What happened to Mars’ atmosphere?
NASA’s bombshell announcement last month finally confirmed the presence of liquid water on the surface of Mars. Of course, we’ve already known for quite some time that ancient Mars was covered in water, with vast oceans and lakes not unlike those currently crowding Earth’s continents. We still want to know what happened to those vast bodies of H20, but the real question, the core of the inquiry, may be this: What happened to Mars’ atmosphere?
See, Mars’ atmosphere is about 100 times thinner than Earth’s, and made of 95 percent carbon dioxide, 2.7 percent nitrogen, 0.13 percent oxygen, and several minor gases. But if the planet once boasted bodies of water that flowed then the red planet must have had a thicker atmosphere that would stabilize ambient temperatures and pressures, keeping the water from freezing or evaporating upon exposure to the elements.
At some point, Mars’ atmosphere vanished into thinner air and the water went with it. So, if we want to know where all the Martian water drifted off to, we’ll have to follow the trail of the atmosphere.
And that is presumably what NASA has been doing. The agency is tight-lipped on the details of the Thursday press conference right now, but we do know it’s about the atmosphere and we do know that researchers have been busy of late.
Past hypotheses suggested that past amounts of carbon that dominated the carbon dioxide-heavy atmosphere could have become trapped in the Martian rock, but recent analyses — thanks to new data gathered by the several Mars orbiters snapping up pictures miles above the surface — seems to debunk that theory. There’s not nearly enough carbon in the rock deposits to make up for the lost numbers.
Another theory that’s recently emerged is that the atmosphere might have actually been lost to space. How could something like that have occurred? Solar winds.
In September 2014, the Mars Atmosphere and Volatile EvolutioN Mission space probe, launched by NASA to study the Martian atmosphere, finally made its way into Martian orbit after nearly a year’s time spent in transit. Early data acquired by MAVEN’s Solar Wind Ion Analyzer (SWIA) instrument found high-speed particles from solar winds penetrating deep atmospheres, as far as 124 miles below the ionosphere (the layer of atmosphere comprised of ions that are meant to protect the surface from solar winds). Researchers think those winds — traveling at 279 miles per hour — could essentially give gases enough of an energetic boost to break free of Mars’ gravity and fly off into space, creating atmospheric leaks. If conditions were right, this mechanism could explain why the atmosphere has been stripped off — and why the planet’s water levels dropped.
NASA’s conference on Thursday features several researchers who’ve worked with analyzing ion escape channels on Mars, including Jasper Halekas, the lead scientist for SWIA. We’ll have to wait until Thursday to see what the new findings actually are, but if they confirm the role of solar winds in shaping the current state of Mars, it would help shed new light on the history of a planet that was apparently once like our own.