The solar wind is responsible for escaping the Martian atmosphere and turning it from hot and wet to a cold desert

Maven's data allowed the researchers to determine the rate of gas escape from the Martian atmosphere due to the impact of the solar wind. The findings show that the erosion of the Martian atmosphere is significantly increased during solar storms such as those that raged in March 2015

NASA's Maven spacecraft identified the process that appears to have played a key role in the transition of Mars' climate from an early, warm, wet environment that may have supported life to the dry, arid planet Mars is today.

Maven's data allowed the researchers to determine the rate of gas escape from the Martian atmosphere due to the impact of the solar wind. The findings show that the erosion of the Martian atmosphere is significantly increased during solar storms. The results were published Nov. 5 in an article in the journal Science and in a special issue of Geophysical Research Letters, now a journal of the American Geophysical Union.

"It appears that in the past Mars had a thick atmosphere warm enough to support liquid water which is an essential ingredient for life as we know it today. ” said John Grunsfeld, astronaut and associate director of science missions at NASA Headquarters in Washington. "Understanding what happened to the atmosphere of Mars will improve our knowledge of the dynamics and development of the atmospheres of all the planets and in the process also understand what might cause the Earth to cease to be suitable for life. This is a key question that NASA seeks to answer in the journey to Mars."

Maven measurements indicate that the solar wind blows about 100 grams out of the Martian atmosphere every second. Like stealing a few coins every day that turns into a significant amount over time. says Bruce Jespi, principal investigator of the Maven spacecraft at the University of Colorado at Boulder. "We have seen that erosion in the atmosphere increases significantly during solar storms, so we think the loss rates were much higher billions of years ago when the Sun was younger and more active."

A series of dramatic solar storms hit the Martian atmosphere in March 2015, and Mayvan found that the loss had accelerated. The combination of higher loss rates and solar storms may indicate that the loss of the atmosphere to space may be a central process in the extreme climate change Mars underwent from a place with a dense atmosphere and flowing water to today's cold, rusty, dry desert.
The solar wind is a stream of particles, mainly protons and electrons, emitted from the sun's atmosphere at a speed of about a million kilometers per hour. The magnetic field created by the solar wind in its flow towards Mars can create an electric field, much like a turbine on Earth is used to generate electricity. This electric field accelerates electrically charged gas atoms called ions in the upper atmosphere of Mars and throws them into space.

Maven is already studying solar wind particle time and the sun's ultraviolet radiation in the upper part of the Martian atmosphere. The latest findings indicate increased loss in three desert areas of the Red Planet. The "tail" region where the solar wind flows behind Mars, over the poles of Mars and an increased cloud of gas that surrounds Mars. The scientists determined that almost 75 percent of the neolithic ions come from the tail region, and almost 25 percent from the plume region, with a small contribution from the extended cloud surrounding Mars.

Mars has many ancient areas that testify to the flow of water, similar to valleys carved by rivers and mineral deposits that only form in the presence of liquid water. These features have led scientists to think that billions of years ago, the Martian atmosphere was dense and warm enough to form rivers, lakes and oceans.

Recently, researchers using NASA's Mars Reconnaissance Orbiter (MRO) observed the seasonal ebb and flow of brackish water that currently flows on the surface of Mars (a discovery that has caused a lot of buzz). However, the current Martian atmosphere is too cold and thin to support large amounts of liquid water for long.

"Solar-wind erosion is an important mechanism for atmospheric descent, and was important enough to account for significant change in the Martian climate," said Joe Grebowsky, a Maven project scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "Mayvan is also studying other loss processes - such as loss due to the impact of ions or escape of hydrogen atoms - and these will only increase the importance of escape in the atmosphere."

The goal of the Maven mission, which was launched to Mars in November 2013, is to determine how much atmosphere and water Mars has lost to space. This is the first mission dedicated to understanding how the Sun affects the Martian atmosphere. Maven has been operating on Mars for just over a year and will complete its primary science mission on November 16.
For information on the AGU website

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