The Peacekeeper missile’s navigation suite (2019) | Hacker News Reader

The Peacekeeper missile’s navigation suite (2019)

thedrive.com

104 pointsareoform91 comments

"There are very few applications requiring such precise guidance and independence from external references. In fact, beyond ICBM guidance, none have been identified."

Ballistic missile submarines need very low drift inertial navigation, because they stay submerged for a long time without outside references. The submarines provides a starting position for missiles, so missile error is added to submarine error. Size and weight aren't major issues, so they can use much larger gyros.

There's continuing interest in inertial navigation. Projects show up on DARPA.[1] The military assumes that GPS will be jammed much of the time in wartime, so they want inertial backup.

[1] https://www.darpa.mil/program/micro-technology-for-positioni...

Aren't missiles launched from the surface, enabling a quick calibration just before launch? When there aren't clear skies to see stars, what other sort of non-GPS calibration could be done at sea?

TIL submarines can fire ballistic missiles while submerged. It helps them maintain stealth. Here's a video from the 60's showing Polaris firings:

https://en.m.wikipedia.org/wiki/File:1960-07-21_First_Polari...

Among others (Tomahawk being notable), https://en.wikipedia.org/wiki/UGM-27_Polaris was designed to be launched underwater, in service from 1961.

Not always, but we I understand it even a wire periscope can provide excellent location data.

AFAIK submarine launched ballistic missiles aren't launched that far below the water surface and even a traditional periscope can reach 15+m

> When there aren't clear skies to see stars, what other sort of non-GPS calibration could be done at sea?

It is speculated that you could keep navigational errors bounded with gravimetric measurements. Essentially if you have a detailed pre-surveyed map of the underwater landscape, and high precision gravity measurements you can match your measurements to the undulations of the expected gravity field. Somewhat similar, at least on the math level, to how TERCOM works with cruise missiles.

Wouldn't the movement of the boat cause too much "noise" for these kinds of measurements? How would they cancel out small movements due to e.g water currents?

The short and true answer is that if I would know for sure I could not write about here. Hence all of this is speculation.

Very likely they would use the best motion isolation money can buy. Also the submarine is quite slow (especially at navigation speeds) so the terrain changes under it slowly. Water currents and the motion of people and machinary happens at much higher rate, so you can probably try to eliminate the quick changes and keep the slower changes with filtering and statistics.

It isn't as hard as you might think.

Most gravity-gradient measurements are differential. Common-mode accelerations can be substantially-rejected.

Also, if you're in the precision-measurement game, navigationally-relevant signals can be much larger than the precision of modern instruments. People in the prospecting business sometimes fly gravity-gradiometers in airplanes.

During the day, you can use the sun position as a reference (like it's done using a sextan). You only need an accurate clock, and can determine the sun's location through the clouds.

I suppose you can also do it with the moon. On a dark, cloudy night though? You could risk using the sonar since the launch is going to make a ruckus anyway. Compare measures against seafloor maps.

Boomers aren't supposed to surface for their missile launches for half a century now, it's just too dangerous.

Nope, they're launched from just a bit below the surface to make it harder to spot and chase the sub via aircraft/helicopter. Here's footage: https://www.youtube.com/watch?v=ppz_jj2uw7k&t=25s

Pre GPS navigation methods include sextants, celestial navigation, and LORAN (navigation via bearings to multiple radio towers).

Sub launch ballistic missiles actually have an automated version of celestial navigation: there's a star spotting camera that compares what it sees to a reference database of the couple hundred brightest stars. So even if the missile starts out with a lot of ambiguity about where it's launched from, by the time it gets above the clouds it can correct this.

The missile could still use GPS to correct its trajectory ...

Yes, as long as the GPS (Navstar) satellites haven't been vaporized...

Ballistic missile submarines are primarily second-strike weapons. By the time they launch, our GPS satellites might already be destroyed by anti-satellite weapons. So far no one has demonstrated a working weapon that can knock out satellites in medium orbit (like the Navstar constellation) but I have to assume that China will have such a capability soon.

