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A comment on Orion has splashed down off the coast of Baja, California. Parent comment

Re:Orion has splashed down off the coast of Baja, California by throwawaymaths on Sunday December 11, 2022 @04:29PM (#33947754)
There are currently insurmountable materials science limitations, and even the materials that come close are not currently possible to manufacture at scale, or even assemble (one carbon nanotubes does not necessarily have the same properties of many carbon nanotubes) at scale into structures which will withstand the structural stresses. I believe this is not necessarily true for other celestial objects besides the earth
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Re:Orion has splashed down off the coast of Baja, California by Smaug123 on Sunday December 11, 2022 @05:36PM (#33948333)
For example, Pluto and Charon is a pair that sometimes comes up; a space elevator connecting Pluto to Charon would very possibly just about be within our current civilisation's capabilities, if for some reason we cared to build one enough to sink the Earth's economic output into it. They're tidally locked. (https://en.wikipedia.org/wiki/Space_elevator has its section on "Extraterrestrial elevators".)
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Re:Orion has splashed down off the coast of Baja, California by actionfromafar on Sunday December 11, 2022 @05:42PM (#33948394)
A space elevator for our own moon would be far more interesting to me. It could be built with known materials.
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Re:Orion has splashed down off the coast of Baja, California by throwawaymaths on Sunday December 11, 2022 @06:27PM (#33948792)
Is that true? I thought getting a 28 day period on the moon is beyond the orbit of the moon itself.
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Re:Orion has splashed down off the coast of Baja, California by actionfromafar on Sunday December 11, 2022 @08:07PM (#33949596)
I meant for going from the Moon surface to an orbit around the Moon, not reaching Earth.
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Re:Orion has splashed down off the coast of Baja, California by throwawaymaths on Sunday December 11, 2022 @08:12PM (#33949640)
Yeah I looked up the moon proposals and fundamentally they have to go to L1/L2 points and they are not stationary on the surface or have to pivot around the poles. A tether that was lunostationary is impossible since it would have to cut through the earth
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Re:Orion has splashed down off the coast of Baja, California by actionfromafar on Monday December 12, 2022 @03:12AM (#33952193)
The anchor point on the moon will be fixed. It's the counter weight at L1/L2 that will drift and will need some (small, according to Wikipedia) correction.
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Re:Orion has splashed down off the coast of Baja, California by throwawaymaths on Monday December 12, 2022 @09:38AM (#33955047)
No. Stop and think about it. The moon rotates every 28 days with respect to L1/L2.
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Re:Orion has splashed down off the coast of Baja, California by actionfromafar on Monday December 12, 2022 @12:28PM (#33957452)
I try! :-D

Isn't the moon tidally locked and that's why we never see the "far side" of the moon?

And the lagrange points are between us and the moon?

If so, I don't understand why the anchor on the moon can't be fixed.

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Re:Orion has splashed down off the coast of Baja, California by Smaug123 on Monday December 12, 2022 @01:30PM (#33958264)
For what it's worth, I think you're right, although it's been a very long time since I did any mechanics. The tidal locking isn't completely perfect, so the elevator would probably have to be basically a spool of rope rather than an anchor; and the Moon's axis of rotation precesses every 18 years ish per https://en.wikipedia.org/wiki/Cassini%27s_laws, so again there would need to be quite a lot of flex in the elevator; but I don't see why it couldn't be done.
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Re:Orion has splashed down off the coast of Baja, California by throwawaymaths on Sunday December 11, 2022 @06:26PM (#33948781)
I could be wrong but I remember reading somewhere that mars is doable with reinforced nylon cables
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Re:Orion has splashed down off the coast of Baja, California by throwawaymaths on Sunday December 11, 2022 @11:40PM (#33950949)
Ok downvotes but I looked it up on a not-necessarily-authoritative source it's estimated that a zylon cable would have a taper ratio of 13, with a mass of ~1k tons.
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