SCIENCE GOALS AND OBJECTIVES: THIS PROPOSAL IS TO OPTIMIZE THE PROCEDURE FOR PREPARATION OF MACROSCOPIC SAMPLES OF CO2 ICE TO ENABLE MEASUREMENTS OF ITS MECHANICAL PROPERTIES THAT IN TURN WILL ALLOW US TO BETTER UNDERSTAND THE ROLE OF CO2 ICE IN DRIVING GEOLOGICAL ACTIVITY ON MARS AND ON OTHER SOLAR SYSTEM BODIES. IN THIS SHORT PROJECT WE FOCUS ON SAMPLE PREPARATION BECAUSE MACROSCOPIC CO2 ICE SAMPLES (ON CENTIMETER SCALE AND LARGER) WITH QUALITY ACCEPTABLE FOR MECHANICAL PROPERTIES TESTING WERE NOT YET ACQUIRED IN EXPERIMENTAL SETTINGS. OUR INVESTIGATION WILL ENABLE FUTURE FOLLOW-UP TESTING INCLUDING MECHANICAL AND THERMAL MEASUREMENTS OF SUCH SAMPLES. CO2 ICE IS THE MAIN CONSTITUENT OF SEASONAL POLAR CAPS ON MARS AND IS PRESENT IN COMETARY AND ICY SATELLITES SURFACES. VERY LIMITED MEASUREMENT DATA ON MECHANICAL PROPERTIES OF CO2 ICE CURRENTLY EXIST AND IT ONLY COVERS THE DUCTILE REGIME OF THE MATERIAL BEHAVIOR. REMOTE SENSING INSTRUMENTS PROVIDE WIDE RANGE OF OBSERVATION DATA ON PRESENT-DAY ACTIVITY RELATED TO CO2 ICE AND SEVERAL NUMERICAL MODELS ATTEMPT TO EXPLAIN THE OBSERVED SEASONAL PHENOMENA ON MARS. IN THE PRESENT SHAPE THE HIGHEST UNCERTAINTY OF THESE MODELS COMES FROM THE ABSENCE OF RELIABLE MEASUREMENTS OF PHYSICAL PROPERTIES OF CO2 ICE. METHODOLOGY: WE PROPOSE TO STUDY PHYSICAL PROPERTIES OF CO2 ICE USING JPL ICE PHYSICS LABORATORY. THE LABORATORY EQUIPMENT PROVIDES THE POSSIBILITY TO CREATE AND CHARACTERIZE MACROSCOPIC CO2 ICE SAMPLES. WE WILL DEVELOP AND OPTIMIZE SAMPLE PREPARATION AND CHARACTERIZATION TECHNIQUES TO ASSURE CONSISTENT SAMPLE QUALITY ACCEPTABLE FOR MECHANICAL TESTING AND PARTICULARLY MEASUREMENTS OF THE YIELD STRENGTH YOUNG'S MODULUS AND POISSON'S RATIO. WE AIM TO CREATE A FOUNDATION FOR EXPLORATION OF THE BEHAVIOR OF CO2 ICE UNDER MECHANICAL LOAD IN BRITTLE REGIME WHICH HAS NEVER BEEN DONE THUS FAR. WE WILL IMPROVE PREDICTIONS ON TIMING OF MODELED SEASONAL EVENTS TO ENABLE DIRECT COMPARISON WITH SPACECRAFT OBSERVATIONS. RELEVANCE OF THE PROPOSED RESEARCH: THE PROPOSED WORK IS RELEVANT TO THE {SURFACES AND INTERIORS} "EVOLUTION AND MODIFICATION OF SURFACES" TOPIC OF RESEARCH LISTED IN THE SOLAR SYSTEM WORKINGS (SSW) SOLICITATION TEXT: "CHARACTERIZE AND UNDERSTAND THE {..} PHYSICAL FEATURES OF PLANETARY SURFACES {..} AND FLUID INVENTORIES THAT INTERACT WITH THE SURFACE (INCLUDING {..} CRYOSPHERES {...} DEVELOP THEORETICAL AND EXPERIMENTAL BASES FOR UNDERSTANDING THESE FEATURES IN THE CONTEXT OF THE VARYING CONDITIONS THROUGH TIME AFTER FORMATION." IN GENERAL BY MEASURING PHYSICAL PROPERTIES OF CO2 WE INCREASE THE KNOWLEDGE BASE ON THE BASIC PROPERTIES OF THE MATERIALS PRESENT IN SOLAR SYSTEM.