May 19 2015 Earth has Oxygen, Mars doesn’t … So Why is Mars Rusty?
Presented by Professor Carrick Eggleston, University of Wyoming.
While this may seem like an academic question of planetary geology, the answer to this question may have implications for us all. Earth has undergone a long-term transition from a low-oxygen atmosphere prior to the evolution of biological oxygenic photosynthesis to today’s relatively high oxygen levels. The overall oxidation state of iron in rocks reflects this transition, from banded iron formations to red-beds. There seems to be a logical relationship between rising atmospheric oxygen concentrations and increased amounts of oxidized material (e.g., iron oxides) at Earth’s surface. In contrast, Mars is known as the red planet because of the iron oxides on its surface – despite a lack of atmospheric O2. We tend to think of ferric oxide, for example, as a product of oxidation (e.g., rust), but not as an active cause of oxidation. We will explore the role of metal oxide and metal sulfide minerals in photochemical water splitting, chloride oxidation, and other processes both on Mars and on Earth, including looks at terrestrial banded iron formations, desert varnishes, and next-generation technologies for solar fuels that may be part of our future.