Re: Pentagon to Shoot down Spy Sat

Sylvia Else (sylvia@xxxxxxxxxxxxxxxxxxx) writes:
John Park wrote:
I think that argument also assumes that the densities* of the large object
and the fragments aren't too different. (* More accurately, the masses per
unit (area perpendicular to the direction of motion). )

Certainly the fragments will tend to have lower densities (in the sense
you defined) then the original. But it doesn't appear to require a large
change in energy (as a proportion of the total kinetic + potential) for
the resulting orbit to be mostly outside any significant atmosphere. So
although the fragment undergoes greater deceleration during the time it
spends near the original altitude, that time will not be great.

Actually I was inclined to think the fragments would have higher density
(a solid lump vs. a hollow shell), and that the change in geometry might
let some bits stay up longer (particularly true for any really dense
components--maybe RTGs?).

--John Park

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