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> Space elevators are actually a possible idea being considered by scientists. > The hard part is making a strong enough cable. And finding enough elevator mus

by isgb 11mo ago

> Space elevators are actually a possible idea being considered by scientists. > The hard part is making a strong enough cable. And finding enough elevator music... Most engineers would bring up a lot more issues than just finding a strong cable. Also, most attempts with e.g. carbon nanotubes have been abandoned ages ago https://www.newscientist.com/article/2093356-carbon-nanotubes-too-weak-to-get-a-space-elevator-off-the-ground/ https://www.newscientist.com/article/2093356-carbon-nanotube.... - We don't have a good ascent mechanism other than rockets - and then we might just use rockets without building an elevator. - We don't have a good (and safe) descent mechanism. - Maintenance? Protection from space debris? Protection from oscillations? Ground-protection if the elevator collapses? This is dyson-sphere level of fiction. We can do back-of-the-napkin calcualtions on how things would work, but the practicalities make it completely impossible or impractical.

mrkickling 11mo ago
You didn't even mention the music!
honkostani 11mo ago
The material is actually not a problem, if you consider active structures. https://en.wikipedia.org/wiki/Active_structure https://en.wikipedia.org/wiki/Active_structure https://en.wikipedia.org/wiki/Space_fountain https://en.wikipedia.org/wiki/Space_fountain Then again, when doing mega structures, a launch loop is more plausible.
bombcar 11mo ago
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!
- kubanczyk 11mo ago
  This presents a considerable risk of splitting English into several languages, none of them intelligible with the others.
  - SSLy 11mo ago
    have you ever been to Newcastle?
    - ben_w 11mo ago
      Aye man, wey aye, went doon there worra bairn, didn’t ah? Cannae remember much like, was only a wee nipper at the time, knaa what ah mean? Me mam an’ da took us doon the Toon when ah was nowt but a little’un, like. Divvent really remember owt aboot it proper, but aye, been the once when ah was just a littl’ bairn, me. Proper yonks ago that was, pet! (Translation: yes, once as a kid).
  - notahacker 11mo ago
    The deity in question would also have to smite purveyors of LLM translation. This might of course not be considered a drawback...
- rigmarole 11mo ago
  Related and recommended: Greg Egan “Phoresis” a sci-fi novel of two twin planets in extreme proximity to each other. (I think I read it in one of his anthologies.)
- hermitcrab 11mo ago
  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!
  - bombcar 11mo ago
    3.5x10⁵ km³ you say? 1.08321×10¹² km³ is the volume of Earth, feasibility study done! Implement!
    - hermitcrab 11mo ago
      The molten core probably isn't going to be much use. Surface area is 5x10^8 km^2. So it it 'only' the first ~2m of the crust (~6m if you don't count ocean).
seanc 11mo ago
Kim Stanley Robinson's description of a Martian space elevator falling and wrapping twice around the entire planet convinced me that they aren't a good idea. https://www.kimstanleyrobinson.info/content/clarke https://www.kimstanleyrobinson.info/content/clarke
- enraged_camel 11mo ago
  A version of this also happens in the first season of Foundation, the Apple TV series based on Asimov's novels.
  - joenot443 11mo ago
    Would you recommend that show to the HN crowd? The books are super well liked around here, for good reason. Apple's put out a staggering amount of content the last few years, I wasn't even aware this one debuted!
    - Frotag 11mo ago
      It's pretty and scratches that scifi itch. I've only read a little of the books but it's supposedly an entirely different story that coincidentally shares character names. In terms of hardness, it probably on par with Expanse, so mostly technobabble with the magical tech only used when it's convenient for the plot. The abuse of "psychohistory" is particularly egregious. There's so many scenes where it's visualized a hologram of scribbles and they zoom in on more squiggles while divining the future. But again it's pretty, so if you're okay with drama in space, it's maybe a 8/10.
    - bananaflag 11mo ago
      Not the OP, but that show is a severely dumbed down adaptation of the books. For example, each short story almost completely changes the cast (of course, with some descendants of characters appearing occasionally), as befits a saga that spans centuries. No producer was willing to run with that (as they didn't believe the audience smart enough to follow it would be big enough for the show to make a profit), so they introduced cryonics, clones, sorta-AIs (including robots out of their original context) to have some sort of continuing cast. Also, the books have a quaint 1940s (NOT 1950s as people usually say it) atmosphere, with excitement about "atomic" energy (changed to "nuclear" in the 1950s publication), distant descendents of the slide rule, and generally weird-sounding math and science, that the show totally drops in favor of a "contemporary" feel. And btw, the space elevator scene is lifted from Brin's Foundation's Triumph where it is described as a "future" event, part of Trantor's fall, predicted by Seldon's early team and trickled down to the general population.
michaelbuckbee 11mo ago
In John Scalzi's Old Man's War, there is a discussion of how the more advanced society that they're interacting with deliberately put a space elevator on Earth, not because it was the easiest or cheapest solution, but as a sort of constant reminder of just how much more technologically sophisticated they were.
- cmpb 11mo ago
  Really great book (and series). Though it's not "hard sci-fi" by any means, the technology feels real enough to keep my brain from focusing on the holes and enjoy the fun philosophical and ethical problems that Scalzi comes up with
  - shagie 11mo ago
    IIRC, it started out as a reimagining of Space Cadet by Heinlein but instead of the young it was with the old. After the first book, he then goes to explore all the questions that it brought up. The question of identity (to me) seems like the most reoccurring question. Btw, there's a new book in the series. The Shattering Peace was released in September.
gizmo686 11mo ago
Isn't the entire point of the space elevator to be the ascent/descent mechanism? Once you have the cable up, you can grab onto it and pull yourself up.
- kingkawn 11mo ago
  Doesn’t the weight of the cable itself let alone any payload preclude this from becoming real based on all plausible material science
  - gizmo686 11mo ago
    It's more of the strength-to-weight ratio than just weight. But yes, there is no known material that would work as a cable for a space elevator.
- bisby 11mo ago
  A space elevator doesnt just take you to the karman line (like in the OP website), to get to orbit, you'd need to get up to geostationary height. That's 22,000 miles. What's the best way to pull yourself directly vertical along a cable for 22,000 miles? What's the best way to descend 22,000 miles quickly, but also with a braking mechanism that isn't going to require a heat shield? Some sort of slow cable car going at 10mph even is going to take 2200 hours... 1000mph is going to take 22 hours still. That's a full day to orbit even going REALLY fast. And getting up to 1000mph vertically, for a sustained 22 hours... that's not an easy feat. And if the goal is just to get up past the karman line and use the elevator as a stage 1 for a rocket launch and detaching from the elevator while suborbital is fine, then it's a one way trip, and still need to re-enter the old fashion way. The scale of space makes all of the problems far more complicated (edit: not just the cable strength issue, but traversing the cable)
  - oofbey 11mo ago
    You don’t need to get to geostationary to get to orbit. The reason elevators need to get that high is because that’s the lowest place you could “anchor” the top of the elevator to something fixed relative to the earth.
datadrivenangel 11mo ago
Skyhooks may allow for much easier access to space within the limits of likely practical carbon nanotube based structures. A rotating tether that orbits the planet could be timed to 'catch and throw' supersonic aircraft into space. Lots of engineering still required, but potentially actually feasible compared to space elevators.
reaperducer 11mo ago
Most engineers would bring up a lot more issues than just finding a strong cable. He did. The elevator music!
Symmetry 11mo ago
Impractical on Earth given existing technology, but there are a lot of bodies in the solar system which have enough gravity to make them worth while but where they're small enough that the materials needed are ones we have right now. The Moon in particular.
thijson 11mo ago
I think a space elevator on the Moon would be more practical, pointing towards earth. The gravity force is smaller, so existing materials could work. There's not as much of an atmosphere to deal with. It would go past the L1 point between earth and the moon. It could be extended from the poles, where it's most likely where bases might exist.