For routine operations, modern subs do carry a towed buoy which can be used to exchange radio messages and update GPS position while the sub remains deep underwater. This carries some risk of detection, but less than coming up to periscope depth.

I'm failing to see the difference on the medium orbital range? It's still "just" an intercept. I assumed all tests were done at low orbits to help ensure the junk deorbits as quickly as possible while still fulfilling 100% proof of effect, but that is just an assumption and I'd certainly be curious to know if/why/how I was wrong!

The basic physics are the same regardless of altitude, but the launchers used in current known ASAT weapons systems are only capable of reaching LEO. Need a bigger booster. I assume the US / China / Russia have secret programs working on this right now.

USA Boomers use LRG for INS and SLBMs use star shots for mid-course correction. It’s good enough that the D5 was counter force, which is to say it can hit enemy siloes.

The missile knows where it is at all times. It knows this because it knows where it isn't. By subtracting where it is from where it isn't, or where it isn't from where it is (whichever is greater), it obtains a difference, or deviation. The guidance subsystem uses deviations to generate corrective commands to drive the missile from a position where it is to a position where it isn't, and arriving at a position where it wasn't, it now is. Consequently, the position where it is, is now the position that it wasn't, and it follows that the position that it was, is now the position that it isn't. In the event that the position that it is in is not the position that it wasn't, the system has acquired a variation, the variation being the difference between where the missile is, and where it wasn't. If variation is considered to be a significant factor, it too may be corrected by the GEA. However, the missile must also know where it was. The missile guidance computer scenario works as follows. Because a variation has modified some of the information the missile has obtained, it is not sure just where it is. However, it is sure where it isn't, within reason, and it knows where it was. It now subtracts where it should be from where it wasn't, or vice-versa, and by differentiating this from the algebraic sum of where it shouldn't be, and where it was, it is able to obtain the deviation and its variation, which is called error.

I know this is from a 90's Air Force video.. but it sounds like he's reading the script straight off a corporate patent application.

Like someone trying to explain a Kalman filter with zero math.

https://knowyourmeme.com/memes/the-missile-knows-where-it-is

Reminds me of Douglas Adams' Hitchhiker's guide books. Or even something from Red Dwarf.

I have been collecting inertial guidance systems since the early days of eBay. Autonetics was spun out of North American Aviation to focus on inertial guidance systems.

I'm attracted to them as computing milestones. Autonetics solved the same digital interactive computing problem using the big 3 techniques:

Vacuum Tubes Discreet components Integrated circuits.

I joined today because I now have so many artifacts that I was considering trying to plan a convention to discuss.

If anyone is interested in studying these artifacts. Here is a collection of poor photos of some the artifacts.

https://www.icloud.com/sharedalbum/#B0YG4TcsmGWIVSf

Just this morning I'm looking over some vacuum tube components. Trying to figure out what they are apart of.

Actually related to one of my favorite photographs:

https://en.m.wikipedia.org/wiki/LGM-118_Peacekeeper#/media/F...

The fact that nuclear-tipped multiple independently targetable reentry vehicles (MIRV) have never been tested with live explosives is both a good thing, and a missed photographic opportunity :(

It's a great photo, as interesting historical photography goes anyway. Raises some questions for me:

1) What's the light source for the warheads, are they glowing with reentry heat or is it something else?

2) What's the warhead-warhead distance in this shot? Was it programmed to fit a tactical pattern like "fleet destruction" of 1-mile warhead-to-warhead?

3) Is this a radial pattern or linear? Seems like it's either radial or there's some significant amount of error that's observable. But it might depend on #2 above.

4) The inertial system was not inside each warhead, right? But rather inside the missile itself?

5) Did they chopper & swim out and retrieve this stuff? Wouldn't want the other side to capture it for intel, I'd guess...

