HR: 0800h
AN: P21C-0158    [Abstracts]
TI: Global Distribution of Bedrock on Mars Using THEMIS High Resolution Thermal Inertia
AU: * Edwards, C S
EM: Christopher.Edwards@asu.edu
AF: Arizona State University, PO BOX 876305, Tempe, AZ 85287-6305 United States
AU: Bandfield, J L
EM: joshband@asu.edu
AF: Arizona State University, PO BOX 876305, Tempe, AZ 85287-6305 United States
AU: Christensen, P R
EM: Phil.Christensen@asu.edu
AF: Arizona State University, PO BOX 876305, Tempe, AZ 85287-6305 United States
AU: Fergason, R L
EM: Robin.Fergason@asu.edu
AF: Arizona State University, PO BOX 876305, Tempe, AZ 85287-6305 United States
AB: Mars Odyssey Thermal Emissions Imaging System (THEMIS) one hundred meter per pixel nighttime temperature images were used to compute thermal inertia on a 256 line segment of the image (framelet) basis. Thermal inertias were computed using a thermal model provided by H. Kieffer for the minimum, maximum and average temperatures. The computed thermal inertias were stored in a database and related to other image parameters including solar longitude, latitude, longitude and local time. For this study, bedrock was defined as any pixel in a THEMIS framelet with a thermal inertia over 1200 J K^-1 m^-2 s^-1/2. Data was limited by using only well calibrated THEMIS data and a latitude constraint of plus and minus 60 degrees. Approximately 700 framelets were identified as containing bedrock. These strict constraints, as well as individual inspection, were made in order to ensure that there were no false positive identifications. Other exposures of bedrock are probable as global surface coverage with THEMIS is not 100 percent complete. Bedrock exposures were associated with 3 main morphologies. The most abundant type, with more than 600 instances of bedrock, was valley and crater walls. This bedrock may have been exposed from mass wasting or more recent impacts. Many exposures of crater floor bedrock were also observed, which may be due to impact melts. There were fewer exposures of this type, with approximately 70 instances identified. The least common type identified was plains bedrock, which is not associated with valley and crater walls or crater floors. There were approximately 45 instances identified with this type of bedrock. The data has also compared with Thermal Emissions Spectrometer albedo and Mars Orbiter Laser Altimeter elevation data to try to identify any possible correlations. THEMIS daytime infrared and visible images, along with Mars Orbiter Camera visible images, have also been used to investigate surface morphologies associated with these exposures of bedrock and better constrain their origin.
DE: 5415 Erosion and weathering
DE: 5418 Heat flow
DE: 5460 Physical properties of materials
DE: 5464 Remote sensing
DE: 5470 Surface materials and properties
SC: Planetary Sciences [P]
MN: Fall Meeting 2005