4 ms·

From what I understand, a structure needs to be quite massive to get meaningful gravity from a rotating hull unless you attempt to approach ludicrously unsafe a

From what I understand, a structure needs to be quite massive to get meaningful gravity from a rotating hull unless you attempt to approach ludicrously unsafe angular velocity which would make repair / docking a big challenge. In The Expanse, Ceres station was spun up over many, many years and still only achieved about 1/3G. Not to use a fictional universe as a basis for science but afaik they at least tried to do the math correctly.

AllegedAlec 8y ago
> From what I understand, a structure needs to be quite massive to get meaningful gravity from a rotating hull unless you attempt to approach ludicrously unsafe angular velocity which would make repair / docking a big challenge The reason it has to be so massive is that otherwise the difference in the G-forces between your head and your feet can make you sick[1]. 1: http://www.spacefuture.com/archive/inhabiting_artificial_gravity.shtml http://www.spacefuture.com/archive/inhabiting_artificial_gra...
- alex_duf 8y ago
  They talk about it in the book, it actually makes some of the characters sick
  - AllegedAlec 8y ago
    Yeah, I know. I just wanted to elucidate for others who may not have read the book what some important reasons are for making rotating ring structures quire large.
alex_duf 8y ago
There's also Medina station which has the massive drum they end up spinning. They then grow crops in it. I love the expanse, such an amazing series of books
- kakarot 8y ago
  Easily my favorite contemporary sci-fi series... but please feel free to change my mind on that.
tomp 8y ago
I think it doesn't need to be massive, it just needs to have massive radius. Could be as simple as having a really long and strong wire between two habitation modules. And you can start small (low distance, slow spin, little gravity) and increase gradually. Expanse is neat, but spinning asteroids isn't realistic. The idea is that the acceleration at the surface of Ceres is 1/3g, pointing outwards (i.e. you fall "out" into space). That would imply that the ground/rocks etc literally floats away in space. Unless the surface is structurally strong enough to resist that (unlikely with most asteroids, many of which are literally rubble piles https://en.wikipedia.org/wiki/Rubble_pile https://en.wikipedia.org/wiki/Rubble_pile ) the whole things would just disintegrate.
- kakarot 8y ago
  Very interesting point about the wire. Seems like a great idea and definitely worth exploring, but imagine if that wire got cut ;) > but spinning asteroids isn't realistic Ceres isn't an asteroid. It's a dwarf planet. It's not a pile of rubble. It's big enough to be round from its own gravity. The only object in the asteroid belt with that status, actually. > That would imply that the ground/rocks etc literally floats away in space Yea, but they considered that and planned accordingly. The entire station is underground and the surface is heavily reinforced.
  - deleted 8y ago
    [deleted]
- dsfyu404ed 8y ago
  >Could be as simple as having a really long and strong wire between two habitation modules I.e. "the crane cable you would use to lift the module under normal, 1g, earthly circumstances"

AllegedAlec 8y ago

> From what I understand, a structure needs to be quite massive to get meaningful gravity from a rotating hull unless you attempt to approach ludicrously unsafe angular velocity which would make repair / docking a big challenge The reason it has to be so massive is that otherwise the difference in the G-forces between your head and your feet can make you sick[1]. 1: http://www.spacefuture.com/archive/inhabiting_artificial_gravity.shtml http://www.spacefuture.com/archive/inhabiting_artificial_gra...

alex_duf 8y ago
They talk about it in the book, it actually makes some of the characters sick
- AllegedAlec 8y ago
  Yeah, I know. I just wanted to elucidate for others who may not have read the book what some important reasons are for making rotating ring structures quire large.

alex_duf 8y ago

There's also Medina station which has the massive drum they end up spinning. They then grow crops in it. I love the expanse, such an amazing series of books

kakarot 8y ago
Easily my favorite contemporary sci-fi series... but please feel free to change my mind on that.

tomp 8y ago

I think it doesn't need to be massive, it just needs to have massive radius. Could be as simple as having a really long and strong wire between two habitation modules. And you can start small (low distance, slow spin, little gravity) and increase gradually. Expanse is neat, but spinning asteroids isn't realistic. The idea is that the acceleration at the surface of Ceres is 1/3g, pointing outwards (i.e. you fall "out" into space). That would imply that the ground/rocks etc literally floats away in space. Unless the surface is structurally strong enough to resist that (unlikely with most asteroids, many of which are literally rubble piles https://en.wikipedia.org/wiki/Rubble_pile https://en.wikipedia.org/wiki/Rubble_pile ) the whole things would just disintegrate.

kakarot 8y ago
Very interesting point about the wire. Seems like a great idea and definitely worth exploring, but imagine if that wire got cut ;) > but spinning asteroids isn't realistic Ceres isn't an asteroid. It's a dwarf planet. It's not a pile of rubble. It's big enough to be round from its own gravity. The only object in the asteroid belt with that status, actually. > That would imply that the ground/rocks etc literally floats away in space Yea, but they considered that and planned accordingly. The entire station is underground and the surface is heavily reinforced.
- deleted 8y ago
  [deleted]
dsfyu404ed 8y ago
>Could be as simple as having a really long and strong wire between two habitation modules I.e. "the crane cable you would use to lift the module under normal, 1g, earthly circumstances"