Scientists said they have decoded the long-standing mystery of missing carbon on the Red Planet. A thin layer of CO2 has covered Mars, which is the reason atmosphere of the planet is dry and cold. But situation wasn’t same many years ago, according to the scientists.

Long time ago, the second smallest planet in the solar system was warm and wet. Scientists revealed ultraviolet (UV) rays from the sun caused the planet’s atmosphere to lose carbon dioxide. The solar winds made Mars and arid planet, the scientists explained. The process is not over yet as solar winds are still removing significant amount of atmospheric carbon dioxide.

Scientists from California Institute of Technology and NASA's Jet Propulsion Laboratory believe Martian atmosphere still have more carbon. More than 3 billion years ago, Martian atmosphere was more or less same as our home planet’s atmosphere. The missing carbon either lost in the air or it incorporated into rocks, the scientists explained.

The scientists think measurements of carbon isotopic could reveal more about the mystery. Nucleus of carbon-12 and carbon-13 isotopes has same number of protons, but neutrons are in different number. This could help in determining mass of the carbon.

Different processes could change carbon-13 to carbon-12 isotope numbers in a planet’s atmosphere. Renyu Hu, a postdoctoral scholar at JPL and lead scientist in the new research, said, “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”.