Water as a Clue to the Evolution of the Atmosphere and Climate History of Mars: Evidence for Circum-polar/non-polar Ice Deposits, Running Water and Standing Bodies of Water in the History of Mars

I. Introduction: Water is a key guide to understanding the history of the atmosphere and climate of Mars [1]. Geological evidence that illustrates the state of water (solid or liquid) and its distribution at various stages in the history of Mars is essential in documenting this history. In this analysis, evidence for the recent climate record in the polar cap is assessed, and non-polar ice deposits are tracked as a record of climate change throughout Mars history. Evidence for the presence and abundance of running water and standing bodies of water in past Mars history provide indications of when the atmosphere and climate were considerably different than they are at present. Together with mineralogical data and crater chronologies, a new picture of the history of the atmosphere and climate are emerging. A review, with selected references, is presented here. II. Amazonian Polar and Circumpolar Deposits: The polar caps provide a record of the recent climate history of Mars [1]. Studies of the spin-axis/orbital parameter history of Mars provide a robust solution for the most recent ~20 Ma of martian history, but cannot be mapped further back into the past due to the chaotic nature of the solutions [2]. Thus, deconvolving the complex climate history of Mars requires analysis of the basic geological information, and interpretation of the deposi-tional record of glaciation and glacial conditions at non-polar latitudes. These interpretations are assisted by an understanding of glacial and periglacial conditions in areas that are polar analogs to Mars (such as the Antarctic Dry Valleys) [3], and an understanding of the behavior of polar ice under different insolation conditions, using global climate models (GCMs) [4-5]. Finally, the availability of very high resolution images and topography (e.g., MOLA, MOC, CTX, HRSC, HiRISE) provide the ability to characterize and interpret these deposits. Recent analyses to assess the presence, age, and significance of non-polar ice deposits provide evidence of the history of climate on Mars and are clues to the current water cycle. In the current environment polar regions represent cold traps for planetary volatiles and analysis of these areas permits an assessment of the amounts and types of volatiles, their stability and mobility, and the long-term geological record of climate change. Present polar deposits on Mars consist of a thin residual ice unit (Api) over-lying a thick sequence of layered deposits (Apl), and are of Late Amazonian age [6]. The individual layers in the …