Discussion of High Thermal Inertia Craters on Mars in the Isidis and Syrtis Major Regions Jordana Friedman Arizona State University

Background Why the Isidis and Syrtis Major regions? – Volcanic history/diversity – Large impact basin Why moderate-high thermal inertia? – Lower than bedrock, higher than unconsolidated material Looking to distinguish between in situ bedrock vs. cemented finer grains – Primary martian magma composition – Alteration products, chemical weathering, and cementation

Methods Used THEMIS database to locate high TI ( JK -1 m -2 s -1/2 ) craters Examined each instance (87 total) for: – Albedo – Depth – Diameter – Floor diameter – Thermal inertia – Latitude/longitude – Morphology

Crater Examples THEMIS day image THEMIS night image Low thermal inertia High thermal inertia floor High thermal inertia walls Central peak Flat floored

High Resolution CTX Images High thermal inertia Low thermal inertia

Results The craters have different albedo, with similar thermal inertias: Bimodal albedo distribution Relatively low average thermal inertia

Dust Cover Index The red areas are dustier, and the blue areas are less dusty. There are craters in each area that have elevated thermal inertia.

Conclusions It was not possible to differentiate between in situ rock and cemented rock in this study However, it may be possible that there is a thin layer of dust on some surfaces – Enough to affect the albedo of these surfaces, but not enough to affect thermal inertia

Future Studies Study the composition of these craters using TES, THEMIS and CRISM – Better constrain the nature/formation mechanism of the surfaces Study larger and other areas, potentially global – Areas where other weathering products identified – Look for global trends

Thank You! A special thanks to Chris Edwards, my advisor Thanks to the NASA Space Grant Program for this opportunity! Thanks to my family and friends for their support 2001 Mars Odyssey/THEMIS Project and support staff