4 ms·
The experiment sounds great. But should this work and a real cable to orbit is built, what happens when the cable snaps!? Can such a structure be made failsafe
by rietta 8y ago
The experiment sounds great. But should this work and a real cable to orbit is built, what happens when the cable snaps!? Can such a structure be made failsafe?
- deleted 8y ago[deleted]
- tarzip 8y agoThat's what safeties are for! We already have a lot of engineering around making elevators safe. TLDR the elevator will clamp on to the rails to slow the free fall. Neat info below on snapping elevator cables and some of the things that would help you. https://science.howstuffworks.com/science-vs-myth/everyday-myths/question730.htm https://science.howstuffworks.com/science-vs-myth/everyday-m...
- jessaustin 8y agoWhat rails? They're not going to run more than one of these difficult-to-build structures up for each elevator. There will be a single cable, and the car will climb it. What happens if the cable snaps will depend on how far up the car is. Low enough, and it will descend to the surface on a builtin parachute. High enough, and it will perform some portion of an orbit, before descending on its parachute.
- ghaff 8y agoPresumably you could have redundant cables. But two almost adjacent cables would still be exposed to many single points of failure, especially any caused by a deliberate attack on the system. And just a cable falling could be a significant disaster by itself.
- ben_w 8y agoOnce you have a space elevator, it’s relatively easy to send up some rockets and demolition explosives that just sit on the cables at appropriate locations and stay there waiting for a disaster; should the cable be broken by malice, accident, or natural causes, the explosives can cut the falling cable into pieces small enough that the rockets can safely guide to the ocean (or orbit, whichever has the lowest delta-v). The travel pods, likewise, can always have rockets on them whose sole purpose is to get the passengers to safely. Yes, it means you’re taking up more mass than you strictly need to, but the great thing about a space elevator is that the mass is no longer a hyper-critical parameter. But yes, no rails here.
- robotrout 8y agoThe rails? The car will travel over a stationary structure, not be pulled up by a pulley like a conventional elevator is. So it is failure of that stationary structure that we are talking about.
- ethbro 8y agoPhysics would tend towards "No." Assuming a catastrophic break near the upper end of the cable (before the counterweight), there's not much you can do to keep it from coming down.
- zadler 8y agoPerhaps unless you decide to detach the cable at the earth end? You might be able to react to a break faster than the cable can fall.
- Atheros 8y agoEven if you could react and cut the cable in 1 ms, if the counterweight is disconnected, the rest of the cable is coming down to Earth.
- Turbots 8y agoAnd most of it will probably burn up at reentry, although some of it will fall into the ocean. Isaac Arthur runs over all the options to prevent this from even happening in his Upward Bound series, eg. automatically breaking up the cable in parts by blowing fuses and having parachutes on all the parts to slow them down.
- vorg 8y agoDepending on what it's made of, a break in the cable wouldn't be instantaneous, but happen in stages. Perhaps cut the earth end at the red alert stage up top.
- KineticLensman 8y agoKim Stanley Robinson [0] explores some of the failure modes when bad actors are involved. Bad actors with serious weapons. People on the satellite end get flung off into space, the cable wraps itself around the equator, and people on the elevator had better hope that there are nearby spacecraft to pick them up. [0] https://en.wikipedia.org/wiki/Mars_trilogy https://en.wikipedia.org/wiki/Mars_trilogy
- tristanj 8y agoThere are various simulations of what may happen. Here is one that demonstrates what may happen if the cable breaks at various points. http://gassend.net/spaceelevator/breaks/ http://gassend.net/spaceelevator/breaks/ In summary, if the cable breaks at the base, the elevator will fly harmlessly into space. If it breaks at the counterweight, a large portion of the cable (several thousand miles long) will collide with the Earth’s equator.
- cantagi 8y agoThe piece that falls to Earth ends up wrapping faster and faster, this causes centrifugal force on the tip, increasing the tension in the ribbon. Often the ribbon breaks on its way down and some fragments go flying out of Earth's gravity well. I didn't expect this at all. The space elevator would become a space whip. I wonder whether this has a use case, like getting hardened unmanned space probes to speeds required for interstellar missions, or just much faster missions to other planets in the solar system.
- Hextinium 8y agoSpace elevators can be used this way because once the tether goes beyond geostationary orbit the tether is going above orbital velocity. Go far enough and its above escape velocity. So you just drag a probe out far enough and let go and it will escape the gravity well.
- ada1981 8y agoHarmless, except for the passengers.
- bencompanion 8y agoSome proposals include spacing charges along the cable to break it into small sections and enable it to come down more safely. Of course, this means lining your vulnerable cable with explosives, which seems like a bit of a design smell.