WEBVTT 00:00:04.433 --> 00:00:10.433 [upbeat music] 00:00:12.633 --> 00:00:15.767 - "OUR WORLD." 00:00:15.767 --> 00:00:17.033 - HI, EVERYBODY. 00:00:17.033 --> 00:00:19.367 I'M LILY, AND THIS IS "OUR WORLD." 00:00:19.367 --> 00:00:21.400 WHAT DO YOU THINK OF MY NEW PLANT? 00:00:21.400 --> 00:00:24.166 I JUST GOT SOME SEEDS TO GROW MORE JUST LIKE IT. 00:00:24.166 --> 00:00:26.233 YOU SEE, I'M GETTING READY TO JOIN 00:00:26.233 --> 00:00:29.800 ONE OF NASA'S ENGINEERING DESIGN CHALLENGES. 00:00:29.800 --> 00:00:32.367 I'M GOING TO DESIGN AND BUILD A PLANT GROWTH CHAMBER 00:00:32.367 --> 00:00:34.233 LIKE THE ASTRONAUTS MIGHT USE. 00:00:34.233 --> 00:00:36.166 I WANT TO MAKE SURE MY SEEDS GROW, 00:00:36.166 --> 00:00:38.033 SO I'VE GOT A LOT TO LEARN. 00:00:38.033 --> 00:00:40.066 I KNOW THAT A PLANT IS A LIVING THING 00:00:40.066 --> 00:00:41.533 JUST LIKE PEOPLE. 00:00:41.533 --> 00:00:42.867 AND JUST LIKE PEOPLE, 00:00:42.867 --> 00:00:45.166 IT HAS SPECIFIC NEEDS IN ORDER TO SURVIVE. 00:00:45.166 --> 00:00:48.266 BUT A PLANT DOES THINGS VERY DIFFERENTLY THAN PEOPLE, 00:00:48.266 --> 00:00:50.033 SO I NEED TO KNOW MORE ABOUT PLANTS 00:00:50.033 --> 00:00:51.867 BEFORE I CAN DESIGN MY CHAMBER. 00:00:51.867 --> 00:00:53.600 MY TEACHER MRS. JONES 00:00:53.600 --> 00:00:57.233 HELPED ME SET UP A VIDEO CHAT WITH DR. GREGORY GOINS. 00:00:57.233 --> 00:01:01.066 HE'S A RESEARCH SCIENTIST AT NASA'S KENNEDY SPACE CENTER, 00:01:01.066 --> 00:01:03.100 AND HE KNOWS A LOT ABOUT PLANTS. 00:01:03.100 --> 00:01:06.133 I HOPE HE'LL BE ABLE TO HELP ME LEARN HOW TO TAKE CARE OF MINE. 00:01:06.133 --> 00:01:07.133 [computer chimes] 00:01:07.133 --> 00:01:08.567 OH, THERE HE IS NOW. 00:01:08.567 --> 00:01:11.633 HELLO, DR. GOINS. I'M LILY. 00:01:11.633 --> 00:01:13.433 - MRS. JONES SAID YOU WOULD BE COMING BY. 00:01:13.433 --> 00:01:14.667 WHAT CAN I HELP YOU WITH? 00:01:14.667 --> 00:01:16.433 - I'M TRYING TO GROW SOME PLANTS, 00:01:16.433 --> 00:01:17.533 AND I WANT TO MAKE SURE 00:01:17.533 --> 00:01:19.567 I TAKE CARE OF ALL OF THEIR NEEDS 00:01:19.567 --> 00:01:21.633 SO THEY CAN GROW BIG AND BEAUTIFUL. 00:01:21.633 --> 00:01:23.233 MRS. JONES SAID THAT LIGHT 00:01:23.233 --> 00:01:25.400 IS A VERY IMPORTANT NEED FOR PLANTS. 00:01:25.400 --> 00:01:26.667 - IT SURE IS. 00:01:26.667 --> 00:01:29.000 - I'M PLANNING ON GROWING MY PLANTS INSIDE. 