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Space Elevator

(neal.fun)
1773 points kaonwarb | 3 comments | | HN request time: 0.626s | source
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tempestn ◴[] No.45640679[source]
TIL it's estimated that over 48 tons of meteors hit the atmosphere every day.

Regarding actual space elevators though, while they're not sci-fi to the extent of something like FTL travel - ie. they're technically not physically impossible - they're still pretty firmly in the realm of sci-fi. We don't have anything close to a cable that could sustain its own weight, let alone that of whatever is being elevated. Plus, how do you stabilize the cable and lifter in the atmosphere?

A space elevator on the moon is much more feasible: less gravity, slow rotation, no atmosphere, less dangerous debris. But it's also much less useful.

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Yizahi ◴[] No.45641279[source]
The problem with space elevator is not only the lack of material today, but also the fact that such elevator is an ultimate and very fragile weapons platform, you basically get stones up the well and then drop them on the enemy. Meaning that any authoritarian country would destroy it even before it is ever built. And sturdy enough space elevator after it's break at any high point would start falling down on the planes in a loop, eventually flattening everything in its path when higher portions reach supersonic speeds. So unfortunately there is low chance it will be built, unless we sort out stuff on the planet first.
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pbmonster ◴[] No.45641357[source]
I don't see it. Why worry about a weaponized space elevator when stealth bombers, cruise missiles and ICBMs exist?

If the power building the space elevator wants to bomb you, you're going to get bombed.

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tsimionescu ◴[] No.45641613[source]
The bigger problem I think is the elevator itself. Cutting it and letting it fall would be far more destructive than any weapon ever fired or even conceived.
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pbmonster ◴[] No.45641919[source]
Probably no easy task.

Snipping off just the first few kilometers is not catastrophically destructive yet, and cutting it down further up would require multistage rocket designs, sophisticated steering/targeting and potentially significant yield (you'd need to cut unobtainium, after all...). If you can build a space elevator, you can defend against those.

You better thoroughly inspect what cargo you put on the elevator itself, of course.

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tsimionescu ◴[] No.45642342[source]
Only if the material is way over provisioned. In general, the higher the intrinsic structural load is on a material, the easier it will be to destroy. So, to defend from these attacks, you not only need a cable that can support its own weight, plus the weight of the desired payload, plus some small-is extra tolerance. Instead, you probably need a cable that can support, say, twice its own weight plus four-five times the payload. Not to mention, now you don't only need excellent strength along the cable, but also across from it, and extreme heat resistance too (all of the strength is irrelevant if it's enough to coat some part of the cable in thermite and ignite it)
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icetank ◴[] No.45642463[source]
You only need to defend the easy to reach parts. So the base and the cargo pod. To hit the upper parts you need advanced rockets and targeting systems.
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1. tsimionescu ◴[] No.45643908[source]
Why advanced? It's a stationary target that's 35,000 km long. I don't think it would be that hard to hit.

Not to mention, securing the cargo would be an extremely difficult task in itself, especially when one of the main thinga you'd like to raise through the space elevators is rocket fuel.

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2. vdqtp3 ◴[] No.45644346[source]
> stationary target that's 35,000 km long

and what, 12" wide? 24"? that's still very difficult to target

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3. tsimionescu ◴[] No.45647227[source]
In general, the more tensile strength you want in a cable made of a given material, the thicker you need to make that cable. Now sure, we can imagine whatever magical properties we want of our space elevator cable material, since no known material that could do this exists anyway. But it's far more likely that you'd need a cable that's a kilometer or more in diameter to achieve the tensile strength needed to support its weight at 35000 km of length, than it is to be a few inches wide.