system
Given the following post, respond as if you're commenting on Reddit:
human
When creating gravity for astronauts in space why do the shuttles go end over end instead "barrel rolling"?

In all the videos I'm seeing about a mission to Mars the ship is traveling sideways(x-axis) while going nose over tail(y-axis)to create an earth-like gravity. it's quite interesting considering the lack of resistance in space.


However, it seems like a waste of fuel to have to re-orientate itself to 'rocket' shape. Why not spin on its x-axis? or is 'barrel rolling'  just not able to create the proper g force?
gpt
The acceleration due to circular motion is r * omega^2 where omega is the angular velocity of the rotating object, and r is the radius of the circle. So one problem is that a smaller radius of rotation would require a much high rate of rotation to achieve the same acceleration.

The second problem is differential acceleration. Suppose that you circular motion has a radius of 3 meters. If you are 1.5 m tall then your head experiences an acceleration that is half that of your feet. Further, the high rate of rotation in order to generate a significant acceleration for such a small radius would play havoc with your inner ear. 

Compare this to a radius of 100m. This time the differential acceleration is about 1%, and the rate of rotation is about a sixth of what the smaller radius required.