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Global circulation of Mars’ upper atmosphere

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Science  13 Dec 2019:
Vol. 366, Issue 6471, pp. 1363-1366
DOI: 10.1126/science.aax1553

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Mapping winds in Mars' upper atmosphere

The atmospheric loss processes that stripped Mars of most of its ancient atmosphere are poorly understood. Benna et al. analyzed atmospheric measurements collected by the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft as it repeatedly dipped into the red planet's upper atmosphere. Combining multiple observing modes allowed the authors to derive wind speeds and map the global circulation of the atmosphere at altitudes of ∼150 kilometers. In some locations, winds followed the slope of the surface topography far below. Such insights into the upper levels of planetary atmospheres are limited, even for Earth.

Science, this issue p. 1363

Abstract

The thermosphere of Mars is the interface through which the planet is continuously losing its reservoir of atmospheric volatiles to space. The structure and dynamics of the thermosphere is driven by a global circulation that redistributes the incident energy from the Sun. We report mapping of the global circulation in the thermosphere of Mars with the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft. The measured neutral winds reveal circulation patterns simpler than those of Earth that persist over changing seasons. The winds exhibit pronounced correlation with the underlying topography owing to orographic gravity waves.

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