NASA Says Solar Winds Stripped Mars of its Atmosphere

An artist's rendering of what it might have looked like when solar storms hit Mars and stripped ions from the planet's upper atmosphere.
An artist's rendering of what it might have looked like when solar storms hit Mars and stripped ions from the planet's upper atmosphere.
Image from NASA

NASA has come out with another revelation in the Mars origin story. 

That's right, only months after NASA scientists announced they'd spotted evidence of water on Mars, the federal space agency has now announced that scientists working on the Mars Atmosphere and Volatile Evolution mission (the Maven spacecraft arrived in the orbit of Mars in September 2014) have found evidence that the sun is likely responsible for destroying the planet's atmosphere. NASA scientists have thought for a long while that Mars was once a warmer, wetter planet, the cuddly kind that could have supported life, but they haven't been sure what happened to change Mars into the cold, barren red planet we know today.

Until now, that is.

NASA scientists working on Maven — a mission launched in 2013 to figure out how much of the planet's air and water have been lost to space — came out with a discovery on Thursday based on their studies.

Right now, what little air there is on Mars is leaking into space at about a quarter pound per second. While that is a partial explanation of where the Martian atmosphere has gone, it doesn't entirely explain how a planet that is believed to have once had an atmosphere at least as thick as the one on Earth lost it so dramatically. 

That's where the solar storms come in. The Maven team announced that they've discovered that when Mars is hit by solar storms the bombardment of particles from the sun strips away the upper atmosphere more quickly. NASA scientists were able to observe the way the atmosphere actually escapes during a solar storm when a solar ejection hit Mars back in March. The atmosphere, already leaking steadily into space, ends up leaving Mars at 10 to 100 times the normal rate during a solar storm. 

See, solar storms are nothing to scoff at. The solar wind that comprises these storms 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. The magnetic field carried by the solar wind as it flows past Mars can generate an electric field, much as a turbine on Earth can be used to generate electricity. This electric field accelerates electrically charged gas atoms, called ions, in Mars' upper atmosphere and shoots them into space. And that's exactly what's been happening on Mars, which has likely been hit with solar storms a few times a year for a very long time, according to NASA. 

On top of that, back when the entire 4.5 billion-year-old solar system was in its younger days the sun was a lot more volatile so the solar storms would have most likely been bigger, the type that would wreak even more havoc on the Martian atmosphere. 

"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," John Grunsfeld, astronaut and associate administrator for the NASA Science Mission Directorate, stated. "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."

Because, of course, what's really interesting about all of this is how it ties back to Earth. Studying what happened to Mars could help us both figure out if it will ever be possible for Mars to sustain life (the human, Earth-grown kind). Plus this might give us some clues about what's waiting for our own planet in its future. But don't start thinking that Earth is next up to lose its atmosphere or anything like that. Earth has a strong global magnetic field that shields it from these solar storms. Mars used to have one but the Martian magnetic field shut down billions of years ago, leaving the planet vulnerable to these storms that have subsequently left the planet with only about one percent of the Martian atmosphere. 

So now we know a little more about how Mars became Mars. 


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