  Context. Astrobiological evolution of the Milky Way (or the shape of its
"astrobiological landscape") has emerged as one of the key research topics in
recent years. In order to build precise, quantitative models of the Galactic
habitability, we need to account for two opposing tendencies of life and
intelligence in the most general context: the tendency to spread to all
available ecological niches (conventionally dubbed "colonization") and the
tendency to succumb to various types of existential catastrophes
("catastrophism"). These evolutionary tendencies have become objects of study
in fields such as ecology, macroevolution, risk analysis, and futures studies,
while a serious astrobiological treatment has been lacking so far. Aims. Our
aim is to numerically investigate the dynamics of opposed processes of
expansion (panspermia, colonization) and extinction (catastrophic mechanisms)
of life in the Galaxy. Methods. We employ a new type of numerical simulation
based on 1D probabilistic cellular automaton with very high temporal
resolution, in order to study astrobiological dynamics. Results. While the
largest part of the examined parameter space shows very low habitability
values, as expected, the remaining part has some observationally appealing
features that imply, among other things, a reduction in the amount of
fine-tuning necessary for resolving the Fermi paradox. Conclusions. Advanced
aspects of Galactic habitability are amenable to precision studies using
massive parallel computer simulations. There are regions of parameter space
corresponding to a quasi-stationary state satisfying observable constraints and
possessing viable SETI targets.
