I am currently reading the The Expanse novel series. In the books there are several space colonies that are basically asteroids or planetoids (in particular Eros and Ceres) that have been spun up to act as huge centrifuges for the people living "upside-down" in tunnels inside of them. The artificial gravity on the lowest levels near the surface is stated as (minus) one third of a g.

Is this feasible? Obviously, as soon as the centrifugal force exceeds gravity everything on the surface (or the surface for that matter) wants to fly off. So you need to have some inherent stability to hold things together. Are asteroids and planetoids stable enough to do that? Intuitively I would assume that bigger bodies are more solid that smaller ones.

I know about the roche limit but that is about tidal forces between two bodies not centrifugal forces acting on one body but I assume the same concepts apply here.

(I thought about asking this to the astronomy stack exchange instead but the question is ultimately about space colonization so I put it here. Feel free to move it if you disagree.)

  • $\begingroup$ As far as I know asteroids/planetoids usually are not formed of one piece of rock but rather a lot of "loose" material held together by gravity, but you would need to have one solid piece (at least one solid outer sheel) with a sufficiently great tensile strength to make something like that possible, which seems unlikely. And even then the question would be how do you even get "on" that body=) (Edit: Perhaps though the poles?) $\endgroup$ – flawr Apr 9 '16 at 10:02
  • $\begingroup$ @flawr There is a lot of variety in asteroids, only some are rubble piles. Others are mostly solid, some are made mostly of metal. $\endgroup$ – kim holder Apr 9 '16 at 16:46
  • $\begingroup$ @kimholder I'm mostly interested in Eros and Ceres as those two are where most of the story is happening. Is their stability known? $\endgroup$ – Roman Reiner Apr 9 '16 at 16:55
  • $\begingroup$ We don't know very much about either body, but Ceres is a minor planet. It is definitely stable. One would need to know how the forces sum as the distance from the spin axis increases - calculus. I must leave that to another. The current theory is that its mantle is mostly ice. So, there is an interesting problem - ice responds to pressure by melting. $\endgroup$ – kim holder Apr 9 '16 at 17:45

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