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i remember reading here on HN someone explaining why space elevators are not possible. I can't recall why, but he/she had very convincing arguments. Anyone here remember that thread and can link it back here? Thanks
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That'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-m...
What 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.
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.
i remember reading here on HN someone explaining why space elevators are not possible. I can't recall why, but he/she had very convincing arguments. Anyone here remember that thread and can link it back here? Thanks
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?
Physics 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.
The cars would travel at up to 200kph and arrive at the space station eight days after departure from Earth. These early cable experiments are important, but someone should also be working on the composing an 8 day Elevator Muzak score that won't drive you insane.
Stairway to Heaven is about 8 minutes long, so they better work hard on speeding the elevator up to match that.
We should probably treat it more like commercial air travel than compressive-structure elevator rides.
0: 200kph*8day/8min/2min => 67.981081 gravity
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Is humor against HN rules? I regularly see such posts being downvoted and it doesn't make sense to me.
Most humor can be categorized as "insubstantive comments" and those are discouraged. It is possible to crack a joke here and get it upvoted, but it's hard to pull it off. I even once had a joke upvoted by quite a lot,* like 50 points or something, but most jokes are downvoted not because humor is forbidden, but because insubstantive comments are discouraged. Some humor is downvoted for being uncivil because a lot of…
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That trip would only take an hour, but I don't think you could build a cable and drive system capable of operating at 18 km/s.
Not sure if this would work, but how about using a wire with evenly-spaced metal beads, then using a magnet (a large one like used in MRI machines) to pull up the cart? You'll probably have to turn the magnet on/off at a specific frequency, depending on the momentum of the cart, which could be a challenge.
If you want constant acceleration, you need to maintain constant force. A higher-velocity vehicle applies that force across a greater distance per unit time, and therefore requires more power.
Accelerating 1 metric ton at 1g requires 9800 N. So at peak velocity (18 km/s), that's 180 megawatts per ton, which is more than 700 times the power to mass ratio of a Tesla P100D.
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Weird to me that they aren't accelerating till the midpoint and then breaking till the destination at a constant 1g. Gets around the space sickness by providing artificial gravity and should take ~hours rather than ~days.
That trip would only take an hour, but I don't think you could build a cable and drive system capable of operating at 18 km/s.
> "...six oval-shaped cars, each measuring 18m x 7.2m holding 30 people, ... eight days ...." Whooooa. Let's think about this for a second. Eight days means people need to sleep (and not just sitting up in a chair, no matter how comfy). At 1m x 2m per bed that would be a 15m x 4m space even without aisles to walk between the beds or down the middle or any sort of privacy separators. Also, a bathroom and actual washin…
six oval shaped cars with those measurements each is about 780 square meters in total. The average Tokyo condo is about 65 square meters (for a family of three). Somewhat unpleasant for 30 people but not really that small. Like 3 people in one Tokyo apartment density wise.
I can’t see how one would read that other than as each car holding 30 people.
You would need an extra comma to make it six cars holding 30 people in total:
”Obayashi envisages a space elevator using six oval-shaped cars, each measuring 18m x 7.2m, holding 30 people, connected by a cable”