The slowing of the tumble is actually more to do with a conductor (the
rocket) rotating and moving in a magnetic field (the earths) and slowing
due to hysteresis effects..basically an induced current makes the rockets
tumble slow down over time.


pj



"William R. Thompson" wrote in message
...
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