posted on Oct, 21 2016 @ 03:28 PM
a reply to: sputniksteve
You asked: "Could this be used as a kinetic weapon for something on earth, if it was stationary? Could you "shoot" it at a building and use it like a
man made meteor or something?"
Sure, anytime you can get an impactor going about 2.7 km/sec or faster, it will pretty much atomize itself and a mass of the target at least as big
A rail gun is one way to do it; a "Rod from God" is another way. In either case, the basic problem is that if you're trying to hit a target that's
stationary on the ground you're faced with the problem of having to move the impactor through the atmosphere at hypervelocity speeds right down where
the atmosphere is the thickest.
With a rocket launched KKV, the impactor is only moving at its fastest speed when it is in space. From the time it launches until it gets out of the
atmosphere, the KKV is underneath a streamlined launch shroud that protects it from aerodynamic forces and aerothermodynamic heating. Once it's
outside the atmosphere, it doesn't much matter what it's shaped like.
If you try to move that fast down on the deck, the impactor has to be a slender, pointy dart shape in order to avoid losing all its energy to
aerodynamic drag. The outer surface also has to be coated with a thermal protection material of some sort to avoid boiling away whatever the impactor
is made of. For example, the Sprint interceptor missile which was part of the old Sentinel Anti Missile system back in 1972 reached Mach 10 at
relatively low altitudes. It's skin temperature got up to 6200 F, which was actually hotter than the flame temperature of the rocket motor.
Nothing can survive at those temperatures for very long. Naval applications of railguns envision a flyout time of about 15 to 20 seconds to surface
targets. A Rod from God avoids that problem by boosting the impactor outside of the atmosphere (either into an orbit or onto a ballistic trajectory)
for most of its lifetime. That allows an approach to the surface target on a relatively steep trajectory, thereby spending the minimum amount of time
down at low altitudes.
Regardless of how you achieve the speed, any kinetic impactor that moves at hypervelocities down near the Earth's surface will be surrounded by a high
temperature plasma sheath. It's pretty hard to see and/or communicate through a plasma sheath, so autonomous tracking and navigation to the target
may not be possible if, for example, you wanted to use the IR portion of the spectrum.