by isgb 11mo ago

mrkickling 11mo ago

You didn't even mention the music!

honkostani 11mo ago

The material is actually not a problem, if you consider active structures. https://en.wikipedia.org/wiki/Active_structure https://en.wikipedia.org/wiki/Active_structure https://en.wikipedia.org/wiki/Space_fountain https://en.wikipedia.org/wiki/Space_fountain Then again, when doing mega structures, a launch loop is more plausible.

bombcar 11mo ago

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!

kubanczyk 11mo ago
This presents a considerable risk of splitting English into several languages, none of them intelligible with the others.
- SSLy 11mo ago
  have you ever been to Newcastle?
  - ben_w 11mo ago
    Aye man, wey aye, went doon there worra bairn, didn’t ah? Cannae remember much like, was only a wee nipper at the time, knaa what ah mean? Me mam an’ da took us doon the Toon when ah was nowt but a little’un, like. Divvent really remember owt aboot it proper, but aye, been the once when ah was just a littl’ bairn, me. Proper yonks ago that was, pet! (Translation: yes, once as a kid).
- notahacker 11mo ago
  The deity in question would also have to smite purveyors of LLM translation. This might of course not be considered a drawback...
rigmarole 11mo ago
Related and recommended: Greg Egan “Phoresis” a sci-fi novel of two twin planets in extreme proximity to each other. (I think I read it in one of his anthologies.)
hermitcrab 11mo ago
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!
- bombcar 11mo ago
  3.5x10⁵ km³ you say? 1.08321×10¹² km³ is the volume of Earth, feasibility study done! Implement!
  - hermitcrab 11mo ago
    The molten core probably isn't going to be much use. Surface area is 5x10^8 km^2. So it it 'only' the first ~2m of the crust (~6m if you don't count ocean).

