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early in its history mars had a far more

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hospitable climate than the one that we

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see today with a thick atmosphere and

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abundant flowing water

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so how did it evolve from warm and wet

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to cold and dry

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since 2015 nasa's maven mission has been

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investigating this question by studying

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the red planet's upper atmosphere

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now it has mapped high-altitude global

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wind patterns at mars for the first time

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during the closest part of its orbit

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maven skims through the upper atmosphere

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ingesting air molecules and determining

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their composition with an instrument

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called engemes

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maven can also rotate engamps back and

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forth to measure the air's velocity

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these measurements provide a snapshot of

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wind speed and direction along a track

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of maven's orbit

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because the orbit evolves over time or

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precesses the spacecraft's closest

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approach to mars drifts across the

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planet allowing it to take snapshots at

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different locations

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over the past four years maven's tracks

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have added up crisscrossing mars at many

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locations and at various seasons and

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times of day wrapping the planet in a

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web of observations

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the measurements reveal how the winds

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vary with location and evolve throughout

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the martian year

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now scientists have used maven data to

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build a global map of wind currents

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roughly 200 kilometers above mars the

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first time the winds have been mapped

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globally and at such high altitude

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anywhere beyond earth

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within the new map scientists discovered

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an unexpected feature imprints of rugged

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terrain far below

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as an example during two of its orbits

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maven saw winds above the tharsis

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plateau diverting away from elevated

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terrain driven by giant shield volcanoes

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reaching twice the height of mount

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everest here's how the process works

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down at the martian surface winds are

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forced around and over obstacles when

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they encounter mountainous terrain

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disturbances in surface level winds also

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disturb the air above propagating up

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through the atmosphere as gravity waves

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when they reach the upper atmosphere the

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gravity waves block the high altitude

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winds causing them to alter course and

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allowing maven to sense the presence of

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mountains and valleys on the surface

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while skimming the edge of space

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high above mars maven is studying the

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upper atmosphere and reaching out to

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feel the breeze

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it has now made the first measurement of

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high-altitude global circulation

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patterns and discovered a surprising

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connection to features on the surface

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these measurements also shed new light

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on ancient mars with its thick

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atmosphere and its warm wet climate

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by revealing how the climate of mars

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works today maven is helping scientists