How Did Carbon Escape From Mars' Atmosphere? Scientists Explain

Posted: Nov 25 2015, 1:37am CST | by , Updated: Nov 27 2015, 2:10am CST, in News | Latest Science News


How Carbon Disappeared from Mars Atmosphere?
Image Credit: Lance Hayashida/Caltech

Carbon isotopic measurements reveal exactly what happened to Mars' atmosphere.

Mars is covered with a very thin layer of carbon dioxide which is the reason why planet’s atmosphere is very cold and dry.

Scientists believe that situation was not the same long time ago. Mars was once a warmer and wetter place than it is today,  but solar winds stripped away its original atmosphere and turned it into an arid planet. The solar winds are still removing tons of carbon dioxide every day.

Scientists think that there should still be more carbon in Modern Martian atmosphere. A team of scientists from California Institute of Technology and NASA's Jet Propulsion Laboratory, both in Pasadena, presents an explanation.

They suggest that around 3.8 billion years ago Mars might have the atmosphere more or less same as the Earth and it gradually transitioned to its current state. The ‘missing’ carbon either incorporated into Martian rocks in the form of carbonate or was lost in their air.

Researchers suggest that carbon isotopic measurements can provide further clues to it. Two stable isotopes of element carbon, carbon-12 and carbon-13 have same number of protons in their nucleus but different number of neutrons which determine the mass of the carbon. Therefore, two isotopes of carbon have different masses.  

Various processes can change the relative amounts of carbon-13 to carbon-12 isotopes in the atmosphere. So, "We can use these measurements of the ratio at different points in time as a fingerprint to infer exactly what happened to the Martian atmosphere in the past.” Renyu Hu, a postdoctoral scholar at JPL, a visitor in planetary science at Caltech, and lead author on the study said in a statement.

To compare the ancient isotopic ratio of Mars with the modern one, scientists started with measuring the ratio in meteorites that contain gases released volcanically from deep inside Mars. The modern ratio comes from measurements by the SAM (Sample Analysis at Mars) instrument on NASA's Curiosity rover.

Another recent research suggests that one way carbon dioxide might have escaped from Mar’s atmosphere is called ‘Sputtering.’ It takes place when solar wind interacts with the upper atmosphere of an object. As a result of it, Mars loses about 100 grams of particles from its atmosphere in every second. It likely the major reason of atmospheric loss. But another process might have also in progress which is enriching planet’s atmosphere with carbon-13 -- in proportion to carbon-12 and causing to change the density of carbon in the planet.

Modeling suggested that the "ultraviolet photodissociation" has the long term effect in changing carbon isotopic radio.  

"This solves a long-standing paradox," said Bethany Ehlmann of Caltech and JPL, a co-author of study. "The supposed very thick atmosphere seemed to imply that you needed this big surface carbon reservoir, but the efficiency of the UV photodissociation process means that there actually is no paradox. You can use normal loss processes as we understand them, with detected amounts of carbonate, and find an evolutionary scenario for Mars that makes sense."


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Hira Bashir covers daily affairs around the world.




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