WEBVTT FILE

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We want to know: has
life ever existed on Mars?

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Do pockets of life
persist on Mars today?

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NASA's approach to answering
these questions is to break them

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down into smaller
and smaller steps.

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First, we need to know if
ancient Mars was habitable.

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Did it once have the right
climate, and the right chemistry

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to support life?

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The Curiosity rover is
investigating these questions by

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looking for organic
molecules: containing carbon.

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Organic molecules are the
backbone of all life on Earth,

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though they can also come
from non-living sources.

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Today the surface of Mars
readily destroys organics,

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making them difficult to detect.

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Six years ago, Curiosity landed
in Gale Crater, on an ancient

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lakebed.

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A few months after arrival, it
drilled into sedimentary rocks

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and detected traces of organic
molecules using an instrument

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called SAM.

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Now, Curiosity is climbing
the mound in the middle of Gale

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Crater, and SAM has made
a subsequent detection of

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organics.

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This new detection is exciting
because it comes from rocks that

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are billions of years old.

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That means that the
organic material within them is

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extremely ancient.

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Some of the organics that SAM
has detected contain sulfur,

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likely introduced
through geological processes.

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Sulfur can act as a
preservative, binding organic

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molecules together to make them
tougher, and protecting them

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from oxidation.

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In fact, sulfur is the element
that makes hair and fingernails

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tough, as well as
vulcanized rubber.

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Martian sulfur has probably had
a similar effect on these old

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organic molecules, helping to
preserve them over geological

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timescales.

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SAM made the new detections by
heating samples of crushed rock

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to very high temperatures, above
a thousand degrees Fahrenheit.

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This vaporized the samples
and released several species of

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small hydrocarbons,
like benzene and propane.

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Because the hydrocarbons
were released at such high

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temperatures, they may be the
fragments of bigger, heavier

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molecules within the
rock similar to kerogens.

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On Earth, kerogens are found in
rocks like black shale and coal,

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and are the products of
ancient plant and bacteria.

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We don't know if the recently
discovered organics on Mars are

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of biological origin, but
it's exciting to find such old

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material preserved
right at the surface.

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This finding is also encouraging
for future exploration.

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NASA and the European Space
Agency are preparing to send the

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next generation of rovers to
Mars in 2020, carrying new

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technologies to search for
signs of microbial life.

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In the distant past, Mars was
much warmer and wetter than it

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is today.

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The rocks at Gale Crater tell us
it was once an environment where

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life as we know it
could have survived.

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The discovery of ancient organic
molecules shows that another

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ingredient of life was present
at that time, and it broadens

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our understanding of
habitability of both ancient and

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modern Mars.

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[Music]

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[Satellite beeping]