.THE APPLICATION of Bayesian inversion to a range of lithologic guidelines in an evaluation of seismic data barely seems the stuff of headings. Yet when the seismic data you are assessing stemmed from Mars, as well as when your reasoning suggests that the most ideal illustration for them is fluid water in the pores between stones, you have an account. There is actually dwarfs thirst for even more, when it relates to worldly scientific research, than water on Mars. Why carries out the possibility provoke such exhilaration-- and what performs this new investigation add to the story?