[upbeat music]
- "OUR WORLD."
- HI, EVERYBODY.
I'M LILY, AND THIS IS "OUR WORLD."
WHAT DO YOU THINK OF MY NEW PLANT?
I JUST GOT SOME SEEDS TO GROW MORE JUST LIKE IT.
YOU SEE, I'M GETTING READY TO JOIN
ONE OF NASA'S ENGINEERING DESIGN CHALLENGES.
I'M GOING TO DESIGN AND BUILD A PLANT GROWTH CHAMBER
LIKE THE ASTRONAUTS MIGHT USE.
I WANT TO MAKE SURE MY SEEDS GROW,
SO I'VE GOT A LOT TO LEARN.
I KNOW THAT A PLANT IS A LIVING THING
JUST LIKE PEOPLE.
AND JUST LIKE PEOPLE,
IT HAS SPECIFIC NEEDS IN ORDER TO SURVIVE.
BUT A PLANT DOES THINGS VERY DIFFERENTLY THAN PEOPLE,
SO I NEED TO KNOW MORE ABOUT PLANTS
BEFORE I CAN DESIGN MY CHAMBER.
MY TEACHER MRS. JONES
HELPED ME SET UP A VIDEO CHAT WITH DR. GREGORY GOINS.
HE'S A RESEARCH SCIENTIST AT NASA'S KENNEDY SPACE CENTER,
AND HE KNOWS A LOT ABOUT PLANTS.
I HOPE HE'LL BE ABLE TO HELP ME LEARN HOW TO TAKE CARE OF MINE.
[computer chimes]
OH, THERE HE IS NOW.
HELLO, DR. GOINS. I'M LILY.
- MRS. JONES SAID YOU WOULD BE COMING BY.
WHAT CAN I HELP YOU WITH?
- I'M TRYING TO GROW SOME PLANTS,
AND I WANT TO MAKE SURE
I TAKE CARE OF ALL OF THEIR NEEDS
SO THEY CAN GROW BIG AND BEAUTIFUL.
MRS. JONES SAID THAT LIGHT
IS A VERY IMPORTANT NEED FOR PLANTS.
- IT SURE IS.
- I'M PLANNING ON GROWING MY PLANTS INSIDE.
IS THAT GOING TO BE A PROBLEM?
- WELL, TELL ME WHAT YOU KNOW ABOUT LIGHT.
- WELL, MRS. JONES TAUGHT US THAT LIGHT TRAVELS IN WAVES
AND VISIBLE LIGHT HAS MANY COLORS, CALLED A SPECTRUM.
BUT I'M NOT SURE WHY PLANTS NEED LIGHT.
- PLANTS NEED LIGHT AS AN ENERGY SOURCE
TO POWER THE FOOD-MAKING PROCESS.
- WAIT. PLANTS MAKE THEIR OWN FOOD?
HOW DO THEY DO THAT?
- IT'S A METABOLIC PROCESS CALLED PHOTOSYNTHESIS
THAT HAPPENS IN THE GREEN PARTS OF THE PLANT.
- PHOTOSYNTHESIS? WHAT'S THAT?
- YOU'LL GET A CLUE IF YOU BREAK THE WORD APART.
"PHOTO" MEANS "LIGHT,"
AND "SYNTHESIS" MEANS "MAKING FOOD."
DURING PHOTOSYNTHESIS,
MOLECULES OF CARBON DIOXIDE AND WATER
ARE RESTRUCTURED INTO SUGAR,
AND THIS RESHUFFLING REQUIRES ENERGY.
- SO THE ENERGY IS THE LIGHT FROM THE SUN?
- EXACTLY.
LIGHT IS ABSORBED BY A SPECIAL PIGMENT IN THE PLANT
CALLED CHLOROPHYLL.
IT'S THE MOLECULE THAT MAKES PLANT LEAVES GREEN.
- HUH.
