1 00:00:00,000 --> 00:00:08,000 Trying to figure out where you are and where you're going has always been a challenge. 2 00:00:08,000 --> 00:00:13,000 Navigation and positioning are crucial to so many activities, and yet the process has not always been easy. 3 00:00:13,000 --> 00:00:19,000 Thankfully, the days of navigating by celestial means or landmarks are long gone since the introduction of GPS, 4 00:00:19,000 --> 00:00:21,000 or the Global Positioning System. 5 00:00:21,000 --> 00:00:23,000 So what is GPS? 6 00:00:23,000 --> 00:00:26,000 For some answers, I spoke with Dr. Kevin Dutton at NASA Langley. 7 00:00:26,000 --> 00:00:28,000 Find out how it works. 8 00:00:28,000 --> 00:00:31,000 GPS stands for the Global Positioning System. 9 00:00:31,000 --> 00:00:38,000 And like the name suggests, it's a system to find your location anywhere on the Earth or near the Earth's surface. 10 00:00:38,000 --> 00:00:43,000 And the way it does that is by using radio frequency broadcast from orbiting satellites. 11 00:00:43,000 --> 00:00:46,000 Can you tell me why GPS was originally developed? 12 00:00:46,000 --> 00:00:51,000 It was developed by the Defense Department to meet all of their navigational needs. 13 00:00:51,000 --> 00:00:55,000 For example, aircraft and ships at sea. 14 00:00:55,000 --> 00:01:02,000 And now even individual soldiers carry little receivers like this in the field to find out where they are. 15 00:01:02,000 --> 00:01:08,000 The Global Positioning System consists of a constellation of 24 satellites and their ground stations working together. 16 00:01:08,000 --> 00:01:13,000 GPS uses these man-made stars as reference points to calculate positions accurate to a matter of meters, 17 00:01:13,000 --> 00:01:15,000 and in some cases centimeters. 18 00:01:15,000 --> 00:01:21,000 As long as you have a GPS receiver and a clear view of the sky and a map, you'll never be lost again. 19 00:01:21,000 --> 00:01:30,000 Today, GPS is finding its way into cars, boats, planes, construction equipment, farm machinery, even laptop computers. 20 00:01:30,000 --> 00:01:32,000 So how does the system work? 21 00:01:32,000 --> 00:01:36,000 Let's say you're backpacking and you have a receiver with you. 22 00:01:36,000 --> 00:01:38,000 You're going to turn on that receiver. 23 00:01:38,000 --> 00:01:43,000 Now the GPS satellites are constantly broadcasting a signal, all 24 of them. 24 00:01:43,000 --> 00:01:49,000 But above you at any one time, there's only 12 available, and then the other 12 are on the other side of the Earth. 25 00:01:49,000 --> 00:01:55,000 So your receiver is going to listen and try to find at least four of these satellites directly above you, 26 00:01:55,000 --> 00:01:59,000 and then it's going to determine a range for each satellite, 27 00:01:59,000 --> 00:02:04,000 and it's going to use those ranges and the known locations of the satellites, 28 00:02:04,000 --> 00:02:09,000 and it's going to do some mathematical calculations and a process called trilateration, 29 00:02:10,000 --> 00:02:13,000 and it's going to figure out where that GPS receiver is. 30 00:02:13,000 --> 00:02:19,000 That'll also give you altitude, and it'll give you speed and the direction that you're traveling in. 31 00:02:19,000 --> 00:02:23,000 A standard GPS receiver will not only place you on a map at any particular location, 32 00:02:23,000 --> 00:02:26,000 but will also trace your path across a map as you move. 33 00:02:26,000 --> 00:02:32,000 If you leave your receiver on, it can stay in constant communication with GPS satellites to see how your location is changing. 34 00:02:32,000 --> 00:02:37,000 With this information and its built-in clock, the receiver can give you several pieces of valuable information, 35 00:02:37,000 --> 00:02:43,000 like how far you've traveled, how long you've been traveling, your current speed and your average speed, 36 00:02:43,000 --> 00:02:48,000 also the estimated time of arrival at your destination if you maintain your current speed. 37 00:02:48,000 --> 00:02:52,000 There's a lot of uses that they hadn't really thought about when they developed the system. 38 00:02:52,000 --> 00:02:59,000 For example, later on it was discovered that if you put multiple antennas on a vehicle, like an aircraft for instance, 39 00:02:59,000 --> 00:03:01,000 you could actually get attitude. 40 00:03:01,000 --> 00:03:06,000 You could figure out its orientation and whether it was rolling or pitching or yawing. 41 00:03:06,000 --> 00:03:13,000 Other things that they didn't realize they could really do were, for instance, seismologists use it for earthquake detection 42 00:03:13,000 --> 00:03:17,000 to find out when tectonic plates are actually shifting apart. 43 00:03:17,000 --> 00:03:18,000 It's that good. 44 00:03:18,000 --> 00:03:19,000 Something else. 45 00:03:19,000 --> 00:03:20,000 Very interesting. 46 00:03:20,000 --> 00:03:22,000 Sure. 47 00:03:22,000 --> 00:03:24,000 So that's how it works. 48 00:03:24,000 --> 00:03:28,000 So the next time you want to know where you are or where you're going, don't reach for a map. 49 00:03:28,000 --> 00:03:30,000 Reach for your GPS. 50 00:03:30,000 --> 00:03:34,000 How much button is it here to press for a date for tonight's gathering?