SIGNIFICANT PROGRESS HAS REVEALED THE CRATERING FLOW FIELD DUE IMPACTS INTO PARTICULATE TARGETS INTO VERY EARLY TIME USING 3D-PARTICLE TRACKING VELOCIMETRY. THIS APPROACH HAS BEEN APPLIED TO VERTICAL AND OBLIQUE IMPACTS AND IS PROVIDING CRITICAL NEW DATA FOR NOT ONLY BENCHMARKING HYDROCODES BUT ALSO UNDERSTANDING MICRO-SCALE PROCESSES. THIS NEW PROPOSAL SEEKS TO BUILD ON THESE RESULTS. OUR GOAL IS TO BETTER UNDERSTAND PROCESSES CONTROLLING THE TRANSITION FROM TRAJECTORY-CONTROLLED TO RADIAL EXCAVATION FOR PARTICULATE TARGETS THROUGH LABORATORY EXPERIMENTS AND MATCHING COMPUTER MODELS. THREE MAJOR TASKS ARE PROPOSED. EACH TASK WILL INCLUDE A COMBINATION OF HYPERVELOCITY EXPERIMENTS AT THE NASA AMES VERTICAL GUN RANGE AND MATCHING HYDROCODE MODELS. (A) CRATER FLOW FIELDS INPARTICULATE TARGETS. THIS TASK WILL COUPLE NEWLY DERIVED EJECTA-VELOCITY DISTRIBUTIONS WITH EJECTED MASS FOR OBLIQUE IMPACTS AND ASSESS THE EVOLUTION OF EARLY-TIME SHOCK COUPLING WITHIN PARTICULATE TARGETS IN DIFFERENT DIRECTIONS. THIS TASK WILL BE ACCOMPLISHED THROUGHEXISTING DATA AND NEW EXPERIMENTS AT THE AVGR THAT WILL INCLUDE NEAR-RIM EJECTA DECAY IN DIFFERENT DIRECTIONS FROM OBLIQUE IMPACTS. (B) EFFECT OF PROJECTILE FAILURE ON CRATER ASYMMETRIES. THE FATE OF THE PROJECTILE INFLUENCES THE EARLIEST STAGES OF CRATER EXCAVATION. THIS TASK ADDRESSES THE MODES OF FAILURE WITHIN THE PROJECTILE AND CONSEQUENCES IN PMMA AND BASALT TARGETS (BOTH PLANAR AND OBLIQUE). ITWILL BE ACCOMPLISHED BY USING HIGH-SPEED CAMERAS AT THE AVGR PROJECTILE/TARGET SECTIONING AND MATCHING MODELS USING CTH. OUR STUDIES WILL INCLUDE APPLICATION TO EXPRESSIONS AT PLANETARY SCALES. (C) EFFECT OF IMPACT ANGLE ON SHOCK COUPLING UNDER ATMOSPHERIC PRESSURE. IMPACTS UNDER AN ATMOSPHERE PROVIDE ANOTHER STRATEGY TO ASSESS EARLY-TIME PROCESSES. THIS TASK WILL USE THE HIGH-SPEED CAMERAS AND PENCIL GAUGES TO MEASURE THE SHOCK ARRIVAL TIMES AND INTENSITIES IN DIFFERENT DIRECTIONS FOR VOLATILE-RICH (E.G. DRY ICE AND DOLOMITE) AND VOLATILE-POOR (E.G. SILICA SAND) TARGETS. THE GOAL IS TO UNDERSTAND THE FRACTION OF ENERGY COUPLED TO AN ATMOSPHERE. THESE EXPERIMENTS ALSO WILL BE COMPARED WITH HYDROCODE MODELS. (D) CONDITIONS AND CONSEQUENCES OF OBLIQUE IMPACTS. THIS LAST TASK WILL USEHIGH-SPEED SPECTROMETERS AND A TUNABLE LASER-INDUCED FLUORESCENCE TO ASSESS HOT AND COOL VAPOR RESPECTIVELY CREATED BY IMPACTS AT DIFFERENT ANGLES AND UNDER DIFFERENT ATMOSPHERIC CONDITIONS. SOME OF THESE EXPERIMENTS WILL BE CONCURRENT WITH THE OTHER TASKS.