My evaluation of the "Mars Face" hypothesis is that the probability is
"negligible/unsupported", that is, around the same probability as the
asteroid belt containing an object one foot across composed entirely of chocolate cake. I say this despite having no familiarity whatsoever with the technical issues, based solely on my a-priori belief that any evidence of an alien visit, if we could detect it at all, would be completely unmistakable. One does not cross the void between stars to leave pointless, ambiguous fingerpaintings on a barren planet. The whole idea is something out of the last generation's science fiction. It requires me to assume complex motives and actions on the alien's part that seem tailored specifically to produce a result that has mimicked a geological process. Occam's Razor slices the Mars Face to ribbons.
Am I dismissing it out of hand? Yes. People have been crying wolf for the last hundred years. If an idea doesn't merit investigation, I don't bother. The question is not if I can examine everything, because I can't. The question is what I choose to spend my time examining. This isn't one of them.
-- email@example.com Eliezer S. Yudkowsky http://pobox.com/~sentience/tmol-faq/meaningoflife.html Running on BeOS Typing in Dvorak Programming with Patterns Voting for Libertarians Heading for Singularity There Is A Better Way