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Ask HN: What would happen if all GNSS (like GPS) satellites go down?

5 points by sn_master ↗ HN
Essentially nobody was using GPS before the Iraq war in 1990. Now in just 30 years all of us using it, including backend systems like datacenters of Google.

I don't know how to use compass for navigation, and don't think any of my friends do either.

Are there any portable easy-to-use self-contained Inertial Navigation Systems out there? I know high-end military machines have them, like fighter jets and navy ships, but I was thinking more in terms of cell-phone sized devices that we can simply enter coordinates of where we're starting from, and they automagically keep track of our location as we're on the move by foot or by car.

6 comments

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LeoPanthera
I think the lack of a universal time signal would have more immediate effects than the lack of positioning.

Positioning is still possible without satellites, albeit with reduced precision, see LORAN: https://en.wikipedia.org/wiki/LORAN

sn_master
There still is universal time signal, at least in the US (don't know if that still makes it "universal")

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

LeoPanthera
That's true (though I think you meant to link to WWVB), though most traditional time signals are broadcast in the longwave band and can only be reliably received at night.

Some areas of the planet do not have a time signal, the most obvious example is Australia.

iab
There are not. Modern Strapdown-based inertial estimators rely heavily on GNSS; if you want something that won’t become unusable after a few minutes then you need significantly better sensors. LORAN is an alternative terrestrial system, but to nowhere near the scale of modern GNSS.
sn_master
I thought LORAN is fully decommissioned already?
iab
Coming back from the grave with eLORAN