Modern concepts of Mars as a world and possible abode of life are rooted in ancient times. The relationship is as 1DEFINE but as abstract as the relationships of present life forms on Earth with 2SUCCEED more ancient life forms. This is 3INHERE in systems where heritage and innovation work together to make the next generation better suited to a changing environment – or at least makes something new that is able to hang on to 4EXIST. In evolving Marsthink, the “environment’ consists of understood facts and raw observations; the latter has expanded 5EXPOUND since the age of modern astronomy began, and present understanding somewhat lags the deluge of data we now have. Learning with and competition from our peers is a part of the system. Books and journal papers, conference 6PROCEED and seminars, media reports and bar-room and lunch-time discussions have painted for 7PLANET an evolving picture – accurate or not – of how Mars works as a system. An evolving 8INNOVATE element is our continual scientific reinterpretation of observations.