Solar wind The Red Planet’s thick atmosphere was eroded over millions ot years
THE PRIMORDIAL ATMOSPHERE of Mars was stripped away by the solar wind, leaving the arid planet we know today. The process has been observed happening on the planet now by NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) mission.
There are many signs that Mars once had a thick, wet atmosphere, but over time this was lost. Now researchers believe they have discovered the reason why. The MAVEN probe observed the remaining Martian atmosphere being stropped by solar winds at the rate of 100g per second.
“Like the theft of a few coins from a cash resister every day, the loss becomes significant over time,” says Bruce Jakosky, MAVEN’s principal investigator. “We’ve seen that the atmospheric erosion increases significantly during solar storms, so we think the loss rate was much higher billions of years ago when the Sun was young and more active.”
The solar wind, made from charged particles being blown off by the Sun, flows past Mars and can cause particles in Mars’s upper atmosphere to become charged and shoot into space.
“Solar-wind erosion is an important mechanism for atmospheric loss, and was important enough to account for significant change in the Martian climate,” says Joe Grebowsky, MAVEN project scientist.
Studying the mechanisms behind this atmospheric loss could have important ramifications for Mars’s habitability, as well as helping us find other potential habitable worlds out in the Galaxy.
“Mars appears to have had a thick atmosphere warm enough to support liquid water, which is a key ingredient and medium for life as we currently know it,” says John Grunsfeld, astronaut and associate administrator for the NASA Science Mission Directorate. “Understanding what happened to the Mars atmosphere will inform our knowledge of the dynamics and evolution of any planetary atmosphere. Learning what can cause changes to a planet’s environment from one that could host microbes at the surface to one that doesn’t is important to know, and is a key question that is being addressed in NASA’s journey to Mars.” http://mars.nasa.gov/maven/