At 02:19 PM 27/05/03, you wrote:
> >why bother with an orbit at all? All you really need (for LEO at least)
> >is to copy and slightly upsize RRS space shot and put a fragmentation
> >warhead on the top of it
>
>I am not an expert on this but I understand that hitting an object that
>goes maybe 9km/sec is fairly hard even if you happen to be directly in
>front of it and assuming it does not maneouver at all. If you will
>calculate a little you will see that your fragmentation thing will be
>spread out very thin very fast if you miss by just milliseconds or tens of
>meters, and it gives you just one try. Ten meters off at 100km is 1:10000
>precision and the miliseconds (about one milisecond for 10 meters at
>9km/s) represents 1:600000 of the about 10 minute launch-to-orbit time.
>iow, you better be rather good at precision. I don't think that this can
>be achieved without several realtime corrections anyway so the projectile
>must be actively guided.
>
>Peter

Denial of NEO can be done with two methods. One is the bullet on a bullet
which you mention which is the hardest technically but has been demonstrated
a few times. The Patriot would be a sub orbital version even though its
actually
a sam. Then there are the enhanced derivatives of that. One is where the
warhead deploys basically a fishing net. They still try to hit the body
which is a
  hard kill, but hitting the net will either damage the target or cause severe
guidance problems which is a soft kill. The target either tumbles and is
unable
to correct before it exhaust propellants or its outside of its guidance
system limits.

The other version is a shotgun approach to things. It's more or less a
fragmentary
warhead. Think of something about the size of a small beer fridge being
stuffed with
steel balls and explosives and you get the idea. Contrary to what you think
you
really don't want to fire it in the face of an oncoming target. The timing
isn't that big
  a problem its more to do with the  further contamination of neo with high
kinetic
particles. I.e. you shoot,explode, and destroy a satellite, the bits and
pieces of the
satellite then become potentially lethal projectiles for everything else.
That's one
of the big problems with this is shooting and then causing a cascade of
destroyed
bits and pieces of things that go onto hit and destroy something else.

It doesn't take much of a particle to do significant damage. A fleck of
paint can penetrate
most vehicles skin. A nut or an old glove can easily penetrate about 6-8
inches of steel.
The skins on the LEM were only 30thou thick aluminum for example and that
is a man capable
vehicle.

There is a worst case scenario where this leads to a catastrophic cascade
of destruction that
results in a layer of debris too thick to safely get through. I believe the
estimate is any where from
2,000 to 8,000 years before it would be safe to pass though again. There is
a natural attrition of the
debris as it hits the odd finger of atmosphere and slows down enough to
re-enter. The atmosphere
fringes expand and contract in reaction to solar winds and not to the
amount of cow methane
produced.....

Dave

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