WEBVTT FILE 1 00:04.066 --> 00:10.066 [upbeat music] 2 00:15.033 --> 00:17.200 - BET YOU PLAYED IN THE DIRT AS A KID. 3 00:17.200 --> 00:18.600 MAYBE YOU MADE MUD PIES 4 00:18.600 --> 00:20.966 OR DUG HOLES WITH A SPECIAL TRUCK, 5 00:20.966 --> 00:23.066 AND YOU PROBABLY CAME HOME WITH DIRT ON YOUR PANTS 6 00:23.066 --> 00:25.733 AND WERE SENT INSIDE TO WASH THE DIRT OFF YOUR HANDS. 7 00:25.733 --> 00:28.766 BUT DO YOU KNOW HOW IMPORTANT THAT DIRT REALLY IS? 8 00:28.766 --> 00:31.600 DIRT, OR SOIL, IS ACTUALLY ONE OF OUR WORLD'S 9 00:31.600 --> 00:33.833 MOST USEFUL NATURAL RESOURCES. 10 00:33.833 --> 00:36.166 WITHOUT SOIL, MOST PLANTS COULD NOT GROW. 11 00:36.166 --> 00:38.266 PEOPLE AND ANIMALS WOULD NOT HAVE FOOD TO EAT. 12 00:38.266 --> 00:40.333 THERE WOULD BE NO WOOD TO BUILD HOUSES 13 00:40.333 --> 00:41.700 OR COTTON TO MAKE CLOTHES. 14 00:41.700 --> 00:43.700 JUST THINK ABOUT ALL THE THINGS YOU USE EVERY DAY 15 00:43.700 --> 00:45.366 THAT STARTED IN THE SOIL. 16 00:45.366 --> 00:48.033 - SOIL BASICALLY TAKES, LIKE, YOU KNOW, LIKE, 17 00:48.033 --> 00:50.766 THOUSANDS OR MILLIONS OF YEARS TO FORM. 18 00:50.766 --> 00:56.566 SOIL IS ACTUALLY A MIXTURE OF MINERALS, AIR, WATER, 19 00:56.566 --> 00:59.666 ORGANIC MATTER, WHICH MAY BE PLANT RESIDUE 20 00:59.666 --> 01:01.266 OR THE ANIMAL REMAINS. 21 01:01.266 --> 01:04.400 - THE DECAYED ANIMAL MATTER AND PLANTS, THAT'S CALLED HUMUS, 22 01:04.400 --> 01:07.600 AND THE HUMUS IS ACTUALLY A REALLY, REALLY DARK, 23 01:07.600 --> 01:09.933 ORGANICALLY RICH SOIL. 24 01:09.933 --> 01:12.200 AND THEREFORE, THE PLANTS THAT ARE IN THAT HUMUS 25 01:12.200 --> 01:13.866 FEED OFF OF THOSE NUTRIENTS 26 01:13.866 --> 01:17.066 IN ORDER TO, YOU KNOW, SUSTAIN THEMSELVES. 27 01:17.066 --> 01:18.966 - BUT THE HUMUS HAS ANOTHER IMPORTANT JOB. 28 01:18.966 --> 01:20.100 IT ACTS LIKE A SPONGE, 29 01:20.100 --> 01:23.033 SOAKING UP THE RAINWATER TO KEEP THE SOIL MOIST. 30 01:23.033 --> 01:26.666 EVERY TIME IT RAINS OR SNOWS, THE WATER SEEPS INTO THE GROUND. 31 01:26.666 --> 01:29.300 THE SOIL IS WHERE ALL THE EXTRA WATER IS STORED 32 01:29.300 --> 01:31.700 SO PLANTS CAN USE IT AT A LATER TIME. 33 01:31.700 --> 01:34.966 SCIENTISTS CAN ACTUALLY MEASURE HOW MUCH WATER IS IN THE SOIL. 34 01:34.966 --> 01:37.266 THEY CALL THIS MEASUREMENT SOIL MOISTURE. 