WEBVTT FILE

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A fleet of robotic spacecraft
is exploring the Red Planet,

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sending back a flood of data and
helping to unlock the secrets of
Mars.

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When NASA's MAVEN orbiter
arrived in 2014, it became the

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first mission dedicated to
observing the Mars upper
atmosphere.

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This region is the conduit
for air to escape to space,


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a process that may have
dried up early Mars.

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The most likely cause of this
process is the solar wind,

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a stream of electrically charged
particles blowing from the Sun.

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When the solar wind reaches
Mars, it interacts directly with

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the upper atmosphere, piling
up ahead of the planet in a bow
shock.

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Charged particles from the Mars
upper atmosphere, seen here in
color,

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feel the pull of the
electric field generated by the
solar wind.

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These particles, or ions, can
pick up sufficient energy from

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the electric field
to escape into space.

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In this simulation,
green particles represent

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medium-energy ions swept back
in the wake of the solar wind.

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High-energy ions, in yellow and
red, follow the electric field

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in a "polar plume" above Mars.

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Now, data from MAVEN are
supporting this model of solar
wind erosion.

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This graph shows the first-ever
measurements of oxygen ion flux

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around Mars, allowing us to
see the solar wind driving the

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atmosphere into space, in both
the polar plume and the tail
regions.

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As the MAVEN mission continues,
new measurements will be key to

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understanding how these
processes operate, shaping the

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ongoing evolution of
the Martian climate.