00:01:29.000 --> 00:01:30.800 IS THAT GOING TO BE A PROBLEM? 00:01:30.800 --> 00:01:32.800 - WELL, TELL ME WHAT YOU KNOW ABOUT LIGHT. 00:01:32.800 --> 00:01:36.033 - WELL, MRS. JONES TAUGHT US THAT LIGHT TRAVELS IN WAVES 00:01:36.033 --> 00:01:39.233 AND VISIBLE LIGHT HAS MANY COLORS, CALLED A SPECTRUM. 00:01:39.233 --> 00:01:41.700 BUT I'M NOT SURE WHY PLANTS NEED LIGHT. 00:01:41.700 --> 00:01:43.867 - PLANTS NEED LIGHT AS AN ENERGY SOURCE 00:01:43.867 --> 00:01:45.967 TO POWER THE FOOD-MAKING PROCESS. 00:01:45.967 --> 00:01:48.600 - WAIT. PLANTS MAKE THEIR OWN FOOD? 00:01:48.600 --> 00:01:50.066 HOW DO THEY DO THAT? 00:01:50.066 --> 00:01:52.767 - IT'S A METABOLIC PROCESS CALLED PHOTOSYNTHESIS 00:01:52.767 --> 00:01:54.867 THAT HAPPENS IN THE GREEN PARTS OF THE PLANT. 00:01:54.867 --> 00:01:57.600 - PHOTOSYNTHESIS? WHAT'S THAT? 00:01:57.600 --> 00:01:59.834 - YOU'LL GET A CLUE IF YOU BREAK THE WORD APART. 00:01:59.834 --> 00:02:01.266 "PHOTO" MEANS "LIGHT," 00:02:01.266 --> 00:02:03.266 AND "SYNTHESIS" MEANS "MAKING FOOD." 00:02:03.266 --> 00:02:04.900 DURING PHOTOSYNTHESIS, 00:02:04.900 --> 00:02:07.266 MOLECULES OF CARBON DIOXIDE AND WATER 00:02:07.266 --> 00:02:09.300 ARE RESTRUCTURED INTO SUGAR, 00:02:09.300 --> 00:02:11.767 AND THIS RESHUFFLING REQUIRES ENERGY. 00:02:11.767 --> 00:02:14.300 - SO THE ENERGY IS THE LIGHT FROM THE SUN? 00:02:14.300 --> 00:02:15.600 - EXACTLY. 00:02:15.600 --> 00:02:18.200 LIGHT IS ABSORBED BY A SPECIAL PIGMENT IN THE PLANT 00:02:18.200 --> 00:02:19.567 CALLED CHLOROPHYLL. 00:02:19.567 --> 00:02:21.967 IT'S THE MOLECULE THAT MAKES PLANT LEAVES GREEN. 00:02:21.967 --> 00:02:23.100 - HUH. 00:02:23.100 --> 00:02:24.867 I'M NOT GREEN, SO I GUESS THAT MEANS 00:02:24.867 --> 00:02:27.000 PEOPLE DON'T HAVE CHLOROPHYLL INSIDE THEM. 00:02:27.000 --> 00:02:28.533 AND I CAN'T MAKE MY OWN FOOD, 00:02:28.533 --> 00:02:31.633 SO PLANTS MUST BE A REALLY IMPORTANT PART OF MY FOOD CHAIN. 00:02:31.633 --> 00:02:32.633 - THAT'S RIGHT. 00:02:32.633 --> 00:02:34.266 PHOTOSYNTHESIS IS CENTRAL 00:02:34.266 --> 00:02:36.166 TO LIFE ON EARTH AS WE KNOW IT. 00:02:36.166 --> 00:02:37.834 EVERYTHING ANIMALS EAT 00:02:37.834 --> 00:02:40.333 HAS COME FROM THE PHOTOSYNTHETIC PROCESS. 00:02:40.333 --> 00:02:43.000 - SO IF LIGHT IS SO IMPORTANT TO PLANTS, 00:02:43.000 --> 00:02:46.300 WHAT DO I NEED TO THINK ABOUT IF I GROW MY PLANTS INDOORS? 