Re: Space Elevator by 2019?

From: Jorge R. Frank (jrfrank_at_ibm-pc.borg)
Date: 06/27/04 

Date: 27 Jun 2004 20:49:43 GMT

Peter Fairbrother <zenadsl6186@zen.co.uk> wrote in
news:BD04E7D2.51791%zenadsl6186@zen.co.uk:

> Jorge R. Frank wrote:
>
>> Peter Fairbrother <zenadsl6186@zen.co.uk> wrote in
>> news:BD04906A.5174D%zenadsl6186@zen.co.uk:
>>
>>> The thing I don't understand about a space elevator is how they are
>>> going to get the first thread in place.
>>>
>>> I read somewhere that they wanted to start at GSO and unreel it both
>>> downwards and upwards simultaneously,
>>
>> That is correct.
>>
>>> but that won't work - the bits
>>> will move sideways. Does anyone know?
>>
>> Only during deployment.
>
> Yes.
>
> At last, someone who agree that it will go sideways! Do you know any
> details of how the deployment actually works?

The sideways angle depends on the ratio of the coriolis and tidal forces.
In turn, the tidal force is proportional to tether length L, and the
coriolis force is proportional to deployment rate Ldot. So the deployment
is governed by a control law of the form Ldot = f(L), such that the tidal
force always dominates the coriolis force and the tether returns to
vertical just as deployment ends (the latter implying that Ldot decays to
zero just as L reaches Lmax).

This is, roughly speaking, the deployment strategy that NASA used with
Shuttle/TSS on STS-46 and 75, and is fairly well documented in the
literature. I imagine the designers of a space elevator would mine the
literature pretty deeply to see what has worked in the past.

I'll have to address your other questions later. 

-- 
JRF
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