Subject:
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Re: NASA IS GOING BACK BABY
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Newsgroups:
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lugnet.space
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Date:
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Tue, 6 Feb 2007 23:56:54 GMT
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Viewed:
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5342 times
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In lugnet.space, Mike Petrucelli wrote:
> > It's that it's not *cost effective* to do it [with rockets].
>
> I would add *yet* to that.
The problem is rockets use reaction mass, and need to carry it along, so the
rocket equation enters into everything you do. And honestly a rocket is not a
very good way to use the energy: you have to launch at high speed (rocket
equation again), which costs you... a lot, actually... in terms of air
"firction". There's a reason rockets go up, and it's to get out of that lousy,
lossy atmosphere before you start trying to build up any significant speed (LEO
orbital velocity = Mach 25 or so. Ouch).
Space elevators and tethers have a big advantage in that energy can be delivered
in a cheap (semi-primary) way (electrical), and the "reaction mass" used doesn't
have to be carried along (the entire Earth). Even better, for something like an
orbital or "space" elevator, a significant part of your energy requirements are
*free*, tapped out of the rotational energy of the Earth - you *don't* have to
supply it.
> I don't know a town layout on the floor with a "space elevator"
> to a manufacturing platform way up on a shelf could make a
> really cool albeit parts intensive MOC.
Well, one thing you could do would be a model of the base of a space elevator.
The mopst likely one at this point would be something like the ones based on a
carbon-fiber "ribbon", where the cable itself would be absolutely invisible at
any MOC scale (current plans are for the ribbon to be perhaps 10 cm across or
less, with a thickness measured in *microns*... and use, that could be used to
haul loads to orbit, and support itself. Impressive). A model of the proposed
base would be interesting (current desings are based on the SeaLaunch platform,
so it looks somewhat like an off-shore floating oil rig without the derrick).
From fiction, a lot of authors have proposed that the base of the tether in
particular grows into a town of some size, piling up around the tether
connection point. That could make an interesting MOC, sort of a furturistic city
on top of a mountain (Kilimangaro (sp)?), forming a cone city tapering to the
nearly infinite-appearing thin cable at the center.
I also remember vividly a scene from Pellegrino's "The Killing Star" of an
Earth-based orbital tower that had essentially grown into a 23,000 mile tall
mega-city, with residences, malls, industries, etc all plaster along the sides.
Not likely, but a beautiful image... just before is was vaporised in a fraction
of a second by an R-bombing attack from another star, but that's a different
story :-).
--
Brian Davis
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Message has 1 Reply:
 | | Re: NASA IS GOING BACK BABY
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| (...) On the other hand "Space Ship One" already surpassed NASA in efficiency with the use of a "carrier plane" to get a much higher start. Building a plane specifically designed for high altitude super sonic launching of "rocket ships" is one easy (...) (17 years ago, 7-Feb-07, to lugnet.space)
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Message is in Reply To:
| | Re: NASA IS GOING BACK BABY
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| (...) I would add *yet* to that. (...) Hmmm... I don't know a town layout on the floor with a "space elevator" to a manufacturing platform way up on a shelf could make a really cool albeit parts intensive MOC. -Mike Petrucelli (17 years ago, 6-Feb-07, to lugnet.space)
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