1 00:00:00,000 --> 00:00:22,080 We're about 25 meters from where we were, and when we last experienced some problems 2 00:00:22,080 --> 00:00:23,080 with the GPS. 3 00:00:23,080 --> 00:00:24,080 Over. 4 00:00:24,080 --> 00:00:25,520 Can you still hear me? 5 00:00:25,520 --> 00:00:27,640 The radio's coming in loud and clear too. 6 00:00:27,640 --> 00:00:28,640 Keep us posted. 7 00:00:28,640 --> 00:00:31,880 We shouldn't really assume whether or not the technical problem was permanent. 8 00:00:31,880 --> 00:00:33,840 My guess is that one of the satellites was broken. 9 00:00:33,840 --> 00:00:36,200 Now, Jacob, don't jump to conclusions. 10 00:00:36,200 --> 00:00:40,680 And besides, Mr. Gunnow said the 29 GPS satellites orbit the Earth. 11 00:00:40,680 --> 00:00:43,200 It's possible, but not likely, that they're all broken. 12 00:00:43,200 --> 00:00:46,600 I guess you're right, but what other explanation is there? 13 00:00:46,600 --> 00:00:52,360 Either way, if we want to complete our assignment, we have to make sure this works. 14 00:00:52,360 --> 00:00:54,480 It should be another 8 meters. 15 00:00:54,480 --> 00:00:55,480 A little to the right. 16 00:00:55,480 --> 00:00:56,480 I don't see anything. 17 00:00:56,480 --> 00:00:57,480 Another 5 meters. 18 00:00:57,480 --> 00:00:58,480 Oh, wait, I see something. 19 00:00:58,480 --> 00:00:59,480 This is so cool. 20 00:00:59,480 --> 00:01:00,480 I can't believe we found it. 21 00:01:00,480 --> 00:01:01,480 RG to Headquarters. 22 00:01:01,480 --> 00:01:02,480 We've found the geocache. 23 00:01:02,480 --> 00:01:16,280 I repeat, we have found the geocache at the exact coordinates listed on the website. 24 00:01:16,280 --> 00:01:17,740 Good work, guys. 25 00:01:17,740 --> 00:01:19,800 Are you sure the coordinates are correct? 26 00:01:19,800 --> 00:01:20,800 We're sure. 27 00:01:20,800 --> 00:01:21,800 We've double-checked and double-confirmed. 28 00:01:21,800 --> 00:01:22,800 Mission accomplished. 29 00:01:22,800 --> 00:01:23,800 We're returning to Headquarters. 30 00:01:23,800 --> 00:01:24,800 Over. 31 00:01:24,800 --> 00:01:28,160 It looks like you were right. 32 00:01:28,160 --> 00:01:30,080 I shouldn't have jumped to a conclusion. 33 00:01:30,080 --> 00:01:33,280 Clearly, the satellites and the GPS devices are working properly. 34 00:01:33,280 --> 00:01:36,400 And that's a good thing, but we still don't know what caused the problem in the first 35 00:01:36,400 --> 00:01:37,400 place. 36 00:01:37,400 --> 00:01:38,400 Let's go to the problem board. 37 00:01:38,400 --> 00:01:39,400 Okay. 38 00:01:39,400 --> 00:01:40,400 What do we know? 39 00:01:40,400 --> 00:01:44,240 We know that our GPS malfunctioned in two different locations at the same time. 40 00:01:44,240 --> 00:01:47,680 And we also know from Catherine and Tony's report that satellites communicate with GPS 41 00:01:47,680 --> 00:01:49,640 devices through radio waves. 42 00:01:49,640 --> 00:01:50,640 Of course. 43 00:01:50,640 --> 00:01:53,000 And now we know that the problem was only temporary. 44 00:01:53,000 --> 00:01:54,000 True. 45 00:01:54,200 --> 00:01:56,600 Satellites and GPS devices are working fine now. 46 00:01:56,600 --> 00:01:57,780 So what do we need to know? 47 00:01:57,780 --> 00:02:00,600 We need to know more about radio waves and how they might be affected. 48 00:02:00,600 --> 00:02:04,200 It might also help if we knew anyone else who had a similar problem. 49 00:02:04,200 --> 00:02:05,400 So where do we go? 50 00:02:05,400 --> 00:02:09,480 Let's email Ulla and Nina in Norway and see if they had the same problem on the same day. 51 00:02:09,480 --> 00:02:10,480 Great idea. 52 00:02:10,480 --> 00:02:13,400 We may not have this problem solved, but we're making progress. 53 00:02:13,400 --> 00:02:14,400 Yes. 54 00:02:14,400 --> 00:02:16,320 And we need to make a report for Tony. 55 00:02:16,320 --> 00:02:18,720 Maybe he can help us from Colorado. 56 00:02:18,720 --> 00:02:22,560 For some great ideas on creating your own reports, visit the Treehouse on the NASA SciFiles 57 00:02:22,560 --> 00:02:23,560 website. 