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

Question

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.

LeoPanthera · Accepted Answer

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

iab · Answer

There are not. Modern Strapdown-based inertial estimators rely heavily on GNSS; if you want something that won&rsquo;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.

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

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

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.