GPS may not be the world’s first satellite-based global radio-navigation system (Transit was), but it is by far the most successful and widely used system of its kind today. While you may consider the steep development costs (~$20B) and annual maintenance costs (~$1B) to be overly pricey, all feelings of buyer’s remorse (taxes…the horror, the horror) should instantly evaporate with the awareness of the unforeseen success and realized global economic benefit of GPS (>$300B per year benefit for >2B users). That’s quite a large profit margin isn’t it? You’re welcome!
GPS, known as Global Position System, was developed by the U.S. Department of Defense in the early 1970’s (declared “operational” in 1995) to facilitate global campaign and military theater operations. The byproduct we know as civilian GPS was a completely unforeseen and unexpected derivative of the military program. Today, billions of users around the world use GPS daily. It has changed our world and the way we live in it.
Meter-level accuracy … from 20,000 kilometers away?
The capability, and accomplishment of the GPS program, impresses me every time I think about it. In a nut shell, GPS gives every civilian user the ability to precisely determine their position within a meter from anywhere on Earth while using a receiver as cheap as $1. And this service is completely free. FREE!
While we owe this accomplishment to many, many people who advanced the science behind the technology (Einstein, to name at least one, giving us time and gravitational Relativity theory), their collective achievements successfully placed 30+ satellites 20,000 kilometers above Earth’s surface (traveling at 4 kilometers per second in orbit) capable of maintaining synchronized time within 10 nanoseconds of each other.
Time, you see, is the heart of GPS. Accurate time (read: very, very accurate). GPS uses the method of Trilateration to measure the time it takes for a radio signal to travel from a satellite to your $1 receiver on Earth. By measuring these times from multiple satellites your receiver converts the times to distances and “triangulates” them to determine your physical position. But, since radio waves travel so fast (speed of light), we need very accurate atomic clocks in the satellites to ensure the time stamps on the signals are incredibly precise. After all you want it to be accurate, right? And this all occurs aboard satellites in outer space, 20,000 kilometers above, zooming over the Earth at 4 kilometers per second. Mind boggling.
The Lord Giveth, and The Lord Taketh Away
Forget not that the U.S. military owns, and operates, all aspects of GPS. In the late 1990’s the U.S. employed Selective Availability in the constellation of satellites, intentionally degrading the public signal accuracy for purposes of national security (in fear, mostly). This practice has been decommissioned since 2000 by Presidential Order (Bill Clinton), but make no mistake that the U.S. military retains the ability to degrade or shut off GPS if it is required for national security. They own it, but we (every person on Earth) reap the benefits.
No Free Lunches, Well Except for GPS
I keep mentioning that GPS is free, but this should truly impress you, especailly in our current day society. Regardless of what country you are standing in or come from, you can turn on your $1 receiver anywhere on Earth and instantly know your position. Nearly every shred of new technology going forward needs to be able to operate in tandem with GPS, as our desire to know and apply our position instantly is no longer a wish, but a requirement of the day.