OBJECTIVES: THE MARTIAN POLAR CAPS REPRESENT SOME OF THE MOST DYNAMIC OBJECTS ON PRESENT DAY MARS. THEY ARE SIGNIFICANT CONTRIBUTORS TO ATMOSPHERIC DYNAMICS AT THE SEASONAL TIMESCALE AND RECORD THE EVOLUTION OF THE MARTIAN CLIMATE AT LONGER TIMESCALES. THEREFORE DETERMINING THE EVOLUTION OF THE POLAR CAPS OVER TIME IS OF PRIME IMPORTANCE FOR CLIMATE MODELING AND UNDERSTANDING RELATED PROCESSES SUCH AS THE TOTAL PRESSURE CYCLE WHICH IS SIGNIFICANTLY AFFECTED BY POLAR CAP SUBLIMATION. THE SOUTH POLAR RESIDUAL CAP (SPRC) INCLUDES SUBLIMATION PITS THE SO-CALLED SWISS CHEESE TERRAINS. SPRC PITS HAVE BEEN OBSERVED TO GROW WITH TIME AND REPRESENT ONE STAGE OF THE MARTIAN CO2 CYCLE IN WHICH CO2 ICE MASS IS RETURNED TO THE ATMOSPHERE THROUGH SEASONAL SUBLIMATION DURING THE SOUTHERN HEMISPHERE SUMMER. HOWEVER THIS GROWTH HAS NOT BEEN FULLY CHARACTERIZED WITH RESPECT TO TIME GEOGRAPHICAL LOCATION AND RELATED PARAMETERS. OUR GOAL IS TO DETERMINE THE TIME EVOLUTION OF SOUTH POLE RESIDUAL CAP (SPRC) PITS AND THE VOLUME OF CO2 ICE LOST BY SUBLIMATION IN THE MARTIAN SOUTH POLE. OUR OBJECTIVES ARE AS FOLLOW: 1 - DETERMINE THE SIZE EVOLUTION OF THE PITS OVER TIME AND AS A FUNCTION OF GEOGRAPHICAL LOCATION ON THE POLAR CAP 2 - DETERMINE THE CORRESPONDING VOLUMES OF CO2 SUBLIMATED FROM THE SURFACE 3 - EXTRAPOLATE THE PREVIOUS RESULTS TO THE WHOLE SOUTHERN POLAR CAP AND ESTIMATE THE RESULTING INFLUENCE ON THE MARTIAN CLIMATE CYCLE. SCIENTIFIC MANAGEMENT: THE PROPOSED WORK WOULD BE CARRIED OUT OVER THE SPAN OF 3 YEARS AND INVOLVES THREE PRIMARY TASKS: IN TASK 1 WE WILL SURVEY THE SPRC FOR SUBLIMATION PIT LOCATIONS WITH RECURRING FREQUENT IMAGES ACQUIRED BY HIRISE. WE WILL INVESTIGATE THE SUBLIMATION PITS OF INTEREST USING OBJECT-BASED IMAGE ANALYSIS (OBIA) TO IDENTIFY AND MEASURE PIT AREAS WHILE SYSTEMATICALLY CALCULATING GROWTH RATES IN TERMS OF AREA CHANGE. THE OBIA APPROACH WILL INCLUDE CREATING TRIMBLE ECOGNITION RULESETS ALLOWING THE PIT SHAPES TO BE EFFICIENTLY EXTRACTED FROM THE HIRISE IMAGES. THE RESULTS OF THE OBIA WILL BE COMPARED WITH PREVIOUS MANUALLY CALCULATED PIT MEASUREMENTS. THE CONCLUSION OF THIS STEP WILL BE TO DETERMINE THE EVOLUTION OF THE PIT SURFACE AREA AS A FUNCTION OF TIME AND GEOGRAPHICAL LOCATION ON THE SOUTH POLAR CAP. IN TASK 2 WE WILL DETERMINE THE VOLUME OF CO2 ICE LOST THROUGH LOCAL SUBLIMATION BY CREATING DIGITAL TERRAIN MODELS (DTMS) OF LOCATIONS ACROSS THE SPRC FOR WHICH HIRISE STEREO-PAIR IMAGES ARE AVAILABLE. DTMS WILL ALSO BE CREATED USING CONTEXT CAMERA (CTX) IMAGES TO ASSESS VOLUME LOSS THROUGH TIME AT A COARSER RESOLUTION OVER LARGER AREAS TO GAIN FULL SPRC COVERAGE. DTMS WILL BE CREATED USING ESTABLISHED WORKFLOWS WITHIN THE NASA AMES STEREO PIPELINE PAIRED WITH THE USGS INTEGRATED SOFTWARE FOR IMAGERS AND SPECTROMETERS (ISIS 3) . FINALLY IN TASK 3 WE WILL QUANTIFY THE CO2 ICE LOST THROUGH SUBLIMATION ON THE CAP BY EXTRAPOLATING AND VALIDATING DATA COLLECTED IN TASKS 2 AND 3 TO LOCATIONS THAT LACK RECURRING HIRISE IMAGE COVERAGE TO CREATE A MAP OF ESTIMATED CO2 ICE LOSS THROUGH TIME FOR THE ENTIRE SPRC. WE WILL THEN COMPARE THE RESULTING ESTIMATES TO VARIATIONS IN OTHER DATASETS AND PARTICULARLY THE SEASONAL PRESSURE CHANGES. RELEVANCE: THIS WORK IS RELEVANT TO NASA S MARS DATA ANALYSIS PROGRAM BECAUSE IT UTILIZES IMAGERY ACQUIRED BY THE HIRISE AND CTX CAMERAS ON THE MARS RECONNAISSANCE ORBITER TO INVESTIGATE OUTSTANDING QUESTIONS ABOUT SUBLIMATION PITS ON THE SPRC ON MARS. STUDYING HOW THESE CO2 ICE PITS HAVE FORMED AND EVOLVED THROUGH TIME WILL ALSO LEAD TO A BETTER UNDERSTANDING OF THE RECENT HISTORY OF THE SPRC AND THE CO2 ICE CYCLE ON MARS.