HR: 1340h
AN: P13A-0978    [Abstracts]
TI: Tracking seasonal changes in the Martian polar regions.
AU: * Ivanov, A B
EM: anton.ivanov@jpl.nasa.gov
AF: Jet Propulsion Laboratory, MS 168-414 4800 Oak Grove Drive, Pasadena, CA 91109
AB: In this work we use the THermal Emission Imaging System (THEMIS) instrument to analyze seasonal changes of the Martian polar regions. THEMIS instrument is operating onboard of the Mars Odyssey spacecraft and has been acquiring data in Thermal IR and Visible wavelengths since February of 2002. Data now spans one full Martian year. We will concentrate our analysis on differences observed by THEMIS in winter/early spring and summer periods in the South Polar Layered Deposits (SPLD) region and illustrate some year to year changes in the North Polar Layered Deposits (NPLD) region. We have successfully obtained a spring time mosaic (VIS subsystem) of South Polar Layered Deposits area ($L_s=170-200$), when it was completely covered by seasonal ice. In order to gain coverage within allocated data volume, images are downsampled to a resolution of 36m/pixel. We were also able to obtain a partial coverage of the summertime SPLD (starting $L_s=300$) at full THEMIS resolution in one color (18m/pixel, 650nm) as well as almost total coverage at 36 m/pixel. In this work we track the process of defrosting of various areas in SPLD region from early spring to summer. Data from the North polar region includes Visible images from two consecutive Martian years, which was taken at 18 and 36 m/pixel resolution. The most interesting phenomena have been so far observed in the SPLD region, during defrosting of the seasonal ice cap. THEMIS Visible images show small variations in the albedo of the $CO_2$ ice covering SPLD. We will speculate on kinds of physical processes responsible for observed variations in albedo. Observations of the $CO_2$ ice cover in the North are problematic due to presence of the north polar hood. However, we still have some examples of the ice-covered terrain in the NPLD region. Boundaries of regional storms are evident in the images. Analysis of polar visible images is often aided by unique high resolution (100m/pixel) Thermal IR images, taken simultaneously with the Visible images. THEMIS platform is an ideal tool for observing seasonal and yearly changes due to 2 hour sun-synchronous polar orbit and consistent performance of the instrument.
DE: 5462 Polar regions
DE: 5464 Remote sensing
DE: 5470 Surface materials and properties
DE: 6225 Mars
SC: Planetary Sciences [P]
MN: 2004 AGU Fall Meeting