From: "Paul F Austin" <paustin@digital.net>
Newsgroups: rec.aviation.military
Subject: Re: Orbital kills
Date: Fri, 1 Oct 1999 15:22:52 -0400

Eric Pinnell wrote
> "Paul F Austin" wrote:
>
>>Directed energy weapons _won't_ be useful for terminal defense. There's a
>>reason the ABL is tasked with boost-phase defense: boosters are soft. RVs
>>are extremely tough objects _designed_ for extreme thermal enviroments.
>>The thermal environments they're designed for are the fireballs of
>>nuclear weapons. The thermal fluences the RVs are designed to survive
>>are such that they are un-lucrative targets for any DEW.
>
>     Not if if you have sufficient power behind the energy weapon.
>The RVs are designed to withstand the heat of re-entry, which is why
>frying them is tough.

What you're describing amounts to "how hard is your target? let there be a
LASER 10x tougher". Eric, you don't know what you're talking about.

The thermal loads that modern RVs are designed to are _not_ the re-entry
loads. They are designed to survive and function after a large nuclear burst
at close range. The people who work on orbital LASER systems know what those
limits are. That's why those systems are designed for _boost phase_
intercept.

Think back on the system proposed by SDIO: orbital DEW or KE interceptors
for boost-phase intercept, a mid-course EXO interceptor layer designed to
engage post-boost RV against a cold space background and finally there's an
ENDO interceptor layer to catch the leakers. All _three_ layers were
required to even begin to promise "no leakers" defense of CONUS.

If orbital LASERs had the infinite puissance that you've fantasize, do you
think that competent system engineers would add the two other (very
expensive) layers for funsies?

The boost phase layer justified its existence because each kill of an ICBM
prior to busing has great payoff with 5-10 nuclear weapons killed with each
booster. Once boost phase is over, the RVs are coasting against a 4K
background. Don't you think that someone might have thought to put the many
LEO LASERs to further use by having the ones that _weren't_ over the launch
area roll over and shoot at the RVs? They _did_ think of that, ran the
numbers and found out that a LASER has low lethality against an RV.

>    But 10 Megwatts is a hell of a beam.  If you focussed it on a
>square meter warhead, it would mean an energy density 10,000 times
>that of ordinary sunlight.  Yow!

Read "The Effects of Nuclear Weapons". Run some of the numbers. Compare them
with 1KW/cm^2.

In any case, large aperature LASERs aren't "focused". They present a
collimated beam that starts out the size of the launching optics and
diverges with distance.

>     Terminal defense could be accomplished by a sandcaster or else an
>air breathing scramjet powered SAM.


Richard Garwin dreamed up the "sandcaster". You're going to have a hard time
selling it to the neighbors since although sand particles are lethal enough
to a M10 RV at 100,000 feet the way you _get_ the sand to 100,000 feet is
with a nuclear weapon of your own. Going off at ground level. Hence the
neighbors' complaints.

Think spears. Another thing that Garwin dreamed up were _very tall_ poles to
impale the RV before it got within the lethal radius of a very hard silo. Of
course that doesn't do your house much good since a nuclear cookie salvage
fuzed a thousand feet up is indistinguishable from a ground burst in your
living room.

As far as SCRAMJET powered interceptors, why bother? Rockets work perfectly
well and are a lot simpler. You're going to have more than enough
difficulties with the tracking RADAR, the engagement control system and the
seeker that you don't want propulsion headaches on top of it.

--
Conscience, that quiet voice that says "Someone may be watching"

Paul F Austin
paustin@digital.net

From: "Paul F Austin" <paustin@digital.net>
Newsgroups: rec.aviation.military
Subject: Re: Orbital kills
Date: Sun, 3 Oct 1999 20:11:26 -0400

Eric Pinnell wrote
>"Paul F Austin" wrote:
>
>     A large nuclear burst at close range would incinerate any
>material object, assuming you were within the zone of total
>destruction.  In case you didn't know, the heat of a nuclear fireball
>is many millions of degrees, and no structure can withstand a close
>range blast.

