Scientists have solved the mystery that the first decade has been wrestling with - the mystery of the origin of the enormous deposits of CO2 and water ice that line the south pole of Mars.
One of the main hypotheses was that during the oscillations of the axis of the Red Planet in relation to the Sun, layers of water vapor and CO2 were frozen on top of each other. Using computer simulations, astronomers simulated this process - and the result confirmed their assumptions.
The ice cap at the south pole of Mars is estimated to extend a kilometer in depth and contains as much CO2 as is observed in the entire atmosphere of the planet today. Its unusual layered structure is the result of a number of factors that led to the formation of ice. Peter Buehler, a planetary scientist at NASA's Jet Propulsion Laboratory, was surprised by the simulation results. “You usually don't expect the results of a computer simulation to match reality so well. Even the thickness of the layers of the model is consistent with radar measurements made with satellites,”he notes.
In fact, there shouldn't be any ice cap at the South Pole. The fact is that water ice is much more thermally stable than frozen CO2, and therefore scientists thought that, once under water, the latter would begin to collapse.
But, according to the model, three factors prevented this: a change in the tilt of Mars as it revolves around the Sun, differences in the way the two types of ice are reflected by sunlight, and a change in atmospheric pressure that occurs when CO2 ice turns into gas.
As a result of oscillations along the axis of the planet, the amount of sunlight reaching the pole changed. As a result, at one time of the year ice was formed there from carbon dioxide, and with the return of the star, it began to collapse. However, along with CO2, water vapor in the atmosphere froze, covering the less stable ice. This went on for about 510,000 years.
We often write that ice is a real cryo chamber with which you can look into the past of our home planet. However, astronomers are confident that the Martian ice will be able to tell us many amazing stories and, perhaps, even retained traces of ancient life.
