From: Mike Lorrey (mlorrey@datamann.com)
Date: Wed Jul 25 2001 - 11:54:41 MDT
John Clark wrote:
>
> Mike Lorrey <mlorrey@datamann.com> Wrote:
>
> > No. A conical shape will deflect a much greater amount of radar energy
> > when it is coming from head on than from the side, while a balloon will
> > have the exact same radar signature during the entire trajectory. Thus,
> > the sig of the warhead will increase in strength as its angle of
> > incidence to the radar signal increases, and decoys will be filtered out
> > as that occurs.
>
> A trivial problem that can be solved very cheaply of course as I pointed out more than
> once, but you don't want it solved, star wars wouldn't work then, that's why you don't put
> the real conical warhead in a round balloon in your scenario. The trouble is, an enemy
> might do things differently, unlike you he just might want to do things that make it hard
> for star wars not easy.
Oh, engineer, enlighten us with your wisdom. Any enemy may TRY to make
things hard for NMD, however, any attempt will detract from the warhead
carrying capability of the missile as well as be less than effective
unless the 'decoy' is of similar mass and shape as an IRV, in which case
you might as well put a warhead in your 'decoy'.
>
> > the ephemerides of a heavy warhead versus a light decoy will show
> > themselves by midcourse. [...] mass differences will show the greatest effect
> > at the apogee point in the trajectory, long before it hits air.
>
> Perhaps in some parallel universe things work that way but not in this one,
> as any high school physics student would tell you, if not an eighth grade
> science class.
a) the ionosphere and near earth space are not pure vacuums, contrary to
the hopes of the anti-NMDers, so there will, in fact, be drag of a very
minor amount throughout the trajectory of the decoys and warheads. The
blunt face of a spherical balloon will create greater IR signature than
the conical shape of the warhead. This is a rather minor amount, but not
beyond the possibility of detection by current IR technology.
b) the system that releases the decoys and thrusts them away from the
bus will have to be different than that of the IRVs, and as such will
never be able to exactly replicate the same delta-v of the IRV system,
so decoys and IRV will always follow different orbits.
>
> >A Missile doesn't follow a circular orbit, it is elliptical [...]
>
> Planets and most satellites are in elliptical orbits, missiles aren't in orbit at all and
> their trajectory is not elliptical, it's parabolic.
Any trajectory is an orbit about a common center of gravity. That the
mass of the other object gets in the way at some point is really
irrelevant to that fact. Yes, I forgot about the conic section rule on
the shape of orbits, sue me.
>
> > Again: What is the point of using decoys?
>
> Again: They weigh almost nothing, they take up almost no room in the rocket,
> they move just like the real warhead in a vacuum and are as cheap as toy balloons.
Decoys that are not of sufficiently similar mass as an actual warhead
are not useful as decoys. Between radar and IR signatures, any decoy
which is not of similar mass and shape as an actual warhead is
detectable, therefore the only proper decoy is an actual IRV. If you are
going to take up that much space on the bus, you might as well fill it
with an actual warhead.
>
> >you need to remove a real warhead to put in one or more decoys
>
> Right, I'm sure it would never occur to an enemy to wait until the rocket was
> in space to inflate the decoy balloons, the decoys would be at full size even
> as the rocket sat on the launch pad.
> I will concede the a perfect ICBM defense is possible provided the enemy is
> a gang of imbeciles.
I'm sure from this snide comment that you have no actual experience with
ICBM or missiles of any kind.
>
> > This was dealing with John's inane notion of having all IRV be spherical.
>
> BALLOONS!! I NEVER SAID ONE WORD ABOUT A SPHERICAL REENTRY WARHEAD!
> Not one fucking word.
On the contrary, you did, as a retort about the radar signature issue.
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