But there has been at least one instance of astronauts creating their own artificial gravity by jogging around the interior of a non-rotating cylindrical space station.
if the centre of the room (i.e the point where the gravity caused by the rotation is 0) is reachable then I think the gravity gradients in a reasonably small space station would make it possible to jump so you reach the centre of the room and hover
I see two problems with this.
The first is a matter of practice - you need to achieve perfectly 0 velocity at the moment you hit the center of the spinning room. I’m not sure you could actually manage it, but I suppose it’s possible.
The second is a matter of size. We are not point masses. So, even though for the purposes of the jump you could treat our body as a point mass, that mass won’t be concentrated at the point of 0 gravity. Our head will point in one direction (and be subject to pseudo-gravity) and our legs in another direction (and be subject to different pseudo-gravity). Incidentally, this is a real potential problem with small, spinning stations. Our heads and our feet will experience different levels of pseudo-gravity if we are standing. It’s obviously less of a problem for large, spinning stations.
I suppose you could do some fancy calculations to try to distribute mass so it works out, but that won’t necessarily put your center of mass at the center of the room. And any movement on your part (waving your arms, legs, or head) will necessarily introduce some problems.
I don’t think it is possible. In order to be moving toward the centre, you need to have momentum, and that momentum won’t be spent getting you there - so at best, you will drift through the weightless centre and through to the opposite side.
How about using a rope ladder?
Right: the middle isn’t stable. The only way to come to rest there would be slowing down by air resistance, and any tiny miscalculation or external effect would push you outside the center.
I don’t think this is such a big problem. It’s not gravity. The only real forces here are centripital (pushing you toward the center, when you’re on the floor) and air resistance. Your head might feel different airflow than your feet, but they won’t have different inertial (gravity-like) forces on them. It won’t be anything like the tidal forces experienced in the short story “Neutron Star”, where the hero was nearly pulled apart as his craft orbited close to the title star. Lucky for him he was in the precise middle of the craft at the time.
I suspect the airflows near the center will be fluky, and you’ll get blown one way or another until you come into the steadier airflow that moves with the outer ring (floor), which will slowly speed you up until you hit the floor. Note that you might be moving pretty fast relative to that floor when you hit it.
So while I don’t think you can effectively hover indefinetly (unless you have a pocket fan and are skilled at using it), you can have a nice long floaty jump.
You might have a bit of a nasty landing, or bump into other people, so there might be rules of etiquette about such leaps of fancy.
The center of the room is no different than any other place in the room, there is no gravity gradient. The “gravity” you feel is the centrifugal force caused by the rotating reference frame. If you or any object in the room were able to cancel out your momentum and not be in contact with the floor, you would be weightless. It doesn’t matter where in the room you are. You could be in the center, or 2 inches from the floor. If you are not rotating with the room, no “gravity”.
If the room has walls however, at some point you are going to be hit from behind by a wall. The wall would push you along and you would eventually slide down the wall and end up on the floor.
Only if you disregard the air inside the vessel, which will tend to be rotating with it.
There is a treadmill in the ISS: The COLBERT.
With a couple of hand fans, and a little practice, I think you’d be able to stay in the center of a rotating space station.
True, but I think the effect of the air would be minimal.
Once you successfully jump there’s no counter force to stop you from continuing along the straight path you’re on. So you’re in a free fall, you have some velocity, and you definitely aren’t hovering in place. You no longer have any acceleration either, rotational or otherwise, so no forces are acting on you once you leave the surface. Once you start “falling” along this path you’ll just end up hitting the surface again at some point and this “landing” point will be “ahead” (relative to the direction of rotation of the station) of wherever you jumped from since you’re moving faster and covering less distance than the surface point you jumped from has to cover.
Exactly. You still have all your tangential (“horizontal”) momentum. You jump up, continue to move horizontally until you intersect with floor, also moving in the same direction but with an upwards component. This is called “landing.” It’s the same reason that when you jump on a moving airliner or train, you don’t suddenly fly backwards.
It’s not a straight jump, you move in the opposite direction to the rotation. I can find no errors with Mangetout’s earlier post with the bike. Basically he said if you ride against the spin, you get “lighter” due to lack of friction and eventually float (disregarding the air).
The movement is straight from an external point of view, but from the POV of someone standing on the floor (or the jumper) it will look curved. That’s half the fun!
That was stunning, thank you.
In a rotating space habitat that contained only a vacuum, you could hover centimetres away from the rotating floor without any tendency to fall towards it. But as soon as you put air in the habitat, the wind would blow with the rotating floor, pushing you along with it; your own inertia would cause you to intercept the floor quite quickly.
But good luck jumping in such a way that you cancel all of that momentum.
I don’t think that would be possible, actually. One way to acheive this situation would be for the space station to be spun up around you; so long as you are in a vacuum, and don’t touch the floor or other components of the station, you could remain suspended above the rotating landscape.