WEBVTT

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[dramatic percussion music]

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- HEY, WELCOME
TO "NASA LAUNCHPAD."

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I'M YOUR HOST,
VINCE WHITFIELD.

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WHAT DOES A CHAIN SAW
HAVE TO DO WITH SCIENCE?

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WELL, KEEP WATCHING,
AND YOU'LL FIND OUT.

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WHAT'S ONE
OF THE MOST IMPORTANT THINGS

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NASA'S INTERESTED IN FINDING

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ON PLACES
LIKE THE MOON AND MARS?

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LET ME GIVE YOU A HINT:

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YOU MIGHT WANT IT
IN YOUR FAVORITE DRINK

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ON A HOT SUMMER'S DAY,

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BUT NASA HAS LOTS
OF OTHER USES FOR IT.

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I'M TALKING ABOUT ICE.

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NOT ONLY COULD WATER ICE
BE BENEFICIAL

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TO THE PRODUCTION
OF BOTH WATER AND OXYGEN

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THAT COULD AID OUR ASTRONAUTS

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AS THEY SET UP
LUNAR AND MARTIAN OUTPOSTS,

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BUT BY STUDYING THE ICE,
A LOT CAN BE LEARNED

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ABOUT THE HISTORY
OF THE MOON OR PLANET.

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HOW?

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WELL, TO ANSWER THAT,
LET'S TURN TO H.O.W.,

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THE HISTORY OF WINTER
CONFERENCE.

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AND TO FIND OUT HOW IT'S DONE
HERE ON EARTH,

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HERE ARE DOCTORS
PETER WASILEWSKI AND TONY GOW

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TO EXPLAIN.

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- I'M SITTING
ON A BLOCK OF ICE

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THAT WE CUT FROM THIS HOLE
IN THE ICE RIGHT HERE.

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FIRST OF ALL, WE DRILLED A HOLE,
AUGERED A HOLE IN THE ICE,

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AND USED THIS BUTTERFLY TOOL
TO DETERMINE HOW THICK IT WAS,

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AND, YOU KNOW, THAT KIND OF
TELLS YOU MENTALLY

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WHETHER YOUR CHAIN SAW
IS LONG ENOUGH TO CUT THROUGH IT

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AND THEN JUST HOW
TO APPROACH IT.

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- WE WERE CUTTING BLOCKS OF ICE
OUT FROM THE LAKE,

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MAINLY TO LOOK AT THE STRUCTURE,
BOTH THE BUBBLE STRUCTURE

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AND ALSO THE STRUCTURE
REVEALED IN THIN SECTIONS.

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WE USE POLARIZED LIGHT

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TO DELINEATE
THE CRYSTAL STRUCTURE.

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THE CRYSTAL SIZE,
CRYSTAL ORIENTATION

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ALLOWS US TO DO THAT.

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- SO THEY'RE CUTTING THE BLOCKS
TO ENABLE

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VERTICAL AND HORIZONTAL
THIN SECTIONS TO BE CREATED.

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WITH THESE THIN SECTIONS,
THE RESEARCHERS WILL HAVE

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A COMPLETE 3-D PICTURE

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OF THE CRYSTAL SIZE,
SHAPE, AND ORIENTATION.

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IN ADDITION, WE'LL BE ABLE
TO USE THE BUBBLE PATTERNS

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TO CREATE A PICTURE
OF THE RATE OF FREEZING

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AND TO CORRELATE THIS
WITH THE WEATHER RECORDS.

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ALL OF THIS JUST TO DECIPHER
THE HISTORY OF WINTER.

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OKAY, SO ONE OF THE THINGS
WE'RE TALKING ABOUT

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IS THE BUBBLE STRUCTURE.

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NOW, THAT'S SOMETHING THAT CAN
BE STUDIED PRETTY EASILY.

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AFTER ALL,
ICE IS TRANSPARENT.

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SO IT'S JUST A MATTER
OF LOOKING

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AT WHERE THE BUBBLES
HAVE FORMED.

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BUT WHAT DOES THAT TELL US?

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WELL, WE'LL LET TONY EXPLAIN.

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- BUBBLES TEND TO CONCENTRATE
DURING PERIODS OF FAST FREEZING,

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AND AS THE FREEZING SLOWS DOWN,
THEY BECOME LESS BUBBLY.

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THE ICE BECOMES LESS BUBBLY.

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AND ON THAT BASIS,
YOU CAN DISTINGUISH

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WHAT'S BEEN FREEZING FAST,
WHAT'S BEEN FREEZING SLOW,

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WHICH MEANS WHAT'S WARMER
AND WHAT'S COLDER.

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WHEN IT WARMED UP,
YOU WOULD GET LESS BUBBLES,

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BUT WHEN IT COOLED DOWN
AT NIGHT,

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YOU GOT LAYERS
WITH MORE BUBBLES.

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- SO SOMETHING
AS SIMPLE AS BUBBLES

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CAN TELL YOU ALL ABOUT
TEMPERATURE PATTERNS.

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I GUESS, IN A SENSE,
THAT'S KIND OF LIKE

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HOW YOU CAN DETERMINE
PRECIPITATION PATTERNS

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REFLECTED IN GROWTH
BY LOOKING AT TREE RINGS.

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OR BY LOOKING AT LAYERS
OF ROCK AND DIRT,

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YOU CAN FIGURE OUT THINGS
LIKE THE AGE OF THE PLANET

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AND THE GEOLOGIC HISTORY
OF THAT LOCATION.