I'M NOT GREEN, SO I GUESS THAT MEANS
PEOPLE DON'T HAVE CHLOROPHYLL INSIDE THEM.
AND I CAN'T MAKE MY OWN FOOD,
SO PLANTS MUST BE A REALLY IMPORTANT PART OF MY FOOD CHAIN.
- THAT'S RIGHT.
PHOTOSYNTHESIS IS CENTRAL
TO LIFE ON EARTH AS WE KNOW IT.
EVERYTHING ANIMALS EAT
HAS COME FROM THE PHOTOSYNTHETIC PROCESS.
- SO IF LIGHT IS SO IMPORTANT TO PLANTS,
WHAT DO I NEED TO THINK ABOUT IF I GROW MY PLANTS INDOORS?
- WHEN GROWING PLANTS INDOORS,
THERE ARE TWO FACTORS TO CONSIDER:
THE QUALITY OF THE LIGHT
AND THE QUANTITY OF THE LIGHT.
- WHAT DO YOU MEAN, "QUALITY OF LIGHT"?
- YOU LEARNED THAT THE SPECTRUM OF SUNLIGHT
HAS MANY COLORS IN IT.
PLANTS REQUIRE MOSTLY RED AND BLUE LIGHT TO GROW WELL.
ARTIFICIAL LIGHT, SUCH AS THE LIGHT FROM LIGHTBULBS,
DOESN'T USUALLY HAVE ALL THE COLORS OF THE SPECTRUM,
AND PLANTS DON'T TEND TO GROW VERY WELL UNDER IT.
- SO IS THERE A BETTER WAY FOR ME
TO GET LIGHT TO MY PLANTS INDOORS
THAN REGULAR LIGHTBULBS?
- YES.
FLUORESCENT BULBS SUCH AS THIS ONE
HAVE A MUCH BETTER BALANCE OF THE SPECTRUM,
AND THEY GROW PLANTS VERY WELL.
- AND WHAT ABOUT THE QUANTITY OF LIGHT?
- THAT REFERS TO THE BRIGHTNESS OF LIGHT.
DIRECT SUNLIGHT USUALLY HAS MORE THAN ENOUGH QUANTITY
AND THE CORRECT QUALITY TO SUCCESSFULLY GROW PLANTS.
- WHAT IF I PUT MY PLANTS
RIGHT IN FRONT OF A LARGE WINDOW?
- AS LONG AS YOUR PLANTS GET DIRECT SUNLIGHT,
ALL PLANTS ARE DIFFERENT, SO YOU'LL NEED TO FIND OUT
HOW MUCH LIGHT YOUR PLANTS NEED.
- I GUESS I'LL NEED TO DO SOME TESTS TO FIGURE THAT OUT.
OH, ONE MORE QUESTION.
WHY DOES NASA STUDY PLANT GROWTH?
- WITH ASTRONAUTS STAYING IN SPACE LONGER
AND EVENTUALLY GOING TO OTHER PLANETS AND BEYOND,
THEY WOULD NEED TO GROW THEIR OWN FOOD.
BUT ON A SPACECRAFT, THERE AREN'T ANY BIG WINDOWS,
AND EVEN IF THERE WERE,
YOU WOULD HAVE ONLY 45 MINUTES OF DAYLIGHT
EVERY 90 MINUTES WHILE ORBITING THE EARTH.
- BUT IF THEY DON'T HAVE ENOUGH TIME
TO GET LIGHT FROM THE SUN,
HOW WILL THE PLANTS GROW?
- ONE LIGHTING SYSTEM THAT HOLDS A LOT OF PROMISE
IS LIGHT-EMITTING DIODES.
THEY LAST A VERY LONG TIME.
THEY ALSO EMIT A VERY NARROW PART OF THE SPECTRUM:
PURE RED OR PURE BLUE.
- THOSE ARE THE COLORS THAT PLANTS LIKE BEST.
