Re: New (?) take on orbital elevators (perhaps dumb!)

On Mar 28, 3:49 am, Richard Burke <i...@xxxxxxxxxxxxxxxxxx> wrote:

Might it not actually be easier than a 'standard' orbital elevator
design? You could fling mass out for very little energy by putting
similar masses out on both arms simultaneously. The stresses at the
pivot-point would presumably balance to zero. Power for the drive that
keeps rotation going could be pumped up the arms. You might even be able
to use the part of the arms that are in the atmosphere to generate lift.
If there's damage to the system, the bits fly off into space. Hey, it
might even be cheaper!

The reason a "space elevator" needs to be equatorial is to have the
bottom move at the same rotations per day as the middle, with no side
forces. If you move it off the equator, then the orbit is a
sinusoidal curve around the earth, because all you do is tilt the
plane of the orbit.

So, no, you can't put it at a pole. Or even a few miles off the
equator.

A polar orbit at the geosynchronous distance would be above the North
pole at 0:00 and the south pole at 12:00.

A Space elevator is a structure in geosynchronous orbit which just
happens to be large enough to reach the ground. Which is over 20,000
miles, it's center of gravity, though, has to be in geosynchronous
orbit.

If you try to leave a space elevator any place bu the geosynchronous
orbit, you would have the wrong orbital velocity. 1000 km up, the
orbital velocity is 7.35 km/sec; a period of 105 minutes, not 24
hours. If you tossed something off the space elevator at an altitude
of 1000 km, it would only have about 0.5 km/sec velocity; it would
plummet to the Earth. At the 35850 km altitude of the geosynchronous
orbit, the velocity is 3.07 km/sec. If you have launches for the rest
of the solar system leave from the far end then you would be at double
that, 71000 km; the orbital velocity is 2.27km/sec, but you'd be going
at over twice the orbital velocity, 5.6 km/sec, which is a bit of a
nice gain.

It's he cumulative difference between the orbital velocity and the 24
hour rotation speed which sets up a consistent strain on the elevator;
I suspect a practical elevator would need to use suspension bridge
techniques and tension cables to take up the stress on the lift
structure.

.

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