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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 curren
by Smaug123 4y ago
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 https://en.wikipedia.org/wiki/Space_elevator has its section on "Extraterrestrial elevators".)
- actionfromafar 4y agoA space elevator for our own moon would be far more interesting to me. It could be built with known materials.
- throwawaymaths 4y agoIs that true? I thought getting a 28 day period on the moon is beyond the orbit of the moon itself.
- actionfromafar 4y agoI meant for going from the Moon surface to an orbit around the Moon, not reaching Earth.
- throwawaymaths 4y agoYeah 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
- actionfromafar 4y agoThe 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.
- throwawaymaths 4y agoNo. Stop and think about it. The moon rotates every 28 days with respect to L1/L2.
- actionfromafar 4y agoI 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.
- Smaug123 4y agoFor 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 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.
- throwawaymaths 4y agoI could be wrong but I remember reading somewhere that mars is doable with reinforced nylon cables
- throwawaymaths 4y agoOk 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.