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NOW, SOMETHING ELSE TONY WAS
TALKING ABOUT WAS THIN SECTIONS.

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AND WHAT THAT MEANS IS,
BASICALLY,

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THEY'RE TAKING
THE BIG BLOCKS,

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SLICING THEM DOWN
AND GETTING THEM REALLY THIN,

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AND THEN LOOKING
AT THOSE PIECES

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WITH SOME NIFTY
OPTICAL EQUIPMENT.

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WHEN THE ICE SECTION
IS ONE TO TWO MILLIMETERS THICK,

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YOU CAN USE POLARIZED LIGHT

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TO DISCOVER THE SIZE,
SHAPE, AND ORIENTATION

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OF THE ICE CRYSTALS
IN THE ICE BLOCK.

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ON TOP OF A LIGHT TABLE,
YOU PUT A POLARIZER SHEET.

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ON TOP OF THIS
GOES THE ICE SECTION.

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THEN ON TOP OF THE ICE,
YOU PUT ANOTHER POLARIZER SHEET.

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- LIGHT COMES
THROUGH THE POLARIZER

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IN ONE VERY NARROW
VIBRATION DIRECTION.

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THE ANALYZER
IS PLACED IN A POSITION

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WHERE IT'S ABSOLUTELY NORMAL
TO THAT DIRECTION,

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SO IT DOESN'T LET LIGHT
THROUGH NORMALLY.

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BUT BECAUSE ICE
IS DOUBLY REFRACTING,

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THERE'S AN INTERACTION
BETWEEN BOTH REFRACTIVE INDICES

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THAT PRODUCE, ESSENTIALLY,
BIREFRINGENCE COLORS,

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AND THAT'S WHAT YOU SEE
COMING OUT.

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IT ALLOWS YOU TO IDENTIFY
THE INDIVIDUAL CRYSTALS,

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WHICH YOU CAN'T DO
IN ORDINARY LIGHT

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BECAUSE IT'S TRANSPARENT.

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- IF YOU'VE EVER
WORN SUNGLASSES,

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YOU'VE PROBABLY USED YOUR OWN
POLARIZED OPTICAL FILTER.

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WE ALL KNOW THAT LIGHT
HAS WAVELIKE PROPERTIES,

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ONE OF WHICH IS VIBRATION.

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ORDINARY WHITE LIGHT VIBRATES
IN MANY DIFFERENT DIRECTIONS.

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BUT A POLARIZING FILTER
BLOCKS OUT ALL LIGHT

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EXCEPT THE WAVES VIBRATING
IN A SINGLE DIRECTION.

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WHEN VIEWED
THROUGH THE POLARIZED FILTERS,

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THE ICE CRYSTALS TAKE ON
A COLORFUL TINT.

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THIS ALLOWS YOU TO SEE DIFFERENT
CRYSTAL STRUCTURES IN THE ICE

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THAT YOU CAN'T SEE
WITH YOUR NAKED EYE.

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THE COLORS AND PATTERNS
IN THE IMAGES

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PRODUCED USING
THE POLARIZED LIGHT

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DEFINE THE TYPE OF ICE AND SNOW
BEING STUDIED.

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AND BECAUSE DIFFERENT
WEATHER CONDITIONS

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PRODUCE UNIQUE KINDS
OF ICE AND SNOW,

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SCIENTISTS CAN BUILD
A LONG-TERM HISTORY

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OF THE WEATHER PATTERNS
FOR THAT AREA.

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WHAT ABOUT OTHER APPLICATIONS
FOR THIS THIN SECTION STUFF?

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- THE PROCESS HAS BEEN
WELL KNOWN FOR A LONG WHILE,

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AT LEAST 150 YEARS,
AND IT'S BEEN APPLIED

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TO LOOKING AT THIN SECTIONS
OF ROCK, FOR EXAMPLE.

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AND NOW WE APPLY IT TO ICE,

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WHICH IS SIMPLY
JUST ANOTHER ROCK.

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IT'S A ONE-MINERAL ROCK.

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IN THAT SENSE,
IT'S RATHER LIKE MARBLE.

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IT JUST CONSISTS
OF CALCITE,

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AND IT'S A ONE-MINERAL ROCK.

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- SO THERE YOU GO.

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THIN SECTIONS
HAVE ALREADY BEEN USED

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FOR SEVERAL DIFFERENT THINGS.

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AND THAT'S WHAT SCIENCE
IS ALL ABOUT.

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BY FOLLOWING PROTOCOLS,
LIKE THE ONES USED

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BY THE HISTORY OF WINTER
SCIENTISTS,

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WE CAN TAKE WHAT WE KNOW
AND APPLY IT TO OTHER QUESTIONS.

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KNOWING HOW ICE CRYSTALLIZES
IN DIFFERENT CONDITIONS

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CAN TELL US ABOUT
THE TEMPERATURE CONDITIONS

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IN THE LAKE, ON THE SEA,
WHEN SEA ICE FORMS, ET CETERA.

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SO WHETHER WE'RE
CARVING HOLES IN ICE,

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LOOKING AT DIRT
AND ROCK LAYERS,

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OR LOOKING AT ALL OF THIS KIND
OF STUFF ON THE MOON OR MARS,

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WE'VE GOT A GOOD IDEA

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ABOUT HOW WE SHOULD BE
GOING ABOUT DOING IT.

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THAT'S IT FOR NOW.
THANKS FOR WATCHING.

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I'M VINCE WHITFIELD,

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AND I'LL CATCH YOU NEXT TIME
ON "NASA LAUNCHPAD."