So big that the Iridium collision is a little disquieting. Hitting some debris is one thing, but hitting another satellite? This isn't horseshoes or hand grenades: a miss by inches is a complete whiff.
It's generally assumed that many "dead" satellites aren't as "dead" as claimed and effort is put into monitoring "failed" launches to make sure they stay failed. The launch of a large communications satellite to GEO that has an upper stage failure that leaves it in a highly inclined & elliptical orbit - that just happens to be a good orbit for a spysat - is going to be monitored for some time... The Russians launch from such a high latitude anyway this is a concern.
In the Iridium case the "dead" Russian satellite had died a decade earlier and had shown no signs of zombification or undeadness since then.
And satellites tend to all be going in roughly the same direction (you get a boost from the rotation rate of the earth if you launch west-east).
Yes, but the orbital plane varies based on mission needs and launch site latitude, and these orbits generally aren't circular - they're all differently shaped ellipses. I don't think there are many low or mid altitude satellites that need equatorial positioning, whereas everything in a Clarke orbit is going to be in essentially the same orbit with the same orbital parameters, other than position in that orbit.
So far they [Clarke orbit sats] have all been successfully put in parking orbits at the end of their life but an explosion in one of these congested spots would be a real pain. Any debris is going to stay there pretty much for ever.
Not quite forever since satellites in Clarke orbits with 20 year life expectancies need fuel to maintain position.
That was the problem with Iridium collision - the Iridium satellites are in a polar orbit (to give a full Earth coverage) the Russian Kosmos was in a nearly equatorial orbit - so every orbit their paths cross (although normally well apart).
The Russian satellite was in a highly inclined orbit - the launch site was well *north* of Moscow!
And now for the really paranoid thought for the day: do any anti-Western countries have the ability to throw a bunch of nuts and bolts high enough into space to knock out satellites?
As NS says it's not that easy since it's a precision & timing problem, not a brute-force "throw a rock far enough" thing. NK can probably get to lower orbits with what they have today, but putting a small debris cloud in the right place & right time, before the debris cloud spreads to the point of making a collision unlikely but after the debris cloud expands enough to give you a chance of hitting anything - that's a lot harder.
Since an ASAT launch is a direct launch without a circularized orbit the cloud of debris from a miss reenters the atmosphere within an orbit - no mess left behind. It's the successful ASAT hits that are a debris problem.
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