What is the most probable origin for the Earth's moon? ... Over the last 20 years, the idea of "Life on Mars" (no, not the TV show), has appeared in and out of the main stream media. Research, find and summarize some of the lines of evidence, gathered over the last 20 years, that help build the case that there may once have been life of Mars How credible do you think is the scientific evidence for the case of life having occurred on Mars? ...