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'[OT]: How to knock a missile out of the sky...?'
2001\02\07@140818
by
M. Adam Davis
|
I'm curious. With Chinese military officials speculating they are going
to be at war with tiawan within 5 years, and the US indicating that their
missile defense shield may be deployed on tiawan... (and let's leave the
political discussion out of this, please :-)
Are there other methods of knocking out or disabling a missile in flight
without being close to it?
Do any modern missiles use GPS, and if so does the US have the capability
of performing real-time modification to the GPS signal? (I'm thinking -
determine the trajectory and most likely target, then change the GPS
signal incrementally so that the target is now located in the ocean - this
would work well for multiple missiles on multiple targets (sure, we moved
New York to Michigan which knocked california's missiles into the ocean,
but is that *really* an improvement? MI may not think so... ;-))
What are typical guidance systems used for missiles?
I'm assuming there are accelerometer/gyro guidance, but can that be very
accurate? Are ground based radio systems in wide use? Is Russia's GPS
equivilant system in use at all?
Anyway. Just some musings I've been having recently... I suppose this
has a lot to do with robot guidance, as well....
-Adam
The article about the war prediction I read is here:
http://www.worldnetdaily.com/news/article.asp?ARTICLE_ID=21634
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2001\02\07@142247
by
O'Reilly John E NORC
The missile I am most familiar with uses inertial (gyroscope/accelerometers)
and star sightings for navigation, and is very accurate.
Some cruise missiles use forward and/or down looking radar and do terrain
comparisons along with inertial navigation.
For a missile that is fired at a moving target, there are a bunch of ways to
guide it: Heat seeking, radar guided, wire guided, TV remote control, etc.
So how do you knock one out of the sky? Hit it with something, preferable
as early as possible even if you just knock it off course or damage it
enough that it can't guide itself. Actually doing it is extremely
difficult.
John
{Original Message removed}
2001\02\07@142642
by
Don Hyde
Good inertial navigation systems are very good. I worked for NASA during
Apollo days, and the guidance people down the hall were not happy unless
they hit the orbital insertion point within 50 feet.
Everybody uses inertial navigation in preference to GPS if they can afford
it, because they assume that the US military will tamper with it. Even the
airlines use inertial navigation to cross the oceans because they don't
trust the government to keep GPS turned on. In fact it is the FAA that
tells them to do so.
> {Original Message removed}
2001\02\07@143305
by
Spehro Pefhany
|
At 02:07 PM 2/7/01 -0500, you wrote:
>I'm curious. With Chinese military officials speculating they are going
>to be at war with tiawan within 5 years, and the US indicating that their
>missile defense shield may be deployed on tiawan... (and let's leave the
>political discussion out of this, please :-)
>
>Are there other methods of knocking out or disabling a missile in flight
>without being close to it?
Particle beam weapons, powerful X-ray lasers, other high-tech stuff, some
of which would have to be located in space.
>Do any modern missiles use GPS, and if so does the US have the capability
>of performing real-time modification to the GPS signal? (I'm thinking -
>determine the trajectory and most likely target, then change the GPS
>signal incrementally so that the target is now located in the ocean - this
>would work well for multiple missiles on multiple targets (sure, we moved
>New York to Michigan which knocked california's missiles into the ocean,
>but is that *really* an improvement? MI may not think so... ;-))
I doubt modern missiles would use GPS. I happen to know someone who
used to design parts of missiles in (unnamed foreign potential foe) but
they're not talking. ;-)
>What are typical guidance systems used for missiles?
Inertial guidance, I think. Cruise missiles, IIRC, use a combination of
stored patterns of landmarks and inertial guidance. I've worked with
star-trackers which apparently have similar applications for the military.
>I'm assuming there are accelerometer/gyro guidance, but can that be very
>accurate? Are ground based radio systems in wide use? Is Russia's GPS
>equivilant system in use at all?
There are export controls on very accurate intertial guidance systems,
IIRC, the ones used in commercial airliners are deliberately degraded
so they cannot be used for such purposes effectively.
>Anyway. Just some musings I've been having recently... I suppose this
>has a lot to do with robot guidance, as well....
<political>
I don't think that China has any real intention of attacking Taiwan,
unless they were to foolishly declare independence. The US star wars
program is provocative and deprives them of their only defense, which
would be to nuke LA or NYC with one of their few available nukes,
clearly a suicidal path for them. The article you cite seems quite
unbalanced to me, maybe you can put that publication in perspective?
</political>
The problems with the relatively small production disruptions due to
the earthquake in Taiwan (the earthquake was centred near Keelung,
out at the airport in Taipei Hsien, and nowhere near the science park in
Hsinchu) were troublesome. A war would cause huge disruptions in the
economies of the West. I believe it would be avoided by negotiation.
Best regards,
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2001\02\07@151910
by
steve
> What are typical guidance systems used for missiles?
