1 00:00:04,066 --> 00:00:10,066 [upbeat music] 2 00:00:15,033 --> 00:00:17,200 - BET YOU PLAYED IN THE DIRT AS A KID. 3 00:00:17,200 --> 00:00:18,600 MAYBE YOU MADE MUD PIES 4 00:00:18,600 --> 00:00:20,966 OR DUG HOLES WITH A SPECIAL TRUCK, 5 00:00:20,966 --> 00:00:23,066 AND YOU PROBABLY CAME HOME WITH DIRT ON YOUR PANTS 6 00:00:23,066 --> 00:00:25,733 AND WERE SENT INSIDE TO WASH THE DIRT OFF YOUR HANDS. 7 00:00:25,733 --> 00:00:28,766 BUT DO YOU KNOW HOW IMPORTANT THAT DIRT REALLY IS? 8 00:00:28,766 --> 00:00:31,600 DIRT, OR SOIL, IS ACTUALLY ONE OF OUR WORLD'S 9 00:00:31,600 --> 00:00:33,833 MOST USEFUL NATURAL RESOURCES. 10 00:00:33,833 --> 00:00:36,166 WITHOUT SOIL, MOST PLANTS COULD NOT GROW. 11 00:00:36,166 --> 00:00:38,266 PEOPLE AND ANIMALS WOULD NOT HAVE FOOD TO EAT. 12 00:00:38,266 --> 00:00:40,333 THERE WOULD BE NO WOOD TO BUILD HOUSES 13 00:00:40,333 --> 00:00:41,700 OR COTTON TO MAKE CLOTHES. 14 00:00:41,700 --> 00:00:43,700 JUST THINK ABOUT ALL THE THINGS YOU USE EVERY DAY 15 00:00:43,700 --> 00:00:45,366 THAT STARTED IN THE SOIL. 16 00:00:45,366 --> 00:00:48,033 - SOIL BASICALLY TAKES, LIKE, YOU KNOW, LIKE, 17 00:00:48,033 --> 00:00:50,766 THOUSANDS OR MILLIONS OF YEARS TO FORM. 18 00:00:50,766 --> 00:00:56,566 SOIL IS ACTUALLY A MIXTURE OF MINERALS, AIR, WATER, 19 00:00:56,566 --> 00:00:59,666 ORGANIC MATTER, WHICH MAY BE PLANT RESIDUE 20 00:00:59,666 --> 00:01:01,266 OR THE ANIMAL REMAINS. 21 00:01:01,266 --> 00:01:04,400 - THE DECAYED ANIMAL MATTER AND PLANTS, THAT'S CALLED HUMUS, 22 00:01:04,400 --> 00:01:07,600 AND THE HUMUS IS ACTUALLY A REALLY, REALLY DARK, 23 00:01:07,600 --> 00:01:09,933 ORGANICALLY RICH SOIL. 24 00:01:09,933 --> 00:01:12,200 AND THEREFORE, THE PLANTS THAT ARE IN THAT HUMUS 25 00:01:12,200 --> 00:01:13,866 FEED OFF OF THOSE NUTRIENTS 26 00:01:13,866 --> 00:01:17,066 IN ORDER TO, YOU KNOW, SUSTAIN THEMSELVES. 27 00:01:17,066 --> 00:01:18,966 - BUT THE HUMUS HAS ANOTHER IMPORTANT JOB. 28 00:01:18,966 --> 00:01:20,100 IT ACTS LIKE A SPONGE, 29 00:01:20,100 --> 00:01:23,033 SOAKING UP THE RAINWATER TO KEEP THE SOIL MOIST. 30 00:01:23,033 --> 00:01:26,666 EVERY TIME IT RAINS OR SNOWS, THE WATER SEEPS INTO THE GROUND. 31 00:01:26,666 --> 00:01:29,300 THE SOIL IS WHERE ALL THE EXTRA WATER IS STORED 32 00:01:29,300 --> 00:01:31,700 SO PLANTS CAN USE IT AT A LATER TIME. 33 00:01:31,700 --> 00:01:34,966 SCIENTISTS CAN ACTUALLY MEASURE HOW MUCH WATER IS IN THE SOIL. 34 00:01:34,966 --> 00:01:37,266 THEY CALL THIS MEASUREMENT SOIL MOISTURE. 