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Comment by vlehto | Hacker News Reader

If USSR would get capability to kill GPS satellites, U.S. nuclear subs could not target their missiles anymore. The rest of U.S. nuclear arsenal is in B2 bombers in known airfields and ICBM's in known silos. So by using their ICBM's to knock off airfields and silos, USSR could theoretically kill U.S. nuclear cabability withouht being hit.

This would mean that "pre-emptive" strike is suddenly lot sweeter deal for U.S. Alternatively restart midgetman program. Yay, more nukes. https://en.wikipedia.org/wiki/MGM-134_Midgetman

This would be "destabilizing" technology. I hope it goes nowhere.

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I have a real hard time believing that US missile subs must have GPS to launch missiles.

It's obviously not as applicable to a ballistic launch, but here's an example of publicly known missile guidance that doesn't care about satellites:

https://en.wikipedia.org/wiki/TERCOM

I expect even without improvements like that they are prepared to launch and hope that the inertial navigation system in the missile is good enough.

GPS was created for U.S. nuclear subs. The problem is about knowing where the sub exactly surfaces, because after launch, the trajectory is ballistic. Subs have very good inertial navigation, but the accuracy deteriorates with time and movement.

TERCOM is very nice, but only applicable for cruise missiles flying close to ground and able to change their course.

Yes yes, the cruise missile thing was just pointing out that there are some quite advanced non satellite capabilities.

The more important point is the question of whether GPS is actually required for a launch or if it merely improves the process (accuracy, speed, etc).

> If USSR would get capability to kill GPS satellites, U.S. nuclear subs could not target their missiles anymore.

While GPS might be used to refine locations, both subs and their missiles use inertial navigation that isn't dependent on satellite clusters. A long term lack of GPS would hurt accuracy, but a Russian attack on the GPS system would be such a provocative act that its direct long-term effects on targeting and navigation would probably be insignificant compared to the indirect long-term effects by way of the broader conflict it provokes.

Good points. I guess I was overly sensational.

But anyhow just the capability to kill satellites would mean increased tension between the nuclear superpowers.

> But anyhow just the capability to kill satellites would mean increased tension between the nuclear superpowers.

The US demonstrated that capability in 1963, the USSR in 1978.

I like how you're using 'USSR' as if it's still an actual country.

Mandatory Simpsons gif: https://media.giphy.com/media/axMy0g9z9khZC/giphy.gif

Missile subs can work just fine without GPS position fixes - maybe not as accurate, but just as fine.

Since by definition the US missile sub fleet would be used for a second strike role in this situation (by definition, since someone else nuked the satellites first), the strikes would primarily be retaliatory in nature - ie, nuke the cities. Big whoop if your CEP is now 500m when you're nuking Moscow.

Missile sub main point is to be second strike. GPS was created because US sub fleet was so inaccurate.

Though Russian missile subs worked without such positioning, so they would probably still mean business.

Every statement in here is wrong, but the greatest error is this: the most potent leg of the US triad is invulnerable to the threat you describe, and is capable of annihilating the USSR. Yes, US SSBN's are equipped with time-travel technology to destroy the Russian arsenal before its designers were even born.

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