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[electronic music]

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- Humans explore Earth,
diving deep beneath its waters

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and flying high
above its surface.

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For more than 20 years,
humans have lived

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beyond Earth's boundaries.

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Have you ever wondered
what living in space

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would do to your body?

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For this and more,
find out next

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on "Real World."

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♪ ♪

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Our exploration of living
in space starts

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by examining the tiny units
that make up our bodies.

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Cells make up
all the components

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in your body,
and they keep you going

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without you
even having to think about it.

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Let's find out more
about how cells work

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and how they keep us alive.

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- I study what happens
to astronauts in space,

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which means I need
to study what happens

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to their cells in space.

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So cells are important because
they are the basic unit

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of structure and function.

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That means
that every living organism,

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including me and you
and astronauts in space,

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are made of cells.

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So if you take a cell
and look at it

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through a microscope,
you will see that it is packed

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with different structures.

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These structures
are called organelles,

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and these organelles are like
different factories in a city.

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Each organelle has a function
that helps the cell survive.

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So I like the big picture
because basically mitochondria

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and other organelles are parts
of the cell.

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Cells from tissues.
Tissues form organs.

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Organs form organisms,
for example, humans.

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So if I want to answer
the big question

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of how spaceflight
affects the human body,

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I can start by studying
how spaceflight

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affects the organelles
of the cells.

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- So clearly our cells
are super important.

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They make sure our bodies
keep doing all the things

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that need to be done every day
here on Earth,

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but what happens
if you leave Earth

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and go into space?

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How do our human cells
function in space?

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Does anything different
happen to them up there?

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- What is difference in space
compared to on Earth?

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On Earth, we have gravity,
and all of us,

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which means all our cells,
have evolved

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to live in gravity.

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In space, especially in orbit

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on the International
Space Station,

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the gravity is extremely low,

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and they're not used
to the lack of gravity at all,

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which makes them
behave differently

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and get more damaged.

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For example,
they are not able

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to renew themselves
quite as well,

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making them look as if
they were older than normal.

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Now, on Earth,
we are protected

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from space radiation
by the magnetic field

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of the Earth, which stops
radioactive particles

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from getting to us.

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The space station
is just close enough

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to the Earth
that it mostly fits

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inside the magnetic field,

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but on missions
to the moon and to Mars,

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they will be exposed
to space radiation,

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so other scientists and I
have discovered

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that space radiation
causes mutations.

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Mutation is damage
in the DNA of the cell.

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That would be the code
that describes

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all the functions of the cell.

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If a cell is mutated
because of radiation,

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then it may die
or it may develop

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in a wrong way and become
a wrong kind of cell,

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for example, a cancer cell.

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In addition,
space radiation causes damage

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to the cells similarly
to what an injury would do

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to a whole organism,
which causes inflammation,

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which can hurt both the brain
and the immune system.

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- So NASA is studying
what happens to our cells

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in space, but how do they know
how cells change

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in different settings?

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How do they keep track
of the changes?

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- We can look at the cell
through a microscope

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and count the number
of mutations,

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but also we can count
how many cells

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have been affected
by radioactive particles,

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and we can calculate it
as a percentage.

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So we would compare the number
of cells that are damaged

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to the total number of cells
to find out

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what percentage of the cells

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are damaged
by space radiation.

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This is a very good example
of quantitative data,

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which means the type of data
that we can count.

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In addition
to quantitative data,

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we also work
with qualitative data.

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For example, if you look
at the cells in a tissue,

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do they change shape?

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Do they connect to each other
in a different way

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after they were exposed
to space radiation

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compared to before they were
exposed to space radiation?

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We need to know
how spaceflight

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and space radiation affects
normal functions of cells.

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Then we can work to find out
how to reduce

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the harmful effects
of spaceflight

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so that astronauts
could travel to Mars

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without worrying
about how space radiation

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affects their cells.
Who does this work?

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Everyone.

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I am one member of a huge team

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of people working together.

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In all science,
people work together

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to discover new things,
similarly to how it takes

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a lot of cells with
different individual functions

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working together
to make organs

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that make the human body.

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- Well, that was ex-cell-ent.

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Cells truly are
the building blocks of life.

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We are who we are
thanks to the structure

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and function of cells,
and thanks to NASA,

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we're learning as much
as we can to help prepare

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for current and future
space travel.

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Science, technology,
engineering, and mathematics

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are all working together

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to help make
exploring new worlds

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as safe as possible for us
and our cells.

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See you next time
on "Real World."