Transcripts of G2012-011 TIRS Overview final mix redo_youtube_hq

[00:00:05.87] [ Narrator ] NASA and the USGS are preparing a new satellite,
[00:00:08.55] the Landsat Data Continuity Mission, called LDCM.
[00:00:12.73] Landsat satellites have been orbiting earth since 1972,
[00:00:16.86] taking scientific measurements of land cover and land use. LDCM is the eighth Landsat satellite
[00:00:20.96] and will continue the world's longest global data record of changes of the Earth's land surfaces.
[00:00:21.09] and will continue the world's longest global data record of changes of the Earth's land surfaces.
[00:00:25.28] LDCM data will also play a critical role in monitoring, understanding, and managing
[00:00:29.46] the world's forests, agriculture and water. [ Betsy Forsbacka ] What this data is useful for
[00:00:33.84] is to provide information to the scientists, particularly
[00:00:38.02] out in the Western states where water is a very
[00:00:42.20] big deal. This data, this remote data allows them to determine
[00:00:46.38] where areas are being irrigated, and how much and how often.
[00:00:50.56] [ Jim Irons ] TIRS is the Thermal Infrared Sensor
[00:00:54.73] that is being built and tested here at Goddard Space Flight Center for flight on the
[00:00:58.86] next Landsat mission. It's designed to measure the amount of
[00:01:03.01] thermal radiation emitted by the surface of the earth as a function of the earth's temperature.
[00:01:07.13] All objects that are warmer than zero,
[00:01:11.24] absolute zero, emit radiation.
[00:01:15.26] The hotter an object is, the shorter in wavelength is the peak radiation.
[00:01:19.31] [ Narrator ] For example, the sun is very hot, about 10,000 degrees,
[00:01:23.35] and its radiation peaks at about 0.5 micrometers. That's exactly in the region
[00:01:27.48] our eyes can see. Earth is much cooler, so its radiation has a much longer
[00:01:31.58] wavelength, about 10 micrometers. And that's in the far infrared region, well beyond
[00:01:35.67] what we can see. [ Jim Irons ] So, basically what the Thermal Infrared
[00:01:39.85] Sensor allows us to do is to determine
[00:01:44.04] the temperature of the surface of the earth at different locations around the globe.
[00:01:48.35] [ Narrator ] Using these surface temperatures, resource managers can determine how fast
[00:01:52.43] a field uses water. Rain or irrigation starts a cycle
[00:01:56.52] in which water ultimately returns to the atmosphere. Evaporation of water
[00:02:00.59] from the ground, and the transpiration of water from leaves, cools off both the soil and the plants.
[00:02:05.50] [ Betsy Forsbacka ] You put those two words together and you have
[00:02:08.58] the science term, evapotranspiration, and that's precisely what TIRS is measuring.
[00:02:12.64] These hot and cold signatures, that give us
[00:02:16.68] information on evapotranspiration where
[00:02:20.86] the water is transpiring through the plants and evaporating into the atmosphere
[00:02:25.03] The instrument is going to pick that up as a cool signature in areas that are not
[00:02:29.21] irrigated well will come across as a warm area to the instrument.
[00:02:33.38] [ Narrator ] To measure these warm areas and cool signatures, the TIRS instrument
[00:02:36.47] uses a technology array developed primarily
[00:02:39.64] at NASA's Goddard Space Flight Center, called
[00:02:42.69] Quantum Well Infrared Photodetectors. These QWIPS are
[00:02:45.85] more sensitive and precise than the thermal detectors used on previous
[00:02:48.88] Landsat satellites. But to operate correctly they need to be kept very cold.
[00:02:52.02] [ Betsy Forsbacka ] They have to be cooled to less than
[00:02:55.21] 43 degrees Kelvin and so that's only
[00:02:58.33] 43 degrees above absolute zero
[00:03:01.52] which is the coldest you can get. Very, very cold.
[00:03:04.67] [ Veronica Otero ] The interesting thing about TIRS is we have
[00:03:07.86] different thermal zones, you know like
[00:03:10.97] our detectors are around 43 Kelvin
[00:03:14.14] and then you have our telescope at 180 Kelvin
[00:03:17.24] and then you go to the warmer end of our instrument which is the
[00:03:20.42] structure and some other components that are around,
[00:03:23.51] you know, zero C or 273 Kelvin.
[00:03:26.69] [ Narrator ] Keeping these different TIRS components at these different temperatures
[00:03:29.74] is challenging because as the satellite orbits the earth every
[00:03:32.87] 90 minutes its either being blasted by the heat of the sun or being frozen
[00:03:35.91] by the cold of space. [ Veronica Otero ] So you're exposing the
[00:03:39.05] instrument to these two harsh conditions
[00:03:42.23] and you're cycling it from one to the other.
[00:03:45.38] One of the things that we do on our sensor unit is we have multi-
[00:03:48.56] layer insulation blankets. These work really well
[00:03:51.69] in space because there's no
[00:03:54.86] environment, there's no air.
[00:03:57.96] The blankets protect us from these extreme conditions
[00:04:01.14] The other thing we use is we have an earth shield.
[00:04:04.25] [ Betsy Forsbacka ] It is basically a five foot door.
[00:04:07.43] It's about five feet long and it shields much of the instrument
[00:04:10.53] from the earth, from parts of the earth
[00:04:13.69] that we're not imaging. That's a tremendous help
[00:04:16.76] in trying to make sure that we only detect the signals that we're interested in.
[00:04:19.94] The heat sources that we're interested in. [ Narrator ] And detecting those heat
[00:04:22.97] sources accurately helps to monitor water use in irrigated fields.
[00:04:27.50] [ Jim Irons ] Observations that are collected with
[00:04:29.18] Landsat sensors are much more than pretty pictures.
[00:04:32.32] They are accurate,
[00:04:35.50] well calibrated, precise
[00:04:38.64] scientific measurements. One of the things we're learning
[00:04:42.3] with thermal data and will continue to learn more about
[00:04:44.95] with TIRS is just how much water
[00:04:48.14] is being used for
[00:04:51.25] food production and how much more
[00:04:54.43] might be needed in the future to increase food production
[00:04:57.53] to keep up with a growing population.
[00:05:00.72] [ Narrator ] TIRS' thermal data, as part of the LDCM mission,
[00:05:03.78] will add to the more than 3 Million images of the Earth that make up the Landsat data archive.