WEBVTT FILE 1 00:00:00.020 --> 00:00:04.170 2 00:00:04.190 --> 00:00:05.850 3 00:00:05.870 --> 00:00:08.530 [ Narrator ] NASA and the USGS are preparing a new satellite, 4 00:00:08.550 --> 00:00:12.710 the Landsat Data Continuity Mission, called LDCM. 5 00:00:12.730 --> 00:00:16.840 Landsat satellites have been orbiting earth since 1972, 6 00:00:16.860 --> 00:00:20.939 taking scientific measurements of land cover and land use. LDCM is the eighth Landsat satellite 7 00:00:20.960 --> 00:00:21.070 and will continue the world's longest global data record of changes of the Earth's land surfaces. 8 00:00:21.090 --> 00:00:25.259 and will continue the world's longest global data record of changes of the Earth's land surfaces. 9 00:00:25.280 --> 00:00:29.440 LDCM data will also play a critical role in monitoring, understanding, and managing 10 00:00:29.460 --> 00:00:33.820 the world's forests, agriculture and water. [ Betsy Forsbacka ] What this data is useful for 11 00:00:33.840 --> 00:00:38.000 is to provide information to the scientists, particularly 12 00:00:38.020 --> 00:00:42.180 out in the Western states where water is a very 13 00:00:42.200 --> 00:00:46.360 big deal. This data, this remote data allows them to determine 14 00:00:46.380 --> 00:00:50.540 where areas are being irrigated, and how much and how often. 15 00:00:50.560 --> 00:00:54.710 [ Jim Irons ] TIRS is the Thermal Infrared Sensor 16 00:00:54.730 --> 00:00:58.839 that is being built and tested here at Goddard Space Flight Center for flight on the 17 00:00:58.860 --> 00:01:02.990 next Landsat mission. It's designed to measure the amount of 18 00:01:03.010 --> 00:01:07.110 thermal radiation emitted by the surface of the earth as a function of the earth's temperature. 19 00:01:07.130 --> 00:01:11.220 All objects that are warmer than zero, 20 00:01:11.240 --> 00:01:15.240 absolute zero, emit radiation. 21 00:01:15.260 --> 00:01:19.290 The hotter an object is, the shorter in wavelength is the peak radiation. 22 00:01:19.310 --> 00:01:23.330 [ Narrator ] For example, the sun is very hot, about 10,000 degrees, 23 00:01:23.350 --> 00:01:27.460 and its radiation peaks at about 0.5 micrometers. That's exactly in the region 24 00:01:27.480 --> 00:01:31.560 our eyes can see. Earth is much cooler, so its radiation has a much longer 25 00:01:31.580 --> 00:01:35.650 wavelength, about 10 micrometers. And that's in the far infrared region, well beyond 26 00:01:35.670 --> 00:01:39.830 what we can see. [ Jim Irons ] So, basically what the Thermal Infrared 27 00:01:39.850 --> 00:01:44.020 Sensor allows us to do is to determine 28 00:01:44.040 --> 00:01:48.330 the temperature of the surface of the earth at different locations around the globe. 29 00:01:48.350 --> 00:01:52.410 [ Narrator ] Using these surface temperatures, resource managers can determine how fast 30 00:01:52.430 --> 00:01:56.500 a field uses water. Rain or irrigation starts a cycle 31 00:01:56.520 --> 00:02:00.570 in which water ultimately returns to the atmosphere. Evaporation of water 32 00:02:00.590 --> 00:02:05.480 from the ground, and the transpiration of water from leaves, cools off both the soil and the plants. 33 00:02:05.500 --> 00:02:08.560 [ Betsy Forsbacka ] You put those two words together and you have 34 00:02:08.580 --> 00:02:12.620 the science term, evapotranspiration, and that's precisely what TIRS is measuring. 35 00:02:12.640 --> 00:02:16.660 These hot and cold signatures, that give us 36 00:02:16.680 --> 00:02:20.840 information on evapotranspiration where 37 00:02:20.860 --> 00:02:25.010 the water is transpiring through the plants and evaporating into the atmosphere 38 00:02:25.030 --> 00:02:29.190 The instrument is going to pick that up as a cool signature in areas that are not 39 00:02:29.210 --> 00:02:33.360 irrigated well will come across as a warm area to the instrument. 