Like I said before: you don't know what you're talking about. Study up.
Spartan warheads (MT range) were optimized for X-ray kills of incoming RVs.
Read up on the mechanisms. You may learn something. I would suggest George
Messenger's book (chapter 4).


>>Think back on the system proposed by SDIO: orbital DEW or KE interceptors
>>for boost-phase intercept, a mid-course EXO interceptor layer designed to
>>engage post-boost RV against a cold space background and finally there's an
>>ENDO interceptor layer to catch the leakers. All _three_ layers were
>>required to even begin to promise "no leakers" defense of CONUS.
>
>    This is primarily due to the fact that the weapons are
>projectiles, not energy weapons.  None of the energy weapons developed
>by SDI were ever deployed, except on the ground for testing purposes.

_None_ of the SDI systems were even prototyped. The SDIO architecture
projected technology for _all_ systems rather than monomaniacally focusing
of "my favorite coool weapon". Those people know a great deal more than you
do. You would learn something from reading about their plans.


>>...Once boost phase is over, the RVs are coasting against a 4K
>>background. Don't you think that someone might have thought to put the
>>many LEO LASERs to further use by having the ones that _weren't_ over
>>the launch area roll over and shoot at the RVs? They _did_ think of
>>that, ran the numbers and found out that a LASER has low lethality
>>against an RV.
>
>   No, the problem has always been weapon power.  They have only
>recently been able to make a megawatt plus class laser.

The people working at SDIO on Directed Energy Weapons were aiming for
precisely the LASER battle stations you're dreaming about. They didn't
see them as GodSats at the time and they're not now.

>And I'd like
>to point out something else.  If the RV is indeed undetectable, then
>*ANY* weapon system will not function post boost phase, since by
>definition you can't attack the undetectable object.

Go back and read again. I didn't say anything about "undetectable".
Midcourse intercept depends on something like SBIRS-Low, looking up at cold
space to detect RVs in flight: relatively easy. A high orbit system like
SBIRS-High has to look down at a warm earth and pick the RVs out of clutter:
very difficult.

The detection systems (SBIRS and Ground Based RADAR) provide track data for
interceptors. If the LASERs _could_ kill RVs, they would be superior to
Kinetic Energy Kill Vehicles. They can't so they're not.

>   High powered LASERS are the *ONLY* effective means of attacking a
>target during boost phaser.  Orbiting missile killer platforms would
>require the deployment of vast numbers of platforms, and they could
>easily be overwhelmed, since only a portion of the platforms would be
>in range at any given moment.

_Any_ boost-phase attack system is going to be flying in LEO in large
numbers. Even a HEO system is too distant to be effective, never mind GEO.
Believe it, if you want an orbital boost-phase killer, you're going to buy a
lot of satellites and put them in LEO.

If you can't understand anything else, calculate the two-way delay between
GEO and the surface. You're going to try to hold a 20 nanoradian-precise
pointing system with a quarter-second delay while the target moves about 20
_micro-radians_ during your loop delay. Your target can be anywhere in a
1000-spot size volume by the time your LASER pulse arrives. Moving to HEO
cuts that uncertainty by a factor of 4 to only 250-spot size uncertainty.



>>In any case, large aperature LASERs aren't "focused". They present a
>>collimated beam that starts out the size of the launching optics and
>>diverges with distance.
>
>  All lasers have mirrors that are capable of shaping and focussing
>the beam.


No shit? They also generate a collimated beam that's "focused" on infinity.
If you think your "orbital battle station" is going to dynamically point
focus its beam, you're wrong.


>>Richard Garwin dreamed up the "sandcaster". You're going to have a hard
>>time selling it to the neighbors since although sand particles are
>>lethal enough to a M10 RV at 100,000 feet the way you _get_ the sand to
>>100,000 feet is with a nuclear weapon of your own. Going off at ground
>>level. Hence the neighbors' complaints.
>
>    Well, technically, they plan to use some sort of super dense ball
>bearings, but the principle is the same.

