The Mars Atmosphere and Volatile Evolution (MAVEN) mission led by NASA has recognised the process that could have caused the transition of the Martian atmosphere from an early warm and wet environment.
Using the MAVEN data, NASA researchers discovered that corrosion of the Martian atmosphere significantly intensifies during solar storms. Furthermore, they established the rate at which solar wind is stripping the Martian atmosphere by making it lose gas at nearly 100 grams each second.
Solar winds consist of a stream of particles — mainly protons and electrons — flowing from the sun's atmosphere at a speed of nearly 400 km per second. The magnetic field the wind carries, as it surges past Mars, can produce an electric field quite similar to that of a wind turbine that generates electricity in Earth. This electric field speeds up electrically charged gas atoms known as "ions" in the upper atmosphere of the Red Planet, and eventually shoots them into space.
The research team estimated that Mars lost its magnetic field nearly 4.2 billion years ago. Since then, the Sun's powerful solar winds have stripped particles away from the vulnerable Martian atmosphere at a rate of 100-1,000 times more than the speed today, reported Ars Technica.
Bruce Jakosky, MAVEN principal investigator at the University of Colorado, said the loss rate of the Martian atmosphere "was much higher billions of years ago when the sun was young and more active."
Additionally, several dramatic solar storms hit the Martian atmosphere in March 2015, and fuelled the loss, MAVEN observed. The mixture of higher loss rates and amplified solar storms in the past implied that atmospheric loss to space was possibly a significant process in altering the Martian climate.
MAVEN results showed the Red Planet suffered losses from solar wind in three different regions: down the "tail", above the Martian poles in a "polar plume", and from an enlarged gas cloud engulfing Mars.
The research team established that nearly 75% of the gases were released from the tail region while nearly 25% were released from the plume region, with negligible contribution from the enlarged region.
Joe Grebowsky, MAVEN project scientist from NASA's Goddard Space Flight Centre in Greenbelt, said: "MAVEN is also studying other loss processes — such as loss due to impact of ions or escape of hydrogen atoms — and these will only increase the importance of atmospheric escape."
MAVEN mission — launched by NASA to Mars in November 2013 — aims to establish how much of the atmosphere and water the Red Planet has lost to space. The first of its kind, MAVEN has been operating on Mars for more than a year now, and will have its science mission anniversary on 16 November.
Although worrisome, the new MAVEN results should have little effect on NASA scientists trying to produce carbon dioxide in Mars' atmosphere as a resource to potentially generate rocket fuel and oxygen, Ars Technica reported.
The MAVEN mission findings appear in the journal "Science and Geophysical Research Letters".
