Mars’ atmosphere is still not fully understood

(Mirror Daily, United States) – It has been a long-stand paradox, but scientists found where all of Mars’ carbon went that was reportedly “missing” from any theories that actually made sense. Their study suggests that Mars may have once been a warmer and more humid place, and it was covered in much thicker carbon dioxide.

Today, however, the Red Planet is covered in a thin atmosphere of carbon dioxide, so it led to the question on when all that carbon went. Between now and 3.8 billion years ago, there must have been a process that essentially stripped Mars from conditions much closer to Earth than it has today. Even more, their study suggests that pressure levels were almost the same between the two planets.

To back those suggestions, researchers at the California Institute of Technology (Caltech) have claimed that it’s possible for Mars’ “dense atmosphere” to become thinner over time. However, that still left the debate of the missing carbon that once enriched the layer above the foreign planet. There are three types of carbon isotopes found naturally, which is 12, 13, and 14. Both carbon-12 and carbon-13 are found within Mars’ atmosphere.

According to previous studies, there are two possible explanations as to where the “missing” carbon went. However, proof has been lacking.

One theory is rooted in the fact that the carbon dioxide incorporated itself into the Martian rocks, called carbonates. But a recent study, in August 2015, examined the carbonates within the planet’s layers. They found that within the upper half a mile of Mars’ surface, there isn’t near enough of it to explain the “missing” carbon. In essence, the carbon couldn’t have been absorbed into the rocks.

The second theory revolved around the process called ‘sputtering’. It implies the carbon dioxide escaping Mars’ atmosphere and going into the space. This requires an interaction between the solar wind and the planet’s upper atmosphere. While this has been a viable theory, new results from NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) has shown that the solar wind wipes away around 100g of particles per second.

Sputtering favors carbon-12 a bit more than carbon-13, but the difference is not enough to explain the ratio of carbon-12/carbon-13 in Mars’ atmosphere. It’s too rich in carbon-13 by comparison, so it’s doesn’t properly explain the Red Planet’s current state. So, the scientists at Caltech believe there had to be another process at work. Their new theory is centered around the Sun’s ultraviolet (UV) rays.

They believe that the UV rays hit a molecule of carbon dioxide, splitting it into carbon monoxide and oxygen. When it continues and strikes the carbon monoxide, it further turns it into particles of carbon and oxygen. Some of these newly formed carbons have more energy than others to escape the atmosphere.

And their research has shown that carbon-12 has a 40% likelihood of escaping, in comparison to carbon-13, which has only a 24% likelihood of slipping away from Mars’ atmosphere.

This would explain the carbon-12/carbon-13 ratio, which favors the latter. Thus, their theory is that it’s not solar winds that wipe away the carbon dioxide, but instead the Sun’s UV rays, through a process called “ultraviolet photodissociation”.

Image source: space4case.inhetweb.nl