58 00:02:23,560 --> 00:02:35,920 We read about the Treehouse detectives' problem with their GPS, but we weren't much help. 59 00:02:35,920 --> 00:02:38,480 We were not geocaching on the same day. 60 00:02:38,480 --> 00:02:41,560 And we haven't had any problems with our GPS. 61 00:02:41,560 --> 00:02:46,760 We decided to ask Dr. D about it when we meet at the Alomar LiDAR Observatory. 62 00:02:46,760 --> 00:02:50,160 I'm excited to finally be here at the observatory. 63 00:02:50,160 --> 00:02:51,880 I read so much about it. 64 00:02:52,000 --> 00:02:54,440 Dr. D, what kind of research is done here? 65 00:02:54,440 --> 00:02:58,280 The scientists are investigating the middle atmosphere using lasers like this and radar 66 00:02:58,280 --> 00:02:59,280 instruments. 67 00:02:59,280 --> 00:03:02,640 Isn't radar what the police use to bounce off cars and see how fast they're going? 68 00:03:02,640 --> 00:03:05,280 And weathermen use it to track rain and snow storms. 69 00:03:05,280 --> 00:03:06,280 Exactly. 70 00:03:06,280 --> 00:03:10,520 Radar sends out a beam of light which is reflected off the atmosphere and is then analyzed. 71 00:03:10,520 --> 00:03:12,840 Did you just say that radar sends out a light beam? 72 00:03:12,840 --> 00:03:14,720 I thought that radar used radio waves. 73 00:03:14,720 --> 00:03:17,000 It does, but radio waves are a form of light. 74 00:03:17,000 --> 00:03:19,560 There are many forms of light that are not visible. 75 00:03:19,560 --> 00:03:20,560 Like what? 76 00:03:20,560 --> 00:03:25,240 For example, this observatory uses microwave light to measure water vapor, infrared light 77 00:03:25,240 --> 00:03:28,720 to detect clouds, and ultraviolet light to measure the ozone layer. 78 00:03:28,720 --> 00:03:31,120 I've heard of ultraviolet light, but it's not visible. 79 00:03:31,120 --> 00:03:35,840 All these different forms of light are part of what is called the electromagnetic spectrum. 80 00:03:35,840 --> 00:03:41,160 Every form of light travels at 300 million meters per second in a vacuum and has a wavelength. 81 00:03:41,160 --> 00:03:45,240 We learned that the wavelength is the distance between the crest of two successive waves. 82 00:03:45,240 --> 00:03:46,240 That's right. 83 00:03:46,240 --> 00:03:50,440 Some radio light has wavelengths that are hundreds of meters long, where ultraviolet 84 00:03:50,440 --> 00:03:55,280 light wavelengths are very tiny, only about one ten-thousandth of a millimeter. 85 00:03:55,280 --> 00:03:56,840 That's a big difference. 86 00:03:56,840 --> 00:03:57,840 It is. 87 00:03:57,840 --> 00:04:01,520 Light also has a frequency, which is its rate of vibration. 88 00:04:01,520 --> 00:04:04,000 Here, hold on to this spring. 89 00:04:04,000 --> 00:04:07,680 I'm going to make it vibrate and create what's called a standing wave. 90 00:04:16,240 --> 00:04:24,680 The faster you move your hand, the shorter the wavelength. 91 00:04:24,680 --> 00:04:25,680 Exactly. 92 00:04:25,680 --> 00:04:28,200 And the shorter the wavelength, the higher the energy. 93 00:04:28,200 --> 00:04:30,400 Which light has the most energy? 94 00:04:30,400 --> 00:04:35,640 That would be gamma rays, followed by X-rays, ultraviolet, visible light, infrared, and 95 00:04:35,640 --> 00:04:36,640 radio waves. 96 00:04:36,640 --> 00:04:37,640 Wow. 97 00:04:37,640 --> 00:04:39,280 I still can't believe that they're all called light. 98 00:04:39,280 --> 00:04:43,560 Dr. D, the treehouse detectives want to know more about the radio waves the satellite uses 99 00:04:43,560 --> 00:04:45,520 to communicate with GPSs. 100 00:04:45,520 --> 00:04:46,520 Good question. 101 00:04:46,520 --> 00:04:51,040 First, you need to know that there are a lot of different types of radio waves. 102 00:04:51,040 --> 00:04:54,200 GPS satellites communicate with a type of radio wave called microwave. 103 00:04:54,200 --> 00:04:55,920 I've heard of shortwave radio. 104 00:04:55,920 --> 00:04:56,920 That's another type. 105 00:04:56,920 --> 00:04:59,340 There are also AM and FM radio and TV. 106 00:04:59,340 --> 00:05:04,000 But GPS satellites communicate with microwaves because these pass easily through the atmosphere 107 00:05:04,000 --> 00:05:05,240 and are not absorbed. 