MAVEN Studies Mars Upper Atmosphere to Determine "What Happened to the Atmosphere"

The MAVEN mission is the first spacecraft specifically designed to study Mars’ upper atmosphere. MAVEN’s goal is to understand how Mars lost its thick, early atmosphere to space, and how this in turn caused it to lose its once hospitable climate.
MAVEN’s orbit gives it the most comprehensive view of the Martian atmosphere to date. Circling the red planet every 4.5 hours on an elliptical path, MAVEN passes close to the north and south poles at an inclination of 75 degrees. This allows MAVEN to gather a north-south swath of data with each pass. At the same time, Mars itself rotates eastward beneath MAVEN, giving the orbiter longitudinal coverage. The combination of MAVEN’s orbit and Mars’ daily rotation provides a complete picture of the Martian atmosphere every day.

(Video credit: NASA’s Goddard Scientific Visualization Studio)
NASA Goddard
NASA – National Aeronautics and Space Administration
Ancient regions on Mars bear signs of abundant water—such as features resembling valleys and deltas, and minerals that only form in the presence of liquid water. Scientists think that billions of years ago, the atmosphere of Mars was much denser and warm enough to form rivers, lakes, and perhaps even oceans of water. As the planet cooled and lost its global magnetic field, the solar wind and solar storms eroded away to space a significant amount of the planet’s atmosphere, turning ‪#‎Mars‬ into the cold, arid desert we see today. The goal of MAVEN is to determine how much of Mars’ atmosphere and water have been lost to space, and how these processes have changed the climate on the Red Planet over its history.