35 01:37.266 --> 01:40.400 YOU CAN EVEN MEASURE SOIL MOISTURE IN YOUR OWN BACKYARD. 36 01:40.400 --> 01:43.066 ALL YOU NEED IS A SOIL MOISTURE PROBE. 37 01:43.066 --> 01:45.966 YOU PROBABLY DON'T HAVE ONE AT HOME, BUT YOUR SCHOOL MIGHT. 38 01:45.966 --> 01:47.566 YOU JUST STICK THE PROBE INTO THE GROUND 39 01:47.566 --> 01:49.066 AND READ WHAT THE METER SAYS. 40 01:49.066 --> 01:50.233 THE HIGHER THE NUMBER, 41 01:50.233 --> 01:52.266 THE MORE MOISTURE THERE IS IN THE SOIL. 42 01:52.266 --> 01:54.800 NASA UNDERSTANDS HOW IMPORTANT THE SOIL IS 43 01:54.800 --> 01:55.866 TO LIFE HERE ON EARTH 44 01:55.866 --> 01:58.066 AND WHY IT IS IMPORTANT TO UNDERSTAND 45 01:58.066 --> 02:00.166 HOW MUCH MOISTURE SOIL HOLDS. 46 02:00.166 --> 02:03.100 BUT HOW DO SCIENTISTS MEASURE SOIL MOISTURE 47 02:03.100 --> 02:04.600 FOR THE ENTIRE EARTH? 48 02:04.600 --> 02:07.900 - SMAP IS THE SOIL MOISTURE ACTIVE PASSIVE MISSION, 49 02:07.900 --> 02:10.200 AND IT IS A MISSION 50 02:10.200 --> 02:12.666 THAT WILL BE MEASURING SOIL MOISTURE FROM SPACE. 51 02:12.666 --> 02:13.933 - MOST OF THE TIME, 52 02:13.933 --> 02:16.666 PEOPLE UNDERESTIMATE THE IMPORTANCE OF SOIL MOISTURE. 53 02:16.666 --> 02:20.600 - YOU CAN THINK OF HOW IMPORTANT IT IS TO GROW CROPS FOR FOOD. 54 02:20.600 --> 02:22.500 GROWING CROPS, GROWING ANY VEGETATION, 55 02:22.500 --> 02:23.733 TREES, GRASSES, 56 02:23.733 --> 02:25.866 DEPENDS ON HOW MUCH WATER THERE IS IN THE SOILS. 57 02:25.866 --> 02:29.066 SOIL MOISTURE IS KIND OF A NICE INDICATOR OF DROUGHT, 58 02:29.066 --> 02:31.366 BECAUSE DROUGHT IS BASICALLY A LACK OF WATER, 59 02:31.366 --> 02:33.233 AND WHERE DO YOU SEE THAT LACK OF WATER? 60 02:33.233 --> 02:35.900 YOU CAN SEE THAT LACK OF WATER IN THE SOIL. 61 02:35.900 --> 02:40.533 - BY STUDYING THIS ONE VARIABLE IN THE SOIL, SOIL MOISTURE, 62 02:40.533 --> 02:44.200 THERE ARE SO MANY APPLICATIONS THAT BENEFIT MANKIND. 63 02:44.200 --> 02:46.533 - SMAP WILL MEASURE THE ENTIRE PLANET'S SOIL MOISTURE 64 02:46.533 --> 02:47.966 EVERY THREE DAYS. 65 02:47.966 --> 02:50.266 THAT'S DEFINITELY FASTER THAN USING THIS. 66 02:50.266 --> 02:52.800 I KNOW THERE ARE MANY DIFFERENT KINDS OF SOIL. 67 02:52.800 --> 02:55.633 DOES ALL SOIL HOLD THE SAME AMOUNT OF MOISTURE? 