108 00:05:05,240 --> 00:05:07,960 Are the other forms of light absorbed by the atmosphere? 109 00:05:07,960 --> 00:05:08,960 Not all of them. 110 00:05:08,960 --> 00:05:13,560 Ozone in the atmosphere is absorbed most, but not all of the ultraviolet light. 111 00:05:13,600 --> 00:05:17,320 Unfortunately, most of the X-rays and gamma rays are also absorbed. 112 00:05:17,320 --> 00:05:19,320 But visible lights get through pretty easily. 113 00:05:19,320 --> 00:05:22,040 Yes, the atmosphere is transparent to visible light. 114 00:05:22,040 --> 00:05:27,280 I heard that some radio waves, like AM and shortwave radio, can bounce off the atmosphere 115 00:05:27,280 --> 00:05:28,280 and travel great distances. 116 00:05:28,280 --> 00:05:29,280 That's correct. 117 00:05:29,280 --> 00:05:31,280 But FM radio and TV don't. 118 00:05:31,280 --> 00:05:36,800 I also mentioned that all radio waves can be created by moving electrical charges. 119 00:05:36,800 --> 00:05:41,080 The Kids Club members said you might want to learn more about electricity to solve your 120 00:05:41,080 --> 00:05:42,840 GPS problem. 121 00:05:42,840 --> 00:05:43,840 I agree. 122 00:05:43,840 --> 00:05:48,760 And if camping conditions aren't too primitive, I recommend that you look up Dr. Baganal, 123 00:05:48,760 --> 00:05:53,000 a friend of mine who studies electricity at the University of Colorado. 124 00:05:53,000 --> 00:05:57,680 I know that we use electricity all the time, but I'm not sure what it is exactly. 125 00:05:57,680 --> 00:06:01,640 It's a physical phenomenon associated with static and moving electrical charges. 126 00:06:01,640 --> 00:06:03,640 Oh, I get it. 127 00:06:03,640 --> 00:06:06,440 I'm sorry, would you repeat that again? 128 00:06:06,440 --> 00:06:07,440 I know. 129 00:06:07,440 --> 00:06:08,640 It's complex. 130 00:06:08,640 --> 00:06:12,520 Electricity doesn't have a simple explanation, nor is it easy to understand. 131 00:06:12,520 --> 00:06:14,440 So let's start with the basics. 132 00:06:14,440 --> 00:06:17,400 Take this plastic stick and rub it against this cloth. 133 00:06:17,400 --> 00:06:18,400 Okay. 134 00:06:18,400 --> 00:06:27,200 Okay, now take this other one, made of the same material, rub it with the cloth and see 135 00:06:27,200 --> 00:06:36,720 if you can try and put the ends together. 136 00:06:36,720 --> 00:06:38,720 It looks like one is pushing the other. 137 00:06:38,720 --> 00:06:41,520 Now rub this one made of a different material. 138 00:06:42,520 --> 00:06:44,520 So now try and put them together. 139 00:06:52,520 --> 00:06:54,520 The different stick pulled the first stick. 140 00:06:54,520 --> 00:06:55,520 Why did it do that? 141 00:06:55,520 --> 00:06:56,520 Well, let's figure it out. 142 00:06:56,520 --> 00:06:58,520 Do you remember the parts of the atom? 143 00:06:58,520 --> 00:06:59,520 Yes. 144 00:06:59,520 --> 00:07:02,520 There is a nucleus with protons and neutrons surrounded by electrons. 145 00:07:02,520 --> 00:07:03,520 That's correct. 146 00:07:03,520 --> 00:07:07,520 And the protons are positively charged and the electrons are negatively charged. 147 00:07:07,520 --> 00:07:08,520 And the neutrons are neutral. 148 00:07:08,520 --> 00:07:09,520 Very good. 149 00:07:09,520 --> 00:07:12,520 And positive and negative charges are attracted to each other. 150 00:07:12,520 --> 00:07:14,520 We call that the attractive force. 151 00:07:14,520 --> 00:07:16,520 Aren't all atoms basically neutral? 152 00:07:16,520 --> 00:07:20,520 Yes, but when you put different materials together, sometimes the parts of the atoms 153 00:07:20,520 --> 00:07:21,520 like to move. 154 00:07:21,520 --> 00:07:26,520 However, some nuclei like to hang on to their electrons stronger than other nuclei. 155 00:07:26,520 --> 00:07:30,520 The stronger nuclei gather electrons from the weaker nuclei. 156 00:07:30,520 --> 00:07:33,520 Is that what happened when I rubbed the two different sticks with the cloth? 157 00:07:33,520 --> 00:07:37,520 When you rubbed the first two sticks with the cloth, the electrons left the cloth and 158 00:07:37,520 --> 00:07:38,520 gathered on the sticks. 