Is it safe to fly in a spinning hollow asteroid?

[Ken Fabian]

Wouldn't the Coriolis Effect for a person walking on the inside of a centrifuge be between head and feet? Or flying, between their axis side and perimeter side? (And dependent on circling the axis?)

One of the Rama stories (1st?) had someone flying the axis in a person powered craft... and crashing I think when the weather making turned on. Long time since I read that but I thought it correctly described the expected effects.

 

[DaveC426913]

Wouldn't the Coriolis Effect for a person walking on the inside of a centrifuge be between head and feet? Or flying, between their axis side and perimeter side? (And dependent on circling the axis?)

If the enclosure is small enough, yes they will feel the effect. That's why larger enclosures are preferred.

And yes, just like throwing a baseball, flying spinward and flying antispinward will have different effects. It wil be proportional to the speed though. A baseball moving at 100kph will definitely feel a bigger deflection than a human-powered glider travel at 20kph.

Of course, the problem is, if they go into a dive, that speed increases dramatically, making the problem much worse, much faster - and at the worst possible time.

One of the Rama stories (1st?) had someone flying the axis in a person powered craft... and crashing I think when the weather making turned on. Long time since I read that but I thought it correctly described the expected effects.

Yes. Rama is huge. 20 km in diameter. That's a long fall.

ChatGPT seems to think it would be dominated by radial velocity not tangential - impacting at 180-215kph almost vertically - and that accounts for air drag and deflection. I am unable to verify.

 

[A.T.]

Wouldn't the Coriolis Effect for a person walking on the inside of a centrifuge be between head and feet?

The Coriolis force doesn't depend on position, but on velocity in the rotating frame. If the centrifuge is small enough, so walking on the inside of the perimeter requires the head to move substantially slower than the pelvis (for the body to remain oriented radially), then you potentially could notice it.

But in this case you also have a substantial gradient of the centrifugal force, and thus a gradient in the compressive forces to support your body parts. This two effects would by overlaid in additive or subtractive manner, depending on in which direction you walk. Conceptually you can see the radial component of the Coriolis force as a modification of the centrifugal force.

If you walk fast enough against the rotation, they would cancel and you would feel weightless. Seen from the inertial frame you are then simply not moving with the centrifuge anymore, but staying in one place (like in a hamster wheel).

Or flying, between their axis side and perimeter side? (And dependent on circling the axis?)

Here the Coriolis force deflects the whole body tangentially.

 

[A.T.]

A baseball moving at 100kph will definitely feel a bigger deflection than a human-powered glider travel at 20kph.

No, the deflection by the Coriolis force is anti-proportional to the speed in the rotating frame. So something moving at 100 km/h will have less deflection (path curvature) than something moving at 20 km/h. That's because the Coriolis acceleration is proportional to speed, while the normal (centripetal) acceleration required for a given path curvature is proportional to speed squared.

Also, note that you don't "feel" the acceleration by inertial forces (cannot detect it locally with an accelerometer). They are only introduced into the analysis, in order to make Newton's 2nd Law work in the rotating frame.

 

[DaveC426913]

No, the deflection by the Coriolis force is anti-proportional to the speed in the rotating frame. So something moving at 100 km/h will have less deflection (path curvature) than something moving at 20 km/h. That's because the Coriolis acceleration is proportional to speed, while the normal (centripetal) acceleration required for a given path curvature is proportional to speed squared.

I was wondering about that even as I wrote it. Thanks for the catch.

Also, note that you don't "feel" the acceleration by inertial forces (cannot detect it locally with an accelerometer). They are only introduced into the analysis, in order to make Newton's 2nd Law work in the rotating frame.

Right. Because, in reality, it's not you accelerating, it's the station. (Yes?)

 

[A.T.]

Right. Because, in reality, it's not you accelerating, it's the station. (Yes?)

Yes, any off-axis point that is static in the rotating rest frame of the station undergoes proper centripetal acceleration that an accelerometer fixed to that point would indicate.