Um, who's "they"? Game designers? You don't seem to understand.
"Sandcasters" are nuclear mines which are set off prior to the first RV
arriving to fling debris into air to kill incoming weapons. Think about
explaining to a farmer in Nebraska that the site you want to build in the
east forty contains a 100KT nuke that you plan on setting off when you
_think_ an attack is imminent.


>>Think spears. Another thing that Garwin dreamed up were _very tall_
>>poles to impale the RV before it got within the lethal radius of a very
>>hard silo. Of course that doesn't do your house much good since a
>>nuclear cookie salvage fuzed a thousand feet up is indistinguishable
>>from a ground burst in your living room.
>
>   Hey, not all ideas from Sci-Fi have any real world use.


Richard Garwin isn't a science fiction writer. He's an IBM Fellow who was
working under contract to BMDO in the seventies.

--
Conscience, that quiet voice that says "Someone may be watching"

Paul F Austin
paustin@digital.net

From: "Paul F Austin" <paustin@digital.net>
Newsgroups: rec.aviation.military
Subject: Re: Orbital kills
Date: Fri, 8 Oct 1999 23:08:15 -0400

Eric Pinnell wrote
>"Paul F Austin"wrote:
>>Eric Pinnell wrote
>>>"Paul F Austin" wrote:
>>>
>>>     A large nuclear burst at close range would incinerate any
>>>material object, assuming you were within the zone of total
>>>destruction.  In case you didn't know, the heat of a nuclear fireball
>>>is many millions of degrees, and no structure can withstand a close
>>>range blast.
>>
>>Like I said before: you don't know what you're talking about. Study up.
>>Spartan warheads (MT range) were optimized for X-ray kills of incoming
>>RVs. Read up on the mechanisms. You may learn something. I would suggest
>>George Messenger's book (chapter 4).
>
>   OK smart guy.  Name ONE object that can withstand a 1 megaton
>nuclear warhead detonated at a range of 100 meters.  Even
>superhardened missile silos don't cut it.  So tell me, what is this
>magical mystical obtainium you intent to make your RVs out of?


Eric, I was the System Engineer on a project (Advanced Hardened Avionics
Technology) for USASDC in the late '80s. My job was to design and build a
computer for interceptors that would survive and function while inside the
fireball. I succeeded.

If you look in Messenger's book, you see a picture (figure  4.6) of a 1MT
fireball 6ms after detonation. At 300m, the temperature is 16,000K. If you
look at figure 4.12, you see a late time fireball and at 1500m, the
temperature is 2000K. Somewhere in there, you'll find a distance that's
survivable.
--
Conscience, that quiet voice that says "Someone may be watching"

Paul F Austin
paustin@digital.net

From: "Paul F Austin" <paustin@digital.net>
Newsgroups: rec.aviation.military
Subject: Re: Orbital kills
Date: Fri, 8 Oct 1999 23:19:14 -0400

Eric Pinnell wrote in message <37fe4205.4943948@news-s01.ny.us.ibm.net>...

>"Paul F Austin"

>>If you can't understand anything else, calculate the two-way delay between
>>GEO and the surface. You're going to try to hold a 20 nanoradian-precise
>>pointing system with a quarter-second delay while the target moves about
>>20 _micro-radians_ during your loop delay. Your target can be anywhere
>>in a 1000-spot size volume by the time your LASER pulse arrives. Moving
>>to HEO cuts that uncertainty by a factor of 4 to only 250-spot size
>>uncertainty.
>
>   You assume a pulse weapon.  I don't need to fire a pulse.  You
>measure the distance between the target and you, and then calculate
>where it is going to be in order hit it an any give moment in time.
>Hint:  I served as a gunner, ballistics is my forte.


"You assume a pulse weapon.  I don't need to fire a pulse" I assumed no such
thing and in any case, your comment is a nonsequitur. If you served as a
gunner, you know that the only way to hit a jinking target is by filling the
sky with metal.