35 00:01:37,266 --> 00:01:40,400 YOU CAN EVEN MEASURE SOIL MOISTURE IN YOUR OWN BACKYARD. 36 00:01:40,400 --> 00:01:43,066 ALL YOU NEED IS A SOIL MOISTURE PROBE. 37 00:01:43,066 --> 00:01:45,966 YOU PROBABLY DON'T HAVE ONE AT HOME, BUT YOUR SCHOOL MIGHT. 38 00:01:45,966 --> 00:01:47,566 YOU JUST STICK THE PROBE INTO THE GROUND 39 00:01:47,566 --> 00:01:49,066 AND READ WHAT THE METER SAYS. 40 00:01:49,066 --> 00:01:50,233 THE HIGHER THE NUMBER, 41 00:01:50,233 --> 00:01:52,266 THE MORE MOISTURE THERE IS IN THE SOIL. 42 00:01:52,266 --> 00:01:54,800 NASA UNDERSTANDS HOW IMPORTANT THE SOIL IS 43 00:01:54,800 --> 00:01:55,866 TO LIFE HERE ON EARTH 44 00:01:55,866 --> 00:01:58,066 AND WHY IT IS IMPORTANT TO UNDERSTAND 45 00:01:58,066 --> 00:02:00,166 HOW MUCH MOISTURE SOIL HOLDS. 46 00:02:00,166 --> 00:02:03,100 BUT HOW DO SCIENTISTS MEASURE SOIL MOISTURE 47 00:02:03,100 --> 00:02:04,600 FOR THE ENTIRE EARTH? 48 00:02:04,600 --> 00:02:07,900 - SMAP IS THE SOIL MOISTURE ACTIVE PASSIVE MISSION, 49 00:02:07,900 --> 00:02:10,200 AND IT IS A MISSION 50 00:02:10,200 --> 00:02:12,666 THAT WILL BE MEASURING SOIL MOISTURE FROM SPACE. 51 00:02:12,666 --> 00:02:13,933 - MOST OF THE TIME, 52 00:02:13,933 --> 00:02:16,666 PEOPLE UNDERESTIMATE THE IMPORTANCE OF SOIL MOISTURE. 53 00:02:16,666 --> 00:02:20,600 - YOU CAN THINK OF HOW IMPORTANT IT IS TO GROW CROPS FOR FOOD. 54 00:02:20,600 --> 00:02:22,500 GROWING CROPS, GROWING ANY VEGETATION, 55 00:02:22,500 --> 00:02:23,733 TREES, GRASSES, 56 00:02:23,733 --> 00:02:25,866 DEPENDS ON HOW MUCH WATER THERE IS IN THE SOILS. 57 00:02:25,866 --> 00:02:29,066 SOIL MOISTURE IS KIND OF A NICE INDICATOR OF DROUGHT, 58 00:02:29,066 --> 00:02:31,366 BECAUSE DROUGHT IS BASICALLY A LACK OF WATER, 59 00:02:31,366 --> 00:02:33,233 AND WHERE DO YOU SEE THAT LACK OF WATER? 60 00:02:33,233 --> 00:02:35,900 YOU CAN SEE THAT LACK OF WATER IN THE SOIL. 61 00:02:35,900 --> 00:02:40,533 - BY STUDYING THIS ONE VARIABLE IN THE SOIL, SOIL MOISTURE, 62 00:02:40,533 --> 00:02:44,200 THERE ARE SO MANY APPLICATIONS THAT BENEFIT MANKIND. 63 00:02:44,200 --> 00:02:46,533 - SMAP WILL MEASURE THE ENTIRE PLANET'S SOIL MOISTURE 64 00:02:46,533 --> 00:02:47,966 EVERY THREE DAYS. 65 00:02:47,966 --> 00:02:50,266 THAT'S DEFINITELY FASTER THAN USING THIS. 66 00:02:50,266 --> 00:02:52,800 I KNOW THERE ARE MANY DIFFERENT KINDS OF SOIL. 67 00:02:52,800 --> 00:02:55,633 DOES ALL SOIL HOLD THE SAME AMOUNT OF MOISTURE? 