...and probably more...

reentry heat, i don't know, i don't know, yes, destroyed on impact it's coming in at like mach 25

1. Re-entry heat glows the MIRVs. The re-entry package heats up to more than 1000C often. Specialized carbon composites similar to ones in space vehicles are used.

2. I think this photo was more of a time lapse than programmed delivery of warheads at definite spacing. There are videos of MIRV entries which are equally cool. Including one of the impact site, where one can see dummy warheads impacting target zone few seconds apart. (Second video is an animated flight sequence)

https://youtu.be/Eh96NdcgE2Y https://youtu.be/Mvo54LJcXe8

3. Unlikely its radial or linear entirely. The camera perspective makes it look all of them in a line.

4. Terminal guidance is not on each MIRV. But small spin generators stabilize the flight towards target. The warhead bus has onboard computer which releases individual warheads at high velocity once the correct attitude over the target is reached. Terminal flight is unguided ballistics based on calculations prior to release. Needless to say, the warhead bus releases them at a LEO altitude, so by impact they are easily ~10-15 Mach

5. Yes & Yes. US DoD seems very particular on keeping Kwajalein in mostly pristine state. All discernible parts are recovered in the atoll & shallow sea around it. A lot of people from the local population are employed in the upkeep of the facility & maintenance. Usually the impact zone is a very concentrated area. Foreign military access is out of bounds with US Strategic Command presence in the atolls.

Wow, that video is eerie. Thanks for the link.

So that's what the beginning of the end of the world would look like.

https://www.youtube.com/watch?v=dYWf3bD7OlM (excerpt from the documentary MISSILE by Fredrick Wiseman according to the description) was also in this theme

(part of launch sequence, viewpoint in the control room)

I need to track down the full documentary.

http://www.zipporah.com/films/13

Trying to order DVD gives me "Missile - DVD is not orderable."

Very interesting, thanks for the answers & video links.

I am imagining that the terminal inertial guidance --> imparting MIRV guidance phase must have been planned very delicately. Watching the adjustment rockets firing this way and that in the second video gives the intuitive sense that the process is far from easy to plan for.

This exact photo is displayed in the article.

The WECX reporting mark on the prototype garrison railcar (for the MX dispersed deployment plan) indicates it belongs to the Western Electric Corporation Railroad. So I guess they were prime contractor for that part of the project.

https://en.m.wikipedia.org/wiki/Peacekeeper_Rail_Garrison

https://en.wikipedia.org/wiki/List_of_reporting_marks:_W

High accuracy inertial measurement and star tracking are insane, especially against the technology level when they were developed.

But I guess they prove that when you work on an existential weapons problem, with a superpower's budget, "technically reasonable" is a lesser concern than "feasible at all".

On a related note the Museum of Berkshire Aviation [1], about 30 miles west of London, has a Chevaline[2] reentry module. This includes a dummy warhead along with gyroscopes, decoy 'flares', and all the hydrazine pipes and steering systems.

It's fascinating to see close up, especially the quality of workmanship on it all.

They also have things like a Miles M.52 (1943 supersonic project) and a Fairey Jet Gyrodyne (jet exhaust from the rotor tips). It's a great little museum if you're ever in the area.

I've just uploaded some pictures from my visit [3]

[1] https://museumofberkshireaviation.co.uk/

[2] https://museumofberkshireaviation.co.uk/html/exhibits/cheval...

[3] https://www.flickr.com/photos/stevecargill/52524425464/in/al...

Nice. You can even read the component names on the PCB at https://live.staticflickr.com/65535/52524141291_eb04eebb22_k...

Fun fact: high precision/high accuracy inertial navigation systems for modern avionics/missile guidance/similar are some of the most sensitive and controlled ITAR items.

For when you want your $10 million UAV to successfully navigate in a GPS denied/jammed environment or similar.

They also have a number of applications for submarines.

Modern INS are considerably smaller than the thing in the photo and implemented from totally different technology.

