In 1966, a thin layer of carbon dioxide (CO2) was detected in the atmosphere of Mars by the Mariner IV, a NASA fly-by spacecraft. Researchers from the California Institute of Technology (Caltech) theorised at the time that Co2 levels in the atmosphere vary depending on the seasonal changes of Mars.

The scientists believed that as one of the poles faced the Sun, the polar deposit of CO2 ice would melt, leading to more CO2 in the atmosphere.

This would ultimately alter the atmospheric pressure of Mars and have major implications for the Red Planets climate, which has a surface pressure of just 0.6 percent that of Earths.

Scientists Robert B Leighton and planetary scientist Bruce C Murray, believed at the time atmospheric pressure could swing from just one-quarter that of todays Martian atmosphere to twice that of today over cycles of tens of thousands of years.

Now, a new model run by current Caltech experts has proved the 54 year theory to be true, which supports the theory that Mars once had free-flowing water.

The team state that as the CO2 packed ice melted in the past, it allowed more surface pressure to build, which suited for a better environment on Mars.

In theory, the CO2 packed ice deposit should not be possible, because water ice is more thermally stable and darker than CO2 ice; CO2 ice, scientists long believed, would quickly destabilise if it was buried underneath water ice.

A statement from Caltech said: The new model by Buhler and colleagues shows that the deposit could have evolved as a result of the combination of three factors.

These are:

1) the changing obliquity (or tilt) of the planets rotation.

2) the difference in the way water ice and CO2 ice reflect sunlight.

3) the increase in atmospheric pressure that occurs when CO2 ice sublimes.

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Mars mystery solved: Experts find supporting evidence of free flowing water on Mars - Express.co.uk