Obviously the greater a planet's gravity, the stronger the material of the space elevator's cable would need to be in order to support its own weight. However, doesn't greater rotation speed reduce an elevator's required length by increasing centrifugal force?
Absolutely massive super-Earths are probably out of the question with regard to space elevator construction (but correct me if I'm wrong!), but what about a planet of two Earth masses? According to this planet calculator I found through Google, a planet of Earth's density but twice the mass would have 1.26 times the radius and 1.27 times Earth's surface gravity (I'd also love to be corrected here if this is wrong).
Forgive me for being unable to do the math myself, but given a surface gravity of 1.27g:
- Would it even be possible for conceivable materials (such as carbon nanotubes or graphene ribbons or something else I've never heard of) to support a space elevator if the planet had an Earth-like ~24 or ~25 hour day?
- If an elevator at such a rotation speed is in fact feasible, how long could the days be before a space elevator is impossible using conceivable materials?
- If a shorter day is required to build a space elevator on such a planet, how short would the day need to be?
I'm not a physicist or chemist and admit I don't know the bounds of "conceivable materials". I don't want to use unobtainium.
In case it affects any answers, FYI my primary interest in asking this question regards a planet I'm trying to design that is the homeworld of an alien civilization, not humans, so "find a better candidate planet" isn't really an option for them. I'm pretty married to the planet's gravity, so I'm willing to accept the suggestion of discarding the whole space elevator idea if it turns out to be basically impossible to execute.