More directly related to the thing in the post: Google "peacekeeper rail garrison". For a while there was a plan to have whole fleets of ICBM-equipped disguised cargo trains that could travel randomly around the US midwest and mountain states.

https://www.google.com/search?client=firefox-b-d&q=peacekeep...

The title and the site's abstract says "Peacemaker" but it seems to be about the well-known Peacekeeper missile.

"I cherish peace with all of my heart. I don’t care how many men, women and children I kill to get it."

These'll definitely help ratchet up that body count

Nuclear weapons ushered in a period of peace never before seen in human history. Death rates in war have been at historic lows post WWII.

Post hoc ergo propter hoc

Ok, then what else explains the long peace?

Unsustainable prosperity fueled by fossil fuels.

We had fossil fuels during both world wars.

the many men, women and children they kill daily to get it.

just because there's no colonial empires fighting each other, doesn't mean there's peace.

The number of people killed 'daily' is vastly less than it has been at any other point in history. Why is it more peaceful now?

Trade, democracy?

The Greeks and Romans had varying levels of democracy and vast trade networks for hundreds (arguably thousands) of years.

Maybe for citizens of major imperial powers, but looking at a global picture, they've regressed us to the mean.

https://www.vox.com/2015/6/23/8832311/war-casualties-600-yea... (Logarithmic scale, does not include the conflicts of the past 20 years)

For now, maybe. It only takes one escalation or a series of unfortunate mistakes for this status quo to shift dramatically, over the course of a few hours.

No reason for article not to be consistent, but as a piece of trivia it seems it was originally called the "Peacemaker" before undergoing a name change[1].

November 1982 article[2]:

> In addition to the hard time the Reagan Administration had in finding a home for the MX missile, the Government also had a hard time finding a name for the new weapon.

> Until today, the experimental missile was to have been called "Peacemaker." But at the last minute, according to Administration officials, it was changed to "Peacekeeper."

> The officials said someone decided that "Peacemaker" was too close to "pacemaker."

[1]: https://en.wikipedia.org/wiki/LGM-118_Peacekeeper#Deployment

[2]: https://www.nytimes.com/1982/11/23/us/peacemaker-loses-missi...

Changed now. Thanks!

The book to read is Inventing Accuracy by Donald MacKenzie

Ooh. This sounds like a good follow-up to my reading of Simon Winchester's "The Perfectionists" - a history of precision engineering, which starts of discussing the difference between precision and accuracy.

The perfectionists is a phenomenal book. I highly recommend.

It's hard to imagine that ICBMs are available - and always available, at a moment's notice to be launched when a conventional satellite needs weeks to months to achieve something similar. I can't even imagine how liquid fuel is stored on land, let alone on a submarine.

Most ICBMs are solid fueled (at least the US ones)

Yeah, the safety record of liquid fueled weapons isn't very good.

https://en.wikipedia.org/wiki/1980_Damascus_Titan_missile_ex...

Interesting article and story. I don't rightly recall ever hearing about this particular incident. I was 8; so I wonder if/when details were released to the public. You really wonder -- this would be a hugely dangerous incident and very embarrassing for the general public to find out about it, so you'd expect that the military would keep a lid on it, so to speak, for as long as possible. The cat was out of the bag by 1988, because a film was made about the incident, so it says.

Highly recommend reading Eric Schlosser's fantastic book Command and Control. It goes into great detail about the failings at the Damascus Incident, but also features some truly hair-raising accounts of other near-catastrophic nuclear near-misses.

Seconded.

Add to that the (insane?) early SIOP, a plan for an all-out attack on the USSR with waves of nuke-armed strategic bombers.

As for the Damascus accident, I'd love to watch a high-budget movie about it (preferably on the level of "Deepwater Horizon", with Mark Wahlberg to boot).

The ones talked about in TFA are three staged, with the third stage being liquid. Can you launch an orbital solid fueled rocket? I thought that liquid (oxygen) was needed.

https://en.wikipedia.org/wiki/Scout_(rocket_family)

US missiles are entirely solid fueled but they do not achieve orbit either. They spent short time exoatmospheric and then reenter, well, ballistically.

