The recently-demised Mars Global Surveyor has left us a legacy – evidence for flowing water today on Mars. Here’s the NASA press release and a BBC Science News story. The findings will be reported in Science tomorrow.
Let’s not get too excited. Planetary photogeology is a very interpretive science. Interpretations have been wrong before and always seem to split scientists into “for” and “against” – in this case the water versus CO2 camps. On the other hand, the possibility of subterranean water is very exciting. I’ve always had a sneaking admiration for Gilbert Levin, the Viking mission scientist who maintains that the Viking lander has already found evidence of microbial life. One of his arguments is that surface water is quite possible based on temperature/pressure measurements from Viking. It would be fun if the evidence finally brought NASA around to his position after all these years.
update – Science abstract, also reports present-day impact craters.