I agree on the hugeness of this discovery. My son, Sky, working on his physics Ph.D. at the U. of Arizona, figured that out before I did. Here's part of a note he sent me yesterday. -- Joe A couple years ago, the ESA's Mars Express found what looked like spectral lines for methane in the red planet's atmosphere. Methane should only be able to last temporarily. Therefore, any methane on Mars must have been produced recently. The explanations proposed were recent volcanism and biological activity. There certainly are volcanoes an Mars, but they are ancient. If liquid water exists beneath Mars' surface, then that provides a mechanism for biological processes. I believe Mars has all the right chemical ingredients for life. Up until now, the one thing it lacked was liquid water.