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Uh oh, where are we?

The global positioning system we all know as GPS has gone from being a tool of the military a few decades ago, to being an essential part of life for business and many people.

Does anyone remember the days when you used to have to keep maps in the glove-box of your car if you intended to venture outside your normal areas of travel?

Who can recall when ships and aircraft navigated by way of directional radio beacons and dead-reckoning?

I wonder how many of those reading thus used to watch spy movies and TV programs back in the 1960s and 70s which showed the ridiculously impossible image of a vehicle being tracked in realtime on a map.

Well of course GPS has made this, and a whole lot of other stuff, very possible and insanely simple to do.

In principle, GPS is pretty straight forward.

A bunch of satellites whiz around the earth, beaming precisely synchronised and timed signals back to earth and, if you can receive enough of those satellite signals, you can very quickly determine your exact position (latitude, longitude and altitude) anywhere on the face of the planet.

Once upon a time, a GPS receiver device was an expensive bit of kit -- so expensive in fact that it really was beyond the reach of "regular folk" like you and I.

Larger land surveying companies might be able to afford such a system. Government organisations (including the military) probably had them if they needed them -- but that was about it.

But then, in a relatively short period of time, GPS receivers became ubiquitous. Their size and cost shrunk enormously until now, everything from your smartphone to your car, to your camcorder or camera probably has one.

A bare-bones GPS receiver module with inbuilt receiver can be had for less than US$25 in 1-off quantities and that unit will be accurate to within 2-3m.

Businesses have lapped up GPS-enabled devices with transport operators using them to track their trucks, rental car companies fitting sat-nav to their cars and the printed map industry probably taking a big-hit as a result.

So what happens when GPS stops working?

I say "when" rather than "if" because the odds are pretty good that, at some stage, the network of satellites above is will be hit by the effects of a solar storm or war will break out again and the USA will deliberately dither the GPS signal so as to dramatically reduce its accuracy.

If worst came to worst -- and GPS stopped working reliably or altogether, just what effect would that have on the world?

One thing's for sure -- a lot of ship's captains and aircraft pilots would have to brush up on their navigational skills using "old-school" techniques.

The Google Maps (or "get lost with Apple Maps") system on your smartphone would be a lot less useful.

Insurgents in Afghanistan would be a whole lot safer from Predator drones.

But is that all?

Fortunately, there are two other GPS systems, Glonass and Galileo. Glonass has been operational for some time now and Galileo is getting closer to realisation -- with a full constellation of satellites expected to be orbiting by the middle of this decade.

These systems have the potential to provide redundancy for the US GPS, so long as the gear you're using can receive them and so long as their birds aren't also blown-away by any major solar storm that might wreak havoc on orbiting satellites.

Why this subject for today's column?

Well the penultimate step towards the commissioning of the Galileo system occurred last week when satellites 3 and 4 of that system were inserted into orbit. With four satellites in operation, it now becomes possible to validate the system-design and start some serious testing -- before launching the remaining birds.

Given the huge reliance we (as a planet) now place on GPS systems, it's rather surprising that so many of us rely solely on the US-made offering -- don't you think?

And just a little tip -- if you're like me and don't have a smartphone or other GPS-equipped personal device -- just get a piece of paper and, with a permanent marker, write on it "you are here -- X". That way, even during the biggest solar storm, you will *never* get lost!

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