Re: Pentagon to Shoot down Spy Sat

In sci.space.policy message <47c48acc$0$31016$afc38c87@xxxxxxxxxxxxxxxxx
..au>, Wed, 27 Feb 2008 08:55:24, Sylvia Else
<sylvia@xxxxxxxxxxxxxxxxxxx> posted:

An impact in a higher orbit scatters stuff all over the shop. If
there's a mechanism that selectively avoids creating debris with
increased momentum roughly in the original direction, it's not at all
clear to me what that mechanism would be.


USA 193 was clouted rather hard on and through its bottom. That gives a
strong tendency for the pieces to go more upwards than before.

Now look at the right-hand side of the height/time graph for 193 at
Heavens-Above. Clearly, anything sent upwards will have a higher apogee
and an equally-lower perigee half an orbit after that; and if it goes up
more than about 20 miles it will not survive more than about one
subsequent perigee. And anything sent downwards cannot go down far if
it is to come up again, and so cannot rise far above the impact
altitude.

Now look at the whole of the graph. Anything passively orbiting
anywhere at all near USA 193's final height has little life left anyway,
and so is of little residual value.

So, for anything to be hazardous other than briefly, it must be of
higher areal density than 193 was and it must after the impact be moving
almost horizontally with circular-orbit speed or higher; and it can do
little harm unless it reaches a considerably higher apogee.

--
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