O'Neil cylinder instability

Message text written by INTERNET:spacesettlers@yahoogroups.com
>> Over at
>
> howtobuildaspacehabitat-owner@yahoogroups.com
>
> there was a discussion about a long cylinder having a tendency to
wobble
> because it wants to tumble end over end. I think some long
asteroids do
> this. Any comments?<

This is a real effect, which can probably be found in many textbooks. In
"Spaceflight Dynamics" by William Wiesel (1989) there is a discussion of
this starting on page 131. He says that the effect has been observed
several times in the space program, starting with Explorer I. Energy
dissipation in its whip antennas led to a steady state of tumbling about
the major axis (end over end) after a few orbits.

Active control could prevent this. If only passive means are desired it
should be noted that it's not actually the geometric shape, but rather the
moments of inertia that matter. If the high density and low density
cylinders that I've seen discussed on this list were combined, with high
density near the "equator" and open geometry toward the ends, a longer
cylinder could be dynamically stable.