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Missile Defense

Russian military leaders have expressed concern about US plans for a national missile defense system. Will defense technology be limited by possibilities for a strategic imbalance? Is this just SDI all over again?

rshowalter - 03:29pm Jul 7, 2001 EST (#6736 of 6750)
Robert Showalter showalte@macc.wisc.edu

"spinning an ICBM that needs to be guided to a very specific trajectory to release its MIRV bus would seem impractical. Remember that the inertial navigaion system for an ICBM controls a vectored thrust rocket. That guidance system needs to give constant feedback to the thrust vectoring system to assure that the booster is on just the right trajectory at the instant of payload release."

the spin of the rocket itself would be a small, and easily compensated complication -- and a pretty cheap way of making a missile immune to a boost phase lasar (assuming an accurate enough and powerful enough one was even available.)

VERY cheap, compared to the missile defense system itself, even if a lasar one could be built.

The compensation is easier, now that the military has made missile design much easier, with the global positions system.

And of course, since rockets, even the best of them, shake a lot - if much accuracy is needed, and GPS isn't used - gyros aren't the main referent anyway, though they've gotten very good -- for accuracy, and immuity to built up errors, best control is from celestial navigation -- and the stars motion is exact and predictable indeed, for the needs of warhead guidance.

gisterme - 03:50pm Jul 7, 2001 EST (#6737 of 6750)

dirac wrote ( smartalix 7/6/01 8:28pm ): Well, you can answer me later then on the other points of my post. ( smartalix 7/6/01 3:31pm )

Patiece, smartalix...I'm only one guy and Robert has been keeping my buisy showing that his MIRACLES have already come to pass. :-) See gisterme 7/7/01 1:58pm for discussion about "spinning' ICBMs.

WRT to "armor" on an ICBM body as a defense against laser attack...

http://www.permanent.com/i_refrac.htm#aerobrak "...The Space Shuttle's tiles are made from silica (SiO2) (with a thin borosilicate coating to provide a smooth, aerodynamic surface..."

I presume you've dropped your 1" thick titanium armor idea for the ablative or refractory tile approach to ICBM armor. Silica (SiO2) tiles like those used on the space shuttle need to be very precisely machined for exact fit and then installed one-by one. Not as big a probelm for an ICBM that is symmetric in shape as it is for the space shuttle, but still expensive.

Fused SiO2 powder has a density of about 2.2g/cm^3. So for an ICBM that's 20m tall and 3m in diameter (let's assume it's just a cylinder and ignore the ends for the sake easy calculation) an added 1cm thick shell of silica tiles would have a volume of about 1.9 cubic meters. That's a volume of 1.9m^3(10^6 cm^3/m^3) or 1,900,000 cm^3. The total mass at 2.2g/cm^3 would come to about 4.2 million grams or 4,200kg. That's about 9,200 pounds mass...about as much as two large automobiles. I wonder how many warheads and decoys you'd have to omit from your ICBM if you wanted to add a couple of '68 Cadillacs to it's payload instead. :-) If you did, that might make Robert's headlight example more relvevant... :-) The "two-Cadillac MIRV"; what a concept!

Why do you make me do all this work smartalix? Why don't you check out some of your ideas before you just assume they're feasible? Is dirac is right about your physics ability? After all, calculating the volume and mass of a cylinderical shell of a given material is not quite rocket science...it's a first-course high school physics problem. Don't feel too bad though, smartalix; Robert's even worse about this because he's the one who's always harping about "checking". He just seems to be above doing any for himeself. He'd rather proclaim a need for miracles than do a little high school level trigonometry to check his proclamation first.

gisterme - 03:59pm Jul 7, 2001 EST (#6738 of 6750)

rshowalter wrote( rshowalter 7/6/01 8:55pm ):

".... That takes energy -- total energy -- not just a high energy per unit time for an unspecified time.

Gisterme , you're quoting units of watts -- that's energy per unit time.

How much time? ..."

CHECK the websites I posted before, Robert. I believe they say about 5 seconds at 1kw/cm^2. If you are curious, why can't you CHECK for yourself?

rshowalter - 04:45pm Jul 7, 2001 EST (#6739 of 6750)
Robert Showalter showalte@macc.wisc.edu

I saw the 5 seconds a 1 kw/cm^2 all right. My question was -- how damaging is that? -- How much will actually be absorbed as heat, for instance -- and how much damage could that amount of thermal energy do?

That is, if you can get it delivered.

5 seconds is a long time to stay on target, in a case like this.

You wouldn't happen to have pictures of the destruction that happens for 5 seconds worth of 1 kw/cm^2, would you?

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