68 02:55.633 --> 02:59.300 - DIFFERENT SOIL TEXTURES, DIFFERENT SOIL SIZES 69 02:59.300 --> 03:02.233 HAVE DIFFERENT ABILITIES TO HOLD THE WATER. 70 03:02.233 --> 03:04.266 YOU CAN THINK OF A TEXTURE OF A SOIL AS BEING 71 03:04.266 --> 03:08.000 HOW MUCH SAND YOU HAVE VERSUS HOW MUCH CLAY YOU HAVE 72 03:08.000 --> 03:09.766 VERSUS HOW MUCH SILT YOU HAVE. 73 03:09.766 --> 03:12.333 THOSE RELATIVE AMOUNTS, THOSE RELATIVE PERCENTAGES 74 03:12.333 --> 03:14.300 DETERMINE THE TEXTURE OF A SOIL. 75 03:14.300 --> 03:17.133 THEY AFFECT HOW THE WATER DRAINS THROUGH THE SOIL 76 03:17.133 --> 03:20.133 AND HOW MUCH WATER THE SOIL CAN HOLD. 77 03:20.133 --> 03:22.866 - SO DIFFERENT TYPES OF SOIL HOLD DIFFERENT AMOUNTS OF WATER. 78 03:22.866 --> 03:26.333 I WONDER, WHAT OTHER THINGS CAN AFFECT SOIL MOISTURE? 79 03:26.333 --> 03:28.133 - SOIL MOISTURE CAN ALSO BE AFFECTED 80 03:28.133 --> 03:30.466 BY THINGS LIKE FROZEN SOIL, 81 03:30.466 --> 03:31.900 YOU KNOW, WHEN THE GROUND IS FROZEN. 82 03:31.900 --> 03:33.033 - WHY IS THAT IMPORTANT? 83 03:33.033 --> 03:36.000 BECAUSE WHEN THE GROUND IS FROZEN, 84 03:36.000 --> 03:39.066 THEN A LOT OF WHAT WE CALL THE HYDROLOGICAL CYCLE 85 03:39.066 --> 03:41.600 INVOLVING THE LAND, THE MOVEMENT OF WATER 86 03:41.600 --> 03:43.066 BETWEEN THE LAND AND THE ATMOSPHERE, 87 03:43.066 --> 03:45.000 FOR EXAMPLE, STOPS. 88 03:45.000 --> 03:47.166 WHAT WE'RE GONNA BE ABLE TO DETERMINE 89 03:47.166 --> 03:48.900 IS THE FREEZE/THAW CYCLE. 90 03:48.900 --> 03:51.666 IT'S A SEASONAL CYCLE OF FREEZE/THAW. 91 03:51.666 --> 03:55.033 EVEN THOUGH IT IS FROZEN, IT IS STILL PART OF THE SOIL. 92 03:55.033 --> 03:58.600 - YOU CAN SEE THAT STUDYING SOIL MOISTURE IS VERY IMPORTANT. 93 03:58.600 --> 04:01.366 IT CAN HELP PREDICT WHEN A DROUGHT MAY OCCUR 94 04:01.366 --> 04:03.566 OR IF A FLOOD IS LIKELY TO HAPPEN. 95 04:03.566 --> 04:05.600 IT CAN EVEN HELP FARMERS IMPROVE THEIR CROPS 96 04:05.600 --> 04:07.633 OR HELP US UNDERSTAND MORE ABOUT WATER 97 04:07.633 --> 04:08.900 IN THE FROZEN GROUND. 98 04:08.900 --> 04:12.066 SO AS SMAP COLLECTS MEASUREMENTS ABOUT SOIL MOISTURE, 99 04:12.066 --> 04:14.033 NASA WILL BE HELPING MAKE OUR WORLD 100 04:14.033 --> 04:15.666 A BETTER PLACE TO LIVE. 101 04:15.666 --> 04:21.666 [upbeat music] 102 04:23.033 --> 04:25.566 children: OUR WORLD!