Why would cranes fly so high?
Space Elevator
241–250 of 414 posts
Re: Space Elevator
#242Very cool. One thing I wish was better shown: space is close, it's just hard to go up. Our liveable breathable atmosphere is razor thin compared to the size of earth. In most cases, 100km is less than the distance between sizeable metropolitan areas. It's a day long bike ride. Air runs out less than a bus ride across town. A 15k jog/hike would put you in the stratosphere. Those jet aircraft that seem so high are clos…
> it's just hard to go up.
Eh. Going up is easy. A Frenchman, a sheep, duck, and rooster solved the whole ‘up’ thing over two centuries ago.
But going DOWN? That’s far more difficult. What wonders may lie beneath our feet: vast caverns, ore, underground oceans… hard to get to though.
Re: Space Elevator
#243Very cool. One thing I wish was better shown: space is close, it's just hard to go up. Our liveable breathable atmosphere is razor thin compared to the size of earth. In most cases, 100km is less than the distance between sizeable metropolitan areas. It's a day long bike ride. Air runs out less than a bus ride across town. A 15k jog/hike would put you in the stratosphere. Those jet aircraft that seem so high are clos…
> it's just hard to go up Going up is the comparatively easy part, it's not exactly rocket science. Going fast enough sideways so you stay up there is the tricky bit.
It's NOT rocket science?
Re: Space Elevator
#244Very cool. One thing I wish was better shown: space is close, it's just hard to go up. Our liveable breathable atmosphere is razor thin compared to the size of earth. In most cases, 100km is less than the distance between sizeable metropolitan areas. It's a day long bike ride. Air runs out less than a bus ride across town. A 15k jog/hike would put you in the stratosphere. Those jet aircraft that seem so high are clos…
True statement, but disclaimer: your friends may be closer if you live in a European city without American suburban sprawl...
Re: Space Elevator
#245Earlier quoted context omitted.
All we have to do is make the global religion require bringing a rock to a specific location; after long enough we’ll have a mountain so high it extends out of the atmosphere!
To get to the Kármán line (100k) a mountain with a 60 degree slope would require a base of 115km. A cone with 115km diameter base has a volume of 3.5×10^5 km^3. Which is 3.5x10^14 m^3, which is about 10^15 kg of rock. So it is going to take you a while!
3.5x10⁵ km³ you say?
1.08321×10¹² km³ is the volume of Earth, feasibility study done! Implement!
Re: Space Elevator
#246Earlier quoted context omitted.
> it's just hard to go up Going up is the comparatively easy part, it's not exactly rocket science. Going fast enough sideways so you stay up there is the tricky bit.
It's NOT rocket science?
You can reach space using air breathing jets. You can’t stay in space using air breathing jets.
Re: Space Elevator
#247TIL 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,…
> A space elevator on the moon is much more feasible: less gravity, slow rotation The slow rotation is a minus, it means you've got to string the tether up to L1 instead of "just" up to geo/luna-stationary orbit. A lunar space elevator needs to be at least 56000 km long, more than 20000 km longer than the one to earth. > But it's also much less useful. Yeah, especially because all the things that make lunar space ele…
Ah, good catch. Stand corrected on that one.
Re: Space Elevator
#248Very cool. One thing I wish was better shown: space is close, it's just hard to go up. Our liveable breathable atmosphere is razor thin compared to the size of earth. In most cases, 100km is less than the distance between sizeable metropolitan areas. It's a day long bike ride. Air runs out less than a bus ride across town. A 15k jog/hike would put you in the stratosphere. Those jet aircraft that seem so high are clos…
For a standard globe that you might see in a classroom, the Earth's atmosphere is about as thick as the paper glued to the outside that displays the map.
Re: Space Elevator
#249Earlier quoted context omitted.
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 elevat…
One nuke will kill any realistic sci-fi material. And guidance for those is a cheap and tested.
Nukes are a lot less effective when there is little or no atmosphere to push on.
Re: Space Elevator
#250TIL 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,…
Have you ever tried to balance a string on its end? It gets harder, the longer the string is. There aren’t any other physics than that.
I think most plans envisage a large mass (such as a captured asteroid) in geostationary orbit to anchor the top of the elevator cable.