Your notions put this quote by Liddell Hart in mind: "An important
difference between a military operation and a surgical operation is that the
patient is not tied down. But it's a common fault of generalship to assume
that he is".


--
Conscience, that quiet voice that says "Someone may be watching"

Paul F Austin
paustin@digital.net

From: "Paul F Austin" <paustin@digital.net>
Newsgroups: rec.aviation.military
Subject: Re: Orbital kills
Date: Wed, 13 Oct 1999 22:21:06 -0400

Eric Pinnell wrote
>"Paul F Austin"wrote:
>
>>If you look in Messenger's book, you see a picture (figure  4.6) of a 1MT
>>fireball 6ms after detonation. At 300m, the temperature is 16,000K. If you
>>look at figure 4.12, you see a late time fireball and at 1500m, the
>>temperature is 2000K. Somewhere in there, you'll find a distance that's
>>survivable.
>
>  Srurvable from a WARHEADS point of view?  Remember, we're not
>talking something that's made out of reinforced concrete.  But even if
>you say 1 KM is a kill range, that's certainly easily obtained even
>with 1960s style interceptor missiles.
>   And it's a lot less accuracy than you need to score a kill with a
>kinetic kill vehicle


RVs are a lot tougher than reinforced concrete. The heat shield is made of
carbon-carbon composites. If you look up graphite, you find that it's
maximum use temperature is 2500K. The bomb itself is fairly simple and very
rugged. I'm sure you read about the latest mod to the B-61 bomb that makes
it an earth-penetrating weapon.

It _does_ require a lot less accuracy with a nuke but it's a lot easier to
get weapons free when nuclear munitions aren't involved. One of the major
reasons why interceptors went to KKVs instead of nuclear warheads was
precisely that.

They still had to deal with a nuclear threat because an obvious
countermeasure was to salvage-fuze the RVs so as to kill the follow-on
interceptors.

As far as nuclear weapons in space is concerned, the major weapons effect is
heating from soft X-rays. The Spartan warhead was a 1MT weapon optimized for
X-ray effects. In a vacuum, there's no blast and little heating from
conductive transfer from the blast medium. It's just too rarefied to
transfer any appreciable energy. The X-rays on the other hand have _very_
long range in a vacuum. A megaton range nuke detonation in LEO can kill
(unhardened) satellites in GEO.

Another major effect is trapping of fission fragments in the Van Allen
belts. The fission fragments just bounce back and forth between the magnetic
poles, radiating their heads off. It's possible for 1 or 2 fission weapons
to kill all commercial satellites through this mechanism. The Defense
Special Weapons Agency has been trying to alert owners of commercial sats to
this threat. The commercial users don't want to pay the 30% increase in
satellite cost that hardening would bring.

_Military_ satellites on the other hand are fully radiation hardened, so
this isn't a problem.

--
Conscience, that quiet voice that says "Someone may be watching"

Paul F Austin
paustin@digital.net

From: "Paul F Austin" <paustin@digital.net>
Newsgroups: rec.aviation.military
Subject: Re: Orbital kills
Date: Wed, 13 Oct 1999 22:26:03 -0400

Eric Pinnell wrote
> "Paul F Austin" wrote
>>"You assume a pulse weapon.  I don't need to fire a pulse" I assumed no
>>such thing and in any case, your comment is a nonsequitur. If you served
>>as a gunner, you know that the only way to hit a jinking target is by
>>filling the sky with metal.
>
>   Trouble is, we're talking light speed weapons.  A jinking pilot
>isn't going to do diddly poop in the few milliseconds he's got between
>the weapon detection and the time it fires.  It's tough to miss with a
>laser.


That depends on the distance to the target. If your weapon is in GEO, that's
a quarter second round-trip delay. That's a lot of time for evasive action.
LEO LASERs are a lot better. At a range of a thousand kilometers, you're
right. There's no dodging.

The problem with LEO is that you need many orbital planes to insure the
LASERs are where you need them, when you need them. In addition, your LASER
platform is easier to get at by angry strangers.

