An ice age recorded in the polar deposits of Mars

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Science  27 May 2016:
Vol. 352, Issue 6289, pp. 1075-1078
DOI: 10.1126/science.aad6968

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Evidence for ice ages on Mars

Models predict that Mars should have undergone ice ages in the past, but evidence has been scant. Smith et al. used radar measurements from NASA's Mars Reconnaissance Orbiter to probe the planet's polar ice caps. Clear layers within the ice allowed them to calculate how much ice was deposited at different times. The results provide evidence for a recent ice age on Mars. Understanding the martian climate will help determine when the planet was habitable in the past, and how that changed, and may inform studies of climate change on Earth.

Science, this issue p. 1075


Layered ice deposits at the poles of Mars record a detailed history of accumulation and erosion related to climate processes. Radar investigations measure these layers and provide evidence for climate changes such as ice advance and retreat. We present a detailed analysis of observational data showing that ~87,000 cubic kilometers of ice have accumulated at the poles since the end of the last ice age ~370,000 years ago; this volume is equivalent to a global layer of ~60 centimeters. The majority of the material accumulated at the north pole. These results provide both a means to understand the accumulation history of the polar deposits as related to orbital Milankovitch cycles and constraints for better determination of Mars’ past and future climates.

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