Strong solar winds stripped Mar's atmosphere: NASA

Strong solar winds likely played a key role in the transition of the Martian climate from an early, warm and wet environment that might have supported life to the cold, arid planet Mars is today, according to NASA.
NASA's Mars Atmosphere and Volatile Evolution (MAVEN) mission data has enabled researchers to determine the rate at which the Martian atmosphere currently is losing gas to space via stripping by the solar wind.
The findings show that the erosion of Mars' atmosphere increases significantly during solar storms.
"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," said John Grunsfeld, associate administrator for the NASA Science Mission Directorate in Washington.

"Understanding what happened to the Mars atmosphere will inform our knowledge of the dynamics and evolution of any planetary atmosphere," said Grunsfeld.
"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," he said.

MAVEN measurements indicate that the solar wind strips away gas at a rate of about 100 grammes every second.
"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," said Bruce Jakosky, MAVEN principal investigator at the University of Colorado, Boulder.

In addition, a series of dramatic solar storms hit Mars' atmosphere in March 2015, and MAVEN found that the loss was accelerated.
The combination of greater loss rates and increased solar storms in the past suggests that loss of atmosphere to space was likely a major process in changing the Martian climate.
The solar wind is a stream of particles, mainly protons and electrons, flowing from the Sun's atmosphere at a speed of about one million miles per hour.
MAVEN has been examining how solar wind and ultraviolet light strip gas from of the top of the planet's atmosphere.
New results indicate that the loss is experienced in three different regions of the Red Planet: down the "tail," where the solar wind flows behind Mars, above the Martian poles in a "polar plume," and from an extended cloud of gas surrounding Mars.

The science team determined that almost 75 per cent of the escaping ions come from the tail region, and nearly 25 per cent are from the plume region, with just a minor contribution from the extended cloud.
Ancient regions on Mars bear signs of abundant water - such as features resembling valleys carved by rivers and mineral deposits that only form in the presence of liquid water, NASA said.
The research was published in the journals Science and Geophysical Research Letters.