THE APPLICATION of Bayesian inversion to a spread of lithologic parameters in an evaluation of seismic knowledge hardly ever turns out the stuff of headlines. But if the seismic knowledge you’re assessing come from Mars, and when your reasoning means that the most efficient reason behind them is liquid water within the pores between rocks, you may have a tale. There’s little other people thirst for extra, on the subject of planetary science, than water on Mars. Why does the chance galvanize such pleasure—and what does this new analysis upload to the tale?