Geology of Mars time. This section introduces several of the larger physiographic regions of Mars. Together, these regions illustrate how geologic processes involving volcanism, tectonism, water, ice, and impacts have shaped the planet on a global scale. The northern and southern hemispheres of Mars are strikingly different from each other in topography and physiography. This dichotomy is a fundamental global geologic feature of the planet. Simply stated, the northern part of the planet is an enormous topographic depression. About one-third of the planet’s surface (mostly in the northern hemisphere) lies 3–6 km lower in elevation than the southern two-thirds. This is a first-order
The Case for Mars Mars. The Mars Direct plan was originally detailed by Zubrin and David Baker in 1990. "The Case for Mars" is, according to Zubrin, a comprehensive condensation for laymen of many years' work and research. Chapters one and four deal with Mars Direct most completely. For Robert Zubrin, the attractiveness of Mars Direct does not rest on a single cost-effective mission. He envisions a series of regular Martian missions with the ultimate goal of colonization, which he details in the seventh through ninth chapters. As initial explorers leave hab-structures on the planet, subsequent missions become easier to undertake. Large subsurface, pressurized