A wealth of information about the climate cycle and ice budget of Mars is recorded within the layers of Martian polar caps. Using primarily subsurface observations with the Shallow Radar (SHARAD) instrument on board Mars Reconnaissance Orbiter (MRO), along with optical observations of the surface, we study the stratigraphic record of the ice caps to detect alternating periods of accumulation and erosion.
Analysis of subsurface stratigraphy on both poles, especially near to geomorphic features such as the ubiquitous spiral troughs, tells us of climatic changes that occur on different time scales. The youngest water ice deposits on the planet belong to the northern cap and provide a record of ice age advance and subsequent ice age retreat. The southern cap is in general much older than the northern cap, but very young, massive CO2 deposits reside near to the surface and reveal periodic atmospheric collapse on a shortened time scale. Both of these observations agree well with climate models, which have predicted both the ice age cycle and periodic atmospheric collapse.
In this talk, I will discuss each of these observations and broadly discuss their significance. Included will be many pretty pictures of the poles and descriptions of the formation of major landforms that have proven enigmatic until the arrival of MRO.