Ed Cannon wrote:

By the way, besides Okean O Rk, quite a few other Zenits started
out as fast tumblers. They have all slowed down or even stopped.

Do you know if any of them have broken up before they slowed down?
I estimate that 2004-021B is spinning at 45 RPMs; if it's 11 meters
long and the axis is at its midpoint, then the ends experience a
centripetal acceleration of approximately 12 Gs. That seems
like a lot of stress for something that must have been built to
take lower accelerations.

I've tried to track down various Zenit-2 launchers through the
astronautix.com and heavens-above archives, but so far I've only
found one potential break-up candidate: 98-043, which may have
shed a few parts weeks after its launch.

Incidentally, I tracked 2004-021B a short while ago. It transited
Cygnus from my location, as did the Kosmos 2237 booster. They were
both heading north, with a separation of about 15 degrees, and almost
seemed to be flying in formation. It was a remarkable sight.

--Bill Thompson