# You enter a gigantic space habitat like Rama from the hub... **URL:** \ **Category:** Factual Questions\ **Created:** [February 20, 2018, 10:40pm UTC](https://boards.straightdope.com/t/you-enter-a-gigantic-space-habitat-like-rama-from-the-hub/809232 "2018-02-20T22:40:52Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![SamuelA](https://avatars.discourse-cdn.com/v4/letter/s/c77e96/32.png) [@SamuelA](https://boards.straightdope.com/u/SamuelA)\ **Post date:** [February 20, 2018, 10:40pm UTC](https://boards.straightdope.com/t/you-enter-a-gigantic-space-habitat-like-rama-from-the-hub/809232/1 "2018-02-20T22:40:52Z")
[Rama](https://en.wikipedia.org/wiki/Rendezvous_with_Rama) is an alien space habitat that is basically a gigantic hollow drum. It spins, and let’s just assume that the gravity at the surface is 1 G. Say you enter the hub and are basically floating there in your suit. Pressure should be lower there, because the atmosphere is spinning with the main drum. What has bothered me for years is that if you use a thruster to get started and begin to head for the surface (say you have a parachute you are going to deploy), reference frame wise the drum is going to appear to be spinning around you at a high velocity. As you get closer to the surface, the wind would be pushing you, but it seems to me that the wind wouldn’t necessarily speed you up all that quickly. You would not be falling towards the surface as fast as you “should” be falling. Instead the surface would still seem to have a large relative velocity. Would parachutes work correctly or would there be an enormous shock on deployment? ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [February 20, 2018, 11:26pm UTC](https://boards.straightdope.com/t/you-enter-a-gigantic-space-habitat-like-rama-from-the-hub/809232/2 "2018-02-20T23:26:31Z")
So long as you’re not rotating with the station, you won’t be “falling”. Rotate a little, and you’ll be falling a little. The end result is that, if you start in the center with almost no velocity, you’ll spiral out and end up hitting the surface at the same speed as you would if freefalling from great height on a planet with comparable surface gravity and atmosphere (but at an angle). ---
**Author:** ![MindsEye\_Watering](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mindseye_watering/32/3619_2.png) [@MindsEye\_Watering](https://boards.straightdope.com/u/MindsEye_Watering)\ **Post date:** [February 20, 2018, 11:39pm UTC](https://boards.straightdope.com/t/you-enter-a-gigantic-space-habitat-like-rama-from-the-hub/809232/3 "2018-02-20T23:39:08Z")
It seemed to me that one should remain in free fall all the way from the axis of the cylinder until one contacts the inner surface of the cylinder, excluding atmospheric effects close to the boundary of the shell. I have to assume that the air would be quite roiled close to the spinning cylinder, and what that would do to a mass moving from the axis to eventual contact with the inner surface I have no idea. If the above is true, then I expect a parachute would be no help or have an effect at all, as a mass moving from the axis to the surface would have only the initial velocity required to make the movement. I expect that the parachute would barely inflate. On contact with the surface, I would expect the “falling” body to quickly accelerate to the cylinder’s velocity and a lot of tumbling would be involved. ---
**Author:** ![MindsEye\_Watering](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mindseye_watering/32/3619_2.png) [@MindsEye\_Watering](https://boards.straightdope.com/u/MindsEye_Watering)\ **Post date:** [February 20, 2018, 11:44pm UTC](https://boards.straightdope.com/t/you-enter-a-gigantic-space-habitat-like-rama-from-the-hub/809232/4 "2018-02-20T23:44:10Z")
> [@Chronos](#): > > So long as you’re not rotating with the station, you won’t be “falling”. Rotate a little, and you’ll be falling a little. The end result is that, if you start in the center with almost no velocity, you’ll spiral out and end up hitting the surface at the same speed as you would if freefalling from great height on a planet with comparable surface gravity and atmosphere (but at an angle). But the inside of Rama would have very very little intrinsic gravity like a planet. The body moving from the axis to the surface is not “falling” at all as it would on a planet. Yes? ---
**Author:** ![markn\_1](https://avatars.discourse-cdn.com/v4/letter/m/f9ae1b/32.png) [@markn\_1](https://boards.straightdope.com/u/markn_1)\ **Post date:** [February 20, 2018, 11:58pm UTC](https://boards.straightdope.com/t/you-enter-a-gigantic-space-habitat-like-rama-from-the-hub/809232/5 "2018-02-20T23:58:37Z")
This was discussed on this board a couple of years ago: [https://boards.straightdope.com/sdmb/showthread.php?t=795675](https://boards.straightdope.com/sdmb/showthread.php?t=795675) ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [February 21, 2018, 12:40am UTC](https://boards.straightdope.com/t/you-enter-a-gigantic-space-habitat-like-rama-from-the-hub/809232/6 "2018-02-21T00:40:10Z")
All of the references to “falling” or gravity in my post were referring to the centrifugal force inside of the cylinder. I’m not worrying about “real gravity” at all, not that there’s actually all that much distinction between them. ---
**Author:** ![Chimera](https://avatars.discourse-cdn.com/v4/letter/c/8e8cbc/32.png) [@Chimera](https://boards.straightdope.com/u/Chimera)\ **Post date:** [February 21, 2018, 3:07am UTC](https://boards.straightdope.com/t/you-enter-a-gigantic-space-habitat-like-rama-from-the-hub/809232/7 "2018-02-21T03:07:26Z")
> [@markn\_1](#): > > This was discussed on this board a couple of years ago: > [https://boards.straightdope.com/sdmb/showthread.php?t=795675](https://boards.straightdope.com/sdmb/showthread.php?t=795675) Which point to still older threads. 🆒 Babylon 5. Captain Sheridan jumped out of the central train and free-fell. The danger was that he would hit the ground at about 60mph, if I recall. ---
**Author:** ![Projammer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/projammer/32/559_2.png) [@Projammer](https://boards.straightdope.com/u/Projammer)\ **Post date:** [February 22, 2018, 12:21am UTC](https://boards.straightdope.com/t/you-enter-a-gigantic-space-habitat-like-rama-from-the-hub/809232/8 "2018-02-22T00:21:28Z")
But the atmosphere within the sphere will be rotating along with the sphere unless the interior is a completely smooth frictionless surface. That motion alone should be enough to inflate the chute while centrifugal (centripetal?) force would keep you moving towards the surface. Or have I had too much to drink since my last physics class? ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [February 22, 2018, 1:33am UTC](https://boards.straightdope.com/t/you-enter-a-gigantic-space-habitat-like-rama-from-the-hub/809232/9 "2018-02-22T01:33:23Z")
Yes, a parachute would work, as long as the habitat is big enough to give it enough time to deploy.