If you didn’t mind being a little heavier than Earth-normal, the cloud tops of Saturn, Uranus and Neptune would be candidates for floating balloon cities.
Easy space elevators?
I’m with Black Hat guy here.
Nope; a space elevator on Saturn would need to be 53,000km long to reach the cloud-tops, compared to Earth’s 35,790km. That is a lot more weight to be supported from orbit, so even carbon nanotube wouldn’t be strong enough.
From the Wikipedia article cited upthread:
… so that, for fixed mean density, the surface gravity g is proportional to the radius r.
What is left off is that the proportionality of mass over radius squared can, to some extent, be rewritten as radius times density. (Since we are using proportionality, we can substitute diameter… or circumference, or semi-circumference, or any linear measure used consistently.)
This helps understand why Uranus is slightly LESS than earth. The advantage of the former’s diameter is overcome by the latter’s density.
Asimov pointed out that when speaking of a fixed distance from planet center, say a quarter million miles, gravitation would always be only dependent on mass.
You could therefore take whatever satellite of Saturn most matches the Moon in orbital radius, and figure SQUARE ROOT OF (95.152) as how much faster it would take to complete its orbit.
BTW, I’ve recently wondered whether “contained platforms” just at the cloud-cover visibility threshholds would work to test out the giant planets “surface gravity” by classical assumptions.
… Of course, the simple proportionality, linear measure times density, is useful largely for getting over the surprise of similar surface gravity. If you want to be at all precise, you have to take into account the departures from spheres involved in several bodies.
I’m not sure what test you’re thinking would be needed.
We can measure the gravity just by throwing something like the Galileo probe at the planet and taking measurements as it descends. A falling object would require some correcting calculations compared to a stable platform, but it wouldn’t be a terribly difficult adjustment if you had the right measurements to work from.
I think FUTBOL means floating something in the atmosphere, maybe a platform inside the gondola of a hot hydrogen balloon. Trouble is, the balloon would need to be massive to give any lift in the atmospheres of Jupiter or Saturn, which are already mostly hydrogen.
We won’t be doing this any day soon, but we may well do it some day.