It was the best of times, it was the worst of times, as the storyline begins. Shifted to a planetary context, the classic Dickens phrase also can be applied to Earth and Mars. The two worlds, created at about the same time in the history of the solar system and similar in size and composition, both started along the path to a livable environment. The findings by NASA’s twin Mars exploration rovers this year have made that assumption clear.
October 15th, 2004