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One scheme for building elevators is to start from an anchor mass in synchronous orbit and to extend tethers down and up. The tether above will pull the anchor mass up and the tether below would pull the mass down. Care is taken to balance the two and keep building until the tether reaches the planet's surface. Synchronous orbit for earth is about 36,000 ...

12

In theory, yes, one could build a bridge. There are several potential problems. The first problem is that no known natural orbit is circular; all of them are ellipses. If, for example, the semi-major axis of the co-orbital elipse is 11000km, and the semi-minor axis is 10000 km, you need 1000km of "flex" in your bridge. Further, the "stable" point in ...

12

But I wonder whether they're also tidally locked, meaning a certain side of the satellite always points to the same direction relative to Earth I can not write a definitive answer about satellites in GEO, but the chances are extremely low that there are spacecraft at or near geosynchronous atlitude that are using gravity gradient stabilization (a kind of ...

8

The standard for any tidally locked body, of which Europa is a member, is to have the 0 longitude be the point at the center of the planet-facing side. That being the case, the middle of the map should be the portion facing Jupiter, the edges the part that never faces Jupiter. See Wikipedia for the referenced quote below: Tidally-locked bodies have a ...

5

Because of tidal locking. The gravitational forces between two massive bodies like the Earth and the moon will cause their rotations to slow down over long periods of time, eventually stopping them relative to one another. The smaller body will lock first because the larger body's gravitational effect is stronger, but at some point in the distant future, ...

5

The Moon is Tidally locked to the Earth. This effect is known as synchronous rotation. A tidally locked body takes just as long to rotate around its own axis as it does to revolve around its partner. For example, the same side of the Moon always faces the Earth. We have a few questions centering around the concept of tidal-locking you may want to take a ...

5

Every action is accompanied by equal and opposite reaction. Specifically, the braking of spin of a planet due to tidal forces exerted by a moon is accompanied by the planet's tidal bulging accelerating the moon's orbital speed (which promptly converts into increase of orbital radius and corresponding reduction of orbital speed). If the moon is massive ...

4

Could the Galilean moons tidally lock Jupiter? No. I think we can just look at the angular momentum for a quick answer. The rotational angular momentum of Jupiter is estimated here to be about 7E+38 kg m^2/s based on uniform density. Surprisingly, it's given as 6.9E+38 kg m^2/s here and here as well. The same link lists the four largest moons and the ...

4

LocalFluff's comment is the key to how such a planet could be habitable. A one-face planet will be uninhabitable as the atmosphere will freeze out on the dark side unless there's something major that prevents this (and that something major probably is pretty dangerous.) However, a tidally locked but eccentric planet isn't inherently uninhabitable. You can ...

2

I find the accepted answer unclear, so I'll try: The two maps in discussion use coordinate systems based on the convention that 0 longitude is the point directly facing Jupiter, but they have chosen to put that point on the far right-hand edge of the map. Dyfed Regio is on Europa's Trailing and Anti-Jovian hemispheres (not the Sub-Jovian). Note that the ...

1

It should also be pointed out that L1 Lagrange points are exceedingly useful for a variety of testing and manufacturing purposes due to pico-gravity. Any elevator constructed will likely have a station at this location anyway, with two ribbons tethered to the location instead of just one passing through. And the ribbons don't need to be simply tied, that can ...

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