159 00:07:38,520 --> 00:07:42,520 And then because they were both negatively charged, they repelled each other. 160 00:07:42,520 --> 00:07:45,520 So why did the different sticks attract one another? 161 00:07:45,520 --> 00:07:48,520 Well, different materials cause electrons to move differently. 162 00:07:48,520 --> 00:07:49,520 Oh, I get it. 163 00:07:49,520 --> 00:07:53,520 With the different stick, the electrons gathered on the cloth, leaving the stick positively charged. 164 00:07:53,520 --> 00:07:56,520 Because one stick was positively charged and the other one was negatively charged, 165 00:07:56,520 --> 00:07:57,520 they attract each other. 166 00:07:57,520 --> 00:07:59,520 Yeah, I think you've got it. 167 00:07:59,520 --> 00:08:03,520 So this kind of electricity is called static electricity because the charges are stationary 168 00:08:03,520 --> 00:08:04,520 and don't move. 169 00:08:04,520 --> 00:08:08,520 Now, shuffle your feet on the carpet and then touch this metal object. 170 00:08:08,520 --> 00:08:10,520 I have a bad feeling about this. 171 00:08:13,520 --> 00:08:14,520 Shocking. 172 00:08:14,520 --> 00:08:15,520 Can you explain why? 173 00:08:15,520 --> 00:08:16,520 I'll try. 174 00:08:16,520 --> 00:08:20,520 When I shuffled my feet, I gathered electrons from the carpet, making me negatively charged. 175 00:08:20,520 --> 00:08:21,520 That's correct. 176 00:08:21,520 --> 00:08:23,520 And what happened when you touched the metal object? 177 00:08:23,520 --> 00:08:27,520 The extra electrons jumped over to the metal, causing pain. 178 00:08:28,520 --> 00:08:30,520 Sorry, but you're right. 179 00:08:30,520 --> 00:08:33,520 It's an example of what we call current electricity. 180 00:08:33,520 --> 00:08:38,520 Watch what happens when I connect this end of the wire to this end of the hand generator. 181 00:08:39,520 --> 00:08:42,520 This looks like a complete circuit, where the light bulb has the load. 182 00:08:42,520 --> 00:08:46,520 When you turn the crank, you produce current, which is electrons flowing through the circuit. 183 00:08:46,520 --> 00:08:48,520 And the light bulb glows. 184 00:08:49,520 --> 00:08:50,520 Exactly. 185 00:08:50,520 --> 00:08:55,520 Now watch what happens when I connect the generator to this circuit near these compasses. 186 00:08:56,520 --> 00:08:57,520 Wait a minute. 187 00:08:57,520 --> 00:08:58,520 The compasses moved. 188 00:08:58,520 --> 00:08:59,520 Why'd they do that? 189 00:08:59,520 --> 00:09:02,520 Initially, the compass was pointing towards the Earth's North Pole. 190 00:09:02,520 --> 00:09:07,520 When we cranked the generator to make the current flow, a small magnetic field was created. 191 00:09:07,520 --> 00:09:10,520 This field caused the compass needle to swing, 192 00:09:10,520 --> 00:09:14,520 because the needle is, itself, a small magnet with a north and south end. 193 00:09:15,520 --> 00:09:16,520 Very interesting. 194 00:09:16,520 --> 00:09:18,520 The trails detectives need to know about this. 195 00:09:18,520 --> 00:09:19,520 I'm sure they will. 196 00:09:19,520 --> 00:09:20,520 I'm sure they will. 197 00:09:21,520 --> 00:09:22,520 Very interesting. 198 00:09:22,520 --> 00:09:24,520 The trails detectives need to know about this. 199 00:09:24,520 --> 00:09:25,520 Thanks, Dr. Bagnall. 200 00:09:25,520 --> 00:09:26,520 You're welcome. 201 00:09:26,520 --> 00:09:28,520 I have some more experiments. 202 00:09:28,520 --> 00:09:30,520 I didn't know that electricity was so cool. 203 00:09:30,520 --> 00:09:34,520 Dr. Bagnall said that flowing electricity creates a magnetic field. 204 00:09:34,520 --> 00:09:38,520 If that's true, then we need to know more about magnets and magnetism. 205 00:09:39,520 --> 00:09:40,520 So what's up? 206 00:09:40,520 --> 00:09:43,520 Will learning about magnets help the treehouse detectives? 207 00:09:43,520 --> 00:09:46,520 What other information do they need to solve the mystery? 208 00:09:46,520 --> 00:09:50,520 Find out in the next exciting chapter of The Case of the Technical Knockout.