.   
   what else are you going to use besides steel ?   
   NOTHING can support its own weight of 10,000 km of it.   
      
   go ahead, NAME what you propose to use.   
      
   >   
   >>   
   >> nothing will go into orbit as the accelleration vector is stright down,   
   >> gravity.   
   >>   
   >   
   > Well, no.  When whole, the cable is under tension, not compression.   
   > Remove weight from the bottom or break the tether point and it goes UP   
   > above the break, not down.   
      
   no,  gravity wins over whatever transitory events.   
      
   >   
   >>   
   >>>   
   >>>> how many miles would the top swing back and forth ?   
   >>>   
   >>> Why do you care?   
   >>>   
   >>   
   >> I asking to see if  you know what you are talking about. 20,000 km is   
   >> 12,427 miles, if you support the tower it will swing at least 2 degrees   
   >> sin 2 degrees = 0.035  times 12427 = *434 miles*   
   >>   
   >> does the tip swinging wider than most states bother you ??   
   >>   
   >   
   > You're not smart enough to be asking questions.  It's not a 'tower'.   
      
   what do you propose ?   
      
   >   
   >>>   
   >>>> How much sideways force is pushed on it by a 20 mph wind ?   
   >>>   
   >>> Why do you care?   
   >>   
   >> ...to evaporate your imagination with facts.   
   >>   
   >   
   > That would be refreshing.  When are you going to start?   
      
   what are you proposing ?   
      
   >   
   >>   
   >>>   
   >>>> how much does one guy wire weigh ? (assume 20,000 km elevator height)   
   >>>   
   >>> Why would you put a guy wire? Don't assume 20,000 km elevator height,   
   >>> assume 70,000 km, you want the top of the cable to pull up the bottom of   
   >>> the cable, so you have to go beyond GEO height.   
   >>   
   >> so what is the weight of 70,000 km of cable to support 500# ?   
   >>   
   >   
   > That rather depends on what it's made of.   
      
   you wont name anything, because it is all too heavy.   
      
   got anything ?   
      
   >   
   >>   
   >> [there is no cable that will support itself 70,000 km, darling)   
   >>   
   >   
   > There is no cable that will support its own weight like that YET.  You   
   > really need to STFU until you educate yourself.   
      
   and there never will be.  do the math. check the materials, imaginarium   
   won't work either.   
      
   >   
   >>   
   >>>   
   >>>> how much does one copper cable weigh if moving 200 amps ?   
   >>>   
   >>> Don't put a copper cable. Send energy to the climber using some kind of   
   >>> beamed energy. (A laser on the ground, maybe another one in   
   >>> geosynchronous orbit, and photocells on the climber to convert back to   
   >>> electricity. Or something of that kind.)   
   >>   
   >> Use McGinn's patented plasma's and water vapor it up.   What happens   
   >> when you use a 1000 watt laser to shoot power to it ? the beam heats up   
   >> the air and defocuses the beam and the power splinters out, the power   
   >> does not get there.   
   >>   
   >> there is no know laser that can meet the dispersion requirements either   
   >> (google dispersion  laser)   
   >>   
   >   
   > Hogwash.   
      
   afraid to google for it ?   why doen't the army shoot down missles with   
   lasers ?  -- dispersion and defocusing --   
      
      
      
   >   
   >>>   
   >>>> What voltage is needed at the ground to feed the copper wires ?  assume   
   >>>> 500 V AC needed at the top.   
   >>>>   
   >>>> How much does the tower weigh counting only the copper wires, main   
   >>>> cable, and guy wires ?   
   >>>   
   >>> The copper wires and guy wires are nonexistent and therefore weigh   
      
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