High Resolution Analysis of the "Tooth" Region of the Residual South Cap of Mars Using CRISM
Abstract
The morphologically complex, seasonally dependent south polar residual cap (SPRC) of Mars has been studied extensively using greyscale imagery from the context imager (CTX) on the Mars Reconnaissance Orbiter (MRO). Morphological mapping of the entire SPRC has been performed, identifying multiple distinct units tied to erosional and albedo attributes . Similarly, regional scale compositional mapping at coarse spatial resolution has been performed with both CRISM and OMEGA spectral imaging. These large scale studies point to a seasonal coverage of coarse grained CO2 ice, with very little water ice present in the higher elevations of the cap, even during the southern summer. Preliminary analysis using higher resolution CRISM observations noted variability of water ice throughout the SPRC, but did not identify a compositional relationship to erosional morphology. Both THEMIS and OMEGA observed water ice to be more abundant at the edges of the cap, and in a large outlier at the base of the polar dome. Spectral mapping of water ice was recorded at the margins of the SPRC CO2 ice at higher latitudes during the summer. These detections are inferred to be either a thin, seasonally dependent layer, or the uppermost portion of the water-ice dominated units underlying the residual cap as identified by radar. Recent work by Calvin and Seelos points to a relationship between water ice abundance and dark, erosional features revealed after retreat of the seasonal cap in the summer. In this study we map water ice, dust, and CO2 ice abundances and grain sizes at 18m/pixel scale of CRISM targeted (FRT) observations covering the "tooth" region during the summer. The "tooth" is an albedo feature at (~ 86.3 S, 0.5 W) that has been present since the Viking era. We illustrate that spatially segregated, mixed water ice deposits with abundances as high as 35% are present at these high latitudes and correlated with the edges of dark erosional features. Additionally we observe variation in CO2 grain size in the area; a markedly different result from the coarse grained nature of seasonal winter coverage. We also present exploratory work utilizing a convolutional neural network to map composition of the SPRC using a fusion of CTX imagery, terrain models, and illumination information, potentially allowing for expanded spatial and temporal resolution of mapping.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.P32A..07R
- Keywords:
-
- 0758 Remote sensing;
- CRYOSPHERE;
- 5410 Composition;
- PLANETARY SCIENCES: SOLID SURFACE PLANETS;
- 5464 Remote sensing;
- PLANETARY SCIENCES: SOLID SURFACE PLANETS