HR: 10:20h
AN: P21C-01    [PDF]
TI: Martian Surface Emissivity and Surface Spectral Units: Results from the Thermal Emission Imaging System
AU: * Bandfield, J L
EM: joshband@asu.edu
AF: Arizona State University, Box 876305, Tempe, AZ 85287-6305 United States
AU: Rogers, D
EM: Deanne.Rogers@asu.edu
AF: Arizona State University, Box 876305, Tempe, AZ 85287-6305 United States
AU: Smith, M D
EM: Michael.D.Smith@nasa.gov
AF: NASA Goddard Space Flight Center, Code 693.0, Greenbelt, MD 20771 United States
AU: Christensen, P R
EM: Phil.Christensen@asu.edu
AF: Arizona State University, Box 876305, Tempe, AZ 85287-6305 United States
AB: A number of atmospheric correction techniques have been developed for use with data returned from the Thermal Emission Imaging System (THEMIS) onboard the Mars Odyssey spacecraft. Three separate algorithms are used for mapping and determining Martian surface mineralogical units. The radiative contribution of atmospheric dust and water ice emission are variable relative to the signal received from surfaces of different temperatures, causing a distortion in relative equivalent emissivity. The atmospheric emission contribution to a THEMIS scene is determined and removed using a training region of constant emissivity, but variable temperature, in a non-linear, least-squares solution. With the removal of atmospheric emission contributions to a scene, the atmospheric correction problem is greatly simplified and only a single multiplicative term is required for each spectral band to solve for surface emissivity. This term can be found using either a training region (typically a dusty surface) or the scene average emissivity determined using lower resolution surface emissivity maps produced from Thermal Emission Spectrometer (TES) data. A third algorithm was developed to produce spectral unit maps using a least-squares fit of spectral endmember shapes to the THEMIS scene surface emissivity. This algorithm produces spectral unit maps and can also be used to account for and correct variable water ice within an image. Initial results are consistent with results from the TES investigation and a limited number of spectral units are apparent including surface dust, basaltic to andesitic compositions, and olivine. Mineralogically unique compositions are not common on Mars at the sub-kilometer scale.
DE: 5410 Composition
DE: 5494 Instruments and techniques
DE: 6225 Mars
SC: Planetary Sciences [P]
MN: 2003 Fall Meeting