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NASA Probe Charts Wind Circulation in Mars’ Upper Atmosphere

A NASA spacecraft recently achieved the remarkable feat of mapping the elusive winds that blow high above the surface of Mars – providing astronomers long-sought data for the first time in history, according to a new study.

(CN) – A NASA spacecraft recently achieved the remarkable feat of mapping the elusive winds that blow high above the surface of Mars – providing astronomers long-sought data for the first time in history, according to a new study.

The Mars Atmosphere and Volatile Evolution orbiting spacecraft (MAVEN) is designed to measure the global circulation of Mars’ upper atmosphere. Designed by various branches of the NASA space program, it was launched in November 2013 and reached Mars’ orbit in September the following year.

MAVEN’s primary goal involved exploring the upper atmosphere of Mars, the ionosphere, and providing an understanding of Mars’ interaction with the sun and solar winds, according to scientists at Colorado University. A secondary mission involved investigating the loss of Mars’ volatile compounds – CO2, N2, and H2O.

Mars rovers and orbiters have identified physical features on the surface of Mars, including extensive networks of carved rock most likely caused by water erosion like rain or melting snow. According to Rob Lillis, associate research physicist at the University of California Berkeley Space Sciences Laboratory and member of the MAVEN Science team, rovers have actually driven through ancient streambeds and discovered minerals that can only form over long years underwater.

Currently, the planet’s extremely thin atmosphere prohibits substantial existence of liquid water. The evidence of previous bodies of water, however, gives scientists reason to believe an event must have happened to cause this deterioration. Furthermore, the surface of Mars shows no signs of absorption of the missing volatile compounds, indicating that they must have escaped through the atmosphere into space.

With MAVEN’s help, scientists hoped to understand this atmospheric loss and gain insight into the planet’s history. And now, after years of gathering atmospheric data, MAVEN has successfully allowed researchers to produce a first look at what goes on far above the red planet.

Like other Earth-like planets in our solar system, the circulation of Mars’ upper atmosphere, specifically the thermosphere and the ionosphere, is driven by the solar energy from above as well as the energy ascending from the lower atmosphere below. The lack of disturbance on the planet’s surface, along with the fact that it is devoid of bodies of water, makes Mars’ circulation patterns much simpler than that of the Earth.

The two planets’ atmospheric tendencies are quite different however due to their vastly different surfaces. In fact, in November 2015 MAVEN discovered that the deterioration of the atmosphere increases greatly after a solar storm – a large flare of energy and plasma from the sun. The planet also lacks an ozone layer which prevents any significant warming. Additionally, Mars does not have a global magnetic field apart from small umbrella shaped fields throughout the planet, so when energy particles descend from outer space, auroras can occur almost anywhere.

The circulation in the upper atmosphere is responsible for the transportation and redistribution of materials and energy across the planet. This phenomenon has been widely studied in Earth’s atmosphere for decades, but the nature of Mars’ upper atmosphere has remained an uncharacterized mystery thus far.

In their recent study, planetary scientist Mehdi Benna from the University of Maryland and his colleagues report new data collected by MAVEN as it dipped into Mars’ upper atmosphere at altitudes of roughly 87 – 250 miles. This data allowed scientists to measure wind speeds in the Martian thermosphere and ultimately map the atmospheric circulation that resulted. Their findings show how Mars has lost most of the ancient atmosphere, as well as provide researchers with a useful comparison and better understanding of the upper atmosphere here on Earth.

Benna and his team explain that the circulation patterns are in fact much simpler than that on Earth and remains stable across Mars’ changing seasons. This is indicative of the long-term stability scientists have observed of the planet’s climate throughout the whole Martian year.

Furthermore, the atmospheric winds in specific locations follow the topography of the planet’s surface quite closely, suggesting the possible detection of what are known as orographic gravity waves. In Mars’ upper atmosphere, when winds blow over surfaces that dramatically change in height, it produces these massive atmospheric waves, the authors say.

This first look into the detailed wind patterns high above Mars has been unattainable until now, but the results of the study show promise in understanding the composition, history, and future of our neighbor planet.

The results were published Thursday in the journal Science.

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