Acoustic sensors that home in on superpowers rattling their sabers.
Steve.
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2001\02\07@154900
by
John A. Craft
2001\02\07@204217
by
Sean Breheny
John,
That was GREAT! LOL! Who made that?! I played it for several people here
and they all loved it (they are engineers, of course ;-)
Sean
On Wed, 7 Feb 2001, John A. Craft wrote:
{Quote hidden}
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2001\02\07@212330
by
Roman Black
|
M. Adam Davis wrote:
>
> I'm curious. With Chinese military officials speculating they are going
> to be at war with tiawan within 5 years, and the US indicating that their
> missile defense shield may be deployed on tiawan... (and let's leave the
> political discussion out of this, please :-)
>
> Are there other methods of knocking out or disabling a missile in flight
> without being close to it?
Pulse laser, once the missile is accurately tracked the laser
gets there instantly and punches a hole in the fuel tank,
the fuel "wake" behind missile is ignited and the fuel tank
bleves. Big bang. I believe the US used pulse laser on
some scud missiles in the gulf war.
> Do any modern missiles use GPS, and if so does the US have the capability
> of performing real-time modification to the GPS signal? (I'm thinking -
> determine the trajectory and most likely target, then change the GPS
> signal incrementally so that the target is now located in the ocean - this
> would work well for multiple missiles on multiple targets (sure, we moved
> New York to Michigan which knocked california's missiles into the ocean,
> but is that *really* an improvement? MI may not think so... ;-))
I doubt anyone would consider that, especially countries
with the tech advantage (like US) get the most benefit
from GPS. We would lose more than the enemy. I think most
missiles have GPS, but not as their only system. And military
GPS has a lot of tamperproofing on the signal too, so
it can't be hacked.
>
> What are typical guidance systems used for missiles?
>
> I'm assuming there are accelerometer/gyro guidance, but can that be very
> accurate? Are ground based radio systems in wide use? Is Russia's GPS
> equivilant system in use at all?
I saw a documentary on cruise missiles, they can use fully
internal means like gyro, internal landscape maps, etc, to
get within a couple of miles of their target from 1000 miles
away. No GPS or signal jamming will matter, and thats why
they do it that way! With GPS added they can get within
2 meters of the target! There is a web page that shows the
results, I saw it a couple of months back.
> Anyway. Just some musings I've been having recently... I suppose this
> has a lot to do with robot guidance, as well....
Some nasty intercontinental robots you're building there! ;o)
-Roman
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2001\02\07@213534
by
Andrew Warren
|
M. Adam Davis <.....PICLISTKILLspam
@spam@MITVMA.MIT.EDU> wrote:
> Are there other methods of knocking out or disabling a missile in
> flight without being close to it?
Ronald Reagan seemed to believe that "giant mirrors in space"
could disable incoming ICBMs; I don't think anyone else thought
it was a good idea.
> Do any modern missiles use GPS
No.
> does the US have the capability of performing real-time
> modification to the GPS signal?
Of course.
> What are typical guidance systems used for missiles?
Missiles that are only going to be fired on cloudless nights can
take star sightings. Missiles that don't mind getting lost can
use RF guidance. Short-range missiles can be guided by wire, by
lasers projected on the target, by internally-stored terrain
maps, etc.
ICBMs, which must work perfectly under any conditions, use
inertial guidance based on mechanical (not laser) gyros.
> I'm assuming there are accelerometer/gyro guidance, but can that be
> very accurate?
It's EXTREMELY accurate; the best publicly-available information
puts the circular probable error for a state-of-the-art ICBM at
less than 100 meters.
> Are ground based radio systems in wide use?
No.
> Is Russia's GPS equivilant system in use at all?
Don't know, but it would be stupid to guide anything important
with radio signals.
> I suppose this has a lot to do with robot guidance, as well
Only if your robot has to be launched into the stratosphere,
coast for a few thousand miles, then land within 100 meters
of some arbitrary target.
-Andrew
=== Andrew Warren --- aiw
KILLspamcypress.com
=== Staff Systems Engineer, IPD
=== Cypress Semiconductor Corporation
===
=== Opinions expressed above do not
=== necessarily represent those of
=== Cypress Semiconductor Corporation.
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2001\02\07@224206
by
Matt Bennett
|
Andrew Warren wrote:
>
> M. Adam Davis <.....PICLISTKILLspam
.....MITVMA.MIT.EDU> wrote:
> > What are typical guidance systems used for missiles?
>
> Missiles that are only going to be fired on cloudless nights can
> take star sightings. Missiles that don't mind getting lost can
> use RF guidance. Short-range missiles can be guided by wire, by
> lasers projected on the target, by internally-stored terrain
> maps, etc.
>
> ICBMs, which must work perfectly under any conditions, use
> inertial guidance based on mechanical (not laser) gyros.