00:02:46.300 --> 00:02:47.867 - WHEN GROWING PLANTS INDOORS, 00:02:47.867 --> 00:02:49.600 THERE ARE TWO FACTORS TO CONSIDER: 00:02:49.600 --> 00:02:50.834 THE QUALITY OF THE LIGHT 00:02:50.834 --> 00:02:52.266 AND THE QUANTITY OF THE LIGHT. 00:02:52.266 --> 00:02:54.500 - WHAT DO YOU MEAN, "QUALITY OF LIGHT"? 00:02:54.500 --> 00:02:56.233 - YOU LEARNED THAT THE SPECTRUM OF SUNLIGHT 00:02:56.233 --> 00:02:57.667 HAS MANY COLORS IN IT. 00:02:57.667 --> 00:03:01.400 PLANTS REQUIRE MOSTLY RED AND BLUE LIGHT TO GROW WELL. 00:03:01.400 --> 00:03:04.633 ARTIFICIAL LIGHT, SUCH AS THE LIGHT FROM LIGHTBULBS, 00:03:04.633 --> 00:03:07.333 DOESN'T USUALLY HAVE ALL THE COLORS OF THE SPECTRUM, 00:03:07.333 --> 00:03:09.900 AND PLANTS DON'T TEND TO GROW VERY WELL UNDER IT. 00:03:09.900 --> 00:03:11.734 - SO IS THERE A BETTER WAY FOR ME 00:03:11.734 --> 00:03:13.834 TO GET LIGHT TO MY PLANTS INDOORS 00:03:13.834 --> 00:03:15.600 THAN REGULAR LIGHTBULBS? 00:03:15.600 --> 00:03:16.600 - YES. 00:03:16.600 --> 00:03:19.033 FLUORESCENT BULBS SUCH AS THIS ONE 00:03:19.033 --> 00:03:21.433 HAVE A MUCH BETTER BALANCE OF THE SPECTRUM, 00:03:21.433 --> 00:03:23.033 AND THEY GROW PLANTS VERY WELL. 00:03:23.033 --> 00:03:25.233 - AND WHAT ABOUT THE QUANTITY OF LIGHT? 00:03:25.233 --> 00:03:27.400 - THAT REFERS TO THE BRIGHTNESS OF LIGHT. 00:03:27.400 --> 00:03:31.100 DIRECT SUNLIGHT USUALLY HAS MORE THAN ENOUGH QUANTITY 00:03:31.100 --> 00:03:34.333 AND THE CORRECT QUALITY TO SUCCESSFULLY GROW PLANTS. 00:03:34.333 --> 00:03:35.700 - WHAT IF I PUT MY PLANTS 00:03:35.700 --> 00:03:37.300 RIGHT IN FRONT OF A LARGE WINDOW? 00:03:37.300 --> 00:03:39.767 - AS LONG AS YOUR PLANTS GET DIRECT SUNLIGHT, 00:03:39.767 --> 00:03:42.233 ALL PLANTS ARE DIFFERENT, SO YOU'LL NEED TO FIND OUT 00:03:42.233 --> 00:03:44.133 HOW MUCH LIGHT YOUR PLANTS NEED. 00:03:44.133 --> 00:03:46.800 - I GUESS I'LL NEED TO DO SOME TESTS TO FIGURE THAT OUT. 00:03:46.800 --> 00:03:48.367 OH, ONE MORE QUESTION. 00:03:48.367 --> 00:03:50.767 WHY DOES NASA STUDY PLANT GROWTH? 00:03:50.767 --> 00:03:53.400 - WITH ASTRONAUTS STAYING IN SPACE LONGER 00:03:53.400 --> 00:03:56.133 AND EVENTUALLY GOING TO OTHER PLANETS AND BEYOND, 00:03:56.133 --> 00:03:58.266 THEY WOULD NEED TO GROW THEIR OWN FOOD. 00:03:58.266 --> 00:04:01.367 BUT ON A SPACECRAFT, THERE AREN'T ANY BIG WINDOWS, 00:04:01.367 --> 00:04:02.633 AND EVEN IF THERE WERE, 00:04:02.633 --> 00:04:05.367 YOU WOULD HAVE ONLY 45 MINUTES OF DAYLIGHT 00:04:05.367 --> 00:04:07.967 EVERY 90 MINUTES WHILE ORBITING THE EARTH. 