68 00:02:55,633 --> 00:02:59,300 - DIFFERENT SOIL TEXTURES, DIFFERENT SOIL SIZES 69 00:02:59,300 --> 00:03:02,233 HAVE DIFFERENT ABILITIES TO HOLD THE WATER. 70 00:03:02,233 --> 00:03:04,266 YOU CAN THINK OF A TEXTURE OF A SOIL AS BEING 71 00:03:04,266 --> 00:03:08,000 HOW MUCH SAND YOU HAVE VERSUS HOW MUCH CLAY YOU HAVE 72 00:03:08,000 --> 00:03:09,766 VERSUS HOW MUCH SILT YOU HAVE. 73 00:03:09,766 --> 00:03:12,333 THOSE RELATIVE AMOUNTS, THOSE RELATIVE PERCENTAGES 74 00:03:12,333 --> 00:03:14,300 DETERMINE THE TEXTURE OF A SOIL. 75 00:03:14,300 --> 00:03:17,133 THEY AFFECT HOW THE WATER DRAINS THROUGH THE SOIL 76 00:03:17,133 --> 00:03:20,133 AND HOW MUCH WATER THE SOIL CAN HOLD. 77 00:03:20,133 --> 00:03:22,866 - SO DIFFERENT TYPES OF SOIL HOLD DIFFERENT AMOUNTS OF WATER. 78 00:03:22,866 --> 00:03:26,333 I WONDER, WHAT OTHER THINGS CAN AFFECT SOIL MOISTURE? 79 00:03:26,333 --> 00:03:28,133 - SOIL MOISTURE CAN ALSO BE AFFECTED 80 00:03:28,133 --> 00:03:30,466 BY THINGS LIKE FROZEN SOIL, 81 00:03:30,466 --> 00:03:31,900 YOU KNOW, WHEN THE GROUND IS FROZEN. 82 00:03:31,900 --> 00:03:33,033 - WHY IS THAT IMPORTANT? 83 00:03:33,033 --> 00:03:36,000 BECAUSE WHEN THE GROUND IS FROZEN, 84 00:03:36,000 --> 00:03:39,066 THEN A LOT OF WHAT WE CALL THE HYDROLOGICAL CYCLE 85 00:03:39,066 --> 00:03:41,600 INVOLVING THE LAND, THE MOVEMENT OF WATER 86 00:03:41,600 --> 00:03:43,066 BETWEEN THE LAND AND THE ATMOSPHERE, 87 00:03:43,066 --> 00:03:45,000 FOR EXAMPLE, STOPS. 88 00:03:45,000 --> 00:03:47,166 WHAT WE'RE GONNA BE ABLE TO DETERMINE 89 00:03:47,166 --> 00:03:48,900 IS THE FREEZE/THAW CYCLE. 90 00:03:48,900 --> 00:03:51,666 IT'S A SEASONAL CYCLE OF FREEZE/THAW. 91 00:03:51,666 --> 00:03:55,033 EVEN THOUGH IT IS FROZEN, IT IS STILL PART OF THE SOIL. 92 00:03:55,033 --> 00:03:58,600 - YOU CAN SEE THAT STUDYING SOIL MOISTURE IS VERY IMPORTANT. 93 00:03:58,600 --> 00:04:01,366 IT CAN HELP PREDICT WHEN A DROUGHT MAY OCCUR 94 00:04:01,366 --> 00:04:03,566 OR IF A FLOOD IS LIKELY TO HAPPEN. 95 00:04:03,566 --> 00:04:05,600 IT CAN EVEN HELP FARMERS IMPROVE THEIR CROPS 96 00:04:05,600 --> 00:04:07,633 OR HELP US UNDERSTAND MORE ABOUT WATER 97 00:04:07,633 --> 00:04:08,900 IN THE FROZEN GROUND. 98 00:04:08,900 --> 00:04:12,066 SO AS SMAP COLLECTS MEASUREMENTS ABOUT SOIL MOISTURE, 99 00:04:12,066 --> 00:04:14,033 NASA WILL BE HELPING MAKE OUR WORLD 100 00:04:14,033 --> 00:04:15,666 A BETTER PLACE TO LIVE. 101 00:04:15,666 --> 00:04:21,666 [upbeat music] 102 00:04:23,033 --> 00:04:25,566 children: OUR WORLD!