I think the general assumption is GPS is denied in most combat zones, it's constantly being jammed in and around Ukraine.

For most things the fallback is going to be everything we used to use. Maps, stellar navigation, inertial navigation that sort of thing.

Guided weapons wise, terrain mapping is pretty common for cruise missiles. Storm Shadow, for example uses GPS, terrain and inertial guidance systems. Trident uses inertia and stellar navigation.

As for why it hasn't proliferated into civilian use? Mostly it has its just the old things. You can perfectly well drive your car with a road map and sign posts. Pilots still train to use dead reckoning and beacons. Etc.

Right, in future conflicts between major countries the satellites will be first casualties. The US military is aware of this and still trains personnel on analog navigation techniques. Inertial navigation works well for some missions and research is underway on alternative technologies. Civil airliners can still navigate without GPS, although this may reduce safety and increase workload.

https://interestingengineering.com/military/us-military-nail...

We're also going to need a prompt launch capability to replace attrition losses. There should be warehouses full of spare navigation, reconnaissance, and communications satellites ready to mount on a reusable booster and launch within hours. Concerns have been raised over a "Kessler syndrome" due to orbital debris but in lower orbits with significant atmospheric drag this won't be a serious problem.

The US military has been funding plenty of projects related to what it calls Alt-PNT, or "alternative position, navigation, and timing" systems. I imagine other nations have invested in this as well.

Which systems are actually getting deployed, and in what pieces of equipment? No idea, I imagine that's super duper classified.

I’m sure we’ll go back to beacons [1] here in the UK

”Using fire to signify a message is thousands of years old. The earliest use of beacons in the UK dates back to the medieval period, primarily as a means of communication to warn of impending invasions or other dangers. Positioned on hilltops and along coastlines, these beacons were part of an early warning system signalling the presence of a threat, such as an approaching enemy fleet.

One of the most famous early examples is the network of beacons used during the Spanish Armada in 1588. As around 150 Spanish battleships approached, beacons were lit along the southern coast of England, from Cornwall to London. As a result of this rudimentary but effective system Lord Francis Drake had the time to mobilise the country’s defences and defeat the Spanish fleet before they were able to reach the English shore.”

[1] https://www.paintersforstal.co.uk/news/the-history-of-beacon...

There's technology now that matches local satellite/aerial images against the imagery that a drone or cruise missile sees to replace the GPS chip.

For fairly obvious reasons, militaries that have it would rather it stay in their hands, for fear of creating a non-state peer competitor that can do cheap long-range strikes on strategic targets.

It's fairly likely it'll fall into private hands anyway though, because anyone who can afford the prices for commercial satellite imagery could build such a thing.

> Whatever that technology is, why hasn’t it proliferated into civilian life so that we all benefit from a resilient, non-GPS backup?

Once a stealth technology is integrated into civilian life, it's no longer stealth, and you lose the element of surprise if you have to use it in warfare. If somebody _does_ feel they have a clever secret work-around, the incentive is pretty high to keep it a secret.

Maps, compass, and celestial navigation.

We may have enough satellite imagery to build visual place recognition system. Geoguesst but for tanks

you can see from russia's response to losing starlink, that the answer is sending people out to die bringing a radio repeater to put into a tree

> Presumably when World War 3 kicks off

That presumes we're not already in it. When historians 100 years from now look back on this period, what's going to be the assassination of Archduke Franz Ferdinand? What's going to be the Reichstag fire of 2027?

That and cut undersea cables. Russia has been messing around with them for a while now.

GPS has relatively few satellites... but if in doubt, I think Starlink with its absurdly large fleet of satellites can be used as an alternative. Maybe not at a precision level good enough for precision farming, but good enough to roughly guide troops to where they need to go.

Modern cruise missiles and stuff like Storm Shadow, Taurus etc. already rely on sensor fusion - GPS, inertial navigation, radar, optics and probably a ton more to always keep track of the position.

Assuming Starlink is a no-show for whatever reason, airliners and ships will have to revert back to stationary navigation aids aka your good old light towers and radio beacons.

> Presumably-squared there is some kind of military backup to survive once the lights (GPS) go dark?

... Star navigation, INS, magnetic navigation...

But nothing like we have today.

> international game theory

Not this quackery again

This is not an attack. The satellites aren't being damaged.

UK is under russian attack. same with canada, germany, sweden, etc.

Let’s launch hard drives back and forth between earth and LEO. Like sneakernet in space.

Laser links for satellites work fine, but if you're up against a 10 year old spy satellite or you're selectively jamming their SAR (radar imaging) or GLONASS positioning rather than their comms...

I mean isn't space X testing satellites with sat to sat lasers?

In that case you don't need to ground lasers, you just beam the data where you have unjammed communications with the cost of higher latency.

Neutrinos

[dead]