If you have a GPS unit - in your car, in your smartphone, in whatever -
it will almost certainly not work if you go above 60,000 feet or go faster than 1200mph.
And the reason...
...is this!
This is the Rocket Garden at Kennedy Space Center in Florida.
And those are intercontinental ballistic missiles that they strapped a person on top of
and sent them into space.
And when GPS was being developed by the US Department of Defense, the Cold War was still going on.
And - well, they didn't want Soviet ICBMs to be incredibly precisely targeted.
And so all the GPS chips that are for consumer use have this restriction in them -
that if you go too fast or too high they will say,
"Oh no, I am a missile!"
And stop working.
And the only time that this has really affected anyone is in the last few years
as high-altitude unmanned ballooning has taken off, the kind of stratospheric weather balloons
that take gorgeous pictures from on high.
Because when they come down they need to be tracked, and the GPS unit suddenly thinks
it's in the stratosphere, it must be a missile, and it shuts down.
And the solution? Some of these GPS units only shut down if you're going too high
AND too fast. Find one of those, you can use it in your balloon.
Otherwise, it's probably best if you stay a little bit closer to Earth.
And that is something you might not have known.
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