[ MUSIC ]
>> HELLO, I'M AKI HOSHIDE.
>> AND I'M MEGAN MCARTHUR.
>> WE'RE ASTRONAUTS,
LIVING AND WORKING ABOARD
THE INTERNATIONAL SPACE STATION.
HAVE YOU EVER WONDERED
HOW ASTRONAUTS ORIENT THEMSELVES
IN SPACE WHEN THERE IS
NO FEELING UP OR DOWN?
IN THIS EPISODE, WE'LL DISCUSS
THE VESTIBULAR SYSTEM,
AND THE EFFECTS OF FREE FALL
ON OUR SENSE OF DIRECTION
UP HERE ON SPACE STATION.
LET'S GO TRY OUT
SOME EXPERIMENTS WITH, UH,
SPATIAL ORIENTATION.
THE VESTIBULAR SYSTEM IS
THE SENSOR SYSTEM OUR BRAINS
USE TO PROCESS MOVEMENT
USING THE PERCEIVED PULL
OF GRAVITY, STRUCTURES IN
OUR INNER EARS, AND THROUGH
PROCESSING VISUAL CUES
FROM OUR EYES.
THIS INFORMATION IS NECESSARY
FOR BALANCE, MOTION,
AND SPATIAL ORIENTATION.
THE VESTIBULAR SYSTEM IS
MADE UP OF SEVERAL PARTS,
PRIMARILY LOCATED
IN THE INNER EARS,
IN A SERIES OF
INTERCONNECTED CHAMBERS
CALLED THE "LABYRINTH."
THE LABYRINTH HAS
THREE SEMI-CIRCULAR CANALS,
EACH ORIENTED
IN A DIFFERENT PLANE
TO DETECT DIFFERENT MOVEMENTS.
>> IN THE MICRO-G ENVIRONMENT
HERE ON THE SPACE STATION,
THE PULL OF GRAVITY OUR BODY
IS ACCUSTOMED TO IS DIFFERENT,
AND THE VESTIBULAR SYSTEM
RECEIVES MIXED MESSAGES.
THE SEMI-CIRCULAR CANALS
SENSE HEAD ROTATION IN SPACE,
JUST AS THEY DO ON EARTH.
BECAUSE THE OTOLITH ORGANS RELY
ON GRAVITY TO DETECT LINEAR MOTION,
THEY DON'T FUNCTION THE SAME WAY
IN MICRO-G AS THEY DO ON EARTH.
>> YOU'VE PROBABLY EXPERIENCED
SIMILAR MIXED MESSAGE ON EARTH.
SOME PEOPLE FEEL DIZZY
WHEN THEY READ A BOOK
IN A MOVING CAR.
THE STRUCTURES IN YOUR EAR
PICK UP ON THE MOTION
OF THE CAR, BUT YOUR EYES ARE
FIXED ON THE MOTIONLESS BOOK.
THESE MIXED MESSAGES CAN
CAUSE DIZZINESS AS YOUR BRAIN
TRIES TO DETERMINE IF YOU'RE
AT REST OR IN MOTION.
WE CALL THAT DIZZY FEELING
"MOTION SICKNESS".
>> DOCKING SEQUENCE IS COMPLETE,
WELCOME TO THE INTERNATIONAL
SPACE STATION.
>> [ INDISTINCT ].
DOCKING COMPLETE, AND HAPPY
TO BE HERE AT THE ISS.
>> THIS IS SIMILAR TO THE WAY
MANY FIRST-TIME ASTRONAUTS
FEEL WHEN THEY ARRIVE
ON THE SPACE STATION.
UP HERE, WE CALL THAT
SPACE ADAPTATION SYNDROME,
OR SPACE MOTION SICKNESS.
THIS IS A PERIOD WHERE
OUR BODIES ARE ADJUSTING
AND ORIENTING TO
THE NEW FREE FALL ENVIRONMENT.
ONE WAY WE FIGHT OFF
SPACE MOTION SICKNESS
IS BY REDUCING
OUR BODY MOVEMENTS
UNTIL WE ARE ACCLIMATED.
WE ALSO USE LABELS, SIGNS,
AND THE DESIGN OF THE STATION
TO HELP ORIENT OURSELVES.
LIGHTS ARE POSITIONED UP ALONG
WHAT WE CALL THE OVERHEAD,
AND AIR INTAKES
ARE POSITIONED DOWN TOWARDS
WHAT WE CALL THE DECK.
WHEN WE RETURN TO EARTH,
OUR BODIES, ONCE AGAIN,
MUST ADAPT TO PERCEIVED CHANGE
IN GRAVITY.
>> CLOSE YOUR EYES AND THINK
ABOUT WHERE YOU ARE RIGHT NOW.
CAN YOU DETERMINE WHICH WAY
IS UP WITH YOUR EYES CLOSED.
WHAT ABOUT DOWN?
NOW, OPEN YOUR EYES
AND THINK ABOUT WHAT SIGNALS
YOU RECEIVE TO HELP YOU
DETERMINE DIRECTION.
ON EARTH, WE PERCEIVE UP
OR DOWN RELATIVE TO GRAVITY,
WHILE IN ORBIT ON STATION,
WE'RE ESSENTIALLY IN FREE FALL.
THERE ISN'T A TRUE UP.
UP COULD BE ANYWHERE.
>> WELCOME TO "WHICH WAY
ARE YOU POINTING?"
WHERE OUR ASTRONAUTS TRY
TO FIGURE OUT THEIR ORIENTATION
WHILE THEY'RE IN MICRO-G.
THEY'LL HAVE EYEMASKS ON
AND EARPLUGS IN TO REMOVE
THOSE SENSES.
ON THE SPACE STATION,
GRAVITY HAS MOSTLY BEEN REMOVED,
AS WELL.
THEY'LL PICK AN OBJECT
AND SEE IF THEY CAN POINT TO IT
AFTER BEING SPUN AROUND.
FIRST, SOME TERMS
YOU SHOULD KNOW.
PITCH IS SHOWN AS
AN EXAGGERATED NOD.
ROLL IS SHOWN AS YOU MOVE
YOUR HEAD FROM SHOULDER
TO SHOULDER.
AND YAW IS SHOWN AS IF YOU WERE
SHAKING YOUR HEAD NO.
LET'S PLAY.
>> TARGET: ESA FLAG.
ROTATION: PITCH.
[ MUSIC ]
>> OH, SORRY, MARK.
LET'S TRY AGAIN.
>> TARGET: ESA FLAG.
ROTATION: ROLL.
[ MUSIC ]
>> WRONG AGAIN, MARK.
OKAY, SHANE,
LET'S SEE HOW YOU DO.
>> TARGET: LAPTOP.
ROTATION: ROLL.
[ MUSIC ]
>> THERE ARE JUST
TOO MANY MISSING PIECES
OF THEIR VESTIBULAR SYSTEMS
TO ACCURATELY ORIENT THEMSELVES.
>> I ENCOURAGE YOU
TO THINK ABOUT THE WAY
YOUR VESTIBULAR SYSTEM
HELPS YOU RESPOND TO INFORMATION
FROM YOUR ENVIRONMENT,
AND TAKE NOTE OF WHAT'S
HAPPENING NEXT TIME YOU FEEL
A LITTLE OFF-BALANCE.
THANKS FOR EXPLORING
THE EFFECTS OF MICRO-G
ON THE VESTIBULAR SYSTEM
WITH US TODAY.
SEE YOU NEXT TIME.