40 00:02:33.380 --> 00:02:36.450 [ Narrator ] To measure these warm areas and cool signatures, the TIRS instrument 41 00:02:36.470 --> 00:02:39.620 uses a technology array developed primarily 42 00:02:39.640 --> 00:02:42.670 at NASA's Goddard Space Flight Center, called 43 00:02:42.690 --> 00:02:45.829 Quantum Well Infrared Photodetectors. These QWIPS are 44 00:02:45.850 --> 00:02:48.859 more sensitive and precise than the thermal detectors used on previous 45 00:02:48.880 --> 00:02:52.000 Landsat satellites. But to operate correctly they need to be kept very cold. 46 00:02:52.020 --> 00:02:55.190 [ Betsy Forsbacka ] They have to be cooled to less than 47 00:02:55.210 --> 00:02:58.310 43 degrees Kelvin and so that's only 48 00:02:58.330 --> 00:03:01.500 43 degrees above absolute zero 49 00:03:01.520 --> 00:03:04.650 which is the coldest you can get. Very, very cold. 50 00:03:04.670 --> 00:03:07.839 [ Veronica Otero ] The interesting thing about TIRS is we have 51 00:03:07.860 --> 00:03:10.950 different thermal zones, you know like 52 00:03:10.970 --> 00:03:14.120 our detectors are around 43 Kelvin 53 00:03:14.140 --> 00:03:17.220 and then you have our telescope at 180 Kelvin 54 00:03:17.240 --> 00:03:20.400 and then you go to the warmer end of our instrument which is the 55 00:03:20.420 --> 00:03:23.489 structure and some other components that are around, 56 00:03:23.510 --> 00:03:26.670 you know, zero C or 273 Kelvin. 57 00:03:26.690 --> 00:03:29.720 [ Narrator ] Keeping these different TIRS components at these different temperatures 58 00:03:29.740 --> 00:03:32.850 is challenging because as the satellite orbits the earth every 59 00:03:32.870 --> 00:03:35.890 90 minutes its either being blasted by the heat of the sun or being frozen 60 00:03:35.910 --> 00:03:39.030 by the cold of space. [ Veronica Otero ] So you're exposing the 61 00:03:39.050 --> 00:03:42.210 instrument to these two harsh conditions 62 00:03:42.230 --> 00:03:45.359 and you're cycling it from one to the other. 63 00:03:45.380 --> 00:03:48.540 One of the things that we do on our sensor unit is we have multi- 64 00:03:48.560 --> 00:03:51.670 layer insulation blankets. These work really well 65 00:03:51.690 --> 00:03:54.840 in space because there's no 66 00:03:54.860 --> 00:03:57.940 environment, there's no air. 67 00:03:57.960 --> 00:04:01.120 The blankets protect us from these extreme conditions 68 00:04:01.140 --> 00:04:04.230 The other thing we use is we have an earth shield. 69 00:04:04.250 --> 00:04:07.410 [ Betsy Forsbacka ] It is basically a five foot door. 70 00:04:07.430 --> 00:04:10.510 It's about five feet long and it shields much of the instrument 71 00:04:10.530 --> 00:04:13.670 from the earth, from parts of the earth 72 00:04:13.690 --> 00:04:16.740 that we're not imaging. That's a tremendous help 73 00:04:16.760 --> 00:04:19.920 in trying to make sure that we only detect the signals that we're interested in. 74 00:04:19.940 --> 00:04:22.950 The heat sources that we're interested in. [ Narrator ] And detecting those heat 75 00:04:22.970 --> 00:04:27.480 sources accurately helps to monitor water use in irrigated fields. 76 00:04:27.500 --> 00:04:29.160 [ Jim Irons ] Observations that are collected with 77 00:04:29.180 --> 00:04:32.300 Landsat sensors are much more than pretty pictures. 78 00:04:32.320 --> 00:04:35.480 They are accurate, 79 00:04:35.500 --> 00:04:38.620 well calibrated, precise 80 00:04:38.640 --> 00:04:42.280 scientific measurements. One of the things we're learning 81 00:04:42.300 --> 00:04:44.930 with thermal data and will continue to learn more about 82 00:04:44.950 --> 00:04:48.120 with TIRS is just how much water 83 00:04:48.140 --> 00:04:51.229 is being used for 84 00:04:51.250 --> 00:04:54.410 food production and how much more 85 00:04:54.430 --> 00:04:57.510 might be needed in the future to increase food production 86 00:04:57.530 --> 00:05:00.700 to keep up with a growing population. 87 00:05:00.720 --> 00:05:03.760 [ Narrator ] TIRS' thermal data, as part of the LDCM mission, 88 00:05:03.780 --> 00:05:06.890 will add to the more than 3 Million images of the Earth that make up the Landsat data archive. 89 00:05:06.910 --> 00:05:16.500