Discussion of High Thermal Inertia Craters

on Mars in the Isidis and Syrtis Major

Regions

Jordana FriedmanArizona 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

MethodsUsed THEMIS database to locate high

TI (800-1200 JK-1m-2s-1/2) cratersExamined 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

ResultsThe craters have different albedo, with similar thermal

inertias:

0

2

4

6

8

10

12

14

0.10.110.120.130.140.150.160.170.180.19 0.20.210.220.230.240.250.26More

Albedo

Frequency

0

5

10

15

20

25

30

35

150 200 250 300 350 400 450 500 550 More

Average Thermal Inertia

Frequency

Bimodal albedo

distribution

Relatively low average

thermal inertia

Dust Cover IndexThe 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 surfacesStudy 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