Statistical Methods for Interpreting Spatial and Temporal Heterogeneity
of Martian Tropical Water Ice Informed by Properties of Crater Ejecta
Types
Abstract
The martian tropical water ice spatial and temporal distribution was
characterized using impact crater ejecta type, location, size, and age
in one of two epochs, <=3.4 Ga and $>3.4 Ga,
using statistical models designed for spatial and temporal correlation
structures. The indicator thought to identify the presence of ice is
craters with layered ejecta, while the indicator thought to identify no
ice is craters with radial ejecta. These indicators imply the location
(longitude and latitude) and, potentially, depth (crater diameter as a
proxy) of ice, and when the ice was present. The spatial and temporal
distribution of layered ejecta versus radial ejecta may inform on the
geography and evolution of ice. A statistical spatial point analysis was
conducted on a 54-sample data set (craters with diameters 2.77 km to
10.00 km) for an equatorial region (0o to -30o S, and 10o E to 340o W.
The analysis shows there is insufficient evidence to support a
non-random spatial and temporal distribution of tropical ice.