>
ICBMs (in particular submarine launched ballistic missles, because
that's what I know) use a *very accurate* accelerometer on the submarine
(there are actually 2 (for redundancy), each the size of a
refrigerator), that gives a baseline for the missle, which is loaded
into the missle from the submarine, which has inertial guidance until it
gets out of the atmosphere, where it takes a sighting on the stars.
Making an inertial guidance system is hard, and the longer you want it
to be accurate, the harder it is. Just remember the equation
d=.5*a*t^2. If you wanted your inertial guidance system to be accurate
to within 50 ft after 12 hours, the offset on your accelerometer has to
be less than 1.7 nano-g. If you want it to be accurate to within 1 foot
over 1 second, the drift has to be less than 62 milli-g. (sure hope I
did my math right). With a good INS you can see the rotation of the
earth, and have to correct for it.
> > I'm assuming there are accelerometer/gyro guidance, but can that be
> > very accurate?
>
> It's EXTREMELY accurate; the best publicly-available information
> puts the circular probable error for a state-of-the-art ICBM at
> less than 100 meters.
>
And I'm glad about that- I got to watch an (inert) missle hit the ocean,
shot from thousands of miles away. These things work.
> > Is Russia's GPS equivilant system in use at all?
>
> Don't know, but it would be stupid to guide anything important
> with radio signals.
Yes, it is called GLONASS, and last I heard it was still active.
Matt Bennett
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2001\02\07@230937
by
Ray Russell
2001\02\08@071317
by
David VanHorn
2001\02\08@115602
by
O'Reilly John E NORC
> Missiles that are only going to be fired on cloudless nights can
> take star sightings.
They take the star sighting after they leave the atmosphere to correct for
errors in their inertial nav.
John
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2001\02\08@120904
by
Sean H. Breheny
Can anyone point me to more info on how they do star sighting? That seems
to me to be a fairly difficult problem. It would be especially interesting
to see how they solved it with 1950s or 60s electronics.
Sean
At 08:54 AM 2/8/01 -0800, you wrote:
{Quote hidden}> > Missiles that are only going to be fired on cloudless nights can
> > take star sightings.
>
>
>They take the star sighting after they leave the atmosphere to correct for
>errors in their inertial nav.
>
>John
>
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2001\02\08@121938
by
M. Adam Davis
|
Well, since they are above the atmosphere (or at least in a region where
the visibility is a constant), then thye don't have to do nearly as much
processing as one would think, but even then I've got to ahdn it to the
people who make it work.
Point a camera away from the earth - there will be several stars which are
brighter (and maybe color variations are used) than the rest.
At that point you can reference your real time clock (which is accurate)
compute the positions of the stars, match up the positions to get a 3d fix
on the camera, and then compute the earth's position and rotation (based
on the RTC), find the error in the inertial navigation and correct for it.
But image processing is probably the hardest part for me to
conceptualize. Since the image is simply a black background with white
dots it should be significantly easier than, say, robot vision on earth.
-Adam
"Sean H. Breheny" wrote:
{Quote hidden}>
> Can anyone point me to more info on how they do star sighting? That seems
> to me to be a fairly difficult problem. It would be especially interesting
> to see how they solved it with 1950s or 60s electronics.
>
> Sean
>
> At 08:54 AM 2/8/01 -0800, you wrote:
> > > Missiles that are only going to be fired on cloudless nights can
> > > take star sightings.
> >
> >
> >They take the star sighting after they leave the atmosphere to correct for
> >errors in their inertial nav.
> >
> >John
> >
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2001\02\08@124059
by
dre Domingos F. Souza
2001\02\08@124620
by
Spehro Pefhany
|
At 12:09 PM 2/8/01 -0500, you wrote:
>Can anyone point me to more info on how they do star sighting? That seems
>to me to be a fairly difficult problem. It would be especially interesting
>to see how they solved it with 1950s or 60s electronics.
Specialized vidicon type tubes that used magnetic deflection. You diddle
current through the deflection coils to center the image of the star.
With care, bandwidths of 100kHz could be achieved, far beyond what you
can do with ordinary CCD imagers today. Price was high, of course.
Best regards,
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2001\02\08@130052
by
Don Hyde
|
There are a bunch of simplifying facts...
1) The favorite star is Canopus, as I understand (I'm no astronomer) it's
the brightest, it's close to the ecliptic, and there are no other bright
stars nearby to be confusing.
2) You know pretty nearly where you are by your inertial system, you're
merely trying to improve on it, so you can point your telescope pretty
close.
3) The image is a single bright point. Your "retina" only needs 4 cells.
You move "up" or "down" until the "up" pair of cells matches the "down" pair
of cells, and similarly for the "left" and "right" ones. You confirm that
you're pointing to the right star by checking the absolute brightness of
what you see. If it's not bright enough, it's the wrong star, you were
looking for the brightest one.