It's hard to get precise velocity changes with a solid fuel rocket. So must orbital class rockets have a liquid fuel stage at the end. And most rockets don't use oxygen for a propellant, because that's cryogenic, and hard to keep liquid. So called storable propellants are frequently used, especially for military rockets. That said, the most launched rocket last year was a cryogenic fueled rocket.

Militaries may need solid fueled satellite launchers to fight future high-intensity conflicts. They are increasingly reliant on satellites for communications, navigation, reconnaissance, targeting, and weather. But anti-satellite weapons are also advancing rapidly, and we can expect satellites to be destroyed quickly once the shooting starts. So there will be a requirement to replace attrition losses by launching replacement satellites within hours.

targeting

Are they? The whole article was about the inertial guidance system. Seems like conflicts don't take GPS-like systems as a given. Ground to Air guidance systems use similar systems, as well as data fed by the launch site until they're close enough to their targets to lock onto things like heat signatures, etc.

Targeting in terms of detecting and maintaining a target track so that other platforms can employ weapons against it. The US Air Force is considering replacing their current fleet of E-3 AWACS aircraft with a satellite system. Obviously those satellites will be vulnerable in a conflict, so there would have to be a way to rapidly replace combat losses.

https://www.thedrive.com/the-war-zone/42487/e-7-wedgetail-ra...

The Russians have worked on this -- It was public more than 20 years ago. I would guess they (and the US too) have some capabilities to put commsats back up in an emergency with sub launch via modified SLBM.

https://archive.ph/0ayQv

There's something so satisfying about a fully self-contained inertial guidance system that magically knows where it is to a reasonable degree of accuracy over a long period of time without any external input. Is it true AIRS was the peak of this technology (in terms of drift)?

How much TLC did they need in terms of maintenance, and how reliable in practice was that complex system of 19,000 parts?

Designed by Draper Labs, manufactured by Northrup. My father-in-law worked on inertial guidance for Draper and retired in 1989, but I don't know if he ever worked on this project. Some things he wouldn't talk about because of security clearances. He did work on the Trident INS.

My dad worked on the Trident guidance in the 1980s for Singer Kearfott. Very interesting career. Specifically, he improved the celestial navigation suite in the guidance system. The missile could determine it's location and plot it's course based on the location of the stars.

That sounds like an interesting challenge with today's technology. It's so impressive that this was accomplished at scale with Cold War era technology levels.

How does this system perform compared to modern laser/fiber based gyros?

I don't know, but I think laser gyros have been surpassed by HGR (Hemispherical resonator gyroscope) [1]

[1] https://en.m.wikipedia.org/wiki/Hemispherical_resonator_gyro...

The MIRV test photo is nightmare fuel. Apocalypse with mathematical precision.

looks like 1980s missile command with a cool background

There’s a nuke museum in Albuquerque NM that has a mirv dispenser with a bunch of inert warheads laying in a pile of other stuff. They also have a bunch of old icbms including a peacekeeper in the back outside like a Cold War junk yard. I think they even have the gun that fired a nuke artillery shell off to the side by the back fence. It’s quite a surreal museum.

> There are very few applications requiring such precise guidance and independence from external references.

nowadays AR needs something like the same level of precision, but over a longer timeline.

Instead of just IMU, AR glasses have the advantage of using SLAM as well as passive wifi to locate as well.

What truly blows my mind: this is technology that is built to be destroyed.

Hopefully it's built to be so scary it's never used at all.

So many ads on the site, a bit unreadable even though I am interested in the subject matter. Maybe it’s better off of mobile. Ah well.

yawn. install the right extensions, use reader mode, etc, and just be done already.

> Maybe it’s better off of mobile

>install the right extensions

or app

that's not the sort of app the app store would tell you

funny, as Apple specifically promoted the fact that you could install blockers with whatever iOS update they released. android has versions of the same desktop blockers. so i'm really confused on your suggestion

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