Twenty years ago today — February 14, 1989 — a Global Positioning System (GPS) Block-IIR satellite launched from Cape Canaveral, Florida. That might not seem like a big deal, since there have been so many GPS satellites launched and so many are operational — but it gives us a chance to point out how vital GPS is to your life, in ways you might not even know.
(GPS IIRM artist’s conception, linked from the Lockheed Martin web site)
Sure, you know about GPS receivers that, combined with mapping software, can tell you where you are and guide you to your destination. Maybe you have a GPS receiver in your car, or even in your cell phone. But did you realize the GPS signal provides more than just position information? That even if you don’t use GPS navigation in your daily life, you probably depend on the system anyway?
One of the most important aspects of the GPS signal is precise timing. Remember the Chicago song “Does Anybody Really Know What Time It Is?” The National Institute of Standards and Technology does know what time it is, and measures that time very precisely. But it wouldn’t do any good for one office to know the precise time, so the timing signal has to be sent out everywhere to keep everything in synch. That’s one of the GPS system’s roles, to distribute that precise timing signal that allows our networked world to keep communicating. If I remember correctly, the 2nd Space Operations Squadron actually maintains the backup timing standard for the whole country, just so they can keep the GPS system clock accurate.
Imagine you’re at your favorite restaurant and have just enjoyed a fantastic meal — it is Valentine’s Day, after all — and you pay with your credit card. The little computer in the credit card machine has to communicate with the computers in the bank or credit card company in order to process your transaction. The problem is, computer signals are time-tagged and if the computers don’t agree on what time it is, they can’t understand each other. But because they have a timing standard, those computers can communicate reliably and your transaction can go through. (As long as you have money in the bank, of course.)
Think of the common things people do every day using networked computers: making credit card transactions, placing phone calls over computerized switches, looking at blogs and websites on the Net. All of those things depend on timing signals between the computers, and what keeps those signals consistent around the world is the GPS satellite constellation.
GPS: it’s not just for navigation.
So if you didn’t know, that’s what space means to you in your everyday life.
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