Stability analysis of the martian obliquity during the Noachian era

We performed numerical simulations of the obliquity evolution of Mars during the Noachian era, at which time the giant planets were on drastically different orbits than today. For the preferred primordial configuration of the planets we find that there are two large zones where the martian obliquity is stable and oscillates with an amplitude lower than 20 degrees. These zones occur at obliquities below 30 degrees and above 60 degrees; intermediate values show either resonant or chaotic behaviour depending on the primordial orbits of the terrestrial planets. (C) 2011 Elsevier Inc. All rights reserved.