seanc 11mo ago

Kim Stanley Robinson's description of a Martian space elevator falling and wrapping twice around the entire planet convinced me that they aren't a good idea. https://www.kimstanleyrobinson.info/content/clarke https://www.kimstanleyrobinson.info/content/clarke

enraged_camel 11mo ago
A version of this also happens in the first season of Foundation, the Apple TV series based on Asimov's novels.
- joenot443 11mo ago
  Would you recommend that show to the HN crowd? The books are super well liked around here, for good reason. Apple's put out a staggering amount of content the last few years, I wasn't even aware this one debuted!
  - Frotag 11mo ago
    It's pretty and scratches that scifi itch. I've only read a little of the books but it's supposedly an entirely different story that coincidentally shares character names. In terms of hardness, it probably on par with Expanse, so mostly technobabble with the magical tech only used when it's convenient for the plot. The abuse of "psychohistory" is particularly egregious. There's so many scenes where it's visualized a hologram of scribbles and they zoom in on more squiggles while divining the future. But again it's pretty, so if you're okay with drama in space, it's maybe a 8/10.
  - bananaflag 11mo ago
    Not the OP, but that show is a severely dumbed down adaptation of the books. For example, each short story almost completely changes the cast (of course, with some descendants of characters appearing occasionally), as befits a saga that spans centuries. No producer was willing to run with that (as they didn't believe the audience smart enough to follow it would be big enough for the show to make a profit), so they introduced cryonics, clones, sorta-AIs (including robots out of their original context) to have some sort of continuing cast. Also, the books have a quaint 1940s (NOT 1950s as people usually say it) atmosphere, with excitement about "atomic" energy (changed to "nuclear" in the 1950s publication), distant descendents of the slide rule, and generally weird-sounding math and science, that the show totally drops in favor of a "contemporary" feel. And btw, the space elevator scene is lifted from Brin's Foundation's Triumph where it is described as a "future" event, part of Trantor's fall, predicted by Seldon's early team and trickled down to the general population.

michaelbuckbee 11mo ago

In John Scalzi's Old Man's War, there is a discussion of how the more advanced society that they're interacting with deliberately put a space elevator on Earth, not because it was the easiest or cheapest solution, but as a sort of constant reminder of just how much more technologically sophisticated they were.

cmpb 11mo ago
Really great book (and series). Though it's not "hard sci-fi" by any means, the technology feels real enough to keep my brain from focusing on the holes and enjoy the fun philosophical and ethical problems that Scalzi comes up with
- shagie 11mo ago
  IIRC, it started out as a reimagining of Space Cadet by Heinlein but instead of the young it was with the old. After the first book, he then goes to explore all the questions that it brought up. The question of identity (to me) seems like the most reoccurring question. Btw, there's a new book in the series. The Shattering Peace was released in September.

gizmo686 11mo ago

Isn't the entire point of the space elevator to be the ascent/descent mechanism? Once you have the cable up, you can grab onto it and pull yourself up.

kingkawn 11mo ago
Doesn’t the weight of the cable itself let alone any payload preclude this from becoming real based on all plausible material science
- gizmo686 11mo ago
  It's more of the strength-to-weight ratio than just weight. But yes, there is no known material that would work as a cable for a space elevator.
bisby 11mo ago
A space elevator doesnt just take you to the karman line (like in the OP website), to get to orbit, you'd need to get up to geostationary height. That's 22,000 miles. What's the best way to pull yourself directly vertical along a cable for 22,000 miles? What's the best way to descend 22,000 miles quickly, but also with a braking mechanism that isn't going to require a heat shield? Some sort of slow cable car going at 10mph even is going to take 2200 hours... 1000mph is going to take 22 hours still. That's a full day to orbit even going REALLY fast. And getting up to 1000mph vertically, for a sustained 22 hours... that's not an easy feat. And if the goal is just to get up past the karman line and use the elevator as a stage 1 for a rocket launch and detaching from the elevator while suborbital is fine, then it's a one way trip, and still need to re-enter the old fashion way. The scale of space makes all of the problems far more complicated (edit: not just the cable strength issue, but traversing the cable)
- oofbey 11mo ago
  You don’t need to get to geostationary to get to orbit. The reason elevators need to get that high is because that’s the lowest place you could “anchor” the top of the elevator to something fixed relative to the earth.

datadrivenangel 11mo ago

Skyhooks may allow for much easier access to space within the limits of likely practical carbon nanotube based structures. A rotating tether that orbits the planet could be timed to 'catch and throw' supersonic aircraft into space. Lots of engineering still required, but potentially actually feasible compared to space elevators.

reaperducer 11mo ago

Most engineers would bring up a lot more issues than just finding a strong cable. He did. The elevator music!

Symmetry 11mo ago

Impractical on Earth given existing technology, but there are a lot of bodies in the solar system which have enough gravity to make them worth while but where they're small enough that the materials needed are ones we have right now. The Moon in particular.

thijson 11mo ago

I think a space elevator on the Moon would be more practical, pointing towards earth. The gravity force is smaller, so existing materials could work. There's not as much of an atmosphere to deal with. It would go past the L1 point between earth and the moon. It could be extended from the poles, where it's most likely where bases might exist.