6
$\begingroup$

In short what effect would thrust induced pseudo-gravity have on the atmosphere of a sealed cylindrical habitat that was already generating spin induced pseudo-gravity?

Assume that the thrust is along the axis of rotation of a standard Type III O'Neill Cylinder and that for the sake of simplicity there are no bodies of liquid water on the inner surface, as a concession to Moving "Day". The "Day" will last for at least a week and up to several months. What happens to the atmosphere and thus the functionality of the internal ecology of the cylinder? I was originally thinking about a situation in which the spin gravity and thrust were both one gee but if there is a rate of acceleration at which the effects are small enough for a mature ecology, including climax temperate rain forest, to survive the time trade off might be considered worthwhile so other thrust ratios are worth exploring.

$\endgroup$
3
  • $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$
    – L.Dutch
    Commented Sep 1, 2021 at 7:44
  • $\begingroup$ @PcMan also take look at comment under the answer for the q - atm it looks like this q is a wrong question for a wrong reason $\endgroup$
    – MolbOrg
    Commented Sep 1, 2021 at 7:47
  • $\begingroup$ @L.Dutch you could wait a few day before removing the comments, atm the comments identified a problem with the q and it is not a discussion but attempt to improve q which is in the scope. In a week no body will care about those comments, move it then(if you have), and it the q even not a hot q, it a niche thing. $\endgroup$
    – MolbOrg
    Commented Sep 1, 2021 at 7:54

1 Answer 1

5
$\begingroup$

The main problem will not be what happens to the air. Yes, it will move towards the rear, with a downward pressure gradient towards the front. Unless the cylinder is really long, the air at the front will still be of breathable pressure. On the Earth, air pressure halves for every 5 km altitude, and we would expect the same gradient even if the 'gravity' is thrust-based rather than mass-based (I believe Einstein showed that there was no difference between the two). So if the cylinder is 5 km long and the acceleration is 1 g, pressure at the front will be half of what it is at the back - which, in turn, will be higher than the normal inside surface pressure. The pressure at the front may even be higher because the rotation stirs up the air, and in the worst case, you could pump air from the back to the front.

A greater problem is that the overall pseudo-gravity will not be at an angle to the surface of the cylinder - 45 degrees, if thrust and rotation both provide 1 g of acceleration. Streets will become steep slides and parks steep hills. Dirt may come lose and cause massive earth slides, and tall trees would topple overunless secured. Animals would find it hard to keep balanced and will be very disoriented by the shift, All loose objects will roll towards the rear of the cylinder. Wind and rain patterns will be severely disturbed in ways that may be hard to predict.

Lower acceleration will certainly mitigate the problems. An acceleration of, say, one-quarter g would make the apparent slope far less steep and the pressure gradient far lower. Steps could probably be taken to minimize damage; for instance, houses may rotate to keep their floors 'horisontal'

$\endgroup$
5
  • 1
    $\begingroup$ the 45 degrees will be very disruptive. It would be better to impart thrust perpendicular to the axis of rotation, and less than 1g (so there is no 0 g periods anywhere!) Having net gravity with thrust maintain its same vector as without thrust would be less disruptive than everything sliding to one end of the cylinder. $\endgroup$
    – Willk
    Commented Aug 31, 2021 at 15:07
  • $\begingroup$ The length of a Type III is given as 32km but what you're saying is move in the ecosphere after the move because you don't have a settled "surface" orientation until then. sweet that works. $\endgroup$
    – Ash
    Commented Aug 31, 2021 at 23:17
  • $\begingroup$ @Ash idk, if removing ecosystem works for you, then probably you should ask about what you need to do with that cylinder. Like - my guys found a cylinder(made one) they need to transport it from point A to point B, preferably with 1g+ what needs to be done to put it in transport mode. Because another way to answer your q would be describing which problems transporting it would there be, but you asked only about ecosystem. Idk it looks like q needs some improvements, or context - wich problem do you try to solve. $\endgroup$
    – MolbOrg
    Commented Sep 1, 2021 at 7:44
  • $\begingroup$ @MolbOrg Not so much remove it as don't start it during the manufacturing process, ecology is moved in by the buyer rather than put in place by the build team. $\endgroup$
    – Ash
    Commented Sep 2, 2021 at 0:15
  • $\begingroup$ I just thought of another option: The cylinder can be split into sections, say 12, along the long axis. When moving the cylinder, you stop the rotation, open the sections like a flower and then start accelerating the assembly at 1g. The sections will seem like long, gentle valleys while accelerating due to their curvature, but nothing unmanageable. Close the "flower" upon arrival and begin rotation anew. The sectioning of the cylinder also adds safety during normal operation; a puncture will only affect one section rather than the entire cylinder. $\endgroup$ Commented Sep 6, 2021 at 7:54

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .