Nevertheless, the pictures of the crevasses of the martian ice caps taken by the Mars Global Surveyor high resolution camera show enough details to allow for the first time to correlate the insolation variations on the martian surface with the observed stratification of the ice caps.
Since the first image of the Viking spacecrafts revealed the stratification of the martian ice caps, it was assumed that the observed layers result from climatic variations on the planet surface, but the quality of the pictures was not sufficient to allow for a precise correlation between the observed data and the computation of the insolation variation on the martian surface. The mechanism governing the accumulation of these ice layers are also very uncertain and many orders of magnitude still remained in the estimated accumulation rates of the layers. The high resolution pictures of the Mars Global Surveyor camera present now enough details to allow for a refined study of these layers.
As for the Earth, the planetary perturbations lead to long period variations of the martian orbital elements and tilt of the spin axis (also called obliquity). On Earth, the obliquity variations are of 1.3 degrees around its mean value (23.3 degrees), but according to Milankovitch theory of paleoclimates, these variations are sufficient to induce large variations of the summer insolation in high latitudes on the Earth surface (at the limit of the ice caps) that are at the origin of the ice ages of the quaternary. On Mars, the orbital and obliquity variations are much larger than on the Earth. The group of the Institute of Celestial Mechanics (Paris Observatory), in collaboration with a researcher from Brown University, was able to establish for the first time a correlation between the observed variations of the luminosity of the ice cap layers and the computed variations of the insolation on the martian surface, resulting from planetary perturbations. These results allow to propose that the more recent 250 m of the ice cap were accumulated in 500 000 years, corresponding to a mean deposition rate of 0.05 cm/year.