--
Conscience, that quiet voice that says "Someone may be watching"

Paul F Austin
paustin@digital.net

From: "Paul F Austin" <paustin@digital.net>
Newsgroups: rec.aviation.military
Subject: Re: Orbital kills
Date: Wed, 13 Oct 1999 23:54:17 -0400

Maury Markowitz wrote in message
>(Paul F Austin) wrote in
>
>>rarefied to transfer any appreciable energy. The X-rays on the other
>>hand have _very_ long range in a vacuum. A megaton range nuke detonation
>>in LEO can kill (unhardened) satellites in GEO.
>
>  Whoa, all from soft-X-ray heating?  I always wondered about that
>actually.  What sort of flux are we talking about here?  I assume that the
>air is a lot more x-ray opaque than I thought.

Not from heating but from displacement damage to active semiconductor
regions and (mostly) trapped charge in oxide layers causing Vt shifts that
knock the hell out of transistor gains.

>>Another major effect is trapping of fission fragments in the Van Allen
>>belts. The fission fragments just bounce back and forth between the
>>magnetic poles, radiating their heads off. It's possible for 1 or 2
>>fission weapons to kill all commercial satellites through this
>>mechanism.
>
>  Kill them, or simply make them non-useable?  ie, is the sat actually
>"hurt" by this, or can its signals just not penetrate the VA belts?


Dead as mackerels. George Messenger's book (The Effects of Radiation on
Electronics Systems) is the bible on space radiation effects.

--
Conscience, that quiet voice that says "Someone may be watching"

Paul F Austin
paustin@digital.net

From: "Paul F Austin" <paustin@digital.net>
Newsgroups: rec.aviation.military
Subject: Re: Orbital kills
Date: Tue, 19 Oct 1999 20:30:31 -0400

Eric Pinnell wrote
>(Maury Markowitz) wrote:
>
>>  That's not true, super-short impulses of this order are hardly impossible
>>for a manned craft.  In fact I'll bet you've pulled more than that for a
>>small delta a few times in your life.  IIRC jumping down off a stool is
>>about 20g.
>>
>>Maury
>
>    But try doing 50Gs CONTINUOUSLY.  If you stop jinking the laser
>has you cold.
>


That depends on the hardness of the target. Boring a hole in an aluminum
tube takes milliseconds. Heating a block of graphite composite up to failure
temperature will take tens of seconds. If dodging can reduce the effective
power to a low enough level (less than about 4MW/m^2), you'll _never_ cook
the target.

--
Conscience, that quiet voice that says "Someone may be watching"

Paul F Austin
paustin@digital.net

From: "Paul F Austin" <paustin@digital.net>
Newsgroups: rec.aviation.military
Subject: Re: Orbital kills
Date: Wed, 20 Oct 1999 22:16:06 -0400

Eric Pinnell wrote
>"Paul F Austin" wrote:
>
>>That depends on the hardness of the target. Boring a hole in an aluminum
>>tube takes milliseconds. Heating a block of graphite composite up to
>>failure temperature will take tens of seconds. If dodging can reduce the
>>effective power to a low enough level (less than about 4MW/m^2), you'll
>>_never_ cook the target.
>
>   Dodging would only help if the laser was not sufficiently powerful
>to crispy fry the target.  And it would also depend on how large the
>beam was on the target surface.
>   If the beam is large enough, some of the craft's surface would
>always be heated.  And if there's enough heat, then kapow.

As usual, an appeal to magic: laser sufficiently powerfull ...Note the power
level required. Now figure the power density of a far-field beam at 22000
miles and work backwards to the amount of launching power and beam width.

As a starting point, Zenith Star's diameter was the same as a Centaur stage
(14 feet). If the beam width at launch is 3m (limited by power density on
the optics), your launch power density is 1.4MW/m^2 for the 10MW godsat.
That's enough to heat a graphite block to an equilibrium temperature of
about 1100K assuming a 4pi steradian, 4K heat sink to radiate to. That's a
best case and the Earth blocks out about a quarter steradian at 300K, to the
temperature might stabilize at, say 1500K. That's far below the maximum
_structural_ working temperature of CC composites.

Which gets us back to where we started: LASERs are a lot more suitable for
shooting at soft targets like boosters and airplanes than they are really
tough objects like warheads.

Eric, part of your conceptual problem is that you think about industrial
LASERs (note the correct capitalization, show respect for your deathray)
which operate in near-field which allows beam collimation so that you can
get pretty much arbitrarily high power densities. An ABM LASER operates in
the very _far_ field and so the beam is going to _diverge_ not converge to
the target. The launching power density is the highest you're going to see
and as the beam diverges, power is going to drop on a R^2 law.

--
Conscience, that quiet voice that says "Someone may be watching"

Paul F Austin
paustin@digital.net

From: "Paul F Austin" <paustin@digital.net>
Newsgroups: rec.aviation.military
Subject: Re: Orbital kills
Date: Thu, 21 Oct 1999 19:07:27 -0400

Eric Pinnell wrote
>"Paul F Austin" wrote:
>
>
>
>>Which gets us back to where we started: LASERs are a lot more suitable for
>>shooting at soft targets like boosters and airplanes than they are really
>>tough objects like warheads.
>
>   True.  But as I pointed out, it's always been a question of power.
>And theoretically, why can't you make a booster out of carbon fiber
>composite?


True enough. You can build tankage out of carbon-carbon composites. It's a
thin-wall structure that doesn't have the broad thermal conduction paths
that a block of graphite has.

An RV heatshield (except near the tip) has fairly low thermal resistance
from one face to the other, allowing the whole surface to serve as a
radiator, cutting the equilibrium temperature. CC composites aren't
superconductors of heat but they _do_ conduct heat as well as copper.

A thin-walled cylinder on the other hand would create serious hot-spots
because there isn't much thickness for the thermal flux to pass through.

--
Conscience, that quiet voice that says "Someone may be watching"

Paul F Austin
paustin@digital.net

Newsgroups: sci.military.moderated
From: "Paul F Austin" <paustin@digital.net>
Subject: Re: Kill Vehicle Intercepts Ballistic Missile
Date: Mon, 13 Dec 1999 16:09:52 GMT

Dirk Bruere wrote in message ...
>
>Maybe I misread.
>I assumed that passive IR was in the intercept vehicle for terminal
>guidance, but now I think of it, it makes more sense to have it external and
>use radar (on-board?) for the final course corrections.


Nope. This is the engagement sequence for a GBI interceptor.

Launch warning and boost-phase track is given from a GEO platform (either
DSP or SBIRS-HIGH) using IR sensors.

Once boost-phase is complete, DSP/SBIRS-HIGH loses the target against the
hot background of the Earth. If SBIRS-LOW is up, then it tracks RVs against
cold space using IR sensors. Otherwise when the targets come over the
horizon, they are acquired by various RADAR sensors on the ground. Cueing by
the satellites is important to the RADARs because they can focus more energy
in the expected area of the RV and get longer detection range as a result.

The RADARs generate track data and the interceptors are launched on that
track. A target update is transmitted to the interceptor during fly-out that
takes into account refined tracks and any changes in target assignment (for
instance if a target is already killed by an earlier interceptor).

The target update is in the form of a "target object map, TOM" which locates
the target against the background stars. That tells the interceptor where to
look for the target. The interceptor Kill Vehicle (KV) uses a LWIR sensor to
detect the target. The sensor is cooled _much_ colder than 77K.

The KV uses the TOM to point toward the target. During essentially all of
the intercept, the KVs sensor sees the target as a point source since it's
too far away to resolve any detail. The KV manuevers to intercept the target
and just before contact deploys a "kill enhancement device" that increases
the physical size of the KV so that the allowable miss distance can be a
little larger.

--
Conscience, that quiet voice that says "Someone may be watching"

Paul F Austin
paustin@digital.net