WE WILL ADDRESS THREE KEY SCIENCE QUESTIONS RELEVANT TO THE FORWARD CONTAMINATION OF ROBOTIC AND HUMAN EXPLORATION ZONES (EZS) ON MARS: 1. HOW ARE MICROORGANISMS REMOVED FROM SPACECRAFT SURFACES BY CLEAR DUST-LADEN AND SAND-LADEN WINDS AND WHAT SPACECRAFT MATERIALS AND CONFIGURATIONS BEST PROTECT AGAINST THIS REMOVAL? 2. HOW QUICKLY WILL BACTERIAL AND FUNGAL SPORES BE INACTIVATED UNDER SIMULATED MARTIAN CONDITIONS? 3. HOW FAR MIGHT VIABLE MICROORGANISMS BE TRANSPORTED BY THE WIND ON MARS? THE FIRST QUESTION WILL BE ADDRESSED WITH THE NASA AMES RESEARCH CENTER'S MARS WIND TUNNEL (MARSWIT) WHICH CAN SIMULATE ASPECTS OF WIND-DRIVEN PARTICLE TRANSPORT AT MARS-LIKE AIR PRESSURES. VARIOUS TYPES OF COUPONS DOPED WITH FLUORESCENT MICROSPHERES (FLMS) COATED WITH SIMULATED EXTRACELLULAR POLYMERIC SUBSTANCES (EPS) TO PRODUCE ADHESION WILL ACT AS PROXIES FOR SPACECRAFT SURFACES CONTAMINATED WITH MICROORGANISMS. THE COUPONS WILL BE PLACED AT VARIOUS POSITIONS ON A RANGE OF MOCK-UP SPACECRAFT COMPONENTS AND SUBJECTED TO AEOLIAN ABRASION. MARSWIT WILL BE RUN AT A RANGE OF WIND SPEEDS AND WITH A RANGE OF DUST AND SAND SIZES AS EROSIONAL AGENTS. THESE EXPERIMENTS WILL EMPIRICALLY DEFINE THE CONDITIONS THAT LEAD TO REMOVAL OF MICROBIAL SURROGATES THEREBY DEFINING THE LIKELIHOOD OF FORWARD CONTAMINATION FROM LANDED SPACECRAFT ON MARS. SPECIFIC EXPERIMENTS WILL UTILIZE INACTIVATED (DEAD) SPORES TO VERIFY THAT THE FLMS ARE MIMICKING MICROBIAL ADHESION AND WIND REMOVAL PROCESSES IN THE MARSWIT TESTS. TO ADDRESS THE SECOND QUESTION WE WILL STUDY THE SURVIVAL OF BACTERIAL AND FUNGAL SPECIES NOT PREVIOUSLY TESTED UNDER SIMULATED MARTIAN CONDITIONS. THE PROPOSED WORK WILL TEST THE SURVIVAL RATES OF 4 BACTERIAL AND 2 FUNGAL SPECIES EXPOSED TO MARS-LIKE CONDITIONS OF SOLAR UV IRRADIATION AIR PRESSURE (10 MBAR) TEMPERATURE (-60 TO +20 DEGREES C) AND A GAS COMPOSITION CONSISTING OF THE TOP 5 GASES IN THE MARTIAN ATMOSPHERE. THE MICROBIAL STRAINS WILL BE SELECTED FROM ISOLATES RECOVERED FROM MARS SPACECRAFT SURFACES PRIOR TO LAUNCH. FOR EXAMPLE B. SAFENSIS (INSIGHT) B. AMYLOLIQUEFACIENS (INSIGHT) AND ACINETOBACTER RADIORESISTENS 50V1 (ODYSSEY) WILL ACT AS NEW SPECIES TESTED FOR SURVIVAL UNDER MARTIAN CONDITIONS. THE FUNGAL SPECIES ASPERGILLUS NIGER AND FUSARIUM OXYSPORUM WILL BE INCLUDED IN THE ASSAYS TO INCLUDE EUKARYA THAT HAVE BEEN IDENTIFIED ON SPACECRAFT SURFACES. THE THIRD QUESTION WILL BE ADDRESSED WITH LARGE-EDDY SIMULATIONS (LES) USING THE MARS REGIONAL ATMOSPHERIC MODELING SYSTEM (MRAMS) A NUMERICAL CLIMATE MODEL CAPABLE OF SIMULATING MICROSCALE ATMOSPHERIC PHENOMENA ON MARS. AEOLIAN TRANSPORT OF MICROORGANISMS WILL BE REPRESENTED IN THE LES AS TRACERS USING SPACECRAFT REMOVAL CONDITIONS DETERMINED FROM MARSWIT TESTS TO PARAMETERIZE A POINT SOURCE IN THE CENTER OF THE LES DOMAIN (E.G. THE RESULT FROM QUESTION #1). AS THEY ARE TRANSPORTED BY THE WIND MICROORGANISM VIABILITY WILL BE DETERMINED BY APPLYING BIOCIDAL KILL KINETICS TO THE TRACERS (E.G. THE RESULT FROM QUESTION #2). LES WILL BE CONDUCTED FOR THREE LOCATIONS ON MARS AT FOUR DIFFERENT SEASONS AND TWO DIFFERENT LOCAL TIMES EACH (I.E. DAYTIME AND NIGHTTIME) IN ORDER TO MODEL A BROAD RANGE OF ENVIRONMENTAL CONDITIONS. RESULTING DATA PRODUCTS FROM THE LES WILL CONSIST OF ISOPLETHS OF MICROBIAL CONCENTRATIONS (I.E. MASS PER UNIT AREA) OVER TIME. THIS WORK WILL PRODUCE THE FIRST BOUNDS ON THE LIKELIHOOD AND DISTANCE OF VIABLE MICROBIAL TRANSPORT ON MARS PROVIDING A RESOURCE FOR FUTURE REASSESSMENTS OF PLANETARY PROTECTION POLICY AND FOR MISSION PLANNERS SEEKING TO AVOID FALSE-POSITIVES WHEN DESIGNING AND PLANNING OPERATIONS FOR INSTRUMENTS TO INVESTIGATE MARTIAN LIFE.