"Humans have a fitful record of exploration. Spanish conquistadors abandoned the American Southwest for about 40 years after the monumental Coronado expedition of 1540, and no one returned to the North or South Poles until a generation after the pioneering forays of Scott, Amundsen and Peary. Human interest in the Moon declined after the last landing in 1972, and we abandoned the surface of Mars for 21 years following the robotic Viking landings of 1976. Perhaps after each wave of exploration, it takes us a while to absorb the new reality and figure out why we want to go back.
Two decades after those first Martian landers came a rising tide of interest in our neighboring planetary island, not too far across the sea of space. In 1997, two space probes reached Mars. Pathfinder landed and deployed its small rover, Sojourner, to look at nearby rocks. The Mars Global Surveyor went into orbit around Mars and has since made more than 100,000 images and maps of the surface, much more detailed images than Viking was able to provide. In 2001, Mars Odyssey, a spacecraft named for Arthur C. Clarke's famous novel, began a new round of photography and sophisticated orbital measurements to study mineral composition, leading to the confirmation of near-surface buried ice deposits. A Traveler's Guide to Mars uses new data and some of the best images from these recent probes in order to take the reader to the most interesting natural wonders we've discovered on the red plant ..."
-- from the Preface