BUT WOULDN'T THESE LIGHTS AFFECT THE WAY THE PLANTS LOOK?
- REMEMBER THAT PLANTS DON'T USE THE GREEN PART OF THE SPECTRUM.
THEY REFLECT GREEN LIGHT MORE THAN ANY OTHER COLOR
WHILE ABSORBING THE RED AND BLUE LIGHT.
THEREFORE, WHEN GROWN UNDER RED AND BLUE LIGHT,
THEY ABSORB 100% OF THE AVAILABLE LIGHT
AND APPEAR BLACK.
- BLACK PLANTS?
THAT WOULDN'T BE VERY PRETTY.
I WONDER IF OTHER COLORS OF LIGHT
WOULD CHANGE THE WAY A PLANT GROWS
OR THE WAY THEY LOOK.
I'D BETTER HIT THE BOOKS AND FIND OUT THE BEST WAY
TO GET LIGHT TO MY PLANTS.
THANKS, DR. GOINS.
WHEW, THAT'S A LOT OF READING.
BUT NOW I KNOW A LOT MORE ABOUT TAKING CARE OF PLANTS.
LET ME TELL YOU WHAT I'VE LEARNED.
IN ORDER TO MAKE FOOD,
PLANTS NEED TO CARRY OUT PHOTOSYNTHESIS.
THAT TAKES PLACE IN THE LEAVES OF THE PLANT.
AND IN ORDER TO DO PHOTOSYNTHESIS,
THE LEAVES NEED WATER, CARBON DIOXIDE, AND SUNLIGHT.
THE CHLOROPHYLL IN THE LEAVES
TRAPS THE ENERGY OF THE SUNLIGHT,
AND THE WATER COMES UP THROUGH THE ROOTS.
THEN THE LEAVES GET CARBON DIOXIDE FROM THE AIR
THROUGH TINY PORES, OR HOLES, ON THE UNDERSIDES OF THE LEAVES.
THE PLANT USES THE TRAPPED SUNLIGHT
TO TURN THE WATER AND CARBON DIOXIDE
INTO OXYGEN AND GLUCOSE, A SPECIAL KIND OF SUGAR.
PLANTS USE THE GLUCOSE FOR ENERGY.
ANOTHER THING I FOUND OUT ABOUT PLANTS
IS THAT THEY CAN MOVE--
NOT LIKE YOU OR ME, OF COURSE.
THAT WOULD BE SCARY.
BUT THEY CAN REACT TO A CHANGE IN THEIR ENVIRONMENT,
OR A STIMULUS.
THESE REACTIONS ARE CALLED TROPISMS.
FOR EXAMPLE, A PLANT WILL GROW TOWARD ITS SOURCE OF LIGHT,
OR IT WILL GROW ITS ROOTS TOWARD A SOURCE OF WATER.
AND THE ROOTS OF MOST PLANTS GROW DOWNWARD,
THE SAME DIRECTION AS THE PULL OF GRAVITY.
HOW DO YOU THINK PLANTS WOULD GROW
IN A REDUCED-GRAVITY ENVIRONMENT
LIKE THE INTERNATIONAL SPACE STATION?
HMM.
WOULD I NEED TO CHANGE MY DESIGN
FOR A PLANT GROWTH CHAMBER
IF IT WENT TO SPACE?
WELL, I HAVE A LOT OF DESIGNING TO DO,
SO I NEED TO GET WORKING.
AFTER ALL, NASA'S WAITING.
AND IF YOU'D LIKE TO JOIN
ONE OF NASA'S ENGINEERING DESIGN CHALLENGES,
JUST CHECK OUT THE NASA WEBSITE AT WWW.NASA.GOV
AND SEARCH FOR "DESIGN CHALLENGES."
I'LL SEE YOU NEXT TIME ON "OUR WORLD."
HEY, MOM, I NEED SOME ADULT SUPERVISION.
- "OUR WORLD."