00:04:07.967 --> 00:04:09.633 - BUT IF THEY DON'T HAVE ENOUGH TIME 00:04:09.633 --> 00:04:11.400 TO GET LIGHT FROM THE SUN, 00:04:11.400 --> 00:04:13.033 HOW WILL THE PLANTS GROW? 00:04:13.033 --> 00:04:15.400 - ONE LIGHTING SYSTEM THAT HOLDS A LOT OF PROMISE 00:04:15.400 --> 00:04:16.900 IS LIGHT-EMITTING DIODES. 00:04:16.900 --> 00:04:18.800 THEY LAST A VERY LONG TIME. 00:04:18.800 --> 00:04:21.834 THEY ALSO EMIT A VERY NARROW PART OF THE SPECTRUM: 00:04:21.834 --> 00:04:23.900 PURE RED OR PURE BLUE. 00:04:23.900 --> 00:04:26.600 - THOSE ARE THE COLORS THAT PLANTS LIKE BEST. 00:04:26.600 --> 00:04:29.400 BUT WOULDN'T THESE LIGHTS AFFECT THE WAY THE PLANTS LOOK? 00:04:29.400 --> 00:04:32.800 - REMEMBER THAT PLANTS DON'T USE THE GREEN PART OF THE SPECTRUM. 00:04:32.800 --> 00:04:35.867 THEY REFLECT GREEN LIGHT MORE THAN ANY OTHER COLOR 00:04:35.867 --> 00:04:37.834 WHILE ABSORBING THE RED AND BLUE LIGHT. 00:04:37.834 --> 00:04:40.700 THEREFORE, WHEN GROWN UNDER RED AND BLUE LIGHT, 00:04:40.700 --> 00:04:43.266 THEY ABSORB 100% OF THE AVAILABLE LIGHT 00:04:43.266 --> 00:04:44.633 AND APPEAR BLACK. 00:04:44.633 --> 00:04:46.000 - BLACK PLANTS? 00:04:46.000 --> 00:04:47.967 THAT WOULDN'T BE VERY PRETTY. 00:04:47.967 --> 00:04:49.900 I WONDER IF OTHER COLORS OF LIGHT 00:04:49.900 --> 00:04:51.867 WOULD CHANGE THE WAY A PLANT GROWS 00:04:51.867 --> 00:04:53.333 OR THE WAY THEY LOOK. 00:04:53.333 --> 00:04:55.600 I'D BETTER HIT THE BOOKS AND FIND OUT THE BEST WAY 00:04:55.600 --> 00:04:57.433 TO GET LIGHT TO MY PLANTS. 00:04:57.433 --> 00:04:59.633 THANKS, DR. GOINS. 00:04:59.633 --> 00:05:01.834 WHEW, THAT'S A LOT OF READING. 00:05:01.834 --> 00:05:04.800 BUT NOW I KNOW A LOT MORE ABOUT TAKING CARE OF PLANTS. 00:05:04.800 --> 00:05:06.300 LET ME TELL YOU WHAT I'VE LEARNED. 00:05:06.300 --> 00:05:07.633 IN ORDER TO MAKE FOOD, 00:05:07.633 --> 00:05:10.300 PLANTS NEED TO CARRY OUT PHOTOSYNTHESIS. 00:05:10.300 --> 00:05:12.600 THAT TAKES PLACE IN THE LEAVES OF THE PLANT. 00:05:12.600 --> 00:05:14.867 AND IN ORDER TO DO PHOTOSYNTHESIS, 00:05:14.867 --> 00:05:19.100 THE LEAVES NEED WATER, CARBON DIOXIDE, AND SUNLIGHT. 