Post by thread:[OT]: How to knock a missile out of the sky...?

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 -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

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, =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Spehro Pefhany --"it's the network..." "The Journey is the reward" spam_OUTspeffTakeThisOuTinterlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com Contributions invited->The AVR-gcc FAQ is at: http://www.bluecollarlinux.com =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

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}> >What are typical guidance systems used for missiles? > > Well, it's technical. Here is a layman's description of the process. :) > > http://www.mscomputercraft.com/Guidance.wav > > It makes perfect sense........ > > John C. > > -- > http://www.piclist.com hint: The list server can filter out subtopics > (like ads or off topics) for you. See http://www.piclist.com/#topics > > > -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

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 -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

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 --- aiwKILLspamcypress.com === Staff Systems Engineer, IPD === Cypress Semiconductor Corporation === === Opinions expressed above do not === necessarily represent those of === Cypress Semiconductor Corporation. -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

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 -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

In a message dated 2/7/01 8:44:18 PM Eastern Standard Time, EraseMEshb7spam_OUTTakeThisOuTCORNELL.EDU writes: {Quote hidden}> What are typical guidance systems used for missiles? > > > > Well, it's technical. Here is a layman's description of the process. :) > > > > http://www.mscomputercraft.com/Guidance.wav > > > > It makes perfect sense........ > > > > John C. > OK who wrote this the three stooges? It scares me though that it makes sense to me. I think I am in trouble now! Ray Russell General Contractor Norfolk & Western Railroad Pocahontas Division Circa 1958 Visit The Pocahontas Website at: <A HREF="http://milliron.home.sprynet.com/Pocahontas/Pocahontas1.htm">Click here: Pocahontas Home</A> OR http://milliron.home.sprynet.com/Pocahontas/Pocahontas1.htm -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

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 > >-- >http://www.piclist.com hint: The PICList is archived three different >ways. See http://www.piclist.com/#archives for details. -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

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 > > > >-- > >http://www.piclist.com hint: The PICList is archived three different > >ways. See http://www.piclist.com/#archives for details. > > -- > http://www.piclist.com hint: The PICList is archived three different > ways. See http://www.piclist.com/#archives for details. -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

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, =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Spehro Pefhany --"it's the network..." "The Journey is the reward" @spam@speffKILLspaminterlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com Contributions invited->The AVR-gcc FAQ is at: http://www.bluecollarlinux.com =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

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}

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" <RemoveMEDonHTakeThisOuTAXONN.COM> To: <spamBeGonePICLISTspamBeGoneMITVMA.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}

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... -- http://www.piclist.com hint: To leave the PICList TakeThisOuTpiclist-unsubscribe-requestEraseMEspam_OUTmitvma.mit.edu

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 **************************************************************************** Freedom is pursuing your carrot, not running from somebody's stick Does society make you enthusiastic, or fearful? The mob rules only what its members achieve. **************************************************************************** -- http://www.piclist.com hint: To leave the PICList RemoveMEpiclist-unsubscribe-requestTakeThisOuTmitvma.mit.edu