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by Teresa Martin

I get lost a lot. Directionally challenged, they call me.

It doesn't usually fluster me that much. I mean, when you expect to get lost you aren't terribly surprised when you do and you always try to factor in a little extra time for taking the scenic route. As a plus, it means you aren't afraid to venture to new places, either. Fear of getting lost is the reason most people hesitate - but when you KNOW you'll get lost anyway, a little detail like that doesn't stop you.

However, the hot holiday gift this year was a balm for that very fear. This was the season in which the GPS receiver was finally in reach for average consumers.

The Global Positioning System is comprised of a couple dozen medium earth orbit satellites that transmit very precise microwave signals that contain the atomic time and the location of the satellite. A GPS receiver uses the data from this geographic coordinate system to determine its own exact location on earth. It displays this onto a visual map and makes it possible to calculate how to move from one location to another.

This may seem a bit like magic, but it is really just a very smart use of applied mathematics. In oversimplified terms, it is using values A, B, C, and D to solve for W - as in Where am I? It is complex math, to be sure, with a high level of detail. And it's also a great answer to that age-old kid-homework-whine, What I am ever going to use math for anyway?

The GPS system in question is named NAVSTAR GPS and it is a constellation of satellites managed by the United States Air Force 50th Space Wing. It was originally developed for military applications in the 1980s and then opened up for commercial use. According to Wikipedia, which cites the NAVSTAR Joint Program Office as its source, it costs about US$750 million per year to maintain the system, including satellite replacement and R&D. The government maintains well-written and understandable information about GPS at http://www.gps.gov/

Frankly, these are pretty good tax dollars at work. It's an infrastructure that everyone can benefit from in a myriad of ways and it something only an organization the scale of a national government could make happen.

Now, I've been reading about these systems for a long time. The first time I experienced one was in the early 90s, in a tech trade show-equipped rental vehicle. I was not the driver and wasn't willing to be a passenger very long either, after that first experience. The driver decided to take the GPS directions very literally, letting them trump that which was in front of his eyes. Like, uhm, a one-way street. "It is telling me to turn left" I seem to remember him screaming to the rest of the carpool group who, like pesky earth-bound humans, kept pointing to the swerving cars and the One Way Only signs.

But my rounds of calls to various friends asking for directions-on-the-fly (How do I find the Mass Pike? I've just passed the same store in Falmouth for the third time, help? I think I'm in Chatham, somewhere, I think) may be a thing of the past. This holiday season I received a spiffy little portable system. And it is downright scary.

"Turn Right Now" it commands, and darn, if I'm not at the exact point where I need to make a right turn. Continue 18.2 miles, it instructs me. And I do. The user interpretation databases have come along way since that memorable San Francisco wrong-way drive.

There are several vendors of these consumer-grade products. Competition is a good thing. They dueled over pricing and features, each highly motivated to be the one the land in the holiday cart. It seems that every time I've turned around this week, someone is talking about his or her new navigation tool and two others say they are just about ready to buy one. It's the kind of moment that must give consumer goods folks the warm fuzzies.

Sometimes space and mathematics and the physics of sound seem very far away and the province only of a special few. But in my little black GPS box with color monitor and friendly voice, this high reaching technology has landed firmly on earth. And, as I successfully parked the car in the parking lot of this morning's destination, without miss-guessing turn, I realized that this is a very good thing, too.