00:05:19.100 --> 00:05:20.533 THE CHLOROPHYLL IN THE LEAVES 00:05:20.533 --> 00:05:22.500 TRAPS THE ENERGY OF THE SUNLIGHT, 00:05:22.500 --> 00:05:25.233 AND THE WATER COMES UP THROUGH THE ROOTS. 00:05:25.233 --> 00:05:27.667 THEN THE LEAVES GET CARBON DIOXIDE FROM THE AIR 00:05:27.667 --> 00:05:31.333 THROUGH TINY PORES, OR HOLES, ON THE UNDERSIDES OF THE LEAVES. 00:05:31.333 --> 00:05:33.333 THE PLANT USES THE TRAPPED SUNLIGHT 00:05:33.333 --> 00:05:35.266 TO TURN THE WATER AND CARBON DIOXIDE 00:05:35.266 --> 00:05:38.934 INTO OXYGEN AND GLUCOSE, A SPECIAL KIND OF SUGAR. 00:05:38.934 --> 00:05:41.100 PLANTS USE THE GLUCOSE FOR ENERGY. 00:05:41.100 --> 00:05:43.100 ANOTHER THING I FOUND OUT ABOUT PLANTS 00:05:43.100 --> 00:05:44.934 IS THAT THEY CAN MOVE-- 00:05:44.934 --> 00:05:46.734 NOT LIKE YOU OR ME, OF COURSE. 00:05:46.734 --> 00:05:48.400 THAT WOULD BE SCARY. 00:05:48.400 --> 00:05:50.800 BUT THEY CAN REACT TO A CHANGE IN THEIR ENVIRONMENT, 00:05:50.800 --> 00:05:52.100 OR A STIMULUS. 00:05:52.100 --> 00:05:54.467 THESE REACTIONS ARE CALLED TROPISMS. 00:05:54.467 --> 00:05:57.934 FOR EXAMPLE, A PLANT WILL GROW TOWARD ITS SOURCE OF LIGHT, 00:05:57.934 --> 00:06:00.800 OR IT WILL GROW ITS ROOTS TOWARD A SOURCE OF WATER. 00:06:00.800 --> 00:06:03.266 AND THE ROOTS OF MOST PLANTS GROW DOWNWARD, 00:06:03.266 --> 00:06:05.734 THE SAME DIRECTION AS THE PULL OF GRAVITY. 00:06:05.734 --> 00:06:07.300 HOW DO YOU THINK PLANTS WOULD GROW 00:06:07.300 --> 00:06:08.934 IN A REDUCED-GRAVITY ENVIRONMENT 00:06:08.934 --> 00:06:11.166 LIKE THE INTERNATIONAL SPACE STATION? 00:06:11.166 --> 00:06:12.166 HMM. 00:06:12.166 --> 00:06:13.934 WOULD I NEED TO CHANGE MY DESIGN 00:06:13.934 --> 00:06:15.633 FOR A PLANT GROWTH CHAMBER 00:06:15.633 --> 00:06:17.066 IF IT WENT TO SPACE? 00:06:17.066 --> 00:06:19.300 WELL, I HAVE A LOT OF DESIGNING TO DO, 00:06:19.300 --> 00:06:20.767 SO I NEED TO GET WORKING. 00:06:20.767 --> 00:06:22.834 AFTER ALL, NASA'S WAITING. 00:06:22.834 --> 00:06:24.100 AND IF YOU'D LIKE TO JOIN 00:06:24.100 --> 00:06:26.667 ONE OF NASA'S ENGINEERING DESIGN CHALLENGES, 00:06:26.667 --> 00:06:31.033 JUST CHECK OUT THE NASA WEBSITE AT WWW.NASA.GOV 00:06:31.033 --> 00:06:33.266 AND SEARCH FOR "DESIGN CHALLENGES." 00:06:33.266 --> 00:06:36.633 I'LL SEE YOU NEXT TIME ON "OUR WORLD." 00:06:39.133 --> 00:06:42.233 HEY, MOM, I NEED SOME ADULT SUPERVISION. 00:06:53.100 --> 00:06:55.100 - "OUR WORLD."