Atmosphere killer: Solar storms are to blame for a hostile planet

Thanks to Maven — NASA’s Mars Atmosphere and Volatile Evolution mission — humans now have a pretty good idea of what happened to the planet’s atmosphere over the course of hundreds of millions of years.

Blame it on solar storms that strip away the upper atmosphere at an accelerated rate, according to the University of Colorado’s Bruce M. Jakosky, the principal investigator for the Maven mission. He and other scientists disclosed their findings last week in the journal Science. Because Mars has a weak magnetic field, they wrote, the solar storms on the planet have a negative impact that is 10 to 20 times greater than it would be on Earth.

Because Mars is believed to have once been a relatively warm, wet planet with surface water and an atmosphere at least as thick as Earth’s, it is crucial to any understanding of planetary evolution to learn what happened. How did Mars go from being a potentially habitable world to the icy, radioactive desert it is now?

The questions NASA is most eager to answer revolve around those powerful solar storms. Along with Mars’ much-reduced atmosphere, the lakes and the ocean that is believed to have once covered the planet’s northern hemisphere dissipated, too. Maven, which began its Martian orbit in September 2014, has taken truly astonishing measurements of the effect of these storms. Scientists now know that the energy stripping away the planet’s atmosphere is the equivalent of the explosion of 1 million tons of TNT an hour.

No one can say definitively whether life ever existed on Mars, but researchers know a lot more about the adverse conditions that shaped its environment. Maven has opened a big window into the mystery of the planet’s missing atmosphere. In doing so, it has shined a light on planetary formation and insights that can be applied to other realms of space.

— Pittsburgh Post-Gazette