A MAJOR MOTIVATION FOR THE EXPLORATION OF MARS IS THE SEARCH FOR EXTANT LIFE PAST OR PRESENT. THE IDENTIFICATION OF INDIGENOUS BIOLOGICAL MATERIAL OR LIFE ON MARS REQUIRES REASONABLY EXCLUDING THE POSSIBILITY THAT THE SAMPLE IN QUESTION IS OF TERRESTRIAL ORIGIN (I.E. THE FORWARD CONTAMINATION PROBLEM). ALTHOUGH PLANETARY PROTECTION POLICIES ARE IN PLACE TO LIMIT THE BIOLOGICAL LOAD ON SPACECRAFT THAT ENTER THE MARS SYSTEM IT IS NOT POSSIBLE TO COMPLETELY STERILIZE HARDWARE; EVERY SPACECRAFT THAT GOES TO MARS CARRIES SOME AMOUNT OF ORGANIC AND BIOLOGICAL MATERIAL. GIVEN THAT BIOLOGICALLY CONTAMINATED HARDWARE (AND EVENTUALLY PEOPLE) WILL CONTINUE TO GO TO MARS IT IS IMPORTANT TO UNDERSTAND UNDER WHAT CONDITIONS CONTAMINANTS CAN BE MOBILIZED AND TRANSPORTED. IT IS ALSO IMPORTANT TO UNDERSTAND TO WHERE THE CONTAMINANTS MIGHT BE TRANSPORTED WITH PARTICULAR ATTENTION TO THE LOCATION OF KNOWN "SPECIAL REGIONS". CONSEQUENTLY THE GOALS OF THE PROPOSED EFFORT ARE TWO-FOLD: GOAL 1: MATURE AND DEMONSTRATE AT THREE HIGH-PRIORITY EXPLORATION LOCATIONS AN END-TO-END MODELING SYSTEM THAT PREDICTS THE REGIONAL TRANSPORT FATE OF CONTAMINANTS. GOAL 2: IDENTIFY OPTIMALLY PROTECTIVE LANDING SITE LOCATIONS THAT MINIMIZE TRANSPORT CONTAMINATION OF NEARBY SPECIAL REGIONS OR OTHER PLACES OF INTEREST. THE ATTAINMENT OF THESE GOALS REQUIRES ACHIEVEMENT OF THE FOLLOWING OBJECTIVES: OBJECTIVE 1: DEVELOP A CONTAMINANT MOBILIZATION PARAMETERIZATION BASED ON EXISTING DUST/SAND LIFTING PHYSICS AND ADDITIONAL PHYSICAL CONSTRAINTS AND CONSIDERATIONS. OBJECTIVE 2: UTILIZE EXISTING MARS MODELING CAPABILITIES AND ADAPT EXISTING TERRESTRIAL TRANSPORT MODELS TO MARS TO PREDICT THE REGIONAL DISPERSION AND TRANSPORT OF CONTAMINANTS. OBJECTIVE 3: EMPLOY BACK-TRAJECTORY CALCULATIONS TO IDENTIFY DOMINANT REGIONAL AIR SOURCES OF SPECIAL REGIONS. THE OVERALL APPROACH IS TO CLOSELY FOLLOW THE METHODS USED TO DETERMINE AND QUANTIFY TRANSPORT OF POLLUTANTS AND HAZARDS ON EARTH. ON EARTH MESOSCALE MODELS ARE COUPLED TO LAGRANGIAN TRANSPORT MODELS TO PREDICT WHERE A RELEASE OF MATERIAL WILL GO AS A FUNCTION OF TIME. THE SAME MODELING TOOLS CAN ALSO BE USED TO IDENTIFY THE LIKELY SOURCE OF CONTAMINANTS FOR A GIVEN LOCATION. FOR MARS MESOSCALE MODEL TOOLS ARE WIDELY AVAILABLE WHILE LAGRANGIAN MODELING TOOLS FOR EARTH CAN BE ADAPTED FOR MARS WITH A MODEST AND WELL UNDERSTOOD EFFORT. FOR THIS PROJECT THE MARS REGIONAL ATMOSPHERIC MODELING SYSTEM (MRAMS) IS SELECTED AS THE MESOSCALE MODEL AND HYSPLIT IS SELECTED AS THE LAGRANGIAN MODEL. AT THE COMPLETION OF THIS PROJECT AN ATMOSPHERIC TRANSPORT MODELING SYSTEM WILL BE DEMONSTRATED AT THREE LOCATIONS OF HIGH-PRIORITY INTEREST TO THE MARS EXPLORATION PROGRAM (MEP). THE PLANETARY PROTECTION RESEARCH PROGRAM (PPRP) SPECIFICALLY SOLICITS PROPOSALS THAT "MODEL PLANETARY ENVIRONMENTAL CONDITIONS AND TRANSPORT PROCESSES THAT COULD PERMIT MOBILIZATION OF SPACECRAFT-ASSOCIATED CONTAMINANTS TO LOCATIONS IN WHICH EARTH ORGANISMS MIGHT THRIVE FOR EXAMPLE MARS SPECIAL REGIONS..." THE PROPOSED WORK DOES EXACTLY THIS. IT ADDRESSES THE MOBILIZATION AND TRANSPORT OF CONTAMINANTS USING SITE-SPECIFIC MODELING TAKING INTO ACCOUNT THE ENVIRONMENTAL CONDITIONS THAT MOBILIZE AND TRANSPORT CONTAMINANTS BUT ALSO FACTORING IN THE ENVIRONMENTAL CONDITIONS THAT LEAD TO THE DESTRUCTION OF CONTAMINANTS AS WELL AS PREDICTING THE MICROCLIMATES THAT MIGHT FOSTER PROPAGATION. CONTAMINATION POTENTIAL IS SITE SPECIFIC. IT IS NOT POSSIBLE TO DETERMINE THE POTENTIAL AT EVERY PLACE FOR ALL TIME. ENVIRONMENT CONDITIONS CHANGE AS A FUNCTION OF TIME AND DAY AND SEASON. FURTHER THE POTENTIAL SOURCE OF CONTAMINATION AND MOBILIZATION POTENTIAL IS LIKELY TO BE MISSION SPECIFIC. THUS IT IS IMPORTANT TO DEVELOP AND DEMONSTRATE THE TOOLS TO INDIVIDUALLY ASSESS SPECIFIC EXPLORATION LANDING SITES ON AN AS NEEDED BASIS. THIS STUDY DOES THAT.