XPost: sci.space.policy, sci.physics
From: invalid@invalid.com
On 6/19/2018 4:38 PM, Fred J. McCall wrote:
> Sergio wrote on Tue, 19 Jun 2018 15:58:10 -0500:
>
>> 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.
>>
>
> You do the math.
you gave up.
>
>>
>> what else are you going to use besides steel ?
>>
>
> Almost anything.
like what ? anything real ?
>
>>
>> NOTHING can support its own weight of 10,000 km of it.
>>
>
> False. You really need to do some research.
name it, else you are lying.
>
>>
>> go ahead, NAME what you propose to use.
>>
>
> Carbon nanotubes.
they are held in a matrix of epoxy glue. your 10,000 km of glue wont
support itself.
>
>>
>>>
>>>>
>>>> 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.
>>
>
> Don't look now, but I think you just claimed that space satellites and
> the Moon are impossible.
those are your words, now try to refocus on the topic, If your space
elevator is a cable in orbit, atmospheric drag ruins it.
>
>>
>>>
>>>>
>>>>>
>>>>>> 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 ?
>>
>
> And in that question you demonstrate just how clueless you are.
again, no info from you. Because you have no idea what you are typing
about.
>
>>
>>>
>>>>>
>>>>>> 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 ?
>>
>
> I'm proposing you start making sense (but I'm not holding my breath).
so you propose nothing, and state nothing, and know nothing.
>
>>
>>>
>>>>
>>>>>
>>>>>> 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 ?
>>
>
> Jesus, go learn something. Right now you just sound abysmally stupid.
no reason to bring God into this, he cant help you.
>
>>
>>>
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