OBJECTIVES: THE OBJECTIVE OF THE PROPOSED WORK IS TO RECONSTRUCT THE GEOLOGIC HISTORY AND EVOLUTION OF THE EARLY AMAZONIAN HEBRUS VALLES (HV) AND HEPHAESTUS FOSSAE (HF) CHANNEL SYSTEMS LOCATED IN SOUTHERN UTOPIA PLANITIA. OUTFLOW CHANNEL SYSTEMS ON MARS HAVE BEEN LARGELY INTERPRETED AS RESULTING FROM SPORADIC BUT INTENSE EPISODES OF LIQUID WATER FLOW AND THE HV AND HF SYSTEMS ARE UNIQUE AMONG THESE DUE TO THEIR WELL-PRESERVED STATE AND RELATIVELY RECENT ACTIVITY. GEOLOGIC EVIDENCE IN THE HV-HF REGION POINTS TO A WATER-RICH HABITABLE PAST ENVIRONMENT CHARACTERIZED BY MULTIPLE EPISODES OF MELTING AND LIQUID WATER FLOW YET LITTLE IS KNOWN ABOUT THEIR HISTORY AND THIS REPRESENTS A SIGNIFICANT GAP IN OUR UNDERSTANDING OF GEOLOGIC PROCESSES OCCURRING ON MARS IN THE AMAZONIAN PERIOD. WE DELINEATE FUNDAMENTAL QUESTIONS THAT WILL GUIDE OUR RESEARCH TASKS: HOW DID THE HV-HF FLOWS ORIGINATE? HOW MANY EPISODES OF FLOW OCCURRED? WHAT WAS THEIR TIMING THEIR ROLE IN THE MORPHOLOGICAL EVOLUTION OF HV-HF AND WHAT WAS THE FATE OF SEDIMENTS TRANSPORTED BY THE FLOWS? WHAT ARE THE CURRENT SUBSURFACE STRUCTURE AND COMPOSITION OF GEOLOGIC UNITS IN HV-HF? WHAT WAS THE FATE OF THE WATER? METHODS: WE WILL MEET OUR OBJECTIVES WITH AN INTEGRATED ANALYSIS OF DIVERSE COMPLEMENTARY DATASETS INCLUDING RADAR SOUNDING AND HIGH-RESOLUTION VISIBLE IMAGERY AND STEREO-DERIVED DIGITAL TERRAIN MODELS. EXTENSIVE COVERAGE IS AVAILABLE ARCHIVED IN THE NASA PDS MORE THAN 30 DAYS PRIOR TO THE MDAP DUE DATE. WE WILL FIRST CHARACTERIZE THE GEOLOGIC UNITS IN WHICH THE CHANNELS EXTEND. THIS WILL BE ACCOMPLISHED BY IDENTIFYING AND CHARACTERIZING GEOLOGIC UNITS IN TERMS OF THEIR NATURE AND LATERAL EXTENT IN A NEW DETAILED 1:800 000 SCALE GEOLOGIC MAP. THEN WE WILL CONSTRUCT A 1:200 000 SCALE MAP OF GEOLOGIC FACIES DIAGNOSTIC OF LAVA FLOW MAGMATIC INTRUSION COLLAPSE AND OUTFLOW CHANNEL EROSION OUTFLOW DEPOSIT AND POST-OUTFLOW RESURFACING. USING RADAR SUBSURFACE MAPPING WE WILL RECONSTRUCT THE SUBSURFACE STRUCTURE STRATIGRAPHY AND COMPOSITION WHILE RADAR STATISTICAL ANALYSIS WILL BE PERFORMED TO OBTAIN QUANTITATIVE MEASUREMENTS OF SURFACE AND NEAR-SUBSURFACE (5-15 M) COMPOSITION STRUCTURE AND RADAR REFLECTIVITY CHARACTERISTICS. STATISTICAL ANALYSIS OF IMPACT CRATER COUNTS WILL PROVIDE A QUANTITATIVE MEASURE OF THE AGE OF GEOLOGIC UNITS AND RESURFACING EVENTS. FINALLY ANALYSIS OF EXCAVATION DEPTH OF IMPACT CRATERS WITH FLUIDIZED EJECTA WILL PROVIDE NEW CONSTRAINTS ON THE DEPTH TO THE ICE TABLE. PROGRAMMATIC SIGNIFICANCE: THE PROPOSED RESEARCH WORK CONSISTS ENTIRELY OF ANALYSIS TASKS BASED ON PUBLICLY AVAILABLE MISSION DATA AND THUS FULFILLS THE MDAP OBJECTIVE TO ENHANCE THE SCIENTIFIC RETURN FROM MISSIONS TO MARS CONDUCTED BY NASA AND OTHER SPACE AGENCIES. THIS WORK ADDRESSES NASA MEPAG SCIENCE GOALS I A1.1 I A1.2 III A1.1 III A1.3 AND III A1.5 BY ESTABLISHING A GEOLOGIC CONTEXT INVESTIGATING THE ROLE AND TIMING OF MAGMA-ICE INTERACTIONS CHARACTERIZING SURFACE AND SUBSURFACE LIQUID WATER OCCURRENCES AND THUS MEASURING POTENTIAL FOR PAST HABITABILITY. GOALS III A2.1 III A2.2 AND A2.3 ARE ADDRESSED BY REVEALING THE NATURE OF GEOLOGIC UNITS AND QUANTITATIVELY CONSTRAINING THEIR ABSOLUTE AGES VIA GEOLOGIC AND FACIES MAPPING AND BY ANALYZING THE CHARACTERISTICS AND DISTRIBUTION OF IMPACT CRATERS. THE SURFACE GEOLOGIC CHARACTERIZATION (E.G. GEOMORPHOLOGY REGIONAL AND LOCAL SLOPES SURFACE COMPOSITION AND TEXTURE VARIABILITY) ADDRESSES GOALS IV-B5.1 AND IV-B5.2 AND WILL CONTRIBUTE TO THE MDAP OBJECTIVE OF CHARACTERIZING POTENTIAL LANDING SITES FOR FUTURE MARS EXPLORATION MISSIONS (E.G. HV).