To get aligned in 3 dimensions, you need one other star, preferably about 90
degrees away. I think Polaris is the favorite for that, the familiar north
star.
4) An inertial navigation system intrinsically gives your location
"inertially", that is to say, it doesn't turn with the earth, so it doesn't
move around the sky with time of day or seasons, as long as the initial
position that was set just before launch was chosen that way.
For a weapon system that could be launched at any time, I guess it must be
able to use an alternate star in case the one it wants happens to be on the
other side of the earth at the time.
Star tracking should be able to null out the gyro drift, at least during the
coast phase, though I can't see how it could help for accelerometer errors.
> {Original Message removed}
2001\02\08@153427
by
Douglas Wood
2001\02\08@161239
by
O'Reilly John E NORC
It basically uses a telescope with a CCD. The missile will basically aim
the telescope at the expected location of the selected star, analyze the
location of it and surrounding stars in the CCD, and compute an error, which
is then fed to the guidance unit.
John
{Original Message removed}
2001\02\09@041815
by
Jeszs
|
One small and curious thing: the lelescopes of the CCD star trackers are
slightly de-focused. The software computes the center of gravity of the
detector elements illuminated by a single star to achieve a sub-pixel
localisation accuracy. Smart, isn't it?
The big disadvantage of star trackers is the 'agility' to resolve its
attitude when the spacecraft is rotating. Most of the today's star trackers
have 4*pi coverage bt only the expensive ones provide bood performance when
rotating fast.
Hint: typical performance of a 300 gr star tracker -> 20/30 arcsec
--------------------
Jeszs Gonzalo
Lesn (SPAIN)
--------------------
----- Original Message -----
From: "Don Hyde" <RemoveMEDonHTakeThisOuT
AXONN.COM>
To: <spamBeGonePICLISTspamBeGone
MITVMA.MIT.EDU>
Sent: Thursday, February 08, 2001 6:58 PM
Subject: Re: [OT]: How to knock a missile out of the sky...?
{Quote hidden}> There are a bunch of simplifying facts...
>
> 1) The favorite star is Canopus, as I understand (I'm no astronomer) it's
> the brightest, it's close to the ecliptic, and there are no other bright
> stars nearby to be confusing.
>
> 2) You know pretty nearly where you are by your inertial system, you're
> merely trying to improve on it, so you can point your telescope pretty
> close.
>
> 3) The image is a single bright point. Your "retina" only needs 4 cells.
> You move "up" or "down" until the "up" pair of cells matches the "down"
pair
> of cells, and similarly for the "left" and "right" ones. You confirm that
> you're pointing to the right star by checking the absolute brightness of
> what you see. If it's not bright enough, it's the wrong star, you were
> looking for the brightest one.
>
> To get aligned in 3 dimensions, you need one other star, preferably about
90
> degrees away. I think Polaris is the favorite for that, the familiar
north
> star.
>
> 4) An inertial navigation system intrinsically gives your location
> "inertially", that is to say, it doesn't turn with the earth, so it
doesn't
> move around the sky with time of day or seasons, as long as the initial
> position that was set just before launch was chosen that way.
>
> For a weapon system that could be launched at any time, I guess it must be
> able to use an alternate star in case the one it wants happens to be on
the
> other side of the earth at the time.
>
> Star tracking should be able to null out the gyro drift, at least during
the
> coast phase, though I can't see how it could help for accelerometer
errors.
>
> > {Original Message removed}
2001\02\10@011851
by
Dave Bell
Spehro Pefhany wrote:
>At 12:09 PM 2/8/01 -0500, you wrote:
>>Can anyone point me to more info on how they do star sighting? That
>>seems to me to be a fairly difficult problem. It would be especially
>>interesting to see how they solved it with 1950s or 60s electronics.
>Specialized vidicon type tubes that used magnetic deflection. You diddle
>current through the deflection coils to center the image of the star.
>With care, bandwidths of 100kHz could be achieved, far beyond what you
>can do with ordinary CCD imagers today. Price was high, of course.
Of course, you know, now we'll have to kill you, and everyone you've
passed this information to...
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2001\02\10@055226
by
Scott Stephens
|
I read that our nukes use fluidic circuits in their navigation and flight
control to make them immune from EMP and radiation from defensive and other
offensive nukes. But you could hardly implement a star tracker with a
fluidic circuit, so I guess the 'buss' is responsible for that?
BTW one really kewl projectile I've read about it a plasma spheromak. A
megajoule plasma bubble is fired at 100's of Km/s from a rail gun and
releases about half its energy in ionizing x-rays at the target. Now if the
plasma were fissionable like Uranium, and it were fired with a bit more
energy, something really kewl might happen when it hits! Probably great in
space, but dissapointing in the atomosphere where it rains, et.
Scott
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