Climate variations on Mars are much more extreme than Earth’s, because of the Red Planet’s thin atmosphere and lack of a stabilizing Moon to damp out orbital perturbations by its massive next-door neighbor, Jupiter. We see evidence of these past climate cycles recorded in repetitive layers in Mars’ polar ice caps - the polar layered deposits (PLD). How would a future mission to the polar ice caps extract Mars’ paleoclimate record? I co-led a study sponsored by the Keck Institute for Space Studies (KISS), which gathered more than 30 scientists and engineers to develop innovative mission concepts to investigate this question.

(Left) A dramatic view of the north polar ice cap of Mars from the European Space Agency's High-Resolution Stereo Camera. (Right) Periodic climate variations are expressed in the polar layered deposits, with layer thicknesses of ~1 - 100 m.

It is likely that Mars’ long-term climate is forced by the polar insolation, dominated by -kyr variations in the planetary obliquity. However, models have struggled to reproduce observed patterns in the PLD. A physical mechanism for generating layers through ice and dust accumulation/ablation has remained elusive. Measurements of volatiles and isotopic variations within the PLD must be combined with observations and models of the present-day Martian climate, in order to confidently extrapolate to past climate regimes.

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