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(Musical intro)

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NASA's Mars rover Curiosity
celebrates its fourth year

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on Mars since landing at
Gale crater on August 5, 2012.

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Let's take a quick look
back at the past year.

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[Whoosh]

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The rover operations team
at JPL has hit its stride.

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Four years of experience
allows them to plan

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challenging and complex
activities much faster.

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It used to take a month to
drill and analyze a rock sample.

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Now it takes just a week.

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[Whoosh]

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In spite of the
expected wear and tear,

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Curiosity is fully functional
and as busy as ever.

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The drill, the sample
processing system,

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and every science
instrument continue to do

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what they were designed to do.

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The wheels are slowly
gettin' beat up, but testing

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of spare wheels at JPL has shown
that with careful driving,

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they will last long enough to
get the rover to all the places

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on Mount Sharp that the
science team wishes to explore.

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[Whoosh]

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Much of the past
year was spent on an

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obstacle course of sorts
on lower Mount Sharp.

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Our athletic rover climbed
over a rocky plateau and

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had to wind its way through
the Bagnold Dune field,

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a stretch of beautiful and
currently active sand dunes

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that skirt the lower
mountain, blocking Curiosity

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from heading straight
toward higher elevations.

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But the rover reached
a spot where it could

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drive around the dunes,

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making a long-awaited
left turn

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and beginning a
more aggressive climb.

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[Whoosh]

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As Curiosity crossed the
Naukluft Plateau,

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it studied fractures in
the ancient sandstone

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where groundwater
once flowed

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and permeated the
surrounding rock,

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causing changes in
chemistry that created

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light-toned haloes
around the fractures.

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The science team compared
rock powder drilled from

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the halo with that drilled
from unaltered rock.

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The haloed regions were
enriched in silica

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but depleted in other
chemical elements.

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It appears that groundwater
transported chemical elements

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from some rock layers and
deposited them in others.

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[Whoosh]

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Recently, NASA gave
Curiosity the best

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anniversary gift it could
hope for - an extension of

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its mission for at
least two more years.

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We'll use it to reach
progressively higher

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and younger rocks
on Mount Sharp,

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including rock types we've
not yet explored.

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We can't wait to see
how the story of the