Let’s say a few centuries in the future, we have captured an asteroid into orbit and built a space station out of its material. The station is a ring that encircles the equator in Low Earth Orbit, tethered by multiple cables and moves with the planet at orbital speed.

The first parts of the station were built several centuries before the last ones, and is in constant refit to update older tech with newer advancements. The tethers are made out of a strong material like graphene or nanothreads, and are large enough to allow a space elevator to travel through.

Let’s say there is a catastrophe in one of the older sections, one of the old tethers sheers away from the station with great force. What would happen to the cable as it fell to Earth? Is it possible for it to snap to the earth like a rubber band? Would it need to be made of a different material for it to do this, or is it a physical impossibility? How extensive would the damage on earth be, and how far away could the effects be felt? And what effect would the catastrophe have on the station itself?

Alternatively, would there be a major difference if the tether were instead to break in the middle? my understanding is the top half would float along with the Coriolis force, but could the bottom half snap to the ground or would it just fall over?

I’ve read Blaise Gassend’s thoughts on space elevators, but his examples seem to be for a tether that extends into GEO, well past this particular station. Would the mechanics of his simulated tether breaks be relatively the same for a much shorter tether?

  • $\begingroup$ In Low Earth Orbit, station has to move considerably faster than the surface below. If tethering, it should be tethered to something above it. $\endgroup$ – Alexander Jan 14 '20 at 22:29
  • $\begingroup$ If connected with enough tethers, couldn't the station be slowed to orbital speed? $\endgroup$ – carsonogen089 Jan 14 '20 at 22:30
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    $\begingroup$ A station like this needs to be in geosynchronous orbit. That way its tethers to the ground are practical. If it is closer to Earth than geosynchronous orbit, there are only two possibilities. (a) It completes an orbit in less time than earth rotates, so its tethers to the ground snap or (b) it is not moving fast enough to stay in orbit, and falls out of the sky onto the Earth. $\endgroup$ – John Dallman Jan 14 '20 at 22:36
  • $\begingroup$ This means the station is not really orbiting. The antipode tethers are actually bearing the weight of the station. The station itself must be extremely rigid to prevent collapse. $\endgroup$ – Alexander Jan 14 '20 at 22:38
  • $\begingroup$ I got the impression from Isaac Arthur's video on Orbital Infrastructure that a ring could be built lower than GEO and could move with the planet at orbital speed. Is there a trick to getting it to work as described above? youtube.com/watch?v=HkU85zKxK-s $\endgroup$ – carsonogen089 Jan 14 '20 at 22:45

The cable close to the Earth would fall to Earth possibly creating much damage. Higher sections of the cable would be traveling so fast when they hit the atmosphere that they would burn up. Assuming that only the top station in geostationary orbit is truly in orbit and the rest is in a state of tension, once set free sections further out from the station (counter balance object) would be flung out to a higher orbit and those below would eventually fall to Earth and mostly burn up.

  • $\begingroup$ I think lower cable would burn up too - it is even faster moving than upper. If this stuff is carbon that would definitely burn up on re-entry. $\endgroup$ – Willk Jan 15 '20 at 17:12
  • $\begingroup$ Well the cable is stationary with respect to the Earth all the way up so the first few miles is just going to flop onto the ground like a failed indian rope trick, but the higher portions will start coiling and flapping about as they come down and at some height the heating cause it to burn. $\endgroup$ – Slarty Jan 15 '20 at 17:17

The loose tether would burn in the atmosphere. The rest of the station, still holding 99.9999% of the original mass after snapping, would have a tiny-teeny change in its orbit. Maybe some rotational stabilization would be needed, standard issue of anything sitting in orbit.


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