1 00:00:00,000 --> 00:00:04,320 So, how did you do with the questions? 2 00:00:04,320 --> 00:00:05,320 Great job, everyone. 3 00:00:05,320 --> 00:00:08,160 Have you ever heard of the term remote sensing? 4 00:00:08,160 --> 00:00:13,160 Well, it's a rather simple activity that we do every day of our lives. 5 00:00:13,160 --> 00:00:19,240 In fact, as you're watching this program right now, you're actively engaged in remote sensing. 6 00:00:19,240 --> 00:00:23,200 Coming from the screen is energy in the form of visible light. 7 00:00:23,200 --> 00:00:28,120 The radiated light is detected by sensors in our eyes, which collect data about the 8 00:00:28,120 --> 00:00:31,760 energy and transmit that information to the brain. 9 00:00:31,760 --> 00:00:36,080 In the brain, those data are interpreted and meaning is attached to it. 10 00:00:36,080 --> 00:00:39,300 We experience such sensations as heat. 11 00:00:39,300 --> 00:00:42,200 We react to chemical signals from food. 12 00:00:42,200 --> 00:00:47,600 We understand the textures of different surfaces, all without coming in direct contact. 13 00:00:47,600 --> 00:00:50,680 Now, this can be called remote sensing. 14 00:00:50,680 --> 00:00:56,080 Now, at NASA, remote sensing has a slightly more technical definition. 15 00:00:56,080 --> 00:01:03,480 So, let's talk to an expert in that field, Dan Irwin at NASA Marshall Space Flight Center. 16 00:01:03,480 --> 00:01:07,120 Thanks, Jennifer. 17 00:01:07,120 --> 00:01:11,020 Remote sensing is gathering information about the Earth from a distance. 18 00:01:11,020 --> 00:01:14,440 Information can be collected about the land using special cameras or instruments located 19 00:01:14,440 --> 00:01:19,160 just a few feet above the Earth's surface, or an airplane flying hundreds to thousands 20 00:01:19,160 --> 00:01:24,520 of feet above the ground, or even from a satellite orbiting hundreds of miles above the Earth. 21 00:01:24,520 --> 00:01:29,600 Now that you know what remote sensing means, let's talk about terrestrial remote sensing. 22 00:01:29,600 --> 00:01:34,000 Terrestrial refers to the Earth, so terrestrial remote sensing means gathering information 23 00:01:34,000 --> 00:01:36,000 about the Earth from a distance. 24 00:01:36,000 --> 00:01:39,960 This involves the detection and measuring of electromagnetic energy coming from different 25 00:01:39,960 --> 00:01:42,840 objects made of various materials. 26 00:01:42,840 --> 00:01:46,640 The spectrum of sunlight reflected by the Earth's surface contains information about 27 00:01:46,640 --> 00:01:48,800 the materials it is made of. 28 00:01:48,800 --> 00:01:54,000 Since sand, rocks, crops, and dense vegetation each have different temperatures and reflect 29 00:01:54,000 --> 00:01:59,000 light in different ways, sensors can reveal clues about past human activities, such as 30 00:01:59,000 --> 00:02:02,480 agriculture, that our eyes may not be able to detect. 31 00:02:02,480 --> 00:02:04,240 Most of the universe is invisible to humans. 32 00:02:04,240 --> 00:02:08,320 In fact, the only part that we can see with our detectors, or our eyes, is part of the 33 00:02:08,320 --> 00:02:12,800 electromagnetic spectrum known as visible light. 34 00:02:12,800 --> 00:02:17,280 If the entire electromagnetic spectrum were scaled to the size of the Earth's circumference, 35 00:02:17,280 --> 00:02:21,480 the portion of visible light would be as wide as a pencil. 36 00:02:21,960 --> 00:02:25,400 Scientists have been able to build sensors that can see portions of the electromagnetic 37 00:02:25,400 --> 00:02:27,160 spectrum that we cannot. 38 00:02:27,160 --> 00:02:30,440 For example, Norbert is standing next to a hot stove. 39 00:02:30,440 --> 00:02:34,680 He cannot see the infrared energy coming from it, but the sensors in his skin send data 40 00:02:34,680 --> 00:02:37,280 to his brain that's interpreted as heat. 41 00:02:37,280 --> 00:02:38,960 He knows to move away. 42 00:02:38,960 --> 00:02:42,120 We know to protect our skin from ultraviolet radiation. 43 00:02:42,120 --> 00:02:46,620 While we cannot see this energy with our eyes, we can see its effects on our skin. 44 00:02:46,620 --> 00:02:49,200 So what is the electromagnetic spectrum? 45 00:02:49,200 --> 00:02:53,120 The electromagnetic spectrum is just a name that scientists give to a bunch of types of 46 00:02:53,120 --> 00:02:56,740 radiation when they want to talk about them as a group. 47 00:02:56,740 --> 00:03:00,000 Radiation is energy that travels and spreads out as it goes. 48 00:03:00,000 --> 00:03:03,440 Visible light that comes from a lamp in your house or radio waves that come from a radio 49 00:03:03,440 --> 00:03:07,120 station are two types of electromagnetic radiation. 50 00:03:07,120 --> 00:03:12,840 Other examples of electromagnetic radiation are microwaves, infrared and ultraviolet light, 51 00:03:12,840 --> 00:03:14,520 x-rays and gamma rays. 52 00:03:14,840 --> 00:03:20,120 Hotter, more energetic objects create higher energy radiation than cooler objects. 53 00:03:20,120 --> 00:03:24,640 Visible satellite images are similar to pictures a photographer might record in that they relay 54 00:03:24,640 --> 00:03:28,960 and display reflected light just as our eyes would see the scene. 55 00:03:28,960 --> 00:03:35,080 As long as light is available, land features like mountains, river courses, lakes, silt 56 00:03:35,080 --> 00:03:39,880 runoff from rivers into the sea and coastlines are clearly visible. 57 00:03:39,880 --> 00:03:43,080 But what about the energy that we cannot see? 58 00:03:43,080 --> 00:03:46,480 Infrared images display gradients of temperature differences. 59 00:03:46,480 --> 00:03:49,300 Infrared sensors pick up data both day and night. 60 00:03:49,300 --> 00:03:52,040 They show the pattern of heat released from the earth. 61 00:03:52,040 --> 00:03:56,640 Heat-producing areas such as warm water currents or cities with heat-absorbing concrete and 62 00:03:56,640 --> 00:04:02,120 asphalt and heat-producing cars, people and factories are bright spots on the infrared 63 00:04:02,120 --> 00:04:04,120 images. 64 00:04:04,120 --> 00:04:08,280 Archaeologists use data collected by sensors located on satellites to reveal clues about 65 00:04:08,280 --> 00:04:13,440 the past temperature and chemical composition to find potential agricultural and other areas 66 00:04:13,440 --> 00:04:15,120 of human occupation. 67 00:04:15,120 --> 00:04:21,640 For example, let's take a look at a satellite image of the Sahara Desert in Africa. 68 00:04:21,640 --> 00:04:26,000 Right now you're looking at an image in visible light as if you were in an airplane or a spacecraft 69 00:04:26,000 --> 00:04:27,560 looking out the window. 70 00:04:27,560 --> 00:04:32,880 A 50-kilometer-wide path from the Shuttle Imaging Radar mission over the Sahara is now 71 00:04:32,880 --> 00:04:35,760 shown superimposed on the previous image. 72 00:04:35,760 --> 00:04:40,960 The radar penetrated a few meters beneath the desert sand to reveal a prehistoric river 73 00:04:40,960 --> 00:04:42,600 system. 74 00:04:42,600 --> 00:04:46,600 Archaeologists have found artifacts and animal remains showing that this was once a moist 75 00:04:46,600 --> 00:04:48,720 and densely vegetated area. 76 00:04:48,720 --> 00:04:51,800 While each of these instruments creates a different image, imagine if they could be 77 00:04:51,800 --> 00:04:56,800 combined to give scientists and researchers new information about a particular area. 78 00:04:56,800 --> 00:04:58,200 That's what GIS does. 79 00:04:58,200 --> 00:05:01,440 GIS stands for Geographic Information System. 80 00:05:01,840 --> 00:05:08,080 GIS is a system of computer software, computer hardware, data, and humans that help manipulate, 81 00:05:08,080 --> 00:05:12,840 analyze, and present information about a specific geographic location. 82 00:05:12,840 --> 00:05:18,800 The human part of this system is the thinking explorer who is key to the power of GIS. 83 00:05:18,800 --> 00:05:23,600 Simply put, GIS combines layers of information about a place to give you a better understanding 84 00:05:23,600 --> 00:05:25,160 of that place. 85 00:05:25,160 --> 00:05:29,200 What layers of information you combine depends on what you want to know. 86 00:05:29,200 --> 00:05:32,920 If you want to find the best location for a new sporting goods store, you might want 87 00:05:32,920 --> 00:05:35,840 to know the traffic pattern and population density. 88 00:05:35,840 --> 00:05:38,960 You might also want to know if there are any potential customers living nearby.