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What about Mt. Chimborazo in Ecuador as a starting point, saving some miles, thinner atmosphere etc? It's the farthest point from Earth's center, even compared to Mt. Everest because of the bulge. Has anyone proposed starting here yet? Or using a space bola system starting around this point? But I am unsure if the 1 degree 28 minute 9 second difference from equator would cause too many difficulties with geosynchronous orbit.

Could combining space bolas with the elevator make up for the distance?

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    $\begingroup$ What do you mean by "too much"? $\endgroup$ – Phiteros Sep 17 '16 at 17:50
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    $\begingroup$ I'm not entirely sure what you mean by a "space bola", and how that might affect anything. $\endgroup$ – Nathan Tuggy Sep 18 '16 at 4:56
  • $\begingroup$ A bola:" a spacecraft or habitat connected by a cable to a counterweight or other habitat...proposed as a Mars ship, initial construction shack for a space habitat,..comfortably long and slow rotational radius for a relatively small station mass...if equipment can form the counter-weight, then equip.for artificial gravity just a cable, ...for long-term habitation, radiation shielding must rotate with the habitat, and is heavy, requiring a much stronger and heavier cable." Curreri, Peter A. A Minimized Technological Approach towards Human Self Sufficiency off Earth $\endgroup$ – RTachoir Feb 13 '17 at 5:07
  • $\begingroup$ In "too much" I mean that a geosynchronous orbit is defined as "a high Earth orbit that allows satellites to match Earth's rotation. Located at 22,236 miles (35,786 kilometers) above Earth's equator" this makes a satellite appear to stay in place over a single longitude. space.com/29222-geosynchronous-orbit.html If doing a space tether (space elevator but instead of building up it's tethered down) the item would need to have this kind of orbit if attached to the earth. Was trying to establish if the 100 miles from equator to Mt. Chimborazo too much. $\endgroup$ – RTachoir Feb 13 '17 at 5:09
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Shouldn't be a problem. I think these are the correct equations, but I haven't tried to solve them explicitly. I think the terminal mass will end up just slightly north of the equator depending on exactly how long the tether is (assumes ideal perfectly-light, perfectly-strong tether cable). If you anchored near the north pole it would be nearly horizontal and you could drive your car right onto it.

force diagram for space tether anchored at non-zero latitude

Here's a simple example where I've set two angles equal. the terminal mass will be at about 25% greater radius than for geostationary. The greater 'centrifugal force' is exactly compensated by the sum of the weaker gravitational force plus the identical tether force. Nothing about being practical, just interesting solutions

simple symmetric configuration easy to analyse

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    $\begingroup$ Can you add a citation for that material? If it's yours then please note it. If it's from somewhere else, can you give proper credit, and a link for people to go there to read further? $\endgroup$ – uhoh Dec 26 '16 at 6:38
  • $\begingroup$ The idea that you couldn't anchor off the equator didn't seem quite right, so I sketched the equations out in powerpoint and pasted it in. But I should really learn that nice equation editor you suggested. $\endgroup$ – Roger Wood Dec 28 '16 at 5:10
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I tend to agree with Roger Wood: It's not impossible to anchor a space elevator on a point 1.5 degrees off the equator. This point is 'just' off by 170 km, compared to the distance to GEO of 36,000 km. Nevertheless, this comes with some downsides:

  • You will not reach a geostationary orbit. As Roger shows in his drawing, you will get close to the desired orbit, but won't reach it. Every payload will have to use its own propulsion to get into a stable, geo-synchronous orbit and adjust the inclination to get to geo-stationary orbit.

  • There will be a constant pull on the tether. This will increase the total stress on it, but this increase should be close to negligible. Finding a material that can stand the stress is the most prominent problem, but let's assume this slight increase in load can be covered once we have the technology to build it.

  • You have to get all your payload up onto a mountain in the middle of nowhere. People will need quite some time to adapt to the thin air before they are able to work. A level place close to the ocean would be much easier to operate.

  • The savings are close to nothing - you get to climb 6 km less, compared to a total of 36,000 km distance. Note that a space elevator is not a rocket - atmosphere doesn't do any harm because the speed is low.

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  • $\begingroup$ The reason I suggested Mt.Chimborazo is that geosynchronous orbit is "the distance from the center of the earth, subtract the earth's radius from that if you want altitude above the earth's surface." wyzant.com/resources/answers/3079/… The "true height" of Mt. Chimborazo’s summit may only be 20,564 feet above sea level, but with the underlying bulge is about 89,462 feet (16.9 mi) from center mass. newsmax.com/RichardGrigonis/Google-X-Space-Elevator/2014/04/16/… $\endgroup$ – RTachoir Feb 13 '17 at 5:43
  • $\begingroup$ @RTachoir: The bulge is something all possible locations for a space elevator along the equator share. It's the same bulge you can (very slightly) profit of when installing the elevator close to the ocean. $\endgroup$ – asdfex Feb 13 '17 at 10:41

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