PZeller66 wrote:

If the Zenit-2
upper stage has been strengthened since then, it might not happen
again; on the other hand, it gives me a reason to keep watching
04-021B

That's a really fascinating idea, Bill. Thanks, it gives me more reason to
track it as well!

I looked at the sites Ed Cannon posted (thank you, Ed!) and compared
that against the debris lists on heavens-above. All of the Zenit-2s
seem to shed some debris: the covers over four solid separation
rockets. About a third of all Zenit-2s seem to have generated
more debris than this, so there's a fair chance that something may
happen.

If my calculations are correct, debris will be shed at a maximum of
25 m/sec (about 60 mi/hr). That doesn't lead to a major change
in orbit. Depending on the direction the junk flies off at,
the debris's new orbit will lower its perigee/raise its apogee by up
to 50 km, or change its inclination by about a fifth of a degree.

If there's a major bit of debris shed, I'd expect the booster's tumble
to slow as the debris carries off some momentum.

Okean O (1999-039B) (25861) was an eye-catcher soon after launch. I was able
to see it just three weeks after it was launched in 1999, and it was flashing
like a strobe light! I went out to observe it after reading about it on H-A. I
sort of fell away from satellite observing for a while after that summer and
didn't observe it again until the spring of 2001. I saw it shining with a
steady brightness on that pass, and on eight or nine passes since then.

Can such a rapid tumble in an orbiting rocket stop after less than two years?
Or was I just catching this object at the wrong orientation every time and
missed any kind of flash period? I've always wondered this.

I don't know how long it takes the tumblers to slow down; I think
it depends on several factors--their size and mass, and the
intensity of the Earth's magnetic field. As I understand it, magnetism
is the major factor in slowing a satellite's tumble; the spin sets up
eddy currents in the object.

--Bill Thompson