.THE APPLICATION of Bayesian inversion to a range of lithologic parameters in an examination of seismic data hardly seems to be right stuff of titles. However when the seismic records you are actually determining stemmed from Mars, and when your reasoning recommends that the very best explanation for all of them is liquefied water in the pores in between stones, you have a story. There is dwarfs crave extra, when it relates to planetary science, than water on Mars. Why does the prospect